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{{Short description|Effect of a nuclear explosion on electronic equipment}}
{{Hatnote|This article is about the general weapons effect. For other uses, see the more specific topic (for example, [[Electromagnetic forming]]) }}
{{About|nuclear-generated EMP|other types|Electromagnetic pulse}}
{{Use American English|date=September 2024}}


An '''electromagnetic pulse''' (sometimes abbreviated '''EMP''') is a burst of [[electromagnetic radiation]]. The abrupt pulse of electromagnetic radiation usually results from certain types of high energy explosions, especially a [[nuclear explosion]], or from a suddenly fluctuating [[magnetic field]]. The resulting rapidly-changing [[electric fields]] and magnetic fields may couple with electrical/electronic systems to produce damaging current and [[voltage spike|voltage surges]].
A '''nuclear electromagnetic pulse''' ('''nuclear EMP''' or '''NEMP''') is a burst of [[electromagnetic radiation]] created by a [[nuclear explosion]]. The resulting rapidly varying [[electric field|electric]] and [[magnetic field]]s may couple with electrical and electronic systems to produce damaging current and [[voltage surge]]s. The specific characteristics of a particular nuclear EMP event vary according to a number of factors, the most important of which is the [[altitude]] of the detonation.


In military terminology, a nuclear warhead detonated hundreds of kilometers above the Earth's surface is known as a high-altitude electromagnetic pulse ('''HEMP''') device. Effects of a HEMP device depend on a very large number of factors, including the altitude of the detonation, [[nuclear weapons yield|energy yield]], [[gamma ray]] output, interactions with the [[Earth's magnetic field]], and [[electromagnetic shielding]] of targets.
The term "electromagnetic pulse" generally excludes optical (infrared, visible, ultraviolet) and ionizing (such as X-ray and gamma radiation) ranges. In military terminology, a nuclear warhead detonated tens to hundreds of miles above the Earth's surface is known as a high-altitude electromagnetic pulse (HEMP) device. Effects of a HEMP device depend on factors including the altitude of the detonation, [[nuclear weapons yield|energy yield]], [[gamma ray]] output, interactions with the [[Earth's magnetic field]] and [[electromagnetic shielding]] of targets.


==History==
==History==
The fact that an electromagnetic pulse is produced by a nuclear explosion was known since the earliest days of nuclear weapons testing. The magnitude of the EMP and the significance of its effects, however, were not realized for some time.<ref name="science">Broad, William J. "Nuclear Pulse (I): Awakening to the Chaos Factor", Science. 29 May 1981 212: 1009&ndash;1012</ref>
The fact that an electromagnetic pulse is produced by a nuclear explosion was known in the earliest days of nuclear weapons testing. The magnitude of the EMP and the significance of its effects were not immediately realized.<ref name="science">{{cite journal |last1=Broad |first1=William J. |author-link1=William Broad |date=1981-05-29 |title=Nuclear Pulse (I): Awakening to the Chaos Factor |url= |format= |department= |journal=[[Science (journal)|Science]] |language=en |volume=212 |issue=4498 |pages=1009–1012 |eissn=1095-9203 |issn=0036-8075 |jstor=1685472 |pmid=17779963 |bibcode=1981Sci...212.1009B |lccn=17024346 |oclc=1644869 |df=dmy-all |doi=10.1126/science.212.4498.1009}}</ref>


During the [[Trinity (nuclear test)|first United States nuclear test]] on 16 July 1945, electronic equipment was shielded due to [[Enrico Fermi|Enrico Fermi's]] expectation of an electromagnetic pulse from the detonation. The official technical history for that first nuclear test states, "All signal lines were completely shielded, in many cases doubly shielded. In spite of this many records were lost because of spurious pickup at the time of the explosion that paralyzed the recording equipment."<ref>Bainbridge, K.T., ''Trinity'' (Report LA-6300-H), Los Alamos Scientific Laboratory. May 1976. Page 53 [http://www.fas.org/sgp/othergov/doe/lanl/docs1/00317133.pdf]</ref>&nbsp; During British nuclear testing in 1952&ndash;1953 there were instrumentation failures that were attributed to "[[radioflash]]", which was then the British term for EMP.<ref name="baum1">Baum, Carl E., "Reminiscences of High-Power Electromagnetics", IEEE Transactions on Electromagnetic Compatibility. Vol. 49, No. 2. pp. 211&ndash;218. May 2007. [http://www.ece.unm.edu/summa/notes/History/BaumReminiscences.pdf]</ref><ref name="baum2">Baum, Carl E., "From the Electromagnetic Pulse to High-Power Electromagnetics", Proceedings of the IEEE, Vol.80, No. 6, pp. 789&ndash;817. June 1992 [http://www.ece.unm.edu/summa/notes/SDAN/0032.pdf]</ref>
During the [[Trinity (nuclear test)|first United States nuclear test]] on 16 July 1945, electronic equipment was shielded because [[Enrico Fermi]] expected the electromagnetic pulse. The official technical history for that first nuclear test states, "All signal lines were completely shielded, in many cases doubly shielded. In spite of this many records were lost because of spurious [[Current collector|pickup]] at the time of the explosion that paralyzed the recording equipment."<ref>{{cite report |last1=Bainbridge |first1=K. T. |date=May 1976 |title=Trinity |publisher=[[Los Alamos Scientific Laboratory]] |page=53 |docket=LA-6300-H |via=[[Federation of American Scientists]] |df=dmy-all |url=https://sgp.fas.org/othergov/doe/lanl/docs1/00317133.pdf |access-date=2022-08-10 |url-status=live |archive-url=https://web.archive.org/web/20211009002725/https://sgp.fas.org/othergov/doe/lanl/docs1/00317133.pdf |archive-date=2021-10-09}}</ref>{{rp|page=53}} During [[British nuclear tests at Maralinga|British nuclear testing]] in 1952–53, instrumentation failures were attributed to "[[radioflash]]", which was their term for EMP.<ref name="baum1">{{cite journal |last1=Baum |first1=Carl E. |author-link1= |date=May 2007 |title=Reminiscences of High-Power Electromagnetics |journal=[[IEEE Transactions on Electromagnetic Compatibility]] |language=en |volume=49 |issue=2 |pages=211–218 |eissn=1558-187X |issn=0018-9375 |jstor=1685783 |s2cid=22495327 |lccn=sn78000466 |oclc= |df=dmy-all |doi=10.1109/TEMC.2007.897147}}</ref><ref name="baum2">{{cite journal |last1=Baum |first1=Carl E. |author-link1= |date=June 1992 |title=From the electromagnetic pulse to high-power electromagnetics |journal=[[Proceedings of the IEEE]] |language=en |volume=80 |issue=6 |pages=789–817 |issn=0018-9219 |lccn=86645263 |oclc=807623131 |df=dmy-all |doi=10.1109/5.149443}}</ref>


The first openly reported observation of the unique aspects of high-altitude nuclear EMP occurred during the [[helium balloon]]-lofted Yucca nuclear test of the [[Hardtack I]] series on 28 April 1958. In that test, the electric field measurements from the 1.7 kiloton weapon exceeded the range to which the test instruments were adjusted and was estimated to be about five times the limits to which the oscilloscopes were set.
The [[High altitude nuclear explosion|high altitude nuclear tests]] of 1962, as described below, increased the awareness of EMP beyond the original small population of nuclear weapons scientists and engineers. The larger scientific community became aware of the significance of the EMP problem after a series of three articles were published about nuclear electromagnetic pulse in 1981 by [[William Broad|William J. Broad]] in the weekly publication [[Science (journal)|''Science'']].<ref name="science"/><ref>Broad, William J. "Nuclear Pulse (II): Ensuring Delivery of the Doomsday Signal", Science. 5 June 1981 212: 1116&ndash;1120</ref><ref>Broad, William J. "Nuclear Pulse (III): Playing a Wild Card", Science. 12 June 1981 212: 1248&ndash;1251</ref>
The Yucca EMP was initially positive-going, whereas low-altitude bursts were negative-going pulses. Also, the [[polarization (waves)|polarization]] of the Yucca EMP signal was horizontal, whereas low-altitude nuclear EMP was vertically polarized. In spite of these many differences, the unique EMP results were dismissed as a possible [[wave propagation]] anomaly.<ref name="yucca">Defense Atomic Support Agency. 23 September 1959. [http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA369152 "Operation Hardtack Preliminary Report. Technical Summary of Military Effects] {{Webarchive|url=https://web.archive.org/web/20130620061706/http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA369152 |date=2013-06-20}}. Report ADA369152". pp. 346–350.</ref>

The [[high-altitude nuclear explosion|high-altitude nuclear tests]] of 1962, as discussed below, confirmed the unique results of the Yucca high-altitude test and increased the awareness of high-altitude nuclear EMP beyond the original group of defense scientists. The larger scientific community became aware of the significance of the EMP problem after a three-article series on nuclear EMP was published in 1981 by [[William J. Broad]] in ''[[Science (journal)|Science]]''.<ref name="science"/><ref>{{cite journal |last1=Broad |first1=William J. |author-link1=William Broad |date=1981-06-05 |title=Nuclear Pulse (II): Ensuring Delivery of the Doomsday Signal |url= |format= |department= |journal=[[Science (journal)|Science]] |language=en |volume=212 |issue=4499 |pages=1116–1120 |eissn=1095-9203 |issn=0036-8075 |jstor=1685373 |pmid=17815204 |bibcode=1981Sci...212.1116B |lccn=17024346 |oclc=1644869 |df=dmy-all |doi=10.1126/science.212.4499.1116}}</ref><ref>{{cite journal |last1=Broad |first1=William J. |author-link1=William Broad |date=1981-06-12 |title=Nuclear Pulse (III): Playing a Wild Card |url= |format= |department= |journal=[[Science (journal)|Science]] |language=en |volume=212 |issue=4500 |pages=1248–1251 |eissn=1095-9203 |issn=0036-8075 |jstor=1685783 |pmid=17738820 |bibcode=1981Sci...212.1248B |lccn=17024346 |oclc=1644869 |df=dmy-all |doi=10.1126/science.212.4500.1248}}</ref>


===Starfish Prime===
===Starfish Prime===
{{Main|Starfish Prime}}
{{Main article|Starfish Prime}}
In July 1962, a 1.44 [[Nuclear weapon yield|megaton]] (6.0 PJ) United States nuclear test in space, {{convert|400|km}} above the mid-Pacific Ocean, called the [[Starfish Prime]] test, demonstrated to nuclear scientists that the magnitude and effects of a [[high altitude nuclear explosion]] were much larger than had been previously calculated. Starfish Prime also made those effects known to the public by causing electrical damage in Hawaii, about {{convert|1445|km}} away from the detonation point, knocking out about 300 streetlights, setting off numerous burglar alarms and damaging a telephone company microwave link.<ref>Vittitoe, Charles N., "Did High-Altitude EMP Cause the Hawaiian Streetlight Incident?" Sandia National Laboratories. June 1989. [http://www.ece.unm.edu/summa/notes/SDAN/0031.pdf]</ref>
In July 1962, the US carried out the [[Starfish Prime]] test, exploding a {{convert|1.44|MtonTNT|abbr=on|lk=on}} bomb {{convert|400|km|mi ft|||}} above the mid-Pacific Ocean. This demonstrated that the effects of a [[high-altitude nuclear explosion]] were much larger than had been previously calculated. Starfish Prime made those effects known to the public by causing electrical damage in [[Hawaii]], about {{convert|1445|km}} away from the detonation point, disabling approximately 300 streetlights, triggering numerous burglar alarms and damaging a microwave link.<ref name="vittitoe">{{cite report |last1=Vittitoe |first1=Charles N. |date=1989-06-01 |title=Did High-Altitude EMP Cause the Hawaiian Streetlight Incident? |publisher=[[Sandia National Laboratories]] |df=dmy-all |url=https://ece-research.unm.edu/summa/notes/SDAN/0031.pdf |access-date=2020-09-15 |url-status=live |archive-url=https://web.archive.org/web/20200823035223/http://ece-research.unm.edu/summa/notes/SDAN/0031.pdf |archive-date=2020-08-23}}</ref>


Starfish Prime was the first successful test in the series of United States high-altitude nuclear tests in 1962 known as [[Operation Fishbowl]]. The subsequent Operation Fishbowl tests gathered more data on the high-altitude EMP phenomenon.
Starfish Prime was the first success in the series of United States high-altitude nuclear tests in 1962 known as [[Operation Fishbowl]]. Subsequent tests gathered more data on the high-altitude EMP phenomenon.


The [[Operation Fishbowl|''Bluegill Triple Prime'']] and [[Operation Fishbowl|''Kingfish'']] high-altitude nuclear tests of October and November 1962 in Operation Fishbowl finally provided electromagnetic pulse data that was clear enough to enable physicists to accurately identify the physical mechanisms that were producing the electromagnetic pulses.<ref name="nbcreport">Longmire, Conrad L., "Fifty Odd Years of EMP", NBC Report, Fall/Winter, 2004. pp. 47-51. U.S. Army Nuclear and Chemical Agency [https://www.cbrniac.apgea.army.mil/Products/Documents/USANCA%20Journals%20and%20Reports/NBC_Report_Fall_Winter04.pdf]</ref>
The [[Operation Fishbowl#Bluegill Triple Prime|Bluegill Triple Prime]] and [[Operation Fishbowl#Kingfish|Kingfish]] high-altitude nuclear tests of October and November 1962 in Operation Fishbowl provided data that was clear enough to enable physicists to accurately identify the physical mechanisms behind the electromagnetic pulses.<ref name="nbcreport">{{cite journal |last1=Longmire |first1=Conrad L. |author-link1=Conrad Longmire |journal=NBC Report |date=2004 |pages=47–51 |publisher=U.S. Army Nuclear and Chemical Agency |issue=Fall/Winter |title=Fifty Odd Years of EMP |url=https://www.futurescience.com/emp/NBC_Report_Fall_Winter04.pdf}}</ref>


The EMP damage of the Starfish Prime test was quickly repaired because of the ruggedness (compared to today)<ref name="tn353">[http://www.ece.unm.edu/summa/notes/TheoreticalPDFs/TN353.pdf Theoretical Notes - Note 353 - March 1985 - EMP on Honolulu from the Starfish Event*] Conrad L. Longmire - Mission Research Corporation</ref> of the electrical and electronic infrastructure of Hawaii in 1962.
The EMP damage of the Starfish Prime test was quickly repaired due, in part, to the fact that the EMP over Hawaii was relatively weak compared to what could be produced with a more intense pulse, and in part due to the relative ruggedness (compared to today)<ref>{{cite thesis |last=Reardon |page=53 |first=Patrick J. |date=2014 |location=Fort Leavenworth |title=The Effect of an Electromagnetic Pulse Strike on the Transportation Infrastructure of Kansas City |type=Master's Thesis |chapter=Case Study: Operation Starfish Prime Introduction & EMP analysis |publisher=U.S. Army Command & General Staff College |chapter-url=https://www.hsdl.org/c/view?docid=762798 |access-date=2019-07-26}}</ref> of Hawaii's electrical and electronic infrastructure in 1962.<ref name="tn353">{{cite report |docket=Theoretical Notes Note 353 |date=March 1985 |title=EMP on Honolulu from the Starfish Event |last1=Longmire |first1=Conrad L. |author-link1=Conrad Longmire |publisher=Mission Research Corporation |via=[[University of New Mexico]] |url=https://ece-research.unm.edu/summa/notes/TheoreticalPDFs/TN353.pdf}}</ref>


The relatively small magnitude of the Starfish Prime EMP in Hawaii (about 5600 volts/metre) and the relatively small amount of damage done (for example, only 1 to 3 percent of streetlights extinguished)<ref>Rabinowitz, Mario (1987) "Effect of the Fast Nuclear Electromagnetic Pulse on the Electric Power Grid Nationwide: A Different View". IEEE Trans. Power Delivery, PWRD-2, 1199&ndash;1222 {{arxiv|physics/0307127}}</ref> led some scientists to believe, in the early days of EMP research, that the problem might not be as significant as was later realized. Newer calculations<ref name="tn353"/> showed that if the Starfish Prime warhead had been detonated over the northern continental United States, the magnitude of the EMP would have been much larger (22 to 30 kilovolts/metre) because of the greater strength of the [[Earth's magnetic field]] over the United States, as well as the different orientation of the Earth's magnetic field at high latitudes. These new calculations, combined with the accelerating reliance on EMP-sensitive microelectronics, heightened awareness that the EMP threat could be a very significant problem.
The relatively small magnitude of the Starfish Prime EMP in Hawaii (about 5.6 kilovolts/metre) and the relatively small amount of damage (for example, only 1% to 3% of streetlights extinguished)<ref>{{cite journal |last1=Rabinowitz |first1=Mario |date=October 1987 |title=Effect of the Fast Nuclear Electromagnetic Pulse on the Electric Power Grid Nationwide: A Different View |journal=IEEE Transactions on Power Delivery |volume=2 |issue=4 |pages=1199&ndash;1222 |arxiv=physics/0307127 |s2cid=37367992 |issn=1937-4208 |lccn=86643860 |oclc=1236229960 |doi=10.1109/TPWRD.1987.4308243}}</ref> led some scientists to believe, in the early days of EMP research, that the problem might not be significant. Later calculations<ref name="tn353"/> showed that if the Starfish Prime warhead had been detonated over the northern continental United States, the magnitude of the EMP would have been much larger (22 to 30 kV/m) because of the greater strength of the [[Earth's magnetic field]] over the United States, as well as its different orientation at high latitudes. These calculations, combined with the accelerating reliance on EMP-sensitive microelectronics, heightened awareness that EMP could be a significant problem.<ref>{{cite book |editor-first=Mark |editor-last=Cancian |date=2018 |title=Project on Nuclear Issues: A Collection of Papers from the 2017 Conference Series & Nuclear Scholars Initiative (CSIS Reports) |page=24 |publisher=Center for Strategic & International Studies |isbn=978-1442280557 |url=https://books.google.com/books?id=msVNDwAAQBAJ&pg=PA24 |access-date=2019-07-26}}</ref>


===Soviet Test 184===
===Soviet Test 184===
{{Main|The K Project}}
{{Main article|Soviet Project K nuclear tests}}
In 1962, the [[Soviet Union]] also performed a series of three EMP-producing nuclear tests in space over Kazakhstan, which were the last in the series called "[[The K Project]]".<ref>Zak, Anatoly "The K Project: Soviet Nuclear Tests in Space", The Nonproliferation Review, Volume 13, Issue 1 March 2006 , pp. 143-150 [http://www.informaworld.com/smpp/content~db=all?content=10.1080/10736700600861418]</ref> Although these weapons were much smaller (300 [[Nuclear weapon yield|kiloton]] or 1.3 PJ) than the Starfish Prime test, since those tests were done over a populated large land mass (and also at a location where the [[Earth's magnetic field]] was greater), the damage caused by the resulting EMP was reportedly much greater than in the [[Starfish Prime]] nuclear test. The [[geomagnetic storm]]–like E3 pulse (from the test designated as "Test 184") even induced an electric current surge in a long underground power line that caused a fire in the power plant in the city of [[Karaganda]]. After the collapse of the Soviet Union, the level of this damage was communicated informally to scientists in the United States.<ref>[http://nuclearweaponarchive.org/News/Loborev.txt SUBJECT: US-Russian meeting – HEMP effects on national power grid & telecommunications] From: Howard Seguine, 17 Feb. 1995 MEMORANDUM FOR RECORD</ref>&nbsp; Formal documentation of some of the EMP damage in Kazakhstan exists<ref>Greetsai, Vasily N., et al. "Response of Long Lines to Nuclear High-Altitude Electromagnetic Pulse (HEMP)" IEEE Transactions on Electromagnetic Compatibility, Vol. 40, No. 4, November 1998, [http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?tp=&arnumber=736221&isnumber=15868]</ref><ref name="euroem">Loborev, Vladimir M. "Up to Date State of the NEMP Problems and Topical Research Directions", Electromagnetic Environments and Consequences: Proceedings of the EUROEM 94 International Symposium, Bordeaux, France, 30 May – 3 June 1994, pp. 15&ndash;21</ref> but is still sparse in the [[Open science|open scientific]] literature.
In 1962, the [[Soviet Union]] performed three EMP-producing nuclear tests in space over Kazakhstan, the last in the "[[Soviet Project K nuclear tests]]".<ref>{{cite journal |last1=Zak |first1=Anatoly |title=The K Project: Soviet Nuclear Tests in Space |journal=The Nonproliferation Review |volume=13 |issue=1 |date=March 2006 |pages=143–150 |s2cid=144900794 |issn=1746-1766 |lccn=2008233174 |oclc=173322619 |doi=10.1080/10736700600861418}}</ref> Although these weapons were much smaller (300 [[nuclear weapon yield|kiloton]]) than the Starfish Prime test, they were over a populated, large landmass and at a location where the Earth's magnetic field was greater. The damage caused by the resulting EMP was reportedly much greater than in Starfish Prime. The [[geomagnetic storm]]–like E3 pulse from Test 184 induced a current surge in a long underground [[power line]] that caused a fire in the [[power plant]] in the city of [[Karaganda]].{{citation needed|date=August 2016}}


