Measurement of the Anisotropic Temperature Relaxation Rate in a Pure Electron Plasma

The anisotropic temperature relaxation rate is obtained from the measured time evolution of $T_{\perp }$ and $T_{\parallel }$ in a magnetized plasma consisting of only electrons. The velocity-space anisotropy is induced by an essentially one-dimensional compression (or expansion) which changes $T_{\parallel }$ but not $T_{\perp }$. $T_{\perp }$ and $T_{\parallel }$ are then measured as they relax to a common value. The relaxation rate is obtained as a function of plasma density and temperature. Good agreement with collisional Fokker-Planck theory is found over a range of two decades.