Development of Compact Quasi-Axisymmetric Stellarator Reactor Configurations
Authors: L.P. Ku, M. Zarnstorff, R.B. White, W.A. Cooper, R. Sanchez, H. Neilson, and J.A. Schmidt
Date of PPPL Report: September 2003
To be presented: at the 14th International Stellarator Workshop, Greifswald, Germany, 22-26 September 2003
We have started to examine the reactor potential of quasi-axisymmetric (QA) stellarators with an integrated approach that includes systems evaluation, engineering considerations, and plasma and coil optimizations. In this paper, we summarize the progress made so far in developing QA configurations with reduced alpha losses while retaining good MHD stability properties. The minimization of alpha losses is achieved by directly targeting the collisionless orbits to prolong the average resident times. Configurations with an overall energy loss rate of ~10% or less, including collisional contributions, have been found. To allow remotely maintaining coils and machine components in a reactor environment, there is a desire to simplify to the extent possible the coil design. To this end, finding a configuration that is optimized not only for the alpha confinement and MHD stability but also for the good coil and reactor performance, remains to be a challenging task.