DIFFUSION IN A MICROWAVE-EXCITED PLASMA.
Final scientific rept.,
SYRACUSE UNIV N Y DEPT OF ELECTRICAL ENGINEERING
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The experimental investigation of diffusion in a microwave-excited plasma is reported. The plasma is contained in a microwave cavity and driven in the TM010 mode at approximately 8.4 GHz. The cavity is immersed in a static uniform magnetic field variable up to 3750 G. Gases used in these experiments were argon, helium and hydrogen at pressures of .02, .16, and .65 Torr. The diffusion was determined from measurements of the net power absorbed by a constant density plasma as a function of magnetic field. Instabilities were observed only in argon at a pressure of .02 Torr. For stable plasmas, the power was essentially a monotonic decreasing function of the magnetic field. While some aspects of the experimental results agree with ambipolar diffusion theory, others do not. A marked difference is the strong dependence of the radial density distribution on the magnetic field. Also investigated was the decay of an afterglow helium plasma at .16 and .65 Torr. The plasma was observed to decay approximately 2-3 times faster than predicted by ambipolar diffusion. Author
- Plasma Physics and Magnetohydrodynamics