Accession Number : AD0886107

Title :   Electrostatic Sheath Phenomena in Thermionic Converters.

Descriptive Note : Final rept. Nov 69-Nov 70,

Corporate Author : GENERAL ELECTRIC CO PLEASANTON CA NUCLEAR THERMIONIC POWER OPERATION

Personal Author(s) : Rush, Donald J. ; Wilkins, Daniel R.

Report Date : MAR 1971

Pagination or Media Count : 65

Abstract : A generalized theoretical description of electrostatic sheath phenomena in thermionic converters is developed. The analysis goes beyond existing treatments in taking into account discontinuous distribution functions for emitted, plasma, and trapped particles; non-equilibrium particle trapping; sheath electric fields consistent with particle densities and temperatures within the sheath; and Schottky effects at the electrode surface. The resulting sheath criteria and models are applicable to both monotonic and double sheaths, and are expressed in a form suitable for incorporation into an existing digital computer program for thermionic converter analysis. The improved treatment has been applied to thermionic converters. The results indicate the following: non-monotonic sheaths at the emitter in the lower region of the ignited mode for electron rich conditions--this is in agreement with previous investigations; the ignition region hysteresis is probably associated with a bistable sheath at the collector; The collector sheath is non-monotonic for nearly all operating conditions of practical interest. The latter provides a possible explanation of reported collector work function anomalies. (Author)

Descriptors :   (*PLASMA SHEATHS, ELECTROSTATIC FIELDS), (*THERMIONIC CONVERTERS, PLASMA SHEATHS), ELECTRON DENSITY, IONS, TRANSPORT PROPERTIES, DISTRIBUTION FUNCTIONS, MATHEMATICAL MODELS, DIFFERENTIAL EQUATIONS, CURVE FITTING, NUMERICAL ANALYSIS, COMPUTER PROGRAMMING.

Subject Categories : Electric Power Production and Distribution
      Plasma Physics and Magnetohydrodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE