Theory of Electron Emission Effects in Symmetric Probe and Spacecraft Sheaths.
Final rept. 1 Nov 75-30 Jun 76,
PARKER (LEE W) INC CONCORD MASS
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A computer model developed earlier, for the rigorous theory of the steady-state sheath structure about and the particle fluxes to a conducting spherical body in a collisionless plasma, has been extended to include the contributions of emitted electrons in addition to those of the ambient plasma. The method is also extended to apply to long cylinders as well as to spheres. Potential barriers and general non-monotonic potential distributions are taken into account. Solutions are possible for wide ranges of the values of the relevant parameters, and are applicable to the sheaths and fluxes of emitting spacecraft, and to the current-voltage characteristics of emitting Langmuir probes. Solutions are presented for a number of sample problems, using a code PARKSS based on the analysis of this report. The discussion of these solutions includes comparisons with previous theories and experimental data. In these problems the effects are considered of variations of a surface potential, B monoenergetic versus Maxwellian emission velocity distributions, c emission flux relative to ambient fluxes weak versus strong emission, and d emission temperature relative to ambient temperatures cold versus warm emission, on potential barriers and net surface fluxes.
- Test Facilities, Equipment and Methods
- Plasma Physics and Magnetohydrodynamics
- Unmanned Spacecraft