ENERGY TRANSFER IN PLASMAS
Abstract
Problems associated with energy transfer mechanisms in a plasma are described. Relaxation effects, nonlinear effects, and transport effects, are considered. These effects are significant only when a longitudinal component is present in the wave motion. A theoretical treatment is given for propagation in a non-uniform plasma, and approximation techniques developed for various plasma profiles. The case of linear variation of the electron density with density is treated in detail. Computer data indicate that under proper conditions large absorption occurs even for a relatively steep rise in the electron density. Measurements in a shock tube using an interferometer at 18 kmc indicate that under certain conditions a shock wave is preceded by large numbers of electrons and that the electron density profile is smoothly tapered. Techniques for producing a prescribed non-uniform plasma were studied. An electrodeless discharge vessel with moving Langmuir probes was designed and a systematic comparison was made between microwave and probe measurements. In spite of certain systematic pressure-dependent deviations, with proper calibration, the probe method can be applied to the measurement of non-uniform plasmas. An experimental program for the measurement of the thermal conductivity in a plasma by acoustic techniques was unsuccessful because of noise and instabilities in the plasma. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 10, 1961
- Accession Number
- AD0258771