Several parallel approaches were undertaken which, between them, amounted to an attack on plasma research. Two of these approaches, the pinch and the stellarator, were based on the idea of containing the plasma in an annular region. Taking an entirely different approach, the advantages of a confinement geometry based on externally generated, cylindrically symmetric magnetic fields were recognized by Richard Post and Herbert York. Starting with these concepts, Post evolved an approach which has come to be called the Mirror Machine, which uses various applications of the magnetic mirror principle in its operation. A comparison of the different approaches is made. There is one additional design which has received serious consideration but on which little experimental work has proceeded. The design is the picket fence or cusp geometry considered by J. Tuck and H. Grad. The problems with plasma instability, effects of impurities and neutrons are also discussed. It is suggested that the interaction of hot plasma with magnetic fields opens up the way to the direct production of electrical energy. Other possible applications of fusion energy are discussed.
Teller, Edward 
- University of California Radiation Laboratory, Livermore, CA (United States)