Temperature and anisotropic-temperature relaxation measurements in cold, pure-electron plasmas

Plasma temperatures in the range 25 to 2x106 K have been measured using a cryogenic, ultra-high vacuum, pure-electron plasma trap. The rate ν at which the temperatures parallel and perpendicular to the applied magnetic field relax to a common value has been measured over the temperature range 28 to 3.8x105 K and the magnetic field range 20 to 60kG. This rate ν is closely related to the plasma collision frequency. When the cyclotron radius rc is large compared to the classical distance of closest approach b (rc/b>1), the measured values of ν are in agreement with conventional collision theory. When the cyclotron radius is small compared to the classical distance of closest approach (rc/b<1), ν drops precipitously as rc/b is decreased, in agreement with the many-electron adiabatic invariant theory of O close-quote Neil and Hjorth. copyright 1996 American Institute of Physics