Compact Stellarators

摘要

Stellarators offer advantages for reactors, namely the potential for steady state operation with low recirculating power (high engineering Q) and without disruptions. A substantial portion of the world fusion program is devoted to the development of stellarators as a magnetic confinement system. The world stellarator program, as it currently exists, is focused on high-aspect-ratio (R/a = 5 - II) designs that lead to very large reactors. For example the German advanced stellarator reactor design HSR has an aspect ratio of 12 and a major radius of 22 m. An important issue for stellarator research is whether more compact reactor designs are possible. Could the advantage of stellarators also be realized at dimensions and performance levels closer to those of the advanced tokamak reactor ARIES-RS (R = 5.5 m, neutron wall load of 4 MW/m2)? Theory has identified a class of “compact stellarator” plasma configurations that could be the basis for such a design. They are promising, but need to be studied experimentally in order to realistically assess their potential. The most cost-effective way to accomplish this is to carry out the compact stellarator proof-of-principle program that has been proposed by the U.S. stellarator community. This program would answer the basic physics questions for compact stellarators and make important contributions to the world stellarator knowledge base at a cost (about $30M/year) that is modest compared to expenditures for stellarator and tokamak research world-wide.