MEASUREMENT OF COLLISIONAL ANISOTROPIC TEMPERATURE RELAXATION IN A STRONGLY MAGNETIZED PURE ELECTRON-PLASMA

The rate at which the temperatures parallel and perpendicular to a magnetic field relax to a common value has been measured in a pure electron plasma. This rate was measured over the temperature range 28 to 10(4) K and for magnetic fields in the range 30 to 60 kG. When the cyclotron radius r(c) is large compared to the classical distance of closest approach b, the measured rates are described by conventional scattering theory. When r(c)/b < 1, the measured rate drops precipitously as r(c)/b is decreased, in agreement with the adiabatic-invariant theory of O'Neil and Hjorth.