Experiments on whistler mode electron‐cyclotron resonance plasma startup and heating in an axisymmetric magnetic mirror

Abstract

Whistler mode electron‐cyclotron resonance heating (ECRH) has been performed simultaneously with whistler mode electron‐cyclotron emission measurements on an axisymmetric magnetic mirror plasma. Results presented include a study of the early plasma startup phase and two instability phases, one believed to be caused by a whistler instability and another by magnetohydrodynamic (MHD) flute instability. Enhanced microwave emission at frequencies below the midplane electron‐cyclotron frequency has been correlated with enhanced electron endloss during the whistler instability. Cyclotron emission spectra during the startup phase match predictions for a ‘‘sloshing electron’’ type distribution based on numerical modeling. This distribution also agrees with anisotropic distributions resulting from electron‐cyclotron heating as predicted by Fokker–Planck computer simulations. Experimentally measured heating rates show good agreement with simplified analytical models based on stochastic heating.