Linear Stability of the Large Larmor Radius Z-Pinch

Abstract

For the first time, calculations of large Larmor radius (LLR) effects on the linear stability of realistic Z‐pinch equilibria have been performed. The fixed boundary m=0 instability of the pure Z‐pinch (no external magnetic field) is considered (free‐boundary and m=1 modes are presently under study). We use the Vlasov‐Fluid model, where ions are treated fully kinetically and electrons are modelled as a cold, massless fluid. Stability is found to be remarkably sensitive to equilibrium profiles. A flat current equilibrium is increasingly stabilized (smaller growth rate) by LLR effects as the normalized average Larmor radius e is increased to about 0.1. Complete stabilization cannot be obtained. For larger values of e the growth rate increases to reach above the small Larmor radius value when e≈0.3. The Bennett equilibrium, however, is increasingly destabilized as e increases.