Direct Simulation of Ionization around Power-Law Leading Edges in Rarefied Hypersonic Flow

The Air Force Flight Test Center mandates that a flight test vehicle maintain an uninterrupted telemetry link with the controllers for flight safety and data telemetry reasons. Satisfying this requirement comes into jeopardy for any vehicle which has the required altitude, velocity, and configuration to ionize the flowfield. Considering that air-breathing hypersonic cruise flight will soon become a reality, the problem of telemetering through a plasma sheath takes on great importance. To this end, a Direct Simulation Monte Carlo rarefied flow solver has been developed to calculate the flowfield around powerlaw shaped leading edges. This serves as a useful tool for not only determining aerodynamic forces in rarefied flight conditions, but also to calculate the level of leading edge ionization in hypersonic flight. The degree of ionization (and hence electron production) by a leading edge configuration is directly coupled to the issue of telemetry through a plasma sheath. The ability to tailor the leading-edge plasma to known characteristics is therefore highly desirable. Results will show the effects of leading-edge plasma formation for the high altitude flight corridor, as well as the ability to derive the desired electron concentrations for telemetry through the plasma sheath by specifying the appropriate leading-edge geometry.