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.