Cascade Arc Studies of Nonequilibrium Hydrogen/Nitrogen Plasma Propellants.
Final rept. 15 Sep 95-14 Sep 97,
TENNESSEE UNIV SPACE INST TULLAHOMA
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A cascade arc facility was developed to study the characteristics of nonequilibrium plasma propellants for electric propulsion applications. The cascade arc was operated with hydrogen arcs at 2.0 and 6.0 psi. Spatially resolved spectral emission data were collected using a two dimensional Optical Multichannel Analyzer OMA. Electron density was determined by fitting theoretical line profiles to experimentally measured Abel inverted emission line profiles. Radial distributions of plasma temperature also were estimated from Boltzmann plots of spectral line intensity. The measured electron number densities and plasma temperatures were compared to values predicted by nonequilibrium cascade arc simulations using the UTSI Cascade Arc Plasma Simulation CAPS code. The simulations underpredicted the peak experimental number densities by as much as an order of magnitude and over predicted peak plasma temperatures by as much as a factor of 2.5. The experimental electric field has been accurately predicted by varying chemical kinetics in the CAPS code. Kinetic models developed at the University of Illinois were found to give the best agreement with the Cascade Arc measurements. Electron number density profiles for simulated ammonia and hydrazine were also obtained at pressures of 2, 6 and 10 psi. Kinetic models for these mixtures will be evaluated when the CAPS code has been modified to simulate these propellants.
- Atomic and Molecular Physics and Spectroscopy
- Plasma Physics and Magnetohydrodynamics