Aerothermal Testing in a Pulsed Arcjet Tunnel with Laser Preheating

This paper presents a novel and cost-effective experimental setup for high-temperature material testing and gas–surface interaction characterization. A 3 kW radiative heating laser has been integrated with the 500 kW pulsed arcjet tunnel of the University of Tennessee. This facility is a Mach 6, high-enthalpy wind tunnel with typical run times of approximately 500 ms. While the short test duration significantly reduces operating costs, it limits the ability to reach flight-relevant surface temperatures and to observe gas–surface interaction phenomena in detail. To overcome this limitation, the heating laser is used to preheat material samples before exposure to the high-enthalpy plasma flow. A validation campaign was conducted using graphite disks as target material, selected for their low cost, good machinability, and the abundance of reference data available in the literature. The effects of surface preheating temperature (700°C, 900°C, and 1100°C) and flow enthalpy (ranging from 2 to 7 MJ/kg) were systematically studied. Oxidation phenomena were assessed by comparing tests in air and nitrogen plasma flows. Infrared pyrometry and thermography were employed to monitor surface temperatures, and emission spectroscopy was used to investigate gas–surