Review of Controlled Fusion Power at Megagauss Field Levels

For well over half a century, there has been interest in using megagauss magnetic fields for thermonuclear fusion. Efforts at IAE Kurchatov under E.P. Velikhov for controlled fusion using “theta-pinch with liner” inspired similar work (c. 1970-79) at the Naval Research Laboratory in the Linus program. Apart from the many scientific problems of electrical conductors at megagauss field levels, and the several instabilities that could plague the dynamics of liner implosions, there are issues of converting single-shot technologies into economical fusion power reactors. Linus ended in 1980 because it lacked a proper plasma target for liner compression, but interest has revived recently driven by the recognition that a substantial minimum in cost and size exists in a regime between the mainline fusion approaches of magnetic-confinement (e.g., ITER) and inertial confinement (e.g., NIF). Attainment of this low-cost minimum, which occurs at about a megagauss, requires successfully overcoming three main challenges: 1) combination of the flux compression process with an appropriate plasma target that can be adiabatically compressed to fusion temperatures and densities; 2) repetitive operation of this implosion in an economically useful manner; and 3) protection of the reactor, especially electrical components, from the very high output of high-energy neutrons. Issues of the fusion power reactor and experimental development are discussed.