Ruby-Laser Scattering Diagnostics of a Supersonic Plasma Flow for Low-Pressure Plasma Spraying

Truly reliable measurements of electron temperature and density in a plasma flow for low-pressure plasma spraying (LPPS) were performed for the first time, using incoherent Thomson scattering of ruby-laser light. The results indicate the characteristic feature of a supersonic nozzle flow, namely, successive appearance of oblique shock-wave heating (~1 eV) and compression (4×1021 m-3), and subsequent cooling (~0.2 eV) and rarefaction (1×1021 m-3).