Measurements of Air Plasma/Ablator Interactions in an Inductively Coupled Plasma Torch
Abstract
Studies of the ultraviolet and visible emission from an atmospheric pressure air plasma and its interaction with two carbon-based ablative materials were performed in an inductively coupled plasma torch. These experiments were conducted at a plate power of 40 kW, which produced an air plasma in local thermodynamic equilibrium with a maximum temperature of approximately 6200 K, corresponding to a specific enthalpy of 16.4 MJ/kg. Three techniques were developed to measure the ablator surface temperature. Recession rates and product species profiles were measured for two different materials (ASTERM™ and carbon-bonded carbon fiber) at a plasma velocity of approximately 20 m/s. Measured surface temperatures were in the range of 2100 to 2300 K, and corresponding hot-wall heat fluxes were approximately 1.4 MW/m2. Spatially resolved profiles of the main species detected in the boundary layer were recorded, and they showed evidence of strong coupling between the ablated material and the freestream.