Size Optimization Studies for a Stellarator Reactor

Abstract

Stellarators are steady state, have an absence of disruptive instabilities, have low recirculating power, and are natural divertors—all of which are intrinsic properties that make stellarators especially attractive as fusion reactors. The question is addressed of the minimum size requirements for a stellarator reactor, independent of the specific configuration chosen to optimize physics and technology aspects. A one-dimensional model is used to deduce by postulating specific plasma profiles the power balance between alpha-particle heating, radiation, and conductive losses in the plasma and to determine the minimum size compatible with the level of output power of the reactor and the operational limits due to plasma confinement, pressure, and density. Also considered is the influence on stellarator reactor size requirements of particle accumulation and of the presence of impurities in the plasma. Additionally, with regard to practical realization of the device, the limitations of wall power deposition and device aspect ratio are considered. Available stellarator reactor designs are reviewed based on these results.