Investment in Tokamak Fusion

Abstract

The debate over the future of the International Thermonuclear Experimental Reactor (ITER) (J. Glanz, “Requiem for a heavyweight at meeting on fusion reactors,” News & Comment, 8 May, p. [818][1]), unfortunately, does not go far enough. The real issue is not how much money should be invested in the next large tokamak, but whether any further investment in tokamak confinement is warranted at this time. The tokamak has been the main approach to magnetic confinement fusion since its inception almost 50 years ago. During the intervening half century, great progress has been made in understanding the physics of toroidal confinement and in translating that understanding into improvements and innovations in tokamak design. Although tokamak design is still based on empirical scaling laws, confidence in these laws has been strengthened by a wealth of experimental data. Numerous reviews of the ITER design have concluded that if the machine is built to the ITER design specifications, there is little doubt that it can achieve its scientific goal of a sustained thermonuclear burn. This statement reflects both the triumph and the tragedy of fusion research, because it also implies that if a tokamak is significantly smaller than the ITER design, it will not achieve a sustained thermonuclear burn and thus will not provide the basis for a power-producing reactor. The scientific community needs to reexamine the premise on which the public was originally asked to support fusion research, namely, that it would lead to the development of a practical, power-producing technology. In light of today's knowledge, it is highly unlikely that further development of the tokamak will lead to that outcome. [1]: /lookup/doi/10.1126/science.280.5365.818