A Fluid Model of the Sheath Formation in Front of an Electron Emitting Electrode with Space Charge Limited Emission Immersed in a Plasma that Contains a One-Dimensional Mono-Energetic Electron Beam

摘要

Sheath formation in front of a large, planar, electron emitting electrode (collector) immersed in a plasma that contains a mono-energetic, one-dimensional electron beam is studied by a one-dimensional fluid model. A current-voltage characteristics of the collector is calculated. For certain beam parameters triple valued floating potentials of the collector are found. The calculated current-voltage characteristics is qualitatively similar to experimental characteristics observed by [Nam et al J. Appl. Phys., 63, 5674 (1988)] and also by [MC. Griskey and R.L. Stenzel, Phys. Rev. Letters, 82, 556 (1999)]. We suggest that the triple valued floating potential are a consequence of a non-monotonic dependence of the space charge limited emission current on the collector potential, which is caused by the penetration of the electron beam in the collector sheath and does not depend on the physical mechanism (e.g. thermal or secondary) of the electron emission from the collector.