Recent advances in stellarator development

Large stellarator research programs are being pursued in Europe and Japan (>$1 billion in new facilities). These programs are important to the US because the similarities and differences between stellarators and tokamaks can be used both to improve our understanding of toroidal confinement and to develop an improved reactor concept. Stellarators have performance similar to that of comparable tokamaks. New large stellarator experiments under construction with superconducting coils will have parameters comparable to those of present tokamaks. Significant experimental and theoretical progress has been made in understanding transport, finite-beta behavior in three-dimensional toroidal geometry, and concept improvement. Ideas to further improve the stellarator concept will be tested in new experiments. Recent studies have improved the stellarator reactor concept and shown that stellarators can be competitive with tokamaks as reactors