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Transport Processes in Beamed Energy Propulsion Systems
Final technical rept. 1 Sep 1989-30 Sep 1991,
ILLINOIS UNIV AT URBANA DEPT OF ELECTRICAL ENGINEERING
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A model of a microwave-induced plasma propulsion system has been developed in one dimension for a transverse electric mode TE sub 10 of operation in a rectangular waveguide. Available experimental data are compared to the computational results for the case of a planar propagating plasma wave and, using a TE sub 10 mode-shape approximation, for a wave propagating in a waveguide. Temperature profiles, plasma propagation velocities, velocity profiles, and absorbed power histories are obtained for flow of helium from .5 to 1 atmosphere pressure and 500 to 3000 watts input power at a frequency of 2. 45 GHz. The computational results show the observed jumping of the plasma towards the microwave source. Peak plasma temperatures range from 8000 to 9000 K over the input power range. For an input power of 1081.7 W the calculated percentage of power absorbed in approximately 70 percent for the planar case and 40 percent for the waveguide case. Comparisons with experimental data indicate other mechanisms not involving transient processes, most likely associated with the nonequilibrium behavior of the plasma, are responsible for the disagreement between the model results and the observed plasma propagation velocities.
APPROVED FOR PUBLIC RELEASE