Stabilization of Flute Instability by High Frequency Field

Abstract

The effects of external inhomogeneous high-frequency field on the flute instability is studied theoretically from a point of view of non-linear particle interaction instead of an approach using a time averaged quasi-static potential or the Mathieu stability diagram. In this paper, it is assumed that the electric field component of the high-frequency field is perpendicular to the steady state confining magnetic field. It turns out that the hf field can compensate the perturbation of the flute instability with the aid of the ion drift induced by the field. The results appear to show that this field has the stabilizing effect in case that ω₀>ω_ci and has the exciting effect in case that ω₀<ω_ci, provided that the hf intensity increases with distance outwardly from the plasma, where ω₀ is the hf field frequency and ω_ci is the ion cyclotron frequency.