User:Yousaf hashmi

   The best defination of plasma is partially ionized gas containing equal number of postive and negative charges that behave in a collective way because of attractive and repelling electric forces. When solid is heated on a very high temperature solid melted down to form liquid after that liquid heated to boiling point then liquid convert in to gas and when gas is heated to most high temperature then atoms collide each other's and electron go outside of the wall formed plasma, which is the fourth state of matter. Separation between ions and electrons creates electric field in plasma and movement of charges creates current and magnetic field1. It is believed that 99% of the matter in the visible universe is in the plasma state and we live in 1% of the universe where plasma does not exist [2]. About 84 years ago Tonks and Langmuir (1929) first invented the term `plasma' to describe the inner region of a glowing ionized gas produced by means of an electric discharge in a tube [3]. Plasma not exist only in electron-ion form, it also exist or coexist with charged dust particulates. Dusty plasma is formed by mixture of such charged dust, ions, electrons and neutral particles. In the last two decades, the electron-positron plasma, electron-positron-ion plasma, quark-gluon plasma have also been studied extensively. Quantum effects become dominant for high density regime of plasma where the average interparticle distance is equal or less than the thermal de Broglie wavelength of the charged particles. We called this plasma degenerate or quantum plasma. The plasma environments where relativistic corrections to particle's mass and velocity become important and the particle speed is greater than 0.86c, and plasma is called relativistic plasma. Plasma is made in laboratory a small amount of gas is heated and ionized by driving electric current through it or by using light wave in to it. Plasma is a very good conductor of electricity and it is also affected by magnetic field and it has indefinite shape. it is common state of matter.
   

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   Naturally plasma exist in astrometry and space like solar and stellar winds, ionospheres, aurora and magnetospheres of planets, stars,shocks,coronal mass ejections, solar atmosphere, flux ropes, pulsars's magnetosphere, intergalactic medium, interstellar medium, astrophysical jets, Ball lightning and lightning etc. Fluorescent Lights, arcs, Spark gaps, Controlled Fusion welding, lighting, , plasma lenses for particle accelerators, Plasma discharge pumped lasers are the examples of the occurrence of plasmas on the earth.
   There are manny application of plasma in different fields and areas that are given below.
   In material fabrication, arc plasma processing, semiconductor processing, plasma chemistry and surface modification thermal and chemical energy of plasmas is used.
   In magneto-hydrodynamic (MHD) power generation and propulsion in space kinetic energy of plasmas is used to control the position and orientation of spacecraft.
   The emitted electromagnetic waves from plasmas are used in laser pumping, light sources
   and in plasma display panels.
   Controlled thermonuclear fusion is another example of plasma . Manny energy sources on the Earth surface are exactly and non-exactly connected to the sun. Fusion of light elements gives energy to all stars including sun. Producing the energy of a star on Earth aimed by researchers in 1940. By chance the first hope of this research came in the form of Hydrogen bomb . Since that time, reseachers started genration from thermonuclear fusion peacefully. This ultimate energy source for the human race is expected to be realized within a generation with great efforts of time.

Brief History of Plasma

   There is transparent liquid after when blood is cleared of it,s corpuscles which was named plasma (after the Greek word which mean moldable substance or jelly Greek word is πλασµα), and the scientist name is Johannes Purkinje and Czech medical scientist (1787-1869). Irving Langmuir was a american chemist who first describe an ionized gas by using plasma term in 1927. Langmuir reported that red and white corpuscles carried by the blood plasma by the way an electrons and ions carried by electrified fluid. He is also investigating the chemistry and physics of the tungsten filament bulb and with a view to extend the lifetime of the filament, that investigation was achieved with his friend colleague LewiTonks. the boundary layers which form between ionized plasmas and solid surfaces this boundary layers is called plasma sheaths this theory was developed by Langumir. He also discovered the Langmuir waves in which certain regions of a plasma discharge tube exhibit periodic variations of the electron density. After Langmuir this field spread in other direction in which five are important.
   Firstly,the discovery Earth's ionosphere led by the development of radio broadcasting which is a layer of partially ionized gas in the upper atmosphere which reflects radio waves, and because of it radio signals can be received when the transmitter is over the horizon.
   Secondly it is recognized by the astrophysicsts that alot of universe consist of plasmas. Hannes Alfven was the pioneer of this field, he nearby 1940 devloped a theory magnetohydradynamic or MHD in which plasma treated as conducting fluids. This theory is used to investigate the solar flares, sunspots, star formation, solar wind and other topic in astrophysics. Magnetic reconnection and Dynamo theory are the two topics of particular interest in MHD theory. The process by which magnetic field-lines instantly change their direction is called Magnetic reconnection it convert like (acceleration of some charged particles to extremely high energies) magnetic energy in to thermal energy, and it is thought to be a basic process behind solar flares. The motion of an MHD fluid can give rise to the generation of a macroscopic magnetic field is studied in dynamo theory.
   Thirdly, in1952 the hydrogen bomb creation generated a great interest in controlled thermonuclear fusion like accesible and reliable power source for the future.
   Fourthly, in 1958 James A.Van Allen's discovered  the Van Allen radiation belts these radiation belts surrounding the Earth,by the U.S.Explorer satellite using data transmitted, marked with the help of satellite start of the systematic exploration of the Earth's magnetosphere, and opened up the space plasma physics which is important field in the plasma physics.
   Finally, in the 1960 opened up the field of laser plasma physics for the development of high powered laser. When the laser beam which is high powerd strikes a solid target then, a plasma forms at the boundary between the beam and the target, and material is immediately ablated. Inertial confinement fusion is a majora pplication of laser plasma physics, and it is the main approach to fusion energy. Laser have alot of properties e.g densties charcterstics of solids not in the conventional plasmas. In this approach, before achieving the densities and tempretures characteristic of nuclear fusion(i.e., the centre of a hydrogen bomb) tightly focused laser beams are used to implode a small solid target. The use of the extremely strong electric fields generated, when a high intensity laser pulse passes through a plasma to accelerate the particles is another interesting application of laser plasma physics. High-energy physicists hope to dramatically reduce the size and cost of particle accelerators by the use of plasma acceleration techniques.