Development of the Cathode Fall in a Planar Discharge in Helium.

摘要

The time and spatial evolution of the cathode region of a planar discharge in helium has been modeled using numerical solutions of the electron and positive ion continuity equations and Poisson's equations. Single step ionization, electron and ion drift and diffusion, and electron-positive ion recombination are included using rate and transport coefficients based on experiment. The model is applied to high pressure, high current discharges such as found in electron-beam or photon initiated lasers. The cathode fall is found to approach steady-state voltage drop and sheath thickness are compared with experiment and previous theory using appropriate scaling laws.