Calculated electron number density profiles for the aeroassist flight experiment

Basic features of a Microwave Reflectometer lonization Sensor (MRIS) as designed for use on the Aeroassist Flight Experiment are described. The MRIS is designed to measure the distances into the shock layer of four critical electron number densities corresponding to four frequencies (20, 44, 95, and 140 GHz). A parametric study of the effects of trajectory and several thermochemical nonequilibrium models for reaction rates, translational and vibrational-electronic energy exchange rates, the average electronic excitation level of atoms, and axisymmetric vs three-dimensional effects is conducted for evaluating MRIS contributions to the code validation process. The parametric study, implemented with the Langley Aerpthermodynamic Upwind Relaxation Algorithm program, reveals a particular sensitivity of the onset and severity of an electron avalanche phenomena associated with changes in these physical models that lead to strong electron-impact ionization. Predicted electron number density profiles are sensitive to reasonable variations in certain kinetic models; consequently, MRIS measurements could assist the code validation process.