Supersonic nonequilibrium plasma wind-tunnel measurements of shock modification and flow visualization

Experiments conducted in a new, small-scale, nonequilibrium plasma wind tunnel recently developed at Ohio State University are discussed. The facility provides a steady-state supersonic flow of cold nonequilibrium plasma with well-characterized, near uniform, properties. The plasma is produced in aerodynamically stabilized high-pressure glow discharge that forms the plenum of the supersonic nozzle, The possible modification of the supersonic flow due to ionization is studied by measuring the angle of oblique shocks attached to the wedge located in the nozzle test section. The results do not show any detectable shock weakening or attenuation in weakly ionized nitrogen plasma, compared to the measurements in a nonionized gas flow. Experiments in supersonic flowing nitrogen and helium afterglow also demonstrate a novel technique for high-density supersonic Row visualization. It allows identifying all key features of the supersonic Row, including shocks, boundary layers, flow separation regions, and wakes by recording intense visible radiation of the weakly ionized plasmas. Interpretation of radiation intensity distributions in nonequilibrium supersonic Rowing afterglow may provide information on key mechanisms of energy storage and ultraviolet radiation in high-altitude rocket plumes. In addition, these flow visualization experiments can be used for validation of multidimensional computer flow codes used for internal Row simulation.