Study on Characteristics of Special ICP-Heated Wind Tunnel by Improved HCN Laser Interferometer

The results of the experimental investigation of a plasma jet created by a large-volume, high-enthalpy plasma wind tunnel are presented. The plasma wind tunnel generates an electric field by applying a time-varying power with a frequency of 440 kHz, which excites the plasma and ejects it from the nozzle due to the pressure difference. This article uses high-voltage probes, cameras, and laser interferometers to understand the properties of plasma wind tunnels. In order to diagnose the electron density at different positions of the plasma jet, a laser interferometer is improved in this article. The waveform of the power supply, the length of the plasma jet, and the brightness and electron density of the plasma jet were obtained during the experiment. The results show that the electron density increases by about an order of magnitude when the supply voltage rises from 8 to 12 kV. As the distance increases by 150 mm, the plasma electron density decreases by a factor of 1.5 or 2, but the electron density increases with the increase of pressure. Finally, the electron density distribution characteristics can be explained by the simulation results.