Inertial fusion power plant

Inertial Fusion Energy is a proposed approach to building a nuclear fusion power plant based on performing inertial confinement fusion at industrial scale. This approach to fusion power is still in a research phase. ICF first developed shortly after the development of the laser in 1960, but was a classified US research program during its' earliest years. In 1972, John Nuckolls wrote a paper predicting that compressing a target could create conditions where fusion reactions are chained together, a process known as fusion ignition or a burning plasma. On August 8th 2021, the NIF at Livermore National Laboratory became the first ICF facility in the world to demonstrate this (see plot) . This breakthrough drove the US Department of Energy to create an Inertial Fusion Energy program in 2022 with a budget of 3 million dollars in its first year .

Design of a IFE power plant

This kind of fusion reactor would consist of two parts:

• Targets which can be small capsules (<7 millimeter diameter) that contain fusion fuel. Although many kinds of targets have been tested including: cylinders, shells coated with nanotubes, solid blocks, hohlraum, glass shells filled with fusion fuel, cryogenically frozen targets, plastic shells, foam shells and materials suspended on spider silk .
• Drivers which are used to compress and create a shock wave that squeezes the target. This compression wave pushes the material down to the temperature and pressure where fusion occurs. Drivers that have been explored are solid-state lasers, excimer lasers, high velocity solid objects, X-rays, beams of ions (heavy ion fusion (HIF)) and beams of electrons.

The basic kind of IFE plant would place a target at the center of a reactor chamber and compress it with a driver repeatedly. Hence, the operation of an IFE reactor is analogous to the operation of the four stroke cycle of a petrol engine:

• intake of the fusion fuel (microcapsule) into the reactor chamber;
• compression of the microcapsule in order to initiate the fusion reactions;
• explosion of the plasma created during the compression stroke, leading to the release of fusion energy;
• exhaust of the reaction residue, which will be treated afterwards to extract all the reusable elements, mainly tritium.

ICF Research Institutions

This program was originally established as a way to develop Nuclear weapons, because ICF mimics the compression physics of a fission-fusion bomb. These facilities have been built around the world, below are some examples.

• Laser Mégajoule in France was developed in 2002 and upgraded in 2014.
• Omega Laser was first built in 1992 at the University of Rochester.
• Omega-EP was first built in 2008 at the University of Rochester as second more powerful laser beam.
• Gecko Laser was first built at Osaka University in Japan in 1983 but has since been upgraded nearly a dozen times.
• NIF was first operational in 2009 at the Livermore National Laboratory.
• NIKE Laser was built at the Naval Research Laboratory to study excimer (gas-based) lasers.
• Electra Laser was built at the Naval Research Laboratory to study excimer (gas-based) lasers.
• PALS laser facility in the Czech Republic was established to research ICF laser implosions.
• Machine 3 was developed by First Light Fusion to accelerate blocks of material to create a shockwave on the target.

There have also been multiple ICF facilities built, tested and decommissioned in the past. For example, Sandia National Laboratory pursued a series (<10 machines) of ion-beam and electron-beam driven ICF research program through the 1970's and into the middle 1980's . Alternatively, Los Alamos built a large, excimer laser facility called Aurora in the late 1980's. Livermore National Laboratory built a succession of laser facilities including Nova, Cyclops, 4-PI, SHIVA and other devices.

Driver Development

To allow such an operation, an inertial fusion reactor is made of several subsets:

Mockup of a golden hohlraum used in laser inertial confinement.

• the injection system, which delivers to the reaction chamber the fusion fuel capsules, and at the same time the possible devices necessary to initiate fusion:
  • the container (hohlraum), intended to take the fuel capsule to a uniform very high temperature, mainly for laser and ion beam confinement techniques;
  • the "wires array" and its power transmission line, for z-pinch confinement technique;
• the "driver" used to compress the fusion fuel capsules which, depending on the technique, can be lasers, an ion beam accelerator or a z-pinch device;
• the reaction chamber, built upon an external wall made of metal, or an internal blanket intended to protect the external wall from the fusion shockwave and radiation, to get the emitted energy, and to produce the tritium fuel;
• the system intended to process reaction products and debris.

Further information: An example of a planned IFE plant can be seen in the Z Pulsed Power Facility article

IFE projects

Several projects of inertial fusion power plants have been proposed, including power production plans based on the following experimental devices, either in operation or under construction:

• in the United States, the National Ignition Facility (laser confinement) and Z machine (z-pinch confinement) experiments
• in France, the Megajoule laser experiment
• in Japan (Osaka University), the KONGOH experiment (laser confinement)

Only the US and French projects are based on z-pinch confinement; others are based on laser confinement techniques.

Livermore's IFE (LIFE) project was cancelled in January 2014.

As of June 2006, Megajoule and NIF lasers were not yet in complete service. Inertial confinement and laser confinement fusion experiments had not gone beyond the first phase. Around 2010, NIF and Megajoule were planned for completion.

Project phases compared to magnetic confinement

In the magnetic confinement field, the 2nd phase corresponds to the objectives of ITER, the 3rd to these of its follower DEMO, in 20 to 30 years, and the 4th to those of a possible PROTO, in 40 to 50 years. The various phases of such a project are the following:

• Burning demonstration: reproducible achievement of energy release
• High gain demonstration: experimental demonstration of the feasibility of a reactor with a sufficient energy gain
• Industrial demonstration: validation of the various technical options, and of the whole data needed to define a commercial reactor
• Commercial demonstration: demonstration of the reactor ability to work over a long period, while maintaining the requirements for safety, liability and cost.

See also

• Nuclear fusion
• Fusion power
• Inertial electrostatic confinement
• Inertial confinement fusion
  • Laser inertial confinement
    • Megajoule laser
    • National Ignition Facility
  • Ion-beam inertial confinement
  • Z-pinch inertial confinement
    • Z Pulsed Power Facility
  • Project PACER
• List of plasma physics articles

Further reading

• "La fusion thermonucléaire par confinement inertiel : de la recherche fondamentale à la production d'énergie" (PDF). Archived from the original (PDF) on 2006-11-25. (1.28 MiB) (Université Bordeaux I, November 2005) (in French)
• Tutorial on Heavy-Ion Fusion Energy(Virtual National Laboratory for Heavy-Ion Fusion)
• "Summary Report of the 2nd Research Coordination Meeting on the Element of Inertial Fusion Energy Power Plants" (PDF). Archived from the original (PDF) on 2007-07-10. Retrieved 2006-07-09. (4.82 MiB) (November 2003)
• "Review of the Inertial Fusion Energy Program" (PDF). Archived from the original (PDF) on 2006-09-23. (4.14 MiB) (Fusion Energy Sciences Advisory Committee, March 2004)
• "Overview of fusion nuclear technology in the US" (PDF). (513 KiB) (June 2005)
• Views on neutronics and activation issues facing liquid-protected IFE chambers
• IEEE-USA Position : Fusion Energy Research & Development(June 2006)