Flow visualization in a low-density plasma channel

A schlieren system and surface-stress-sensitive film system were developed for a plasma channel which posed unique challenges for flow visualization because of the combination of low air density and the presence of plasma discharges. Temperature-sensitive paint and direct-current discharge were also applied to flow visualization. Three pulsed schlieren light sources were evaluated. A light-emitting diode (LED), a xenon NanopulserTM and laser breakdown, were tested on identical flowfields. The LED provided excellent illumination, with pulses ranging from μs to continuous. The NanopulserT