Radio frequency effects on confinement and equilibrium in a magnetic mirror

Abstract

The effect of radio frequency (rf) power in the ion cyclotron frequency range on radial ion transport and plasma equilibrium for the Constance B magnetic mirror [Phys. Rev. Lett. 58, 1853 (1987)] is presented. Low‐frequency rf power increases the ion perpendicular loss rate, which then becomes the dominant ion loss mechanism. The observed radial transport is much in excess of that calculated by classical, neoclassical, or stochastic wave–particle models, with implications for limits on heating in magnetic mirrors and charge state selection in electron cyclotron resonance ion sources. With sufficient rf power, the ion loss rate rivals the ionization source (plasma production) rate, with a resultant loss of plasma equilibrium. The effect of rf power on the ambipolar potential is also studied, and is shown to be an electron effect whose scaling with applied field is consistent with theory.