Experiments with pure electron plasmas

Abstract

A series of experiments at UCSD on pure electron plasmas is described. The apparatus and methods of measurements are discussed. Results are given on various wave experiments including the dispersion of electron plasma waves, feedback growth and damping of the l=1 diocotron wave, and the unstable growth of diocotron waves on plasmas with hollow radial profiles. The nonlinear saturation of diocotron waves, subsequent vortex merging and the decay of the resulting two‐dimensional turbulence are observed. Transport processes resulting from both the single particle and collective response of the plasma to externally imposed field asymmetries have been studied. Evolution of the confined plasma to thermal equilibrium has been observed and scaling of the rate of this evolution with magnetic field has been measured. The relaxation rate of an anisotropic velocity distribution has been measured in both the usual parameter regime and the cryogenic regime where the rate is greatly reduced due to the existence of a many particle adiabatic invariant.