After the [[dissolution of the Soviet Union]], the level of this damage was communicated informally to US scientists.<ref>{{cite web |title=Subject: US-Russian meeting – HEMP effects on national power grid & telecommunications |last1=Seguine |first1=Howard |date=1995-02-17 |website=[[Office of the Secretary of Defense]] |via=The Nuclear Weapon Archive |df=dmy-all |url=https://nuclearweaponarchive.org/News/Loborev.txt |url-status=live |archive-url=https://web.archive.org/web/20220627232815/http://nuclearweaponarchive.org/News/Loborev.txt |archive-date=2022-06-27}}</ref> For a few years US and Russian scientists collaborated on the HEMP phenomenon. Funding was secured to enable Russian scientists to report on some of the Soviet EMP results in international scientific journals.<ref name="combatwmd">{{cite journal |last1=Pfeffer |first1=Robert |last2=Shaeffer |first2=D. Lynn |journal=Combating WMD Journal |publisher=United States Army Nuclear and CWMD Agency (USANCA) |date=2009 |issue=3 |pages=33–38 |title=A Russian Assessment of Several USSR and US HEMP Tests |via=[[Defense Technical Information Center]] |df=dmy-all |url=https://apps.dtic.mil/dtic/tr/fulltext/u2/a495245.pdf |url-status=live |archive-url=https://web.archive.org/web/20131230233322/http://www.dtic.mil/dtic/tr/fulltext/u2/a495245.pdf |archive-date=2013-12-30}}</ref> As a result, formal documentation of some of the EMP damage in Kazakhstan exists, although it is still sparse in the [[open science|open-scientific]] literature.<ref name="greetsai">{{cite journal |last1=Greetsai |first1=V. N. |last2=Kozlovsky |first2=A. H. |last3=Kuvshinnikov |first3=V. M. |last4=Loborev |first4=V. M. |last5=Parfenov |first5=Y. V. |last6=Tarasov |first6=O. A. |last7=Zdoukhov |first7=L. N. |date=November 1998 |title=Response of long lines to nuclear high-altitude electromagnetic pulse (HEMP) |journal=[[IEEE Transactions on Electromagnetic Compatibility]] |language=en |volume=40 |issue=4 |pages=348–354 |eissn=1558-187X |issn=0018-9375 |lccn=sn78000466 |oclc= |df=dmy-all |doi=10.1109/15.736221}}</ref><ref name="euroem">{{cite conference |last1=Loborev |first1=Vladimir M. |title=Up to Date State of the NEMP Problems and Topical Research Directions |conference=Electromagnetic Environments and Consequences: Proceedings of the EUROEM 94 International Symposium |location=Bordeaux, France |date=1994-05-30 |pages=15–21 |df=dmy-all}}</ref>
===Non-nuclear history===


For one of the K Project tests, Soviet scientists instrumented a {{convert|570|km|mi|adj=on|sp=us}} section of telephone line in the area that they expected to be affected by the pulse. The monitored telephone line was divided into sub-lines of {{convert|40|to|80|km}} in length, separated by [[repeater]]s. Each sub-line was protected by [[fuse (electrical)|fuses]] and by [[gas-filled tube|gas-filled]] [[overvoltage]] protectors. The EMP from the 22 October (K-3) nuclear test (also known as Test 184) blew all of the fuses and destroyed all of the overvoltage protectors in all of the sub-lines.<ref name="greetsai"/>
The concept of the [[explosively pumped flux compression generator]] for generating a non-nuclear electromagnetic pulse was conceived as early as 1951 by [[Andrei Sakharov]] in the Soviet Union,<ref name="fcg">Stephen Younger, et al. "Scientific Collaborations Between Los Alamos and Arzamas-16 Using Explosive-Driven Flux Compression Generators" Los Alamos Science, No. 24, pp. 48&ndash;71, 1996 [http://www.fas.org/sgp/othergov/doe/lanl/pubs/00326620.pdf] Retrieved 2009-24-10</ref> but nations have usually kept their most recent work on non-nuclear EMP highly classified until the technology was old enough for similar ideas to be conceived by physicists in other nations.
Published reports, including a 1998 IEEE article,<ref name="greetsai"/> have stated that there were significant problems with ceramic insulators on overhead electrical power lines during the tests. A 2010 technical report written for [[Oak Ridge National Laboratory]] stated that "Power line insulators were damaged, resulting in a short circuit on the line and some lines detaching from the poles and falling to the ground".<ref name="ORNL-3">{{cite report |last1=Savage |first1=Edward |last2=Gilbert |first2=James |last3=Radasky |first3=William |docket=Meta-R-320 |title=The Early-Time (E1) High-Altitude Electromagnetic Pulse (HEMP) and Its Impact on the U.S. Power Grid |section=Section 3 – A Brief History of E1 HEMP Experiences |date=January 2010 |publisher=Metatech Corporation for Oak Ridge National Laboratories |df=dmy-all |url=https://www.ferc.gov/industries/electric/indus-act/reliability/cybersecurity/ferc_meta-r-320.pdf |access-date=2017-09-08 |url-status=dead |archive-url=https://web.archive.org/web/20170520145500/https://www.ferc.gov/industries/electric/indus-act/reliability/cybersecurity/ferc_meta-r-320.pdf |archive-date=2017-05-20}}</ref>


==Characteristics of nuclear EMP==
==Characteristics==
The case of a '''nuclear electromagnetic pulse''' differs from other kinds of electromagnetic pulse (EMP) in being a complex electromagnetic multi-pulse. The complex multi-pulse is usually described in terms of three components, and these three components have been defined as such by the international standards commission called the [[International Electrotechnical Commission]] (IEC).<ref>[http://www.iec.ch/cgi-bin/procgi.pl/www/iecwww.p?wwwlang=E&wwwprog=cat-det.p&wartnum=020728 Electromagnetic compatibility (EMC) - Part 2: Environment - Section 9: Description of HEMP environment - Radiated disturbance. Basic EMC publication], IEC 61000-2-9</ref>
Nuclear EMP is a complex multi-pulse, usually described in terms of three components, as defined by the [[International Electrotechnical Commission]] (IEC).<ref name="iec.ch">{{cite report |date=1996-02-19 |language=en, fr, es |title=Electromagnetic compatibility (EMC) - Part 2: Environment - Section 9: Description of HEMP environment - Radiated disturbance. Basic EMC publication |docket=IEC 61000-2-9:1996 |publisher=[[International Electrotechnical Commission]] |df=dmy-all |url=https://webstore.iec.ch/publication/4141 |url-access=subscription}}</ref>


The three components of nuclear EMP, as defined by the IEC, are called '''E1''', '''E2''' and '''E3'''.
The three components of nuclear EMP, as defined by the IEC, are called "E1", "E2", and "E3".{{r|iec.ch}}{{r|empc}}


The three categories of high-altitude EMP are divided according to the time duration and occurrence of each pulse. E1 is the fastest or "early time" high-altitude EMP. Traditionally, the term "EMP" often refers specifically to this E1 component of high-altitude electromagnetic pulse.<ref name="ORNL-2.4">{{cite report |last1=Savage |first1=Edward |last2=Gilbert |first2=James |last3=Radasky |first3=William |docket=Meta-R-320 |title=The Early-Time (E1) High-Altitude Electromagnetic Pulse (HEMP) and Its Impact on the U.S. Power Grid |section=Section 2.4 – (An Overview of E1 HEMP) - Other Types of EMP |date=January 2010 |publisher=Metatech Corporation for Oak Ridge National Laboratory|df=dmy-all |url=https://www.ferc.gov/industries/electric/indus-act/reliability/cybersecurity/ferc_meta-r-320.pdf |access-date=2017-09-08 |url-status=dead |archive-url=https://web.archive.org/web/20170520145500/https://www.ferc.gov/industries/electric/indus-act/reliability/cybersecurity/ferc_meta-r-320.pdf |archive-date=2017-05-20}}</ref>
===E1===


The E2 and E3 pulses are often further subdivided into additional divisions according to causation. E2 is a much lower intensity "intermediate time" EMP, which is further divided into E2A (scattered gamma EMP) and E2B (neutron gamma EMP).<ref name="ORNL-2.4"/>
The '''E1''' pulse is the very fast component of nuclear EMP. The '''E1''' component is a very brief but intense [[electromagnetic field]] that can quickly induce very high voltages in electrical conductors. The '''E1''' component causes most of its damage by causing electrical [[breakdown voltage]]s to be exceeded. '''E1''' is the component that can destroy computers and communications equipment and it changes too quickly for ordinary lightning protectors to provide effective protection against it.


E3 is a very long-duration "late time" pulse, which is extremely slow in rise and fall times compared to the other components of EMP.<ref name="ORNL-2.4"/> E3 is further divided into E3A (blast wave) and E3B (heave).<ref name="ORNL-2.4"/> E3 is also called [[magnetohydrodynamic]] EMP.<ref name="ORNL-2.4"/>
[[Image:EMP mechanism.GIF|right|333px|thumb|The mechanism for a 400 km high altitude burst EMP: gamma rays hit the atmosphere between 20–40 km altitude, ejecting electrons which are then deflected sideways by the Earth's magnetic field. This makes the electrons radiate EMP over a massive area. Because of the curvature and downward tilt of Earth's magnetic field over the USA, the maximum EMP occurs south of the detonation and the minimum occurs to the north.<ref>U.S. Army White Sands Missile Range, ''Nuclear Environment Survivability''. Report ADA278230. Page D-7. 15 April 1994. [http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA278230&Location=U2&doc=GetTRDoc.pdf]</ref>]]


===E1===
The E1 component is produced when [[gamma radiation]] from the nuclear detonation knocks [[electrons]] out of the atoms in the upper atmosphere. The electrons begin to travel in a generally downward direction at [[Special relativity|relativistic speeds]] (more than 90 percent of the speed of light). In the absence of a magnetic field, this would produce a large pulse of [[electric current]] vertically in the upper atmosphere over the entire affected area. The Earth's magnetic field acts on these electrons to change the direction of electron flow to a right angle to the geomagnetic field. This interaction of the Earth's magnetic field and the downward electron flow produces a very large, but very brief, electromagnetic pulse over the affected area.<ref name="longmire">Longmire, Conrad L. "Justification and Verification of High-Altitude EMP Theory, Part 1" LLNL-9323905, Lawrence Livermore National Laboratory. June 1986 [http://www.ece.unm.edu/summa/notes/TheoreticalPDFs/TN368.pdf] (Retrieved 2010-15-12)</ref>
The E1 pulse is a very fast component of nuclear EMP. E1 is a brief but intense electromagnetic field that induces high voltages in electrical conductors. E1 causes most of its damage by causing electrical [[breakdown voltage]]s to be exceeded. E1 can destroy computers and communications equipment and it changes too quickly (nanoseconds) for ordinary [[surge protector]]s to provide effective protection from it. Fast-acting surge protectors (such as those using [[surge protector#Transient voltage suppression diode|TVS diodes]]) will block the E1 pulse.

[[File:EMP mechanism.png|right|333px|thumb|The mechanism for a {{convert|400|km|mi ft|adj=mid|-high}} burst EMP: gamma rays hit the atmosphere between {{cvt|20-40|km|ft||}} altitude, ejecting electrons which are then deflected sideways by the Earth's magnetic field. This makes the electrons radiate EMP over a large area. Because of the curvature and downward tilt of Earth's magnetic field over the US, the maximum EMP occurs south of the detonation and the minimum occurs to the north.<ref>{{cite report |author=US Army Test and Evaluation Command |publisher=[[White Sands Missile Range|U.S. Army White Sands Missile Range]] |date=1994-04-15 |title=Test Operations Procedure (TOP) 1-2-612, Nuclear Environment Survivability |docket=ADA278230 |page=D-7 |via=[[Defense Technical Information Center]] |df=dmy-all |url=https://apps.dtic.mil/sti/pdfs/ADA278230.pdf |access-date=2022-08-11 |url-status=live |archive-url=https://web.archive.org/web/20210818180829/https://apps.dtic.mil/sti/pdfs/ADA278230.pdf |archive-date=2021-08-18}}</ref>]]


E1 is produced when [[gamma radiation]] from the nuclear detonation [[ionizes]] (strips electrons from) atoms in the upper atmosphere. This is known as the [[Compton effect]] and the resulting current is called the "Compton current". The electrons travel in a generally downward direction at [[relativistic speed]]s (more than 90 percent of the speed of light). In the absence of a magnetic field, this would produce a large, radial pulse of [[electric current]] propagating outward from the burst location confined to the source region (the region over which the gamma photons are attenuated). The Earth's magnetic field exerts a force on the electron flow at a right angle to both the field and the particles' original vector, which deflects the electrons and leads to [[synchrotron radiation]]. Because the outward traveling gamma pulse is propagating at the speed of light, the synchrotron radiation of the Compton electrons adds [[coherence (physics)|coherently]], leading to a radiated electromagnetic signal. This interaction produces a large, brief, pulse.<ref name="longmire">Longmire, Conrad L. LLNL-9323905, Lawrence Livermore National Laboratory. June 1986 "[https://ece-research.unm.edu/summa/notes/TheoreticalPDFs/TN368.pdf Justification and Verification of High-Altitude EMP Theory, Part 1]" (Retrieved 2010-15-12)</ref>
Physicist [[Conrad Longmire]] has given numerical values for a typical case of the E1 pulse produced by a second generation nuclear weapon such as those used in high altitude tests of [[Operation Fishbowl]] in 1962. According to him, the typical gamma rays given off by the weapon have an energy of about 2 [[Electron Volt|MeV]] (million electron volts). When these gamma rays collide with atoms in the mid-stratosphere, the gamma rays knock out electrons. This is known as the [[Compton effect]], and the resulting electrons produce an electric current that is known as the ''Compton current''. The gamma rays transfer about half of their energy to the electrons, so these initial electrons have an energy of about 1 MeV. This causes the electrons to begin to travel in a generally downward direction at about 94 percent of the speed of light. Relativistic effects cause the mass of these high energy electrons to increase to about 3 times their normal rest mass.<ref name="longmire"/>


Several physicists worked on the problem of identifying the mechanism of the HEMP E1 pulse. The mechanism was finally identified by [[Conrad Longmire]] of [[Los Alamos National Laboratory]] in 1963.<ref name="nbcreport"/>
If there were no geomagnetic field and no additional atoms in the lower atmosphere for additional collisions, the electrons would continue to travel downward with an average [[current density]] in the stratosphere of about 48 [[amperes]] per square metre.<ref name="longmire"/>


Longmire gives numerical values for a typical case of E1 pulse produced by a second-generation nuclear weapon such as those of [[Operation Fishbowl]]. The typical gamma rays given off by the weapon have an energy of about 2{{nbsp}}[[electron-volt|MeV]] ([[mega-|mega]] electron-volts). The gamma rays transfer about half of their energy to the ejected free electrons, giving an energy of about 1{{nbsp}}MeV.<ref name="longmire"/>
Because of the downward tilt of the Earth's magnetic field at high [[latitudes]], the area of peak field strength is a U-shaped region to the equatorial side of the nuclear detonation. As shown in the diagram at the right, for nuclear detonations over the continental United States, this U-shaped region is south of the detonation point. Near the [[equator]], where the Earth's magnetic field is more nearly horizontal, the E1 field strength is more nearly symmetrical around the burst location.


In a vacuum and absent a magnetic field, the electrons would travel with a [[current density]] of tens of [[ampere]]s per square metre.<ref name="longmire"/> Because of the downward tilt of the Earth's magnetic field at high [[latitude]]s, the area of peak field strength is a U-shaped region to the equatorial side of the detonation. As shown in the diagram, for nuclear detonations in the [[Northern Hemisphere]], this U-shaped region is south of the detonation point. Near the [[equator]], where the Earth's magnetic field is more nearly horizontal, the E1 field strength is more nearly symmetrical around the burst location.{{citation needed|date=August 2016}}
The Earth's magnetic field quickly deflects the electrons at right angles to the geomagnetic field, and the extent of the deflection depends upon the strength of the magnetic field. At geomagnetic field strengths typical of the central United States, central Europe or Australia, these initial electrons spiral around the magnetic field lines in a circle with a typical radius of about 85 metres (about 280 feet). These initial electrons are stopped by collisions with other air molecules at an average distance of about 170 metres (a little less than 580 feet). This means that most of the electrons are stopped by collisions with air molecules before they can complete one full circle of its spiral around the Earth's magnetic field lines.<ref name="longmire"/>


At geomagnetic field strengths typical of the mid-latitudes, these initial electrons spiral around the magnetic field lines with a typical radius of about {{convert|85|m|||round=5}}. These initial electrons are stopped by collisions with air molecules at an average distance of about {{convert|170|m|||}}. This means that most of the electrons are stopped by collisions with air molecules before completing a full spiral around the field lines.<ref name="longmire"/>
This interaction of the very rapidly-moving negatively-charged electrons with the magnetic field radiates a pulse of electromagnetic energy. The pulse typically rises to its peak value in about 5 nanoseconds. The magnitude of this pulse typically decays to half of its peak value within 200 nanoseconds. (By the IEC definition, this E1 pulse is ended at one microsecond (1000 nanoseconds) after it begins.) This process occurs simultaneously with about 10<sup>25</sup> other electrons.<ref name="longmire"/>


This interaction of the negatively charged electrons with the magnetic field radiates a pulse of electromagnetic energy. The pulse typically rises to its peak value in some five nanoseconds. Its magnitude typically decays by half within 200 nanoseconds. (By the IEC definition, this E1 pulse ends 1000 nanoseconds after it begins.) This process occurs simultaneously on about 10<sup>25</sup> electrons.<ref name="longmire"/>&nbsp; The simultaneous action of the electrons causes the resulting pulse from each electron to radiate coherently, adding to produce a single large-amplitude, short-duration, radiated pulse.<ref name="ORNL-2.12">{{cite report |last1=Savage |first1=Edward |last2=Gilbert |first2=James |last3=Radasky |first3=William |docket=Meta-R-320 |title=The Early-Time (E1) High-Altitude Electromagnetic Pulse (HEMP) and Its Impact on the U.S. Power Grid |section=Section 2.12 – (An Overview of E1 HEMP) - E1 HEMP: Instantaneous and Simultaneous |date=January 2010 |publisher=Metatech Corporation for Oak Ridge National Laboratory|df=dmy-all |url=https://www.ferc.gov/industries/electric/indus-act/reliability/cybersecurity/ferc_meta-r-320.pdf |access-date=2017-09-08 |url-status=dead |archive-url=https://web.archive.org/web/20170520145500/https://www.ferc.gov/industries/electric/indus-act/reliability/cybersecurity/ferc_meta-r-320.pdf |archive-date=2017-05-20}}</ref>
There are a number of secondary collisions which cause the subsequent electrons to lose energy before they reach ground level. The electrons generated by these subsequent collisions have such reduced energy that they do not contribute significantly to the E1 pulse.<ref name="longmire"/>


Secondary collisions cause subsequent electrons to lose energy before they reach ground level. The electrons generated by these subsequent collisions have so little energy that they do not contribute significantly to the E1 pulse.<ref name="longmire"/>
These 2 MeV gamma rays will normally produce an E1 pulse near ground level at moderately high latitudes that peaks at about 50,000 volts per metre. This is a peak [[surface power density|power density]] of 6.6 megawatts per square metre.


