Innovative Plume Signature Methodology for Low Thrust Propulsion Systems

Physical Sciences Inc. (PSI) proposes to develop a unique experimental facility and methodology for developing accurate, validated plume codes for low thrust propulsion systems operating at high altitudes. The facility will include small-scale thrusters and a hypervelocity oxygen atom source (6 to 12 km/s) for simulating the plume conditions observed at high altitude. With this capability we will be able to systematically measure the contribution of reactions of each of the plume constituents of a specified thruster system to the plume radiance. The data from these measurements will be included in a state of the art Direct Simulation Monte Carlo (DMSC) code to develop a plume signature code for the thruster system. Plume signature predictions will then be compared to measurements obtained from the simulation facility to validate the code. In Phase I we will demonstrate our approach to developing a validated code by measuring the velocity dependent cross section for the reaction of hyperthermal oxygen atoms with one component of a thruster exhaust. The data will be input to the plume code, SOCRATES, and the plume radiance from the candidate reaction will be calculated under several observation scenarios.