Design studies of low aspect ratio quasi-omnigenous stellarators

Significant progress has been made in the development of new, compact stell arator devices that could test optimization principles for the design of a more attractive reactor. These are 3 and 4 field period low aspect ratio qu asi-omnigenous stellarators based on an optimization method that aims at im proved confinement, stability, ease of coil design, low aspect ratio and lo w bootstrap current. With respect to the analysis of these devices, the aut hors have developed improved measures of neoclassical transport, collisionl ess loss analyses of ICRF tail and ct population confinement and methods fo r the rapid assessment of ballooning stability boundaries.