Two-fluid interpretation of stability and transport in currentless stellarators

Abstract

The two-fluid equations are used to investigated both stability and transport in currentless stellarators. Some general results are complemented by paradigmatic calculations for large aspect-ratio. Apart from a possible entropy gradient instability, the analysis suggests these machines to be linearly stable. In early work, fluctuations have been invoked to interpret anomalous electron thermal conduction in Tokamaks. A similar application to currentless stellarators indicates fluctuations to give only an unimportant enhancement to both particle and energy transport. Although qualitative, the results suggest that currentless stellarators could be essentially neoclassical.