Toroidal drift mode stability in a contaminated plasma

Abstract

Toroidal drift mode features and stability are studied, using a fluid description, for a plasma with two ion species: impurity and main ions. Impurity and main ion temperature gradient (ITG) modes dominate for larger temperature gradients, ηi≳1, while dissipative trapped electron (DTE) and impurity-induced modes are present also for ηi<1. Simple analytical expressions for the stability thresholds are derived from conditions given by the impurity and main ion fluids.