The process of the gamma rays knocking electrons out of the atoms in the mid-[[stratosphere]] causes this region of the atmosphere to become an electrical conductor due to ionization, a process which blocks the production of further electromagnetic signals and causes the field strength to saturate at about 50,000 volts per metre. The strength of the E1 pulse depends upon the number and intensity of the gamma rays produced by the weapon and upon the rapidity of the gamma ray burst from the weapon. The strength of the E1 pulse is also somewhat dependent upon the altitude of the detonation.
These 2 MeV gamma rays typically produce an E1 pulse near ground level at moderately high latitudes that peaks at about 50,000 volts per metre. The ionization process in the mid-[[stratosphere]] causes this region to become an electrical conductor, a process that blocks the production of further electromagnetic signals and causes the field strength to saturate at about 50,000 volts per metre. The strength of the E1 pulse depends upon the number and intensity of the gamma rays and upon the rapidity of the gamma-ray burst. Strength is also somewhat dependent upon altitude.{{citation needed|date=August 2016}}


There are reports of "super-EMP" nuclear weapons that are able to overcome the 50,000 volt per metre limit by the very nearly instantaneous release of a burst of gamma radiation of much higher energy levels than are known to be produced by second generation nuclear weapons. The reality and possible construction details of these weapons are classified, and therefore cannot be confirmed by scientists in the open scientific literature.<ref name="pry">Statement, Dr. Peter Vincent Pry, EMP Commission Staff, before the United States Senate Subcommittee on Terrorism, Technology and Homeland Security. March 8, 2005 [http://kyl.senate.gov/legis_center/subdocs/030805_pry.pdf]</ref>
There are reports of "super-EMP" nuclear weapons that are able to exceed the 50,000 volts per metre limit by unspecified mechanisms. The reality and possible construction details of these weapons are classified and are, therefore, unconfirmed in the open scientific literature<ref name="pry">{{cite report |title=Foreign Views of Electromagnetic Pulse (EMP) Attack |date=2005-03-08 |last1=Pry |first1=Peter Vincent |publisher=[[United States Senate Committee on Homeland Security and Governmental Affairs|United States Senate Subcommittee on Terrorism, Technology and Homeland Security]] |df=dmy-all |url=http://kyl.senate.gov/legis_center/subdocs/030805_pry.pdf |access-date=2022-08-11 |url-status=dead |archive-url=https://web.archive.org/web/20121108204504/http://kyl.senate.gov/legis_center/subdocs/030805_pry.pdf |archive-date=2012-11-08}}</ref>{{rp|3}}


===E2===
===E2===
The '''E2''' component is generated by scattered gamma rays and inelastic gammas produced by weapon [[neutrons]]. This E2 component is an "intermediate time" pulse that, by the IEC definition, lasts from about 1 microsecond to 1 second after the beginning of the electromagnetic pulse. The E2 component of the pulse has many similarities to the electromagnetic pulses produced by lightning, although the electromagnetic pulse induced by a nearby lightning strike may be considerably larger than the E2 component of a nuclear EMP. Because of the similarities to lightning-caused pulses and the widespread use of lightning protection technology, the E2 pulse is generally considered to be the easiest to protect against.
The E2 component is generated by scattered gamma rays and inelastic gammas produced by [[neutron]]s. This E2 component is an "intermediate time" pulse that, by IEC definition, lasts from about one microsecond to one second after the explosion. E2 has many similarities to [[lightning]], although lightning-induced E2 may be considerably larger than a nuclear E2. Because of the similarities and the widespread use of lightning protection technology, E2 is generally considered to be the easiest to protect against.{{r|empc}}


According to the United States EMP Commission, the main potential problem with the E2 component is the fact that it immediately follows the E1 component, which may have damaged the devices that would normally protect against E2.
According to the United States EMP Commission, the main problem with E2 is that it immediately follows E1, which may have damaged the devices that would normally protect against E2.


According to the EMP Commission Executive Report of 2004, "In general, it would not be an issue for critical infrastructure systems since they have existing protective measures for defense against occasional lightning strikes. The most significant risk is synergistic, because the E2 component follows a small fraction of a second after the first component's insult, which has the ability to impair or destroy many protective and control features. The energy associated with the second component thus may be allowed to pass into and damage systems."<ref>Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack. Volume 1. Executive Report. 2004. Page 6. [http://www.empcommission.org/docs/empc_exec_rpt.pdf]</ref>
The EMP Commission Executive Report of 2004 states, "In general, it would not be an issue for critical infrastructure systems since they have existing protective measures for defense against occasional lightning strikes. The most significant risk is synergistic because the E2 component follows a small fraction of a second after the first component's insult, which has the ability to impair or destroy many protective and control features. The energy associated with the second component thus may be allowed to pass into and damage systems."<ref name="empc">{{cite report |title=Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack: Executive Report |volume=1 |date=2004 |last1=Foster, Jr. |first1=John S. |last2=Gjelde |first2=Earl |last3=Graham |first3=William R. |last4=Hermann |first4=Robert J. |last5=Kluepfel |first5=Henry (Hank) M. |last6=Lawson |first6=Richard L. |last7=Soper |first7=Gordon K. |last8=Wood, Jr. |first8=Lowell L. |last9=Woodard |first9=Joan B. |docket=ADA48449 |publisher=Electromagnetic Pulse (EMP) Commission |via=[[Defense Technical Information Center]] |df=dmy-all |url=https://apps.dtic.mil/sti/pdfs/ADA484497.pdf |url-status=live |archive-url=https://web.archive.org/web/20220427231453/https://apps.dtic.mil/sti/pdfs/ADA484497.pdf |archive-date=2022-04-27}}</ref>{{rp|page=6}}


===E3===
===E3===
{{Main article|Geomagnetically induced current}}
{{See also|Geomagnetic storm}}


The '''E3''' component is very different from the other two major components of nuclear EMP. The E3 component of the pulse is a very slow pulse, lasting tens to hundreds of seconds, that is caused by the nuclear detonation heaving the Earth's magnetic field out of the way, followed by the restoration of the magnetic field to its natural place. The E3 component has similarities to a [[geomagnetic storm]] caused by a very severe solar flare.<ref>[http://www.todaysengineer.org/2007/Sep/HEMP.asp High-Altitude Electromagnetic Pulse (HEMP): A Threat to Our Way of Life], 09.07, By William A. Radasky, Ph.D., P.E. - IEEE</ref><ref name="empc">Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack [http://www.empcommission.org/docs/empc_exec_rpt.pdf]</ref> Like a geomagnetic storm, E3 can produce geomagnetically induced currents in long electrical conductors, which can then damage components such as power line transformers.<ref>Report Meta-R-321: "The Late-Time (E3) High-Altitude Electromagnetic Pulse (HEMP) and Its Impact on the U.S. Power Grid" January 2010. Written by Metatech Corporation for Oak Ridge National Laboratory. [http://www.ornl.gov/sci/ees/etsd/pes/pubs/ferc_Meta-R-321.pdf]</ref>
The E3 component is different from E1 and E2. E3 is a much slower pulse, lasting tens to hundreds of seconds. It is caused by the nuclear detonation's temporary distortion of the Earth's magnetic field. The E3 component has similarities to a [[geomagnetic storm]].<ref>[http://www.todaysengineer.org/2007/Sep/HEMP.asp High-Altitude Electromagnetic Pulse (HEMP): A Threat to Our Way of Life] {{Webarchive|url=https://web.archive.org/web/20140706143245/http://www.todaysengineer.org/2007/Sep/HEMP.asp |date=2014-07-06}}, 09.07, By William A. Radasky, PhD, P.E. IEEE</ref>{{r|empc}} Like a geomagnetic storm, E3 can produce geomagnetically induced currents in long electrical conductors, damaging components such as power line [[transformer]]s.<ref>{{cite report |last1=Sanabria |first1=David E. |last2=Bowman |first2=Tyler |last3=Guttromson |first3=Ross |last4=Halligan |first4=Matthew |last5=Le |first5=Ken |last6=Lehr |first6=Jane|author6-link=Jane Lehr |docket=SAND2020-12133 |title=The Late-Time (E3) High-Altitude Electromagnetic Pulse (HEMP) and Its Impact on the U.S. Power Grid |date=November 2010 |publisher=[[Sandia National Laboratories]] |df=dmy-all |url=https://www.ferc.gov/industries/electric/indus-act/reliability/cybersecurity/ferc_meta-r-321.pdf |url-status=dead |archive-url=https://web.archive.org/web/20170507032644/https://www.ferc.gov/industries/electric/indus-act/reliability/cybersecurity/ferc_meta-r-321.pdf |archive-date=2017-05-07}}</ref>


Because of the similarity between solar-induced geomagnetic storms and nuclear E3, it has become common to refer to solar-induced geomagnetic storms as "solar EMP."<ref name="empact">http://web.archive.org/web/20110726030320/http://www.empactamerica.org/solar_emp.php</ref> At ground level, however, "solar EMP" is not known to produce an E1 or E2 component.
Because of the similarity between solar-induced geomagnetic storms and nuclear E3, it has become common to refer to solar-induced geomagnetic storms as "Solar EMP".<ref name="empact">{{cite web |title=EMP Caused by Geomagnetic Storm |publisher=EMPACT America |date=n.d. |df=dmy-all |url=http://www.empactamerica.org/solar_emp.php |access-date=2022-08-10 |url-status=usurped |archive-url=https://web.archive.org/web/20110726030320/http://www.empactamerica.org/solar_emp.php |archive-date=2011-07-26}}</ref> "Solar EMP" does not include E1 or E2 components.<ref>{{cite news |title=E3 – ProtecTgrid |newspaper=ProtecTgrid |language=en-US |url=http://www.protectgrid.com/glossary/e3/ |access-date=2017-02-16}}{{Dead link|date=April 2020 |bot=InternetArchiveBot |fix-attempted=yes}}</ref>


==Generation==
For a more thorough description of E3 damage mechanisms, see the main article: [[Geomagnetically induced current]]
Factors that control weapon effectiveness include altitude, [[nuclear weapon yield|yield]], construction details, target distance, intervening geographical features, and local strength of the Earth's magnetic field.


===Weapon altitude===
==Practical considerations for nuclear EMP==
[[File: High altitude EMP.gif|right|333px|thumb|How the peak EMP on the ground varies with the weapon yield and burst altitude. The yield here is the prompt [[gamma ray]] output measured in kilotons. This varies from 0.115 to 0.5% of the total weapon yield, depending on weapon design. The 1.4 Mt total yield 1962 [[Starfish Prime]] test had a gamma output of 0.1%, hence 1.4 kt of prompt gamma rays (the '''blue''' '[[ionization|pre-ionisation]]' curve applies to certain types of [[nuclear weapon design|thermonuclear weapons]], for which [[gamma ray|gamma]] and [[X-ray]]s from the primary fission stage ionize the atmosphere and make it electrically conductive before the main pulse from the thermonuclear stage. The pre-ionisation in some situations can literally short out part of the final EMP, by allowing a conduction current to immediately oppose the Compton current of electrons).<ref>Louis W. Seiler, Jr. [https://apps.dtic.mil/sti/pdfs/ADA009208.pdf ''A Calculational Model for High Altitude EMP''] {{Webarchive|url=https://web.archive.org/web/20170429000435/http://www.dtic.mil/get-tr-doc/pdf?AD=ADA009208 |date=2017-04-29}}. Air Force Institute of Technology. Report ADA009208. pp. 33, 36. March 1975</ref>{{r|Glasstone_1977}}]]
Older, [[vacuum tube]] (valve) based equipment is generally much less vulnerable to EMP than newer [[Solid state (electronics)|solid state]] equipment. [[Soviet Union|Soviet]] [[Cold War]]–era military aircraft often had [[avionics]] based on vacuum tubes due to both limitations in Soviet solid-state capabilities and a belief that the vacuum-tube gear would survive better.<ref name="science"/>


According to an internet primer published by the [[Federation of American Scientists]]:<ref name="fas">{{cite web |title=Federation of American Scientists. "Nuclear Weapon EMP Effects" |url=https://fas.org/nuke/intro/nuke/emp.htm |access-date=2016-06-04 |url-status=dead |archive-url=https://web.archive.org/web/20150101064654/https://fas.org/nuke/intro/nuke/emp.htm |archive-date=2015-01-01}}</ref>
Although vacuum tubes are far more resistant to EMP than solid state devices, other components in vacuum tube circuitry can be damaged by EMP. Vacuum tube equipment actually was damaged in 1962 nuclear EMP testing.<ref name="euroem"/>&nbsp; Also, the solid state [[AN/PRC-77 Portable Transceiver|PRC-77]] [[Very high frequency|VHF]] manpackable 2-way radio survived extensive EMP testing.<ref name="PRC77">Seregelyi, J.S, et al. Report ADA266412 "EMP Hardening Investigation of the PRC-77 Radio Set" [http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA266412&Location=U2&doc=GetTRDoc.pdf]&nbsp;Retrieved&nbsp;2009-25-11</ref> The earlier PRC-25, nearly identical except for a vacuum tube final amplification stage, had been tested in EMP simulators but was not certified to remain fully functional.


: A high-altitude nuclear detonation produces an immediate [[flux]] of gamma rays from the nuclear reactions within the device. These [[photon]]s in turn produce high energy free electrons by Compton scattering at altitudes between (roughly) 20 and 40 km. These electrons are then trapped in the Earth's magnetic field, giving rise to an [[oscillating]] electric current. This current is asymmetric in general and gives rise to a rapidly rising radiated electromagnetic field called an electromagnetic pulse (EMP). Because the electrons are trapped essentially simultaneously, a very large electromagnetic source radiates [[coherence (physics)|coherently]].
Many nuclear detonations have taken place using bombs dropped by aircraft. The [[B-29 Superfortress|B-29]] aircraft that delivered the nuclear weapons at [[Hiroshima]] and [[Nagasaki]] did not lose power due to damage to their electrical or electronic systems. This is simply because [[electron]]s (ejected from the air by gamma rays) are stopped quickly in normal air for bursts below roughly 10&nbsp;km (about 6 miles), so they do not get a chance to be significantly deflected by the [[Earth's magnetic field]] (the deflection causes the powerful EMP seen in high altitude bursts), thus the limited use of smaller burst altitudes for widespread EMP.<ref name="glass-dol-2">Glasstone, Samuel and Dolan, Philip J., '' [http://www.princeton.edu/sgs/publications/articles/effects/ The Effects of Nuclear Weapons]''. Chapter 11, section 11.09. United States Department of Defense. 1977.</ref>


: The pulse can easily span continent-sized areas, and this radiation can affect systems on land, sea, and air. ... A large device detonated at 400–500 km (250 to 312 miles) over [[Kansas]] would affect all of the continental U.S. The signal from such an event extends to the visual horizon as seen from the burst point.
If the aircraft carrying the [[Hiroshima]] and [[Nagasaki]] bombs had been within the intense nuclear radiation zone when the bombs exploded over those cities, then they would have suffered effects from the [[photoinduced charge separation|charge separation]] (radial) EMP. But this only occurs within the severe blast radius for detonations below about 10&nbsp;km altitude.


Thus, for equipment to be affected, the weapon needs to be above the [[line-of-sight propagation|visual horizon]].<ref name="fas"/>
During nuclear tests in 1962, EMP disruptions were suffered aboard [[KC-135 Stratotanker|KC-135]] photographic aircraft flying {{convert|300|km|abbr=on}} from the {{convert|410|ktonTNT|abbr=on}} ''[[Operation Fishbowl|Bluegill Triple Prime]]'' and {{convert|410|ktonTNT|abbr=on}} ''[[Operation Fishbowl|Kingfish]]'' detonations ({{convert|48|and|95|km|abbr=on}} burst altitude, respectively)<ref name="glasstone.blogspot.com">[http://glasstone.blogspot.com/2006/03/emp-radiation-from-nuclear-space.html Effects of Nuclear Weapons Tests: Scientific Facts: EMP radiation from nuclear space bursts in 1962]</ref> but the vital aircraft electronics were far less sophisticated than today and the aircraft were able to land safely.


The altitude indicated above is greater than that of the [[International Space Station]] and many [[low Earth orbit]] satellites. Large weapons could have a dramatic impact on [[satellite]] operations and communications such as occurred during Operation Fishbowl. The damaging effects on orbiting satellites are usually due to factors other than EMP. In the [[Starfish Prime]] nuclear test, most damage was to the satellites' solar panels while passing through radiation belts created by the explosion.<ref>{{cite web |last=Hess |first=Wilmot N. |title=The Effects of High Altitude Explosions |publisher=[[National Aeronautics and Space Administration]] |date=September 1964 |id=NASA TN D-2402 |url=https://www.futurescience.com/emp/Hess-Wilmot.pdf |access-date=2015-05-13 |url-status=live |archive-url=https://ghostarchive.org/archive/20221009/http://www.futurescience.com/emp/Hess-Wilmot.pdf |archive-date=2022-10-09}}</ref>
==Generation of nuclear EMP==


For detonations within the atmosphere, the situation is more complex. Within the range of gamma ray deposition, simple laws no longer hold as the air is ionized and there are other EMP effects, such as a radial electric field due to the separation of [[Compton electron]]s from air molecules, together with other complex phenomena. For a surface burst, absorption of gamma rays by air would limit the range of gamma-ray deposition to approximately {{convert|10|mi|order=flip||}}, while for a burst in the lower-density air at high altitudes, the range of deposition would be far greater.{{citation needed|date=August 2016}}
Several major factors control the effectiveness of a nuclear EMP weapon. These are
;
# The altitude of the weapon when detonated;
# The [[nuclear weapon yield|yield]] and construction details of the weapon;
# The distance from the weapon when detonated;
# Geographical depth or intervening geographical features;
# The local strength of the magnetic field of the Earth.


