Stability of Field-Reversed Ion Rings in a Background Plasma

Abstract

A two-fluid energy principle is developed that leads to sufficient conditions for the low frequency stability of an axisymmetric, field-reversed ion ring immersed in a dense, background plasma. It is assumed that the ion ring is described as the rigidly rotating fluid with finite temperature while the background plasma as the stationary fluid. The stability condition is approximately given by the potential energy W(ξ_p, ξ_b)>0, where ξ_p and ξ_b are the displacements of the ring and the background plasma, respectively.
As an application, the stability condition for kink modes of a long ion layer immersed in a cold background plasma is examined in detail in order to compare the existing theories with the present theory.