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

Plasma temperatures in the range 25 to 2310 K have been measured using a cryogenic, ultra-high vacuum, pure-electron plasma trap. The rate n 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 3.8310 K and the magnetic field range 20 to 60 kG. This rate n 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 n are in agreement with conventional collision theory. When the cyclotron radius is small compared to the classical distance of closest approach (rc /b!1), n drops precipitously as rc /b is decreased, in agreement with the many-electron adiabatic invariant theory of O’Neil and Hjorth. © 1996 American Institute of Physics. @S1070-664X~96!00604-0#