===Weapon yield===
Beyond a certain altitude a nuclear weapon will not produce any EMP, as the gamma rays will have had sufficient distance to disperse. In deep space or on worlds with no magnetic field (the moon or Mars for example) there will be little or no EMP. This has implications for certain kinds of nuclear rocket engines, such as [[Project Orion (nuclear propulsion)|Project Orion]].
Typical [[nuclear weapon yield]]s used during [[Cold War]] planning for EMP attacks were in the range of {{convert|1|to|10|MtonTNT|lk=on|abbr=on}}.<ref>{{cite report |title=THREAT POSED BY ELECTROMAGNETIC PULSE (EMP) TO U.S. MILITARY SYSTEMS AND CIVIL INFRASTRUCTURE |author=Committee on National Security {{!}} Military Research and Development Subcommittee |date=1997-07-16 |type=Transcript |docket=H.S.N.C No. 105{{ndash}}18 |publisher=[[United States House of Representatives]] {{!}} [[105th United States Congress]] |location=Washington, D.C. |page=39 |language=en |df=dmy-all |url=https://commdocs.house.gov/committees/security/has197010.000/has197010_1.HTM#39 |access-date=2022-08-11 |url-status=live |archive-url=https://web.archive.org/web/20220811182704/http://commdocs.house.gov/committees/security/has197010.000/has197010_1.HTM |archive-date=2022-08-11}}</ref>{{rp|page=39}} This is roughly 50 to 500 times the size of the Hiroshima and Nagasaki bombs. Physicists have testified at United States Congressional hearings that weapons with yields of {{convert|10|ktonTNT|abbr=on}} or less can produce a large EMP.<ref name="hasc">{{cite report |title=ELECTROMAGNETIC PULSE THREATS TO U.S. MILITARY AND CIVILIAN INFRASTRUCTURE |author=Committee on National Security {{!}} Military Research and Development Subcommittee |date=1999-10-07 |type=Transcript |docket=H.A.S.C. No. 106{{ndash}}31 |publisher=[[United States House of Representatives]] {{!}} [[106th United States Congress]] |location=Washington, D.C. |page=48 |language=en |df=dmy-all |url=https://commdocs.house.gov/committees/security/has280010.000/has280010_0.htm#48 |access-date=2022-08-11 |url-status=live |archive-url=https://web.archive.org/web/20220531152332/http://commdocs.house.gov/committees/security/has280010.000/has280010_0.htm#48 |archive-date=2022-05-31}}</ref>{{rp|page=48}}


The EMP at a fixed distance from an explosion increases at most as the square root of the yield (see the illustration to the right). This means that although a {{convert|10|ktonTNT|abbr=on}} weapon has only {{percentage|7|1000|1}} of the energy release of the {{convert|1.44|MtonTNT|abbr=on}} Starfish Prime test, the EMP will be at least {{percentage|8|100}} as powerful. Since the E1 component of nuclear EMP depends on the prompt gamma-ray output, which was only 0.1% of yield in Starfish Prime but can be {{percentage|5|1000|1}} of yield in low-yield pure [[nuclear fission]] weapons, a {{convert|10|ktonTNT|abbr=on}} bomb can easily be {{math|1=''5'' * ''{{percentage|8|100}}''=''{{percentage|40|100|}}''}} as powerful as the {{convert|1.44|MtonTNT|abbr=on}} Starfish Prime at producing EMP.<ref name="glasstone.blogspot.com"/>{{Unreliable source?|date=December 2022|reason=Blog with annotations (original research?)}}
===Weapon altitude===
[[Image:EMP areas.JPG|right|333px|thumb|How the area affected depends on the burst altitude.]]
[[File:High altitude EMP.gif|right|333px|thumb|How the peak EMP on the ground varies with the weapon yield and burst altitude. The yield here is the prompt [[gamma ray]] output measured in kilotons. This varies from 0.115–0.5% of the total weapon yield, depending on weapon design. The 1.4 Mt total yield 1962 [[Starfish Prime]] test had a gamma output of 0.1%, hence 1.4 kt of prompt gamma rays. (The '''blue''' '[[ionization|pre-ionisation]]' curve applies to certain types of [[Nuclear weapon design|thermonuclear weapon]], where [[gamma ray|gamma]] and [[x-ray]]s from the primary fission stage [[Ionization|ionise]] the atmosphere and make it electrically conductive before the main pulse from the thermonuclear stage. The pre-ionisation in some situations can literally short out part of the final EMP, by allowing a conduction current to immediately oppose the Compton current of electrons.)<ref>Louis W. Seiler, Jr. ''A Calculational Model for High Altitude EMP''. Air Force Institute of Technology. Report ADA009208. Pages 33 and 36. March 1975 [http://stinet.dtic.mil/cgi-bin/GetTRDoc?AD=A009208&Location=U2&doc=GetTRDoc.pdf]</ref><ref name="glass-11">Glasstone, Samuel and Dolan, Philip J., The Effects of Nuclear Weapons. Chapter 11. 1977. United States Department of Defense. [http://www.princeton.edu/sgs/publications/articles/effects/]</ref>]]


The total prompt gamma-ray energy in a fission explosion is {{percentage|35|1000|1}} of the yield, but in a {{convert|10|ktonTNT|abbr=on}} detonation the triggering explosive around the bomb core absorbs about {{percentage|85|100|1}} of the prompt gamma rays, so the output is only about {{percentage|5|1000|1}} of the yield. In the [[nuclear fusion|thermonuclear]] Starfish Prime the fission yield was less than 100% and the thicker outer casing absorbed about 95% of the prompt gamma rays from the pusher around the fusion stage. [[Nuclear weapon design#Fusion|Thermonuclear weapons]] are also less efficient at producing EMP because the first stage can pre-ionize the air<ref name="glasstone.blogspot.com"/>{{Unreliable source?|date=December 2022|reason=Blog with annotations (original research?)}} which becomes conductive and hence rapidly shorts out the [[Compton current]]s generated by the [[nuclear fusion|fusion]] stage. Hence, small pure fission weapons with thin cases are far more efficient at causing EMP than most megaton bombs.{{citation needed|date=August 2016}}
According to an internet primer published by the [[Federation of American Scientists]]<ref name="fas">[http://www.fas.org/nuke/intro/nuke/emp.htm Federation of American Scientists. ''Nuclear Weapon EMP Effects'']</ref>


This analysis, however, only applies to the fast E1 and E2 components of nuclear EMP. The [[geomagnetic storm]]-like E3 component of nuclear EMP is more closely proportional to the total energy yield of the weapon.<ref name="empcnir">{{cite web |title=Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack. Critical National Infrastructures |author=Electromagnetic Pulse (EMP) Commission |url=https://apps.dtic.mil/sti/pdfs/ADA484672.pdf}}</ref>
: ''A high-altitude nuclear detonation produces an immediate [[flux]] of [[gamma ray]]s from the nuclear reactions within the device. These [[photon]]s in turn produce high energy free [[electron]]s by [[Compton scattering]] at altitudes between (roughly) 20 and 40 km. These electrons are then trapped in the [[Earth's magnetic field]], giving rise to an [[Oscillation|oscillating]] [[electric current]]. This current is asymmetric in general and gives rise to a rapidly rising radiated [[electromagnetic field]] called an electromagnetic pulse (EMP). Because the electrons are trapped essentially simultaneously, a very large electromagnetic source radiates [[coherence (physics)|coherently]].''


===Target distance===
: ''The pulse can easily span continent-sized areas, and this radiation can affect systems on land, sea, and air. The first recorded EMP incident accompanied a high-altitude nuclear test over the [[Australasia|South Pacific]] and resulted in power system failures as far away as [[Hawaii]]. A large device detonated at 400–500 km (250 to 312 miles) over [[Kansas]] would affect all of the continental U.S. The signal from such an event extends to the visual horizon as seen from the burst point.''
In nuclear EMP all of the components of the electromagnetic pulse are generated outside of the weapon.<ref name="fas"/>


For [[high-altitude nuclear explosion]]s, much of the EMP is generated far from the detonation (where the gamma radiation from the explosion hits the upper atmosphere). This electric field from the EMP is remarkably uniform over the large area affected.{{r|Glasstone_1977}}
Thus, for equipment to be affected, the weapon needs to be above the [[horizon|visual horizon]]. Because of the nature of the pulse as a large, high powered, noisy [[voltage spike|spike]], it is doubtful that there would be much protection if the explosion were seen in the sky just below the tops of hills or mountains.


According to the standard reference text on nuclear weapons effects published by the U.S. Department of Defense, "The peak electric field (and its amplitude) at the Earth's surface from a high-altitude burst will depend upon the explosion yield, the height of the burst, the location of the observer, and the orientation with respect to the [[geomagnetic field]]. As a general rule, however, the field strength may be expected to be tens of kilovolts per metre over most of the area receiving the EMP radiation."{{r|Glasstone_1977}}
The altitude indicated above is greater than that of the [[International Space Station]] and many [[low Earth orbit]] satellites. Large weapons could have a dramatic impact on [[satellite]] operations and communications such as occurred during the 1962 tests. The damaging effects on orbiting satellites are usually due to other factors besides EMP. In the Starfish Prime nuclear test, most satellite damage was due to damage to the solar panels from satellites passing through radiation belts created by the high altitude nuclear explosion.<ref>{{cite journal
| first = Wilmot N.
| last = Hess
| title = The Effects of High Altitude Explosions
| publisher = [[National Aeronautics and Space Administration]]
| date = September 1964
| url = http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19640018807_1964018807.pdf
| format = [[PDF]]
| id = NASA TN D-2402
| accessdate = 2010-09-30
}}</ref>


The text also states that, "...{{nbsp}}over most of the area affected by the EMP the electric field strength on the ground would exceed 0.5''E''<sub>max</sub>. For yields of less than a few hundred kilotons, this would not necessarily be true because the field strength at the Earth's tangent could be substantially less than 0.5''E''<sub>max</sub>."{{r|Glasstone_1977}}
===Weapon yield===
Typical [[nuclear weapon yield]]s used during [[Cold War]] planning for EMP attacks were in the range of 1 to 10 [[Nuclear weapon yield|megatons]] (4.2 to 42 PJ)<ref>[http://commdocs.house.gov/committees/security/has197010.000/has197010_1.HTM#39 U.S. Congressional hearing Transcript H.S.N.C No. 105&ndash;18, p. 39]</ref> This is roughly 50 to 500 times the sizes of the weapons the [[United States]] used in [[Japan]] at [[Hiroshima]] and [[Nagasaki]]. Physicists have testified at United States Congressional hearings, however, that weapons with yields of 10 [[Nuclear weapon yield|kilotons]] (42 TJ) or less can produce a very large EMP.<ref name="hasc">[http://commdocs.house.gov/committees/security/has280010.000/has280010_0.htm#48 U.S. Congressional hearing Transcript H.A.S.C.No. 106&ndash;31, p. 48]</ref>


(''E''<sub>max</sub> refers to the maximum electric field strength in the affected area.)
If one compares explosions with different yields, the EMP at a fixed distance from a nuclear weapon would not increase at the same rate as the explosion yield, but at most only as the square root of the yield (see the illustration to the right).&nbsp; This means that although a 10 [[Nuclear weapon yield|kiloton]] weapon has only 0.7% of the total energy release of the 1.44-[[Nuclear weapon yield|megaton]] [[Starfish Prime]] test, the EMP will be at least 8% as powerful. Since the E1 component of nuclear EMP depends on the prompt [[gamma ray]] output, which was only 0.1% of yield in [[Starfish Prime]] but can be 0.5% of yield in pure fission weapons of low yield, a 10 kiloton bomb can easily be 5 x 8% = 40% as powerful as the 1.44 megaton [[Starfish Prime]] at producing EMP.<ref name="glasstone.blogspot.com"/>


In other words, the electric field strength in the entire area that is affected by the EMP will be fairly uniform for weapons with a large gamma-ray output. For smaller weapons, the electric field may fall at a faster rate as distance increases.{{r|Glasstone_1977}}
The total prompt gamma ray energy in a fission explosion is 3.5% of the yield, but in a 10 [[Nuclear weapon yield|kiloton]] detonation the high explosive around the bomb core absorbs about 85% of the prompt gamma rays, so the output is only about 0.5% of the yield in kilotons. In the [[Nuclear fusion|thermonuclear]] [[Starfish Prime]] the fission yield was less than 100% to begin with, and then the thicker outer casing absorbed about 95% of the prompt gamma rays from the pusher around the fusion stage. [[Nuclear weapon design#Fusion weapons|Thermonuclear weapons]] are also less efficient at producing EMP because the first stage can [[ionization|pre-ionize]] the air<ref name="glasstone.blogspot.com"/> which becomes conductive and hence rapidly shorts out the electron [[Compton scattering|Compton current]]s generated by the final, larger yield thermonuclear stage. Hence, small pure fission weapons with thin cases are far more efficient at causing EMP than most megaton bombs.


==Super-EMP==
This analysis, however, only applies to the fast E1 and E2 components of nuclear EMP. The [[geomagnetic storm]]-like E3 component of nuclear EMP is more closely proportional to the total energy yield of the weapon.<ref name="empcnir">[http://www.empcommission.org/docs/A2473-EMP_Commission-7MB.pdf EMP Commission Critical National Infrastructures Report]</ref>
Also known as an "Enhanced-EMP", a super-electromagnetic pulse is a relatively new type of warfare in which a [[nuclear weapon]] is designed to create a far greater [[electromagnetic pulse]] in comparison to standard nuclear [[weapons of mass destruction]].<ref>{{cite journal |last1=Gurevich |first1=Vladimir |date=September 2016 |title=EMP and Its Impact on Electrical Power System: Standards and Reports |journal=Journal of Research and Innovation in Applied Science |volume=1 |issue=6 |pages=6–10 |issn=2454-6194 |via=[[Academia.edu]] |df=dmy-all |url=https://www.academia.edu/download/53552388/emp_standards_and_reports.pdf}}{{Dead link|date=October 2022 |bot=InternetArchiveBot |fix-attempted=yes}}</ref> These weapons capitalize on the E1 pulse component of a detonation involving [[gamma ray]]s, creating an EMP yield of potentially up to 200,000 volts per meter.<ref name=":0">{{cite report |last1=Pry |first1=Peter V. |date=2017-07-27 |title=Nuclear EMP Attack Scenarios and Combined-Arms Cyber Warfare |newspaper=Dtic |docket=AD1097009 |language=en |via=[[Defense Technical Information Center]] |df=dmy-all |url=https://apps.dtic.mil/sti/citations/AD1097009 |access-date=2022-08-11 |url-status=live |archive-url=https://web.archive.org/web/20210317144736/https://apps.dtic.mil/sti/citations/AD1097009 |archive-date=2021-03-17}}</ref> For decades, numerous countries have experimented with the creation of such weapons, most notably [[China]] and [[Russia]].


===Weapon distance===
===China===
According to a statement made in writing by the [[Chinese military]], the country has super-EMPs and has discussed their use in attacking [[Taiwan]]. Such an attack would debilitate information systems in the nation, allowing China to move in and attack it directly using soldiers. The Taiwanese military has subsequently confirmed Chinese possession of super-EMPs and their possible destruction to [[power grid]]s.<ref name=":1">{{cite report |last1=Pry |first1=Peter V. |date=2020-06-10 |title=China: EMP Threat: The People's Republic of China Military Doctrine, Plans, and Capabilities for Electromagnetic Pulse (EMP) Attack |docket=AD1102202 |language=en |via=[[Defense Technical Information Center]] |df=dmy-all |url=https://apps.dtic.mil/sti/citations/AD1102202 |access-date=2022-08-11 |url-status=live |archive-url=https://web.archive.org/web/20210502044333/https://apps.dtic.mil/sti/citations/AD1102202 |archive-date=2021-05-02}}</ref>
A unique and important aspect of '''nuclear''' EMP is that all of the components of the electromagnetic pulse are generated '''outside''' of the weapon. The important E1 component is generated by interaction with the electrons in the upper atmosphere that are hit by gamma radiation from the weapon&nbsp;&mdash; and the subsequent effects upon those electrons by the [[Earth's magnetic field]].<ref name="fas"/>


In addition to Taiwan, the possible implications of attacking the [[United States]] with these weapons was examined by China. While the United States also possesses nuclear weapons, the country has not experimented with super-EMPs and is hypothetically highly vulnerable to any future attacks by nations. This is due to the country's reliance on computers to control much of the government and economy.<ref name=":0"/> Abroad, U.S. aircraft carriers stationed within a reasonable range of an exploding bomb could potentially be subject to complete destruction of missiles on board, as well as [[telecommunication systems]] that would allow them to communicate with nearby vessels and controllers on land.<ref name=":1"/>
For [[High altitude nuclear explosion|high-altitude nuclear explosions]], this means that much of the EMP is actually generated at a large distance from the detonation (where the gamma radiation from the explosion hits the upper atmosphere). This causes the electric field from the EMP to be remarkably uniform over the large area affected.


===Russia===
According to the standard reference text on nuclear weapons effects published by the U.S. Department of Defense, "The peak electric field (and its amplitude) at the Earth's surface from a high-altitude burst will depend upon the explosion yield, the height of the burst, the location of the observer, and the orientation with respect to the [[Earth's magnetic field|geomagnetic field]].&nbsp; As a general rule, however, the field strength may be expected to be tens of kilovolts per metre over most of the area receiving the EMP radiation."<ref name="glass-dol">Glasstone, Samuel and Dolan, Philip J., ''The Effects of Nuclear Weapons''. Chapter 11, section 11.73. United States Department of Defense. 1977. [http://www.princeton.edu/sgs/publications/articles/effects/]</ref>
Since the Cold War, Russia has experimented with the design and effects of EMP bombs.


The [[Soviet Union]] designed a [[Fractional Orbital Bombardment System|system]] to deliver nuclear weapons from above the [[Earth's atmosphere]].<ref name=":2">{{cite report |last1=Pry |first1=Peter V. |date=2021-01-28 |title=Russia: EMP Threat. The Russian Federation's Military Doctrine, Plans, and Capabilities for Electromagnetic Pulse (EMP) Attack |docket=AD1124730 |language=en |via=[[Defense Technical Information Center]] |df=dmy-all |url=https://apps.dtic.mil/sti/citations/AD1124730 |url-status=live |archive-url=https://web.archive.org/web/20210502044331/https://apps.dtic.mil/sti/citations/AD1124730 |archive-date=2021-05-02}}</ref> and proposals have been made by Russia to develop [[satellite]]s supplied with EMP capabilities{{Citation needed|date=May 2024}}. This would call for detonations up to {{convert|100|km|mi}} above the Earth's surface, with the potential to disrupt the electronic systems of U.S. satellites suspended in orbit around the planet, many of which are vital for deterrence and alerting the country of possible incoming missiles.<ref name=":0"/>
The same reference book also states that, "...&nbsp;over most of the area affected by the EMP the electric field strength on the ground would exceed 0.5''E''<sub>max</sub>.&nbsp;&nbsp; For yields of less than a few hundred kilotons, this would not necessarily be true because the field strength at the Earth's tangent could be substantially less than 0.5''E''<sub>max</sub>."<ref name="glass-dol"/>


==Effects==
(''E''<sub>max</sub> refers to the maximum electric field strength in the affected area.)
An energetic EMP can temporarily upset or permanently damage electronic equipment by generating high voltage and high current surges; semiconductor components are particularly at risk. The effects of damage can range from imperceptible to the eye, to devices blowing apart. Cables, even if short, can act as antennas to transmit pulse energy to the equipment.<ref name="metaR320"/>


===Vacuum tube vs. solid-state electronics===
In other words, the electric field strength in the entire area that is affected by the EMP will be fairly uniform for weapons with a large gamma ray output; but for much smaller weapons, the electric field may fall off at a comparatively faster rate at large distances from the detonation point.
Older, [[vacuum tube]] (valve)-based equipment is generally much less vulnerable to nuclear EMP than [[solid-state electronics|solid-state]] equipment, which is much more susceptible to damage by large, brief voltage and current surges. [[Soviet]] [[Cold War]]-era military aircraft often had [[avionics]] based on vacuum tubes because solid-state capabilities were limited and vacuum-tube gear was believed to be more likely to survive.<ref name="science"/>


Other components in vacuum tube circuitry can be damaged by EMP. Vacuum tube equipment was damaged in the 1962 testing.<ref name="euroem"/> The solid-state [[PRC-77]] [[VHF]] manpackable two-way radio survived extensive EMP testing.<ref name="PRC77">Seregelyi, J.S, et al. [http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA266412&Location=U2&doc=GetTRDoc.pdf Report ADA266412 "EMP Hardening Investigation of the PRC-77 Radio Set] {{Webarchive|url=https://web.archive.org/web/20111112122352/http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA266412&Location=U2&doc=GetTRDoc.pdf |date=2011-11-12}}" Retrieved 2009-25-11</ref> The earlier PRC-25, nearly identical except for a vacuum tube final amplification stage, was tested in EMP simulators, but was not certified to remain fully functional.{{citation needed|date=August 2016}}
It is the '''peak electric field''' of the EMP that determines the '''peak voltage''' induced in equipment and other electrical conductors on the ground, and most of the damage is determined by induced voltages.


