EXPERIMENTAL STUDY OF NON-EQUILIBRIUM IONIZATION IN A LINEAR MAGNETOHYDRODYNAMIC GENERATOR.
GENERAL ELECTRIC CO PHILADELPHIA PA MISSILE AND SPACE DIV
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The aim of this experimental study was to investigate the ionization relaxation process and the steady non-equilibrium plasma state in a linear, segmented electrode, magnetohydrodynamic generator, operating under conditions of significant elevation of the electron temperature above the stagnation gas temperature. The inert gas generator working fluids were shock heated to static gas temperatures corresponding to equilibrium electron densities between 10 to the 8th powersq. cm to 10 to the 12th powercu cm. A minimum initial electron density of the order of 10 to the 11th powercu cm, which was produced either by thermal ionization or by electric field pre-ionization, was required to obtain strong magnetically induced ionization effects. The pre-ionization power requirements were as small as 10 of the maximum generator power output. The relatively large electrode voltage losses controlled the minimum initial density requirement, the magnetically induced ionization relaxation process, and the maximum generator power output of 4 of the stagnation flow enthalpy. The magnetically induced ionization relaxation in the free stream of the channel was in agreement with the predictions of a one-dimensional plasma theory which considers that electron collisional ionization and recombination dominate the rate equations. The experimental steady state, electron densities in the generator, which were up to 1000 times greater than the equilibrium electron density at the stagnation gas temperature, were in general agreement with the values computed from the electron energy equation, neglecting radiation losses, and the Saha equation at the electron temperature. Author
- Plasma Physics and Magnetohydrodynamics