Numerical Investigation of Operating Characteristics of a Laser Sustained Plasma Wind Tunnel

Abstract

Laser sustained plasma (LSP) wind tunnels have been attracting attention as a new high-enthalpy wind tunnel. But operating limits for a stable plasma generation are not clear. This study numerically investigates the dependence of the plasma generation on the working gas flow rate. As a result, the LSP was found to be maintained at a mass flow rate between 0.6-6.0 g/s, when the laser power is 700 W and the working gas is argon. Moreover, it was found that the electron diffusion is a dominant mechanism for maintaining the LSP in the case of the flow rate under 3.0 g/s. However, in the case of the flow rate over 3.0 g/s, an another but unknown mechanism might maintain the LSP. The value of the laser absorption coefficient strongly depends on the mass flow rate, and can be categorized into the three region according to the mass flow rate.