===Electronics in operation vs. inactive===
For nuclear detonations within the atmosphere, the situation is more complex. Within the range of gamma ray deposition, simple laws no longer hold as the air is [[Ionization|ionised]] and there are other EMP effects, such as a radial electric field due to the separation of [[Compton scattering|Compton electron]]s from air molecules, together with other complex phenomena. For a surface burst, absorption of gamma rays by air would limit the range of gamma ray deposition to approximately 10 miles, while for a burst in the lower-density air at high altitudes, the range of deposition would be far greater.<br style="clear:both" />
Equipment that is running at the time of an EMP is more vulnerable. Even a low-energy pulse has access to the power source, and all parts of the system are illuminated by the pulse. For example, a high-current arcing path may be created across the power supply, burning out some device along that path. Such effects are hard to predict and require testing to assess potential vulnerabilities.<ref name="metaR320">
{{cite report |last1=Savage |first1=Edward |last2=Gilbert |first2=James |last3=Radasky |first3=William |docket=Meta-R-320 |title=The Early-Time (E1) High-Altitude Electromagnetic Pulse (HEMP) and Its Impact on the U.S. Power Grid |section=Appendix: E1 HEMP Myths |date=January 2010 |publisher=Metatech Corporation for Oak Ridge National Laboratories |df=dmy-all |url=https://www.ferc.gov/industries/electric/indus-act/reliability/cybersecurity/ferc_meta-r-320.pdf |access-date=2017-09-08 |url-status=dead |archive-url=https://web.archive.org/web/20170520145500/https://www.ferc.gov/industries/electric/indus-act/reliability/cybersecurity/ferc_meta-r-320.pdf |archive-date=2017-05-20}}</ref>


===On aircraft===
==Non-nuclear electromagnetic pulse==
Many nuclear detonations have taken place using [[aerial bomb]]s. The [[B-29]] aircraft that delivered the nuclear weapons at [[Hiroshima]] and [[Nagasaki]] did not lose power from electrical damage, because [[electron]]s (ejected from the air by gamma rays) are stopped quickly in normal air for bursts below roughly {{convert|10|km|ft||}}, so they are not significantly deflected by the Earth's magnetic field.<ref name="Glasstone_1977">{{cite book |last1=Glasstone |first1=Samuel |author-link1=Samuel Glasstone |last2=Dolan |first2=Philip J. |author-link2=Philip J. Dolan |date=1977 |title=The Effects of Nuclear Weapons |chapter=XI: The Electromagnetic Pulse and its Effect |publisher=[[United States Department of Defense]] and [[United States Department of Energy]] |oclc=1086574022 |ol=OL10450457M |via=[[Google Books]] |df=dmy-all |isbn=978-0318203690 |url={{Google books|KOM8AAAAIAAJ|plainurl=yes}}}}</ref>{{rp|page=517}}
'''Non-nuclear electromagnetic pulse''' ('''NNEMP''') is an electromagnetic pulse generated without use of nuclear weapons. There are a number of devices that can achieve this objective, ranging from a large low-inductance [[capacitor]] bank discharged into a single-loop antenna or a microwave generator to an [[explosively pumped flux compression generator]]. To achieve the frequency characteristics of the pulse needed for optimal [[coupling (electronics)|coupling]] into the target, [[Electromagnetic wave|wave]]-shaping circuits and/or microwave generators are added between the pulse source and the [[Antenna (radio)|antenna]]. A vacuum tube particularly suitable for microwave conversion of high energy pulses is the [[vircator]].<ref name=kopp>{{cite journal |url=http://www.dtic.mil/docs/citations/ADA332511 |url=http://www.airpower.maxwell.af.mil/airchronicles/cc/apjemp.html |title=The Electromagnetic Bomb - A Weapon of Electrical Mass Destruction |date=October 1996 |last=Kopp |first=Carlo |author-link=Carlo Kopp |journal=USAF CADRE Air Chronicles |publisher=U.S. Air Force |id=DTIC:ADA332511 |accessdate=12 January 2012}}</ref>


If the aircraft carrying the [[Hiroshima]] and [[Nagasaki]] bombs had been within the intense nuclear radiation zone when the bombs exploded over those cities, then they would have suffered effects from the [[photoinduced charge separation|charge separation]] (radial) EMP. But this only occurs within the severe blast radius for detonations below about {{convert|10|km|ft|order=flip}} altitude.{{citation needed|date=August 2016}}
NNEMP generators can be carried as a payload of bombs, [[cruise missile]]s and [[Unmanned aerial vehicle|drones]], allowing construction of electromagnetic bombs with diminished mechanical, thermal and ionizing radiation effects and without the political consequences of deploying nuclear weapons.


During [[Operation Fishbowl]], EMP disruptions were suffered aboard a [[KC-135]] photographic aircraft flying {{convert|300|km|abbr=on}} from the {{convert|410|ktonTNT|abbr=on}} detonations at {{convert|48|and|95|km|ft|abbr=on}} burst altitudes.<ref name="glasstone.blogspot.com">{{cite web |title=EMP radiation from nuclear space bursts in 1962 |last1=Glasstone |first1=Samuel |author-link1=Samuel Glasstone |date=2006-03-28 |website=Glasstone's errors in The Effects of Nuclear Weapons, and the strategic implication for deterrence |language=en |df=dmy-all |url=http://glasstone.blogspot.com/2006/03/emp-radiation-from-nuclear-space.html |access-date=2022-08-10 |url-status=live |archive-url=https://web.archive.org/web/20220811022617/https://glasstone.blogspot.com/2006/03/emp-radiation-from-nuclear-space.html?m=1 |archive-date=2022-08-11 |quote=Subsequent tests with lower yield devices [410 kt ''Kingfish'' at 95 km altitude, 410 kt ''Bluegill'' at 48 km altitude, and 7 kt ''Checkmate'' at 147 km] produced electronic upsets on an instrumentation aircraft [presumably the KC-135 that filmed the tests from above the clouds?] that was approximately 300 kilometers away from the detonations.}}<!-- blog source was https://fas.org/spp/starwars/congress/1997_h/h970716u.htm &ndash; testimony to 1997 U.S. Congressional Hearings, Dr. George W. Ullrich, the Deputy Director of the U.S. Department of Defense's Defense Special Weapons Agency --></ref> The vital electronics were less sophisticated than today's and the aircraft was able to land safely.{{citation needed|date=August 2016}}
The range of NNEMP weapons (non-nuclear electromagnetic pulse bombs) is severely limited compared to nuclear EMP. This is because nearly all NNEMP devices used as weapons require chemical explosives as their initial energy source, but nuclear explosives have an energy yield on the order of one million times that of chemical explosives of similar weight.<ref>Glasstone, Samuel and Dolan, Philip J., The Effects of Nuclear Weapons. Chapter 1. 1977. United States Department of Defense. [http://www.princeton.edu/sgs/publications/articles/effects/]</ref>&nbsp; In addition to the large difference in the energy density of the initial energy source, the electromagnetic pulse from NNEMP weapons must come from within the weapon itself, while nuclear weapons generate EMP as a secondary effect, often at great distances from the detonation.<ref name="glass-11"/>&nbsp; These facts severely limit the range of NNEMP weapons as compared to their nuclear counterparts, but allow for more surgical target discrimination. The effect of small e-bombs has proven to be sufficient for certain terrorist or military operations. Examples of such operations include the destruction of certain fragile electronic control systems of the type critical to the operation of many ground vehicles and aircraft.<ref name="Marks">Marks, Paul "Aircraft could be brought down by DIY 'E-bombs'" New Scientist, 01 April 2009, pp. 16-17 [http://www.newscientist.com/article/mg20227026.200-aircraft-could-be-brought-down-by-diy-ebombs.html]</ref>


Modern aircraft are heavily reliant on solid-state electronics which are very susceptible to EMP blasts. Therefore, airline authorities are creating high intensity radiated fields (HIRF) requirements for new air planes to help prevent the chance of crashes caused by EMPs or electromagnetic interference (EMI).<ref>{{cite book |title=Electromagnetic Shielding and Corrosion Protection for Aerospace Vehicles |year=2007 |language=en |last1=Gooch |first1=Jan W. |last2=Daher |first2=John K. |isbn=978-0-387-46094-9 |doi=10.1007/978-0-387-46096-3 |url=https://link.springer.com/book/10.1007/978-0-387-46096-3}}</ref> To do this all parts of the airplane must be conductive. This is the main shield from EMP blasts as long as there are no holes for the waves to penetrate into the interior of the airplane. Also, insulating some of the main computers inside the plane adds an extra layer of protection from EMP blasts.{{citation needed|date=February 2024}}
[[Image:E-4 advanced airborne command post EMP sim.jpg|thumb|A right front view of a [[Boeing E-4]] National Airborne Operations Center aircraft on the electromagnetic pulse (EMP) simulator (HAGII-C) for testing.]]


===On cars===
[[Image:USS Estocin FFG-15 moored near EMPRESS I.jpg|thumb|left|{{USS|Estocin|FFG-15}} moored near the Electro Magnetic Pulse Radiation Environmental Simulator for Ships I (EMPRESS I) facility (antennae at top of image).]]
An EMP would probably not affect most cars, despite modern cars' heavy use of electronics, because cars' electronic circuits and cabling are likely too short to be affected. In addition, cars' metallic frames provide some protection. However, even a small percentage of cars breaking down due to an electronic malfunction would cause traffic jams.<ref name="metaR320"/>


===On small electronics===
Information about the EMP simulators used by the United States during the latter part of the [[Cold War]], along with more general information about electromagnetic pulse, are now in papers under the care of the SUMMA Foundation,<ref>[http://www.ece.unm.edu/summa/index.htm The SUMMA Foundation] The University of New Mexico.</ref> which is now hosted at the University of New Mexico.
An EMP has a smaller effect on shorter lengths of an electrical conductor. Other factors affect the vulnerability of electronics as well, so no hard cutoff length determines whether some piece of equipment will survive. However, small electronic devices, such as wristwatches and cell phones, would most likely withstand an EMP.<ref name="metaR320"/>


===On humans and animals===
The SUMMA Foundation web site includes documentation about the huge wooden [[ATLAS-I]] simulator (better known as TRESTLE, or "The Sandia Trestle") at [[Sandia National Labs]], New Mexico, which was the world's largest EMP simulator.<ref>[http://www.ece.unm.edu/summa/notes/trestle.html The Atlas-I Trestle at Kirtland Air Force Base] Story by Charles Reuben, The University of New Mexico</ref>&nbsp; Nearly all of these large EMP simulators used a specialized version of a [[Marx generator]].<ref name="baum1"/><ref name="baum2"/>&nbsp; The SUMMA Foundation now has a 44-minute documentary movie on its web site called "TRESTLE: Landmark of the Cold War".<ref name="movie">[http://www.ece.unm.edu/summa/notes/trestle_movie.html TRESTLE: Landmark of the Cold War (Documentary Movie)]</ref>
Though electric potential difference can accumulate in electrical conductors after an EMP, it will generally not flow out into human or animal bodies, and thus contact is safe.<ref name="metaR320"/>


EMPs of sufficient magnitude and length have the potential to affect the human body. Possible side effects include cellular mutations, nervous system damages, internal burns, brain damage, and temporary problems with thinking and memory.<ref>{{cite web |last1=Walter |first1=John |title=How an EMP Attack Would Affect Humans |website=Super Prepper |language=en-US |df=dmy-all |url=https://www.superprepper.com/emp-effects-on-humans/ |access-date=2022-08-11 |url-status=live |archive-url=https://web.archive.org/web/20211029222217/https://www.superprepper.com/emp-effects-on-humans/ |archive-date=2021-10-29}}</ref> However, this would be in extreme cases like being near the center of the blast and being exposed to a large amount of radiation and EMP waves.
Many large EMP simulators were also built in the Soviet Union, as well as in the United Kingdom, France, Germany, the [[Netherlands]], Switzerland and Italy.<ref name="baum1"/><ref name="baum2"/>
<br style="clear:both" />


A study found that exposure to 200–400 pulses of EMP caused the leaking of vessels in the brain,<ref>{{cite journal |last1=Ding |first1=Gui-Rong |last2=Li |first2=Kang-Chu |last3=Wang |first3=Xiao-Wu |last4=Zhou |first4=Yong-Chun |last5=Qiu |first5=Lian-Bo |last6=Tan |first6=Juan |last7=Xu |first7=Sheng-Long |last8=Guo |first8=Guo-Zhen |date=June 2009 |title=Effect of electromagnetic pulse exposure on brain micro vascular permeability in rats |journal=Biomedical and Environmental Sciences |volume=22 |issue=3 |pages=265–268 |issn=0895-3988 |pmid=19725471 |doi=10.1016/S0895-3988(09)60055-6|bibcode=2009BioES..22..265D }}</ref> leakage that has been linked to small problems with thinking and memory recollection. These effects could last up to 12 hours after the exposure. Due to the long exposure time needed to see any of these effects it is unlikely that anyone would see these effects even if exposed for a small period of time. Also, the human body will see little effect as signals are passed chemically and not electrically making it hard to be affected by EMP waves.{{citation needed|date=February 2024}}
==Post–Cold War nuclear EMP attack scenarios==


=== Indirect effects on agriculture ===
The United States military services have developed, and in some cases have published, a number of hypothetical EMP attack scenarios.<ref name="miller">Miller, Colin R., Major, USAF "Electromagnetic Pulse Threats in 2010" Air War College, Air University, United States Air Force, November 2005 [http://www.au.af.mil/au/awc/awcgate/cst/bugs_ch12.pdf]</ref>
In addition to these direct effects, it has also been estimated that the disruption caused by the NEMP would have large negative effects on agriculture, due to the disruption of supply chains for agricultural inputs like fertilizers and pesticides. This could reduce yields in highly industrialized agricultural regions like Central Europe by up to 75 %.<ref>{{cite journal |last1=Moersdorf |first1=Jessica |last2=Rivers |first2=Morgan |last3=Denkenberger |first3=David |last4=Breuer |first4=Lutz |last5=Jehn |first5=Florian Ulrich |title=The Fragile State of Industrial Agriculture: Estimating Crop Yield Reductions in a Global Catastrophic Infrastructure Loss Scenario |journal=Global Challenges |date=January 2024 |volume=8 |issue=1 |doi=10.1002/gch2.202300206}}</ref>


==Post–Cold War attack scenarios==
The United States EMP Commission was authorized by the [[United States Congress]] in Fiscal Year 2001, and re-authorized in Fiscal Year 2006. The commission is formally known as the '''Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack'''.<ref>[http://www.empcommission.org Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack]</ref>
The United States EMP Commission was created by the [[United States Congress]] in 2001. The commission is formally known as the commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack.<ref>{{cite web |title=Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack |date=n.d. |df=dmy-all |url=http://www.empcommission.org/ |url-status=live |archive-url=https://web.archive.org/web/20170908212925/http://www.empcommission.org/ |archive-date=2017-09-08}}</ref>


The United States EMP Commission has brought together a group of notable scientists and technologists to compile several reports. In 2008, the EMP Commission released the '''Critical National Infrastructures Report'''.<ref name="empcnir"/> This report describes, in as much detail as practical, the likely consequences of a nuclear EMP on civilian infrastructures. Although this report was directed specifically toward the United States, most of the information can obviously be generalized to the civilian infrastructure of other industrialized countries.
The Commission brought together notable scientists and technologists to compile several reports. In 2008, the Commission released the "Critical National Infrastructures Report".<ref name="empcnir"/> This report describes the likely consequences of a nuclear EMP on civilian infrastructure. Although this report covered the United States, most of the information is applicable to other industrialized countries. The 2008 report was a follow-up to a more generalized report issued by the commission in 2004.{{r|empc}}

The 2008 report was a followup to a more generalized report issued by the commission in 2004.<ref name="empc"/><ref>[http://www.globalsecurity.org/wmd/library/congress/2004_r/04-07-22emp.pdf Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack] Volume 1: Executive Report 2004</ref>


In written testimony delivered to the United States Senate in 2005, an EMP Commission staff member reported:
In written testimony delivered to the United States Senate in 2005, an EMP Commission staff member reported:


:''The EMP Commission sponsored a worldwide survey of foreign scientific and military literature to evaluate the knowledge, and possibly the intentions, of foreign states with respect to electromagnetic pulse (EMP) attack. The survey found that the physics of EMP phenomenon and the military potential of EMP attack are widely understood in the international community, as reflected in official and unofficial writings and statements. The survey of open sources over the past decade finds that knowledge about EMP and EMP attack is evidenced in at least Britain, France, Germany, Israel, Egypt, Taiwan, Sweden, Cuba, India, Pakistan, Iraq under Saddam Hussein, Iran, North Korea, China and Russia.''
{{Cquote|text=The EMP Commission sponsored a worldwide survey of foreign scientific and military literature to evaluate the knowledge, and possibly the intentions, of foreign states with respect to electromagnetic pulse (EMP) attacks. The survey found that the physics of the EMP phenomenon and the military potential of an EMP attack is widely understood in the international community, as reflected in official and unofficial writings and statements. The survey of open sources over the past decade finds that knowledge about EMP and EMP attacks is evidenced in at least Britain, France, Germany, Israel, Egypt, Taiwan, Sweden, Cuba, India, Pakistan, Iraq under Saddam Hussein, Iran, North Korea, China, and Russia.
:. . .


:''Many foreign analysts–particularly in Iran, North Korea, China, and Russia–view the United States as a potential aggressor that would be willing to use its entire panoply of weapons, including nuclear weapons, in a first strike. They perceive the United States as having contingency plans to make a nuclear EMP attack, and as being willing to execute those plans under a broad range of circumstances.''
Many foreign analysts – particularly in Iran, North Korea, China, and Russia – view the United States as a potential aggressor that would be willing to use its entire panoply of weapons, including nuclear weapons, in a first strike. They perceive the United States as having contingency plans to make a nuclear EMP attack, and as being willing to execute those plans under a broad range of circumstances.


:''Russian and Chinese military scientists in open source writings describe the basic principles of nuclear weapons designed specifically to generate an enhanced-EMP effect, that they term "Super-EMP" weapons. "Super-EMP" weapons, according to these foreign open source writings, can destroy even the best protected U.S. military and civilian electronic systems.''<ref name="pry"/>
Russian and Chinese military scientists in open source writings describe the basic principles of nuclear weapons designed specifically to generate an enhanced-EMP effect, which they term "Super-EMP" weapons. "Super-EMP" weapons, according to these foreign open source writings, can destroy even the best protected U.S. military and civilian electronic systems.<ref name="pry"/>}}


The United States EMP Commission determined that long-known protections are almost completely absent in the civilian infrastructure of the United States and that large parts of US military services were less-protected against EMP than during the Cold War. In public statements, the Commission recommended making electronic equipment and electrical components resistant to EMP – and maintaining spare parts inventories that would enable prompt repairs.<ref name="empc"/><ref name="empcnir"/><ref name="med-emp">{{cite journal |last1=Ross Jr. |first1=Lenard H. |last2=Mihelic |first2=F. Matthew |title=Healthcare Vulnerabilities to Electromagnetic Pulse |journal=American Journal of Disaster Medicine |volume=3 |issue=6 |pages=321–325 |date=November 2008 |issn=1932-149X |pmid=19202885}}</ref> The United States EMP Commission did not look at other nations.{{Citation needed|date=August 2016}}
==Clarification of common misconceptions==


In 2011, the [[Defense Science Board]] published a report about the ongoing efforts to defend critical military and civilian systems against EMP and other nuclear weapons effects.<ref>{{cite report |date=2011-08-01 |title=Interim Report of the Defense Science Board (DSB) Task Force on the Survivability of Systems and Assets to Electromagnetic Pulse (EMP) and other Nuclear Weapon Effects (NWE) |docket=Summary Report No. 1 {{!}} ADA550250 |language=en |publisher=[[Under Secretary of Defense for Acquisition and Sustainment|Office of the Under Secretary of Defense For Acquisition, Technology, and Logistics]] |via=[[Defense Technical Information Center]] |df=dmy-all |url=https://apps.dtic.mil/sti/pdfs/ADA550250.pdf |access-date=2022-08-11 |url-status=live |archive-url=https://web.archive.org/web/20220811141009/https://apps.dtic.mil/sti/pdfs/ADA550250.pdf |archive-date=2022-08-11}}</ref>
In non-technical writings about nuclear EMP, both in print and on the Internet, some common misconceptions about EMP are nearly always found. These widely-repeated misconceptions have led to a very considerable amount of confusion about the subject. In 2010, a technical report written for the US government's [[Oak Ridge National Laboratory]] even included a brief section addressing some of those EMP myths.<ref>Report Meta-R-320: "The Early-Time (E1) High-Altitude Electromagnetic Pulse (HEMP) and Its Impact on the U.S. Power Grid." January 2010. Written by Metatech Corporation for Oak Ridge National Laboratory. Appendix: E1 HEMP Myths [http://www.ornl.gov/sci/ees/etsd/pes/pubs/ferc_Meta-R-320.pdf]</ref>&nbsp; Here are some further clarifications on common areas of confusion that have already been discussed (with references) in the above sections of this article:


The United States military services developed, and in some cases published, hypothetical EMP attack scenarios.<ref name="miller">{{cite report |last1=Miller |first1=Colin R. |date=November 2005 |title=Electromagnetic Pulse Threats in 2010 |chapter=Chapter 12 |chapter-url=https://apps.dtic.mil/sti/pdfs/ADA463475.pdf |docket=ADA463475 |pages=385–410 |language=en |location=[[Maxwell Air Force Base]], [[Alabama]] |publisher=Center for Strategy and Technology [[Air War College]], [[Air University (United States Air Force)|Air University]] |via=[[Defense Technical Information Center]] |df=dmy-all |access-date=2022-08-11 |url-status=live |archive-url=https://web.archive.org/web/20220811135601/https://apps.dtic.mil/sti/pdfs/ADA463475.pdf |archive-date=2022-08-11}}</ref>
#Most nuclear weapons effects vary greatly depending upon the altitude of the detonation. This is especially true of nuclear EMP. The standard reference text on nuclear weapon effects published by the U.S. Department of Defense discusses this relationship extensively in the first two chapters, and provides mutually-exclusive definitions for phrases such as "air burst" and "high-altitude burst." <ref>Glasstone, Samuel and Dolan, Philip J., ''The Effects of Nuclear Weapons''. Chapters 1 and 2. United States Department of Defense. 1977. [http://www.princeton.edu/sgs/publications/articles/effects/]</ref> As explained in above sections of this article, nuclear detonations at all altitudes within the Earth's magnetic field will produce an electromagnetic pulse; but the magnitude of the EMP and area that is affected by the EMP are strongly affected by many factors, and is especially strongly dependent upon the altitude of the detonation. (See the discussion above in the [[#Weapon_altitude|"Weapon altitude"]] and [[#Weapon_distance|"Weapon distance"]] sections.)&nbsp; A nuclear explosion in deep space and not in a strong planetary magnetic field would be ineffective at generating EMP.

