Langmuir Probe Theory and Analysis.
Final rept. Jan 71-Apr 72,
GENERAL ELECTRIC CO PLEASANTON CA NUCLEAR THERMIONIC POWER OPERATION
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This report develops a unified theoretical representation of the spherical Langmuir probe in a collision dominated weakly ionized gas. The analysis is performed by numerically integrating Poissons equation and a set of moment equations, derived from the Boltzmann equation, that conserve mass, momentum and energy for electrons and ions. The theory provides for the continuous description of Langmuir probes from collisionless through collision dominated conditions. Numerical techniques are developed to carry out the analysis. The numerical results show that the theoretical model satisfies all known theoretical limits for collisionless and collision dominated operating conditions. A new model for Langmuir probe data analysis is developed. The model provides for the description of sheaths of finite thickness and is found to meet all known theoretical limits in the collisionless and collision dominated extremes and provides a continuous description of operating conditions between these extremes. Systematic data analysis procedures employing the new data analysis model are developed. The feasibility of performing a Langmuir probe experiment in a thermodynamic equilibrium cesium plasma for the purpose of validating theoretical probe models under experimental conditions where plasma properties are known from thermodynamic relations is investigated.
- Test Facilities, Equipment and Methods
- Plasma Physics and Magnetohydrodynamics