Expansion rate measurements at moderate pressure of non-neutral electron plasmas in the Electron Diffusion Gauge (EDG) experiment

Measurements of the expansion rate of pure-electron plasmas have been perfo rmed on the Electron Diffusion Gauge (EDG) device at background helium gas pressures in the 5x10(-8) Torr to 2x10(-5) Torr range, where plasma expansi on due to electron-neutral collisions dominates over plasma expansion due t o trap asymmetries. It is found that the expansion rate, defined as the tim e rate of change of the particles' mean-square radius, scales approximately linearly with pressure and inversely as the square of the magnetic field s trength in this regime, in agreement with classical predictions. (C) 2001 A merican Institute of Physics.