#EMP is not a new kind of weapon effect. As stated in the [[#History|"History"]] section above, nuclear EMP from a nuclear air burst has been known since 1945. The unique characteristics of high-altitude nuclear EMP have been known since at least 1962. Non-nuclear EMP has been known since at least 1951. Electromagnetic pulse is a prompt ''secondary'' effect of a nuclear explosion, and nearly all of the nuclear EMP is produced outside of the weapon.&nbsp; ''All'' nuclear weapons can produce EMP as a secondary effect, but the effect can be enhanced by special weapon design.<ref name="pry"/><ref name="empc"/>
In 2016, the Los Alamos Laboratory started phase 0 of a multi-year study (through to phase 3) to investigate EMPs which prepared the strategy to be followed for the rest of the study.<ref>{{cite report |last1=Rivera |first1=Michael Kelly |last2=Backhaus |first2=Scott N. |last3=Woodroffe |first3=Jesse Richard |last4=Henderson |first4=Michael Gerard |last5=Bos |first5=Randall J. |last6=Nelson |first6=Eric Michael |last7=Kelic |first7=Andjelka |date=2016-11-07 |title=EMP/GMD Phase 0 Report, A Review of EMP Hazard Environments and Impacts |docket=No. LA-UR-16-28380 |publisher=[[Los Alamos National Laboratory]] |df=dmy-all |url=http://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-16-28380 |access-date=2022-08-11 }}{{Dead link|date=December 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>
#The E3 component of nuclear EMP that produces [[geomagnetically induced currents]] in very long electrical conductors is roughly proportional to the [[nuclear weapon yield|total energy yield]] of the weapon. The other components of nuclear EMP are less likely to be dependent on total energy yield of the weapon. The E1 component, in particular, is proportional to prompt gamma ray output; but EMP levels can be strongly affected if more than one burst of gamma rays occurs in a short time period. Large thermonuclear weapons produce large energy yields through a multi-stage process. This multi-stage process is completed within a small fraction of a second, but it nevertheless requires a finite length of time. The first fission reaction is usually of relatively small yield, and the gamma rays produced by the first stage pre-ionize atmospheric molecules in the [[stratosphere]]. This pre-ionization causes the gamma ray emission from the high-energy final stage of the thermonuclear weapon (a fraction of a second later) to be relatively ineffective at producing a large ''E1'' pulse.<ref name="hasc"/><ref name="empcnir"/> (See the blue pre-ionization curve in the "Peak Electric Field at Ground Zero" graph above.)

#It has long been known that there are many ways to protect against nuclear EMP (or to quickly begin repairs where protection is not practical); but the United States EMP Commission determined that such protections are almost completely absent in the civilian infrastructure of the United States, and that even large sectors of the United States military services were no longer protected against EMP to the level that they were during the Cold War. The public statements of the physicists and engineers working in the EMP field tend to emphasize the importance of making electronic equipment and electrical components resistant to EMP &mdash; and of keeping adequate spare parts on hand, and in the proper location, to enable prompt repairs to be made.<ref name="empc"/><ref name="empcnir"/><ref name="med-emp">Ross, Lenard H., Jr. and Mihelic, F. Matthew, "Healthcare Vulnerabilities to Electromagnetic Pulse," American Journal of Disaster Medicine, Vol. 3, No. 6, pp. 321&ndash;325. November/December 2008. [http://www.disastermedicinejournal.com]</ref> The United States EMP Commission did not look at the civilian infrastructures of other nations.
In 2017, the US Department of Energy published the "DOE Electromagnetic Pulse Resilience Action Plan",<ref name="DOE2017">DOE and partners "[https://www.energy.gov/sites/prod/files/2017/01/f34/DOE%20EMP%20Resilience%20Action%20Plan%20January%202017.pdf DOE Electromagnetic Pulse Resilience Action Plan]" DOE, January 2017</ref> Edwin Boston published a dissertation on the topic<ref>{{cite thesis |last1=Boston, Jr. |first1=Edwin J. |date=2017 |title=Critical Infrastructure Protection: EMP Impacts on the US Electric Grid |type=PhD |publisher=[[Utica College]] |bibcode=2017MsT.........47B |df=dmy-all |isbn=978-0355503470}}</ref> and the EMP Commission published "Assessing the threat from electromagnetic pulse (EMP)".<ref>{{cite report |title=Assessing the Threat from Electromagnetic Pulse (EMP) |volume=I: Executive Report |date=July 2017 |docket= |publisher=Electromagnetic Pulse (EMP) Commission |via=[[Defense Technical Information Center]] |df=dmy-all |url=http://apps.dtic.mil/dtic/tr/fulltext/u2/1051492.pdf |access-date=2022-06-02 |url-status=dead |archive-url=https://web.archive.org/web/20191210011936/http://www.dtic.mil/dtic/tr/fulltext/u2/1051492.pdf |archive-date=2019-12-10}}</ref> The EMP commission was closed in summer 2017.<ref>{{cite report |last1=Pry |first1=Peter Vincent |date=2017-07-01 |title=Life Without Electricity: Storm-Induced Blackouts and Implications for EMP Attack |publisher=Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack |s2cid=217195558 |df=dmy-all |url=http://www.firstempcommission.org/uploads/1/1/9/5/119571849/life_without_electricity_-_final_april2018.pdf |access-date=2022-08-10 |url-status=live |archive-url=https://web.archive.org/web/20220503151723/http://www.firstempcommission.org/uploads/1/1/9/5/119571849/life_without_electricity_-_final_april2018.pdf |archive-date=2022-05-03}}</ref> They found that earlier reports had underestimated the effects of an EMP attack on the national infrastructure, highlighted issues with communications from the DoD due to the classified nature of the material, and recommended that the DHS instead of going to the DOE for guidance and direction should directly cooperate with the more knowledgeable parts of the DOE. Several reports are in process of being released to the general public.<ref>{{cite news |last1=Graham |first1=William |last2=Pry |first2=Peter |date=2018-05-18 |title=Trump's actions have been critical to defending the US against an EMP attack |department=Opinion {{!}} National Security |work=[[The Hill (newspaper)|The Hill]] |issn=1521-1568 |oclc=31153202 |df=dmy-all |url=https://thehill.com/opinion/national-security/387148-trumps-actions-have-been-critical-to-defending-the-us-against-an/ |url-status=live |archive-url=https://web.archive.org/web/20210801234720/https://thehill.com/opinion/national-security/387148-trumps-actions-have-been-critical-to-defending-the-us-against-an/ |archive-date=2021-08-01}}</ref>
#

==Protecting infrastructure==
The problem of protecting civilian infrastructure from electromagnetic pulse has been intensively studied throughout the European Union, and in particular by the United Kingdom.<ref>{{cite report |docket=HC 1552 |publisher=House of Commons Defence Committee |title=Developing Threats: Electro-Magnetic Pulses (EMP) {{!}} Tenth Report of Session 2010–12 |date=2012-02-12 |language=en-gb |df=dmy-all |url=https://publications.parliament.uk/pa/cm201012/cmselect/cmdfence/1552/1552.pdf |access-date=2022-08-11 |url-status=live |archive-url=https://web.archive.org/web/20210318192615/https://publications.parliament.uk/pa/cm201012/cmselect/cmdfence/1552/1552.pdf |archive-date=2021-03-18}}</ref><ref>{{cite web |title=Extreme Electromagnetics – The Triple Threat to Infrastructure |publisher=[[Institution of Engineering and Technology]] |date=2013-01-14 |df=dmy-all |url=http://www.theiet.org/communities/electromagnetics/triple-threat/index.cfm |access-date=2022-08-11 |archive-url=https://web.archive.org/web/20130628040443/http://www.theiet.org/communities/electromagnetics/triple-threat/index.cfm |archive-date=2013-06-28}}</ref><ref>''Nuclear Electromagnetic Pulse: Practical Guide for Protection Critical Infrastructure'' - Lambert Academic Publishing, 2023, 460 p. {{ISBN|978-620-5-63396-0}}</ref>

As of 2017, several [[electric utilities]] in the United States had been involved in a three-year research program on the impact of HEMP to the United States power grid led by an industry non-profit organization, [[Electric Power Research Institute]] (EPRI).<ref>{{cite news |date=2017-09-09 |title=America's utilities prepare for a nuclear threat to the grid |newspaper=[[The Economist]] |language=en |issn=0013-0613 |df=dmy-all |url=https://www.economist.com/business/2017/09/09/americas-utilities-prepare-for-a-nuclear-threat-to-the-grid |url-access=subscription |access-date=2022-08-10 |url-status=live |archive-url=https://web.archive.org/web/20211112063607/https://www.economist.com/business/2017/09/09/americas-utilities-prepare-for-a-nuclear-threat-to-the-grid |archive-date=2021-11-12}}</ref><ref>{{cite report |title=Hearing to examine the threat posed by electromagnetic pulse and policy options to protect energy infrastructure and to improve capabilities for adequate system restoration |format=PDF, MP4 |date=2017-05-04 |website=[[United States Senate Committee on Energy and Natural Resources]] |df=dmy-all |url=https://www.energy.senate.gov/hearings/2017/5/hearing-to-examine-the-threat-posed-by-electromagnetic-pulse-and-policy-options-to-protect-energy-infrastructure-and-to-improve-capabilities-for-adequate-system-restoration |access-date=2017-09-20 |url-status=live |archive-url=https://web.archive.org/web/20220721113356/https://www.energy.senate.gov/hearings/2017/5/hearing-to-examine-the-threat-posed-by-electromagnetic-pulse-and-policy-options-to-protect-energy-infrastructure-and-to-improve-capabilities-for-adequate-system-restoration |archive-date=2022-07-21}}</ref>

In 2018, the US Department of Homeland Security released the Strategy for Protecting and Preparing the Homeland against Threats from Electromagnetic Pulse (EMP) and Geomagnetic Disturbance (GMD), which was the department's first articulation of a holistic, long-term, partnership-based approach to protecting critical infrastructure and preparing to respond and recover from potentially catastrophic electromagnetic incidents.<ref>{{cite press release |date=2022-09-03 |title=DHS Combats Potential Electromagnetic Pulse (EMP) Attack |website=[[United States Department of Homeland Security]] |df=dmy-all |url=https://www.dhs.gov/news/2020/09/03/dhs-combats-potential-electromagnetic-pulse-emp-attack |access-date=2022-08-10 |url-status=live |archive-url=https://web.archive.org/web/20220705081707/https://www.dhs.gov/news/2020/09/03/dhs-combats-potential-electromagnetic-pulse-emp-attack |archive-date=2022-07-05}}</ref><ref>{{cite report |title=Protecting and Preparing the Homeland Against Threats of Electromagnetic Pulse and Geomagnetic Disturbances |date=2018-10-09 |website=[[United States Department of Homeland Security]] |df=dmy-all |url=https://www.dhs.gov/sites/default/files/publications/18_1009_EMP_GMD_Strategy-Non-Embargoed.pdf |access-date=2022-08-11 |url-status=live |archive-url=https://web.archive.org/web/20220804091210/https://www.dhs.gov/sites/default/files/publications/18_1009_EMP_GMD_Strategy-Non-Embargoed.pdf |archive-date=2022-08-04}}</ref> Progress on that front is described in the EMP Program Status Report.<ref>{{cite report |title=Electromagnetic Pulse (EMP) Program Status Report |date=2020-08-17 |website=[[United States Department of Homeland Security]] |df=dmy-all |url=https://www.cisa.gov/sites/default/files/publications/emp-program-status-report_508.pdf |access-date=2022-08-11 |url-status=live |archive-url=https://web.archive.org/web/20220514235315/https://www.cisa.gov/sites/default/files/publications/emp-program-status-report_508.pdf |archive-date=2022-05-14}}</ref>

NuScale, the small modular nuclear reactor company from Oregon, US, has made their reactor resistant to EMP.<ref>{{cite magazine |last1=Conca |first1=James |date=2019-01-03 |title=Can Nuclear Power Plants Resist Attacks Of Electromagnetic Pulse (EMP)? |department=Energy |magazine=[[Forbes]] |language=en-us |issn=0015-6914 |df=dmy-all |url=https://www.forbes.com/sites/jamesconca/2019/01/03/can-nuclear-power-plants-resist-attacks-of-electromagnetic-pulse-emp/ |url-access=limited |access-date=2022-08-10 |url-status=live |archive-url=https://web.archive.org/web/20220805222823/https://www.forbes.com/sites/jamesconca/2019/01/03/can-nuclear-power-plants-resist-attacks-of-electromagnetic-pulse-emp/ |archive-date=2022-08-05}}</ref><ref>{{cite conference |last1=Palmer |first1=Camille |last2=Baker |first2=George |last3=Gilbert |first3=James |date=2018-11-11 |title=NuScale Plant Resiliency to an Electromagnetic Pulse |conference=[[American Nuclear Society|Transactions of the American Nuclear Society]] |volume=119 |pages=949–952 |via=[[NuScale Power]] |df=dmy-all |url=https://www.nuscalepower.com/-/media/Nuscale/Files/Technology/Technical-Publications/nuscale-plant-resiliency-to-an-electromagnetic-pulse.ashx |access-date=2022-08-10 |url-status=live |archive-url=https://web.archive.org/web/20211218190126/https://www.nuscalepower.com/-/media/Nuscale/Files/Technology/Technical-Publications/nuscale-plant-resiliency-to-an-electromagnetic-pulse.ashx |archive-date=2021-12-18}}</ref>

==In fiction and popular culture==

By 1981, a number of articles on nuclear electromagnetic pulse in the [[popular press]] spread knowledge of the nuclear EMP phenomenon into the [[popular culture]].<ref>Raloff, Janet. May 9, 1981. "EMP: A Sleeping Electronic Dragon." Science News. Vol. 119. Page 300</ref><ref>Raloff, Janet. May 16, 1981. "EMP: Defensive Strategies." Science News. Vol. 119. Page 314.</ref><ref>Broad, William J. 1983 January/February. "The Chaos Factor" Science 83. Pages 41-49.</ref><ref>Burnham, David. June 28, 1983. "U.S. Fears One Bomb Could Cripple the Nation." New York Times. Page C1. [https://www.nytimes.com/1983/06/28/science/us-fears-one-bomb-could-cripple-the-nation.html]</ref> EMP has been subsequently used in a wide variety of fiction and other aspects of popular culture.

The popular media often depict EMP effects incorrectly, causing misunderstandings among the public and even professionals, and official efforts have been made in the United States to set the record straight.<ref name="metaR320"/> The [[United States Space Command]] commissioned science educator [[Bill Nye]] to narrate and produce a video called "Hollywood vs. EMP", so that inaccurate Hollywood fiction would not confuse those who must deal with real EMP events.<ref>Air Force Space Command, [https://www.tellyawards.com/winners/2009/filmvideo/non-broadcast-productions-training-for-corporate-use/hollywood-vs-emp/98587 ''Hollywood vs. EMP''], Manitou Motion Picture Company, 2009 (not available to the general public).</ref> The video is not available to the general public.
<!-- Please do not post specific media examples here. If you add them here they will be deleted. -->


==See also==
==See also==
{{Columns-list|colwidth=22em|
{{Portal|Electromagnetism}}
<!--alphabetize! thanks! -->
* [[Directed-energy weapon]] (DEW)
* [[Electromagnetic compatibility]] (EMC)
* [[Electromagnetic environment]]
* [[Electromagnetic environment]]
* [[Electromagnetic hypersensitivity]]
* [[Electromagnetic hypersensitivity]]
* [[Electromagnetic pulse in fiction and popular culture]]
* [[Electromagnetic warfare]]
* [[Electromagnetic weapon]]
* [[Electromagnetism]]
* [[Electromagnetism]]
* [[Electronic warfare]]
* [[Explosively pumped flux compression generator]]
* [[Explosively pumped flux compression generator]]
* [[Faraday's law of induction]]
* [[Faraday's law of induction]]
* [[Gamma ray burst]]
* [[F region]]
* [[Gamma-ray burst]]
* [[Geomagnetic storm]]
* [[Geomagnetic storm]]
* [[High Power Microwave]]
* [[High-altitude nuclear explosion]]
* [[Marx generator]]
* [[Marx generator]]
* [[Nuclear terrorism]]
* [[Operation Fishbowl]]
* [[Operation Fishbowl]]
* [[Pulsed power]]
* [[Pulsed power]]
* [[Soviet Project K nuclear tests]]
* [[Starfish Prime]]
* [[Starfish Prime]]
* [[The K Project]]
* [[Ultrashort pulse]]
* [[Ultrashort pulse]]
}}


==References==
==References==
===Citations===
{{Reflist|2}}
*{{FS1037C MS188}}
{{Reflist}}


===Sources===
== Further reading ==
{{Refbegin}}
* ISBN 978-1-59-248389-1 21st Century Complete Guide to Electromagnetic Pulse (EMP) Attack Threats, Report of the Commission to Assess the Threat to the United States from Electromagnetic ... High-Altitude Nuclear Weapon EMP Attacks (CD-ROM)
* {{FS1037C MS188}}
* ISBN 978-0-16-056127-6 Threat posed by electromagnetic pulse (EMP) to U.S. military systems and civil infrastructure: Hearing before the Military Research and Development Subcommittee ... first session, hearing held July 16, 1997 (Unknown Binding)
* {{cite book |last1=Gurevich |first1=Vladimir |title=Cyber and Electromagnetic Threats in Modern Relay Protection |publisher=[[CRC Press]] |date=2014-12-06 |edition=First |lccn=2015000591 |oclc=913991169 |ol=OL28824950M |via=[[Google Books]] |df=dmy-all |isbn=978-1482264319 |url={{Google books|iTjcBQAAQBAJ|plainurl=yes}} |url-access=limited}}
* ISBN 978-0-471-01403-4 Electromagnetic Pulse Radiation and Protective Techniques
* {{cite book |last1=Gurevich |first1=Vladimir |title=Protection of Substation Critical Equipment Against Intentional Electromagnetic Threats |edition=First |publisher=[[Wiley (publisher)|Wiley]] |language=en |date=2017-03-20 |lccn=2016036747 |oclc=973565748 |ol=OL27417713M |df=dmy-all |isbn=978-1119271437}}
* ISBN 978-0-16-080927-9 Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack
* {{cite book |last1=Gurevich |first1=Vladimir |title=Protecting Electrical Equipment: Good Practices for Preventing High Altitude Electromagnetic Pulse Impacts |publisher=[[De Gruyter]] |language=en |date=2021 |oclc=1090000823 |ol=OL37286906M |df=dmy-all |isbn=978-3110635966 |doi=10.1515/9783110723144 |url=https://www.degruyter.com/document/doi/10.1515/9783110723144/html}}
* {{cite book |last1=Vladimir |first1=Gurevich |title=Nuclear Electromagnetic Pulse: Practical Guide for Protection Critical Infrastructure |publisher=Lambert Academic Publishing |date=2023 |isbn=978-620-5-63396-0}}
{{Refend}}

