Stabilization of a low-frequency instability in a dipole plasma

Abstract

AbstractLow-frequency fluctuations are observed in a plasma confined by a strong dipole magnet and containing an energetic high-pressure population of trapped electrons. The quasi-coherent fluctuations have frequencies characteristic of drift frequencies of the lower temperature background plasma and have large toroidal and radial extent. They are excited throughout a wide range of plasma conditions determined by the level of neutral gas pressure. However, for a sufficiently high rate of neutral gas fueling, the plasma density profile flattens and the fluctuations disappear.