ADVANCED TOROIDAL FACILITY II STUDIES

Design studies for a low-aspect-ratio, large next-generation stellarator, Advanced Toroidal Facility II (ATF-II), with high-current-density, high-field, stable NbTi/Cu helical windings are described. A number of low-aspect-ratio physics issues need to be addressed in the design of ATF-II, primarily compromises between high-beta capability and good confinement properties. A six-field-period Compact Torsatron is chosen as a reference design for ATF-II, and its main features and performance predictions are discussed. An integrated (beta capability and confinement) optimization approach and optimization of superconducting windings are also discussed.