==Further reading==
{{Refbegin}}
* A 21st Century Complete Guide to Electromagnetic Pulse (EMP) Attack Threats, Report of the commission to Assess the Threat to the United States from Electromagnetic ... High-Altitude Nuclear Weapon EMP Attacks (CD-ROM), {{ISBN|978-1592483891}}
* Threat posed by electromagnetic pulse (EMP) to U.S. military systems and civil infrastructure: Hearing before the Military Research and Development Subcommittee – first session, hearing held July 16, 1997, {{ISBN|978-0160561276}}
* Electromagnetic Pulse Radiation and Protective Techniques, {{ISBN|978-0471014034}}
{{Refend}}


==External links==
==External links==
{{Commons category|Electromagnetic pulse}}
*[http://www.businessinsider.com/gauging-the-threat-of-an-electro-magnetic-pulse-attack-in-the-us-2010-9 Business Insider: Gauging The Threat Of An Electro-Magnetic Pulse Attack In The US]
{{Wiktionary}}
* [http://www.globalsecurity.org/wmd/library/report/1988/CM2.htm GlobalSecurity.org &ndash; Electromagnetic Pulse: From chaos to a manageable solution]
* [https://www.globalsecurity.org/wmd/library/report/1988/CM2.htm GlobalSecurity.org &ndash; Electromagnetic Pulse: From chaos to a manageable solution]
* [http://cryptome.org/emp.htm Electromagnetic Pulse (EMP) and Tempest Protection for Facilities] &ndash; [[U.S. Army Corps of Engineers]]
* [https://web.archive.org/web/19961213134039/http://www.usace.army.mil/inet/usace-docs/eng-pamphlets/ep.htm Electromagnetic Pulse (EMP) and Tempest Protection for Facilities] &ndash; [[U.S. Army Corps of Engineers]]
* [http://glasstone.blogspot.com/2006/03/emp-radiation-from-nuclear-space.html EMP data from ''Starfish'' nuclear test measured by Richard Wakefield of LANL, and review of evidence pertaining to the effects 1,300&nbsp;km away in Hawaii, also review of Russian EMP tests of 1962]
* [https://glasstone.blogspot.com/2006/03/emp-radiation-from-nuclear-space.html EMP data from ''Starfish'' nuclear test measured by Richard Wakefield of LANL, and review of evidence pertaining to the effects 1,300&nbsp;km away in Hawaii, also review of Russian EMP tests of 1962]
* [http://digital.library.unt.edu/govdocs/crs/permalink/meta-crs-6028 Read Congressional Research Service (CRS) Reports regarding HEMP]
* [https://digital.library.unt.edu/ark:/67531/metacrs6028/ Read Congressional Research Service (CRS) Reports regarding HEMP]
* [http://assist.daps.dla.mil/quicksearch/basic_profile.cfm?ident_number=204459 MIL-STD-188-125-1]
* [https://web.archive.org/web/20090125084016/http://assist.daps.dla.mil/quicksearch/basic_profile.cfm?ident_number=204459 MIL-STD-188-125-1]
* [http://unitedstatesaction.com/emp-terror.htm Electromagnetic Pulse Risks & Terrorism]
* [http://science.howstuffworks.com/e-bomb.htm How E-Bombs Work]
* [https://science.howstuffworks.com/e-bomb.htm How Electromagnetic Pulse Attacks Work]
* [http://www.empcommission.org Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack]
* [http://www.empcommission.org Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack]
* [http://economicsnewspaper.com/economics/are-nuclear-power-plants-would-survive-a-nuclear-electromagnetic-pulse-or-a-solar-storm-5181.html NEMP and Nuclear plant]
* [https://web.archive.org/web/20160304070113/http://economicsnewspaper.com/economics/are-nuclear-power-plants-would-survive-a-nuclear-electromagnetic-pulse-or-a-solar-storm-5181.html NEMP and Nuclear plant]
* [https://trumpwhitehouse.archives.gov/presidential-actions/executive-order-coordinating-national-resilience-electromagnetic-pulses/ U.S. Presidential Executive Order concerning EMP]
* [http://www.cs.monash.edu.au/~carlo The Electromagnetic Bomb - a Weapon of Electrical Mass Destruction]
* {{cite book |last1=Gurevich |first1=Vladimir |title=Protecting Electrical Equipment: Good Practices for Preventing High Altitude Electromagnetic Pulse Impacts |publisher=[[De Gruyter]] |language=en |date=2021 |oclc=1090000823 |ol=OL37286906M |df=dmy-all |isbn=978-3110635966 |doi=10.1515/9783110723144 |url=https://www.degruyter.com/document/doi/10.1515/9783110723144/html}}
{{DEFAULTSORT:Electromagnetic Pulse}}

{{Global catastrophic risks}}
{{Authority control}}

{{DEFAULTSORT:Electromagnetic Pulse, Nuclear}}
[[Category:Bombs]]
[[Category:Electromagnetic compatibility]]
[[Category:Electromagnetic radiation]]
[[Category:Electromagnetic radiation]]
[[Category:Electronic warfare]]
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[[Category:Nuclear weapons]]
[[Category:Nuclear weapons]]
[[Category:Electromagnetic compatibility]]
[[Category:Bombs]]
[[Category:Electronic warfare]]
[[Category:Pulsed power]]
[[Category:Pulsed power]]

[[ar:نبضة كهرومغناطيسية]]
[[cs:Elektromagnetický impuls]]
[[da:Elektromagnetisk puls]]
[[de:Elektromagnetischer Puls]]
[[et:Elektromagnetiline impulss]]
[[el:Ηλεκτρομαγνητικός Παλμός]]
[[es:Pulso electromagnético]]
[[fr:Impulsion électromagnétique]]
[[ko:전자기 펄스]]
[[hi:इलेक्ट्रोमैग्नेटिक पल्स]]
[[is:Rafsegulhögg]]
[[it:Impulso elettromagnetico]]
[[he:פצצה אלקטרומגנטית]]
[[kk:Электрмагниттік импульс]]
[[lb:Elektromagnéiteschen Impuls]]
[[ml:വൈദ്യുത കാന്തിക തരംഗം]]
[[nl:Elektromagnetische puls]]
[[ja:電磁パルス]]
[[no:Elektromagnetisk puls]]
[[nn:Elektromagnetisk puls]]
[[pl:Impuls elektromagnetyczny]]
[[pt:Pulso eletromagnético]]
[[ru:Электромагнитный импульс (поражающий фактор)]]
[[simple:Electromagnetic Pulse]]
[[sk:Elektromagnetický impulz]]
[[fi:Sähkömagneettinen pulssi]]
[[sv:Elektromagnetisk puls]]
[[tr:Elektromanyetik atış]]
[[zh:电磁脉冲]]

Latest revision as of 09:17, 16 December 2024

A nuclear electromagnetic pulse (nuclear EMP or NEMP) is a burst of electromagnetic radiation created by a nuclear explosion. The resulting rapidly varying electric and magnetic fields may couple with electrical and electronic systems to produce damaging current and voltage surges. The specific characteristics of a particular nuclear EMP event vary according to a number of factors, the most important of which is the altitude of the detonation.

The term "electromagnetic pulse" generally excludes optical (infrared, visible, ultraviolet) and ionizing (such as X-ray and gamma radiation) ranges. In military terminology, a nuclear warhead detonated tens to hundreds of miles above the Earth's surface is known as a high-altitude electromagnetic pulse (HEMP) device. Effects of a HEMP device depend on factors including the altitude of the detonation, energy yield, gamma ray output, interactions with the Earth's magnetic field and electromagnetic shielding of targets.

History

[edit]

The fact that an electromagnetic pulse is produced by a nuclear explosion was known in the earliest days of nuclear weapons testing. The magnitude of the EMP and the significance of its effects were not immediately realized.[1]

During the first United States nuclear test on 16 July 1945, electronic equipment was shielded because Enrico Fermi expected the electromagnetic pulse. The official technical history for that first nuclear test states, "All signal lines were completely shielded, in many cases doubly shielded. In spite of this many records were lost because of spurious pickup at the time of the explosion that paralyzed the recording equipment."[2]: 53  During British nuclear testing in 1952–53, instrumentation failures were attributed to "radioflash", which was their term for EMP.[3][4]

The first openly reported observation of the unique aspects of high-altitude nuclear EMP occurred during the helium balloon-lofted Yucca nuclear test of the Hardtack I series on 28 April 1958. In that test, the electric field measurements from the 1.7 kiloton weapon exceeded the range to which the test instruments were adjusted and was estimated to be about five times the limits to which the oscilloscopes were set. The Yucca EMP was initially positive-going, whereas low-altitude bursts were negative-going pulses. Also, the polarization of the Yucca EMP signal was horizontal, whereas low-altitude nuclear EMP was vertically polarized. In spite of these many differences, the unique EMP results were dismissed as a possible wave propagation anomaly.[5]

The high-altitude nuclear tests of 1962, as discussed below, confirmed the unique results of the Yucca high-altitude test and increased the awareness of high-altitude nuclear EMP beyond the original group of defense scientists. The larger scientific community became aware of the significance of the EMP problem after a three-article series on nuclear EMP was published in 1981 by William J. Broad in Science.[1][6][7]

Starfish Prime

[edit]

In July 1962, the US carried out the Starfish Prime test, exploding a 1.44 Mt (6.0 PJ) bomb 400 kilometres (250 mi; 1,300,000 ft) above the mid-Pacific Ocean. This demonstrated that the effects of a high-altitude nuclear explosion were much larger than had been previously calculated. Starfish Prime made those effects known to the public by causing electrical damage in Hawaii, about 1,445 kilometres (898 mi) away from the detonation point, disabling approximately 300 streetlights, triggering numerous burglar alarms and damaging a microwave link.[8]

Starfish Prime was the first success in the series of United States high-altitude nuclear tests in 1962 known as Operation Fishbowl. Subsequent tests gathered more data on the high-altitude EMP phenomenon.

The Bluegill Triple Prime and Kingfish high-altitude nuclear tests of October and November 1962 in Operation Fishbowl provided data that was clear enough to enable physicists to accurately identify the physical mechanisms behind the electromagnetic pulses.[9]

The EMP damage of the Starfish Prime test was quickly repaired due, in part, to the fact that the EMP over Hawaii was relatively weak compared to what could be produced with a more intense pulse, and in part due to the relative ruggedness (compared to today)[10] of Hawaii's electrical and electronic infrastructure in 1962.[11]

The relatively small magnitude of the Starfish Prime EMP in Hawaii (about 5.6 kilovolts/metre) and the relatively small amount of damage (for example, only 1% to 3% of streetlights extinguished)[12] led some scientists to believe, in the early days of EMP research, that the problem might not be significant. Later calculations[11] showed that if the Starfish Prime warhead had been detonated over the northern continental United States, the magnitude of the EMP would have been much larger (22 to 30 kV/m) because of the greater strength of the Earth's magnetic field over the United States, as well as its different orientation at high latitudes. These calculations, combined with the accelerating reliance on EMP-sensitive microelectronics, heightened awareness that EMP could be a significant problem.[13]

Soviet Test 184

[edit]

In 1962, the Soviet Union performed three EMP-producing nuclear tests in space over Kazakhstan, the last in the "Soviet Project K nuclear tests".[14] Although these weapons were much smaller (300 kiloton) than the Starfish Prime test, they were over a populated, large landmass and at a location where the Earth's magnetic field was greater. The damage caused by the resulting EMP was reportedly much greater than in Starfish Prime. The geomagnetic storm–like E3 pulse from Test 184 induced a current surge in a long underground power line that caused a fire in the power plant in the city of Karaganda.[citation needed]

After the dissolution of the Soviet Union, the level of this damage was communicated informally to US scientists.[15] For a few years US and Russian scientists collaborated on the HEMP phenomenon. Funding was secured to enable Russian scientists to report on some of the Soviet EMP results in international scientific journals.[16] As a result, formal documentation of some of the EMP damage in Kazakhstan exists, although it is still sparse in the open-scientific literature.[17][18]

For one of the K Project tests, Soviet scientists instrumented a 570-kilometer (350 mi) section of telephone line in the area that they expected to be affected by the pulse. The monitored telephone line was divided into sub-lines of 40 to 80 kilometres (25 to 50 mi) in length, separated by repeaters. Each sub-line was protected by fuses and by gas-filled overvoltage protectors. The EMP from the 22 October (K-3) nuclear test (also known as Test 184) blew all of the fuses and destroyed all of the overvoltage protectors in all of the sub-lines.[17] Published reports, including a 1998 IEEE article,[17] have stated that there were significant problems with ceramic insulators on overhead electrical power lines during the tests. A 2010 technical report written for Oak Ridge National Laboratory stated that "Power line insulators were damaged, resulting in a short circuit on the line and some lines detaching from the poles and falling to the ground".[19]

Characteristics

[edit]

Nuclear EMP is a complex multi-pulse, usually described in terms of three components, as defined by the International Electrotechnical Commission (IEC).[20]

The three components of nuclear EMP, as defined by the IEC, are called "E1", "E2", and "E3".[20][21]

The three categories of high-altitude EMP are divided according to the time duration and occurrence of each pulse. E1 is the fastest or "early time" high-altitude EMP. Traditionally, the term "EMP" often refers specifically to this E1 component of high-altitude electromagnetic pulse.[22]

The E2 and E3 pulses are often further subdivided into additional divisions according to causation. E2 is a much lower intensity "intermediate time" EMP, which is further divided into E2A (scattered gamma EMP) and E2B (neutron gamma EMP).[22]

E3 is a very long-duration "late time" pulse, which is extremely slow in rise and fall times compared to the other components of EMP.[22] E3 is further divided into E3A (blast wave) and E3B (heave).[22] E3 is also called magnetohydrodynamic EMP.[22]

E1

[edit]

The E1 pulse is a very fast component of nuclear EMP. E1 is a brief but intense electromagnetic field that induces high voltages in electrical conductors. E1 causes most of its damage by causing electrical breakdown voltages to be exceeded. E1 can destroy computers and communications equipment and it changes too quickly (nanoseconds) for ordinary surge protectors to provide effective protection from it. Fast-acting surge protectors (such as those using TVS diodes) will block the E1 pulse.

The mechanism for a 400-kilometre-high (250 mi; 1,300,000 ft) burst EMP: gamma rays hit the atmosphere between 20–40 km (66,000–131,000 ft) altitude, ejecting electrons which are then deflected sideways by the Earth's magnetic field. This makes the electrons radiate EMP over a large area. Because of the curvature and downward tilt of Earth's magnetic field over the US, the maximum EMP occurs south of the detonation and the minimum occurs to the north.[23]

E1 is produced when gamma radiation from the nuclear detonation ionizes (strips electrons from) atoms in the upper atmosphere. This is known as the Compton effect and the resulting current is called the "Compton current". The electrons travel in a generally downward direction at relativistic speeds (more than 90 percent of the speed of light). In the absence of a magnetic field, this would produce a large, radial pulse of electric current propagating outward from the burst location confined to the source region (the region over which the gamma photons are attenuated). The Earth's magnetic field exerts a force on the electron flow at a right angle to both the field and the particles' original vector, which deflects the electrons and leads to synchrotron radiation. Because the outward traveling gamma pulse is propagating at the speed of light, the synchrotron radiation of the Compton electrons adds coherently, leading to a radiated electromagnetic signal. This interaction produces a large, brief, pulse.[24]

Several physicists worked on the problem of identifying the mechanism of the HEMP E1 pulse. The mechanism was finally identified by Conrad Longmire of Los Alamos National Laboratory in 1963.[9]

Longmire gives numerical values for a typical case of E1 pulse produced by a second-generation nuclear weapon such as those of Operation Fishbowl. The typical gamma rays given off by the weapon have an energy of about 2 MeV (mega electron-volts). The gamma rays transfer about half of their energy to the ejected free electrons, giving an energy of about 1 MeV.[24]

In a vacuum and absent a magnetic field, the electrons would travel with a current density of tens of amperes per square metre.[24] Because of the downward tilt of the Earth's magnetic field at high latitudes, the area of peak field strength is a U-shaped region to the equatorial side of the detonation. As shown in the diagram, for nuclear detonations in the Northern Hemisphere, this U-shaped region is south of the detonation point. Near the equator, where the Earth's magnetic field is more nearly horizontal, the E1 field strength is more nearly symmetrical around the burst location.[citation needed]

At geomagnetic field strengths typical of the mid-latitudes, these initial electrons spiral around the magnetic field lines with a typical radius of about 85 metres (280 ft). These initial electrons are stopped by collisions with air molecules at an average distance of about 170 metres (560 ft). This means that most of the electrons are stopped by collisions with air molecules before completing a full spiral around the field lines.[24]

This interaction of the negatively charged electrons with the magnetic field radiates a pulse of electromagnetic energy. The pulse typically rises to its peak value in some five nanoseconds. Its magnitude typically decays by half within 200 nanoseconds. (By the IEC definition, this E1 pulse ends 1000 nanoseconds after it begins.) This process occurs simultaneously on about 1025 electrons.[24]  The simultaneous action of the electrons causes the resulting pulse from each electron to radiate coherently, adding to produce a single large-amplitude, short-duration, radiated pulse.[25]

Secondary collisions cause subsequent electrons to lose energy before they reach ground level. The electrons generated by these subsequent collisions have so little energy that they do not contribute significantly to the E1 pulse.[24]

These 2 MeV gamma rays typically produce an E1 pulse near ground level at moderately high latitudes that peaks at about 50,000 volts per metre. The ionization process in the mid-stratosphere causes this region to become an electrical conductor, a process that blocks the production of further electromagnetic signals and causes the field strength to saturate at about 50,000 volts per metre. The strength of the E1 pulse depends upon the number and intensity of the gamma rays and upon the rapidity of the gamma-ray burst. Strength is also somewhat dependent upon altitude.[citation needed]

There are reports of "super-EMP" nuclear weapons that are able to exceed the 50,000 volts per metre limit by unspecified mechanisms. The reality and possible construction details of these weapons are classified and are, therefore, unconfirmed in the open scientific literature[26]: 3 

E2

[edit]

The E2 component is generated by scattered gamma rays and inelastic gammas produced by neutrons. This E2 component is an "intermediate time" pulse that, by IEC definition, lasts from about one microsecond to one second after the explosion. E2 has many similarities to lightning, although lightning-induced E2 may be considerably larger than a nuclear E2. Because of the similarities and the widespread use of lightning protection technology, E2 is generally considered to be the easiest to protect against.[21]

According to the United States EMP Commission, the main problem with E2 is that it immediately follows E1, which may have damaged the devices that would normally protect against E2.

The EMP Commission Executive Report of 2004 states, "In general, it would not be an issue for critical infrastructure systems since they have existing protective measures for defense against occasional lightning strikes. The most significant risk is synergistic because the E2 component follows a small fraction of a second after the first component's insult, which has the ability to impair or destroy many protective and control features. The energy associated with the second component thus may be allowed to pass into and damage systems."[21]: 6 

E3

[edit]

The E3 component is different from E1 and E2. E3 is a much slower pulse, lasting tens to hundreds of seconds. It is caused by the nuclear detonation's temporary distortion of the Earth's magnetic field. The E3 component has similarities to a geomagnetic storm.[27][21] Like a geomagnetic storm, E3 can produce geomagnetically induced currents in long electrical conductors, damaging components such as power line transformers.[28]

Because of the similarity between solar-induced geomagnetic storms and nuclear E3, it has become common to refer to solar-induced geomagnetic storms as "Solar EMP".[29] "Solar EMP" does not include E1 or E2 components.[30]

Generation

[edit]

Factors that control weapon effectiveness include altitude, yield, construction details, target distance, intervening geographical features, and local strength of the Earth's magnetic field.

Weapon altitude

[edit]
How the peak EMP on the ground varies with the weapon yield and burst altitude. The yield here is the prompt gamma ray output measured in kilotons. This varies from 0.115 to 0.5% of the total weapon yield, depending on weapon design. The 1.4 Mt total yield 1962 Starfish Prime test had a gamma output of 0.1%, hence 1.4 kt of prompt gamma rays (the blue 'pre-ionisation' curve applies to certain types of thermonuclear weapons, for which gamma and X-rays from the primary fission stage ionize the atmosphere and make it electrically conductive before the main pulse from the thermonuclear stage. The pre-ionisation in some situations can literally short out part of the final EMP, by allowing a conduction current to immediately oppose the Compton current of electrons).[31][32]

According to an internet primer published by the Federation of American Scientists:[33]

A high-altitude nuclear detonation produces an immediate flux of gamma rays from the nuclear reactions within the device. These photons in turn produce high energy free electrons by Compton scattering at altitudes between (roughly) 20 and 40 km. These electrons are then trapped in the Earth's magnetic field, giving rise to an oscillating electric current. This current is asymmetric in general and gives rise to a rapidly rising radiated electromagnetic field called an electromagnetic pulse (EMP). Because the electrons are trapped essentially simultaneously, a very large electromagnetic source radiates coherently.
The pulse can easily span continent-sized areas, and this radiation can affect systems on land, sea, and air. ... A large device detonated at 400–500 km (250 to 312 miles) over Kansas would affect all of the continental U.S. The signal from such an event extends to the visual horizon as seen from the burst point.

Thus, for equipment to be affected, the weapon needs to be above the visual horizon.[33]

The altitude indicated above is greater than that of the International Space Station and many low Earth orbit satellites. Large weapons could have a dramatic impact on satellite operations and communications such as occurred during Operation Fishbowl. The damaging effects on orbiting satellites are usually due to factors other than EMP. In the Starfish Prime nuclear test, most damage was to the satellites' solar panels while passing through radiation belts created by the explosion.[34]

For detonations within the atmosphere, the situation is more complex. Within the range of gamma ray deposition, simple laws no longer hold as the air is ionized and there are other EMP effects, such as a radial electric field due to the separation of Compton electrons from air molecules, together with other complex phenomena. For a surface burst, absorption of gamma rays by air would limit the range of gamma-ray deposition to approximately 16 kilometres (10 mi), while for a burst in the lower-density air at high altitudes, the range of deposition would be far greater.[citation needed]

Weapon yield

[edit]

Typical nuclear weapon yields used during Cold War planning for EMP attacks were in the range of 1 to 10 Mt (4.2 to 41.8 PJ).[35]: 39  This is roughly 50 to 500 times the size of the Hiroshima and Nagasaki bombs. Physicists have testified at United States Congressional hearings that weapons with yields of 10 kt (42 TJ) or less can produce a large EMP.[36]: 48 

The EMP at a fixed distance from an explosion increases at most as the square root of the yield (see the illustration to the right). This means that although a 10 kt (42 TJ) weapon has only 0.7% of the energy release of the 1.44 Mt (6.0 PJ) Starfish Prime test, the EMP will be at least 8% as powerful. Since the E1 component of nuclear EMP depends on the prompt gamma-ray output, which was only 0.1% of yield in Starfish Prime but can be 0.5% of yield in low-yield pure nuclear fission weapons, a 10 kt (42 TJ) bomb can easily be 5 * 8%=40% as powerful as the 1.44 Mt (6.0 PJ) Starfish Prime at producing EMP.[37][unreliable source?]

The total prompt gamma-ray energy in a fission explosion is 3.5% of the yield, but in a 10 kt (42 TJ) detonation the triggering explosive around the bomb core absorbs about 85% of the prompt gamma rays, so the output is only about 0.5% of the yield. In the thermonuclear Starfish Prime the fission yield was less than 100% and the thicker outer casing absorbed about 95% of the prompt gamma rays from the pusher around the fusion stage. Thermonuclear weapons are also less efficient at producing EMP because the first stage can pre-ionize the air[37][unreliable source?] which becomes conductive and hence rapidly shorts out the Compton currents generated by the fusion stage. Hence, small pure fission weapons with thin cases are far more efficient at causing EMP than most megaton bombs.[citation needed]

This analysis, however, only applies to the fast E1 and E2 components of nuclear EMP. The geomagnetic storm-like E3 component of nuclear EMP is more closely proportional to the total energy yield of the weapon.[38]

Target distance

[edit]

In nuclear EMP all of the components of the electromagnetic pulse are generated outside of the weapon.[33]

For high-altitude nuclear explosions, much of the EMP is generated far from the detonation (where the gamma radiation from the explosion hits the upper atmosphere). This electric field from the EMP is remarkably uniform over the large area affected.[32]

According to the standard reference text on nuclear weapons effects published by the U.S. Department of Defense, "The peak electric field (and its amplitude) at the Earth's surface from a high-altitude burst will depend upon the explosion yield, the height of the burst, the location of the observer, and the orientation with respect to the geomagnetic field. As a general rule, however, the field strength may be expected to be tens of kilovolts per metre over most of the area receiving the EMP radiation."[32]

The text also states that, "... over most of the area affected by the EMP the electric field strength on the ground would exceed 0.5Emax. For yields of less than a few hundred kilotons, this would not necessarily be true because the field strength at the Earth's tangent could be substantially less than 0.5Emax."[32]

(Emax refers to the maximum electric field strength in the affected area.)

In other words, the electric field strength in the entire area that is affected by the EMP will be fairly uniform for weapons with a large gamma-ray output. For smaller weapons, the electric field may fall at a faster rate as distance increases.[32]

Super-EMP

[edit]

Also known as an "Enhanced-EMP", a super-electromagnetic pulse is a relatively new type of warfare in which a nuclear weapon is designed to create a far greater electromagnetic pulse in comparison to standard nuclear weapons of mass destruction.[39] These weapons capitalize on the E1 pulse component of a detonation involving gamma rays, creating an EMP yield of potentially up to 200,000 volts per meter.[40] For decades, numerous countries have experimented with the creation of such weapons, most notably China and Russia.

China

[edit]

According to a statement made in writing by the Chinese military, the country has super-EMPs and has discussed their use in attacking Taiwan. Such an attack would debilitate information systems in the nation, allowing China to move in and attack it directly using soldiers. The Taiwanese military has subsequently confirmed Chinese possession of super-EMPs and their possible destruction to power grids.[41]

In addition to Taiwan, the possible implications of attacking the United States with these weapons was examined by China. While the United States also possesses nuclear weapons, the country has not experimented with super-EMPs and is hypothetically highly vulnerable to any future attacks by nations. This is due to the country's reliance on computers to control much of the government and economy.[40] Abroad, U.S. aircraft carriers stationed within a reasonable range of an exploding bomb could potentially be subject to complete destruction of missiles on board, as well as telecommunication systems that would allow them to communicate with nearby vessels and controllers on land.[41]

Russia

[edit]

Since the Cold War, Russia has experimented with the design and effects of EMP bombs.

The Soviet Union designed a system to deliver nuclear weapons from above the Earth's atmosphere.[42] and proposals have been made by Russia to develop satellites supplied with EMP capabilities[citation needed]. This would call for detonations up to 100 kilometres (62 mi) above the Earth's surface, with the potential to disrupt the electronic systems of U.S. satellites suspended in orbit around the planet, many of which are vital for deterrence and alerting the country of possible incoming missiles.[40]

Effects

[edit]

An energetic EMP can temporarily upset or permanently damage electronic equipment by generating high voltage and high current surges; semiconductor components are particularly at risk. The effects of damage can range from imperceptible to the eye, to devices blowing apart. Cables, even if short, can act as antennas to transmit pulse energy to the equipment.[43]

Vacuum tube vs. solid-state electronics

[edit]

Older, vacuum tube (valve)-based equipment is generally much less vulnerable to nuclear EMP than solid-state equipment, which is much more susceptible to damage by large, brief voltage and current surges. Soviet Cold War-era military aircraft often had avionics based on vacuum tubes because solid-state capabilities were limited and vacuum-tube gear was believed to be more likely to survive.[1]

Other components in vacuum tube circuitry can be damaged by EMP. Vacuum tube equipment was damaged in the 1962 testing.[18] The solid-state PRC-77 VHF manpackable two-way radio survived extensive EMP testing.[44] The earlier PRC-25, nearly identical except for a vacuum tube final amplification stage, was tested in EMP simulators, but was not certified to remain fully functional.[citation needed]

Electronics in operation vs. inactive

[edit]

Equipment that is running at the time of an EMP is more vulnerable. Even a low-energy pulse has access to the power source, and all parts of the system are illuminated by the pulse. For example, a high-current arcing path may be created across the power supply, burning out some device along that path. Such effects are hard to predict and require testing to assess potential vulnerabilities.[43]

On aircraft

[edit]

Many nuclear detonations have taken place using aerial bombs. The B-29 aircraft that delivered the nuclear weapons at Hiroshima and Nagasaki did not lose power from electrical damage, because electrons (ejected from the air by gamma rays) are stopped quickly in normal air for bursts below roughly 10 kilometres (33,000 ft), so they are not significantly deflected by the Earth's magnetic field.[32]: 517 

If the aircraft carrying the Hiroshima and Nagasaki bombs had been within the intense nuclear radiation zone when the bombs exploded over those cities, then they would have suffered effects from the charge separation (radial) EMP. But this only occurs within the severe blast radius for detonations below about 33,000 feet (10 km) altitude.[citation needed]

During Operation Fishbowl, EMP disruptions were suffered aboard a KC-135 photographic aircraft flying 300 km (190 mi) from the 410 kt (1,700 TJ) detonations at 48 and 95 km (157,000 and 312,000 ft) burst altitudes.[37] The vital electronics were less sophisticated than today's and the aircraft was able to land safely.[citation needed]

Modern aircraft are heavily reliant on solid-state electronics which are very susceptible to EMP blasts. Therefore, airline authorities are creating high intensity radiated fields (HIRF) requirements for new air planes to help prevent the chance of crashes caused by EMPs or electromagnetic interference (EMI).[45] To do this all parts of the airplane must be conductive. This is the main shield from EMP blasts as long as there are no holes for the waves to penetrate into the interior of the airplane. Also, insulating some of the main computers inside the plane adds an extra layer of protection from EMP blasts.[citation needed]

On cars

[edit]

An EMP would probably not affect most cars, despite modern cars' heavy use of electronics, because cars' electronic circuits and cabling are likely too short to be affected. In addition, cars' metallic frames provide some protection. However, even a small percentage of cars breaking down due to an electronic malfunction would cause traffic jams.[43]

On small electronics

[edit]

An EMP has a smaller effect on shorter lengths of an electrical conductor. Other factors affect the vulnerability of electronics as well, so no hard cutoff length determines whether some piece of equipment will survive. However, small electronic devices, such as wristwatches and cell phones, would most likely withstand an EMP.[43]

On humans and animals

[edit]

Though electric potential difference can accumulate in electrical conductors after an EMP, it will generally not flow out into human or animal bodies, and thus contact is safe.[43]

EMPs of sufficient magnitude and length have the potential to affect the human body. Possible side effects include cellular mutations, nervous system damages, internal burns, brain damage, and temporary problems with thinking and memory.[46] However, this would be in extreme cases like being near the center of the blast and being exposed to a large amount of radiation and EMP waves.

A study found that exposure to 200–400 pulses of EMP caused the leaking of vessels in the brain,[47] leakage that has been linked to small problems with thinking and memory recollection. These effects could last up to 12 hours after the exposure. Due to the long exposure time needed to see any of these effects it is unlikely that anyone would see these effects even if exposed for a small period of time. Also, the human body will see little effect as signals are passed chemically and not electrically making it hard to be affected by EMP waves.[citation needed]

Indirect effects on agriculture

[edit]

In addition to these direct effects, it has also been estimated that the disruption caused by the NEMP would have large negative effects on agriculture, due to the disruption of supply chains for agricultural inputs like fertilizers and pesticides. This could reduce yields in highly industrialized agricultural regions like Central Europe by up to 75 %.[48]

Post–Cold War attack scenarios

[edit]

The United States EMP Commission was created by the United States Congress in 2001. The commission is formally known as the commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack.[49]

The Commission brought together notable scientists and technologists to compile several reports. In 2008, the Commission released the "Critical National Infrastructures Report".[38] This report describes the likely consequences of a nuclear EMP on civilian infrastructure. Although this report covered the United States, most of the information is applicable to other industrialized countries. The 2008 report was a follow-up to a more generalized report issued by the commission in 2004.[21]

In written testimony delivered to the United States Senate in 2005, an EMP Commission staff member reported:

The EMP Commission sponsored a worldwide survey of foreign scientific and military literature to evaluate the knowledge, and possibly the intentions, of foreign states with respect to electromagnetic pulse (EMP) attacks. The survey found that the physics of the EMP phenomenon and the military potential of an EMP attack is widely understood in the international community, as reflected in official and unofficial writings and statements. The survey of open sources over the past decade finds that knowledge about EMP and EMP attacks is evidenced in at least Britain, France, Germany, Israel, Egypt, Taiwan, Sweden, Cuba, India, Pakistan, Iraq under Saddam Hussein, Iran, North Korea, China, and Russia.

Many foreign analysts – particularly in Iran, North Korea, China, and Russia – view the United States as a potential aggressor that would be willing to use its entire panoply of weapons, including nuclear weapons, in a first strike. They perceive the United States as having contingency plans to make a nuclear EMP attack, and as being willing to execute those plans under a broad range of circumstances.

Russian and Chinese military scientists in open source writings describe the basic principles of nuclear weapons designed specifically to generate an enhanced-EMP effect, which they term "Super-EMP" weapons. "Super-EMP" weapons, according to these foreign open source writings, can destroy even the best protected U.S. military and civilian electronic systems.[26]

The United States EMP Commission determined that long-known protections are almost completely absent in the civilian infrastructure of the United States and that large parts of US military services were less-protected against EMP than during the Cold War. In public statements, the Commission recommended making electronic equipment and electrical components resistant to EMP – and maintaining spare parts inventories that would enable prompt repairs.[21][38][50] The United States EMP Commission did not look at other nations.[citation needed]

In 2011, the Defense Science Board published a report about the ongoing efforts to defend critical military and civilian systems against EMP and other nuclear weapons effects.[51]

The United States military services developed, and in some cases published, hypothetical EMP attack scenarios.[52]

In 2016, the Los Alamos Laboratory started phase 0 of a multi-year study (through to phase 3) to investigate EMPs which prepared the strategy to be followed for the rest of the study.[53]

In 2017, the US Department of Energy published the "DOE Electromagnetic Pulse Resilience Action Plan",[54] Edwin Boston published a dissertation on the topic[55] and the EMP Commission published "Assessing the threat from electromagnetic pulse (EMP)".[56] The EMP commission was closed in summer 2017.[57] They found that earlier reports had underestimated the effects of an EMP attack on the national infrastructure, highlighted issues with communications from the DoD due to the classified nature of the material, and recommended that the DHS instead of going to the DOE for guidance and direction should directly cooperate with the more knowledgeable parts of the DOE. Several reports are in process of being released to the general public.[58]

Protecting infrastructure

[edit]

The problem of protecting civilian infrastructure from electromagnetic pulse has been intensively studied throughout the European Union, and in particular by the United Kingdom.[59][60][61]

As of 2017, several electric utilities in the United States had been involved in a three-year research program on the impact of HEMP to the United States power grid led by an industry non-profit organization, Electric Power Research Institute (EPRI).[62][63]

In 2018, the US Department of Homeland Security released the Strategy for Protecting and Preparing the Homeland against Threats from Electromagnetic Pulse (EMP) and Geomagnetic Disturbance (GMD), which was the department's first articulation of a holistic, long-term, partnership-based approach to protecting critical infrastructure and preparing to respond and recover from potentially catastrophic electromagnetic incidents.[64][65] Progress on that front is described in the EMP Program Status Report.[66]

NuScale, the small modular nuclear reactor company from Oregon, US, has made their reactor resistant to EMP.[67][68]

[edit]

By 1981, a number of articles on nuclear electromagnetic pulse in the popular press spread knowledge of the nuclear EMP phenomenon into the popular culture.[69][70][71][72] EMP has been subsequently used in a wide variety of fiction and other aspects of popular culture.

The popular media often depict EMP effects incorrectly, causing misunderstandings among the public and even professionals, and official efforts have been made in the United States to set the record straight.[43] The United States Space Command commissioned science educator Bill Nye to narrate and produce a video called "Hollywood vs. EMP", so that inaccurate Hollywood fiction would not confuse those who must deal with real EMP events.[73] The video is not available to the general public.

See also

[edit]

References

[edit]

Citations

[edit]
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  2. ^ Bainbridge, K. T. (May 1976). Trinity (PDF) (Report). Los Alamos Scientific Laboratory. p. 53. LA-6300-H. Archived (PDF) from the original on 9 October 2021. Retrieved 10 August 2022 – via Federation of American Scientists.
  3. ^ Baum, Carl E. (May 2007). "Reminiscences of High-Power Electromagnetics". IEEE Transactions on Electromagnetic Compatibility. 49 (2): 211–218. doi:10.1109/TEMC.2007.897147. eISSN 1558-187X. ISSN 0018-9375. JSTOR 1685783. LCCN sn78000466. S2CID 22495327.
  4. ^ Baum, Carl E. (June 1992). "From the electromagnetic pulse to high-power electromagnetics". Proceedings of the IEEE. 80 (6): 789–817. doi:10.1109/5.149443. ISSN 0018-9219. LCCN 86645263. OCLC 807623131.
  5. ^ Defense Atomic Support Agency. 23 September 1959. "Operation Hardtack Preliminary Report. Technical Summary of Military Effects Archived 2013-06-20 at the Wayback Machine. Report ADA369152". pp. 346–350.
  6. ^ Broad, William J. (5 June 1981). "Nuclear Pulse (II): Ensuring Delivery of the Doomsday Signal". Science. 212 (4499): 1116–1120. Bibcode:1981Sci...212.1116B. doi:10.1126/science.212.4499.1116. eISSN 1095-9203. ISSN 0036-8075. JSTOR 1685373. LCCN 17024346. OCLC 1644869. PMID 17815204.
  7. ^ Broad, William J. (12 June 1981). "Nuclear Pulse (III): Playing a Wild Card". Science. 212 (4500): 1248–1251. Bibcode:1981Sci...212.1248B. doi:10.1126/science.212.4500.1248. eISSN 1095-9203. ISSN 0036-8075. JSTOR 1685783. LCCN 17024346. OCLC 1644869. PMID 17738820.
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  35. ^ Committee on National Security | Military Research and Development Subcommittee (16 July 1997). THREAT POSED BY ELECTROMAGNETIC PULSE (EMP) TO U.S. MILITARY SYSTEMS AND CIVIL INFRASTRUCTURE (Transcript). Washington, D.C.: United States House of Representatives | 105th United States Congress. p. 39. H.S.N.C No. 105–18. Archived from the original on 11 August 2022. Retrieved 11 August 2022.
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Sources

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Further reading

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  • A 21st Century Complete Guide to Electromagnetic Pulse (EMP) Attack Threats, Report of the commission to Assess the Threat to the United States from Electromagnetic ... High-Altitude Nuclear Weapon EMP Attacks (CD-ROM), ISBN 978-1592483891
  • Threat posed by electromagnetic pulse (EMP) to U.S. military systems and civil infrastructure: Hearing before the Military Research and Development Subcommittee – first session, hearing held July 16, 1997, ISBN 978-0160561276
  • Electromagnetic Pulse Radiation and Protective Techniques, ISBN 978-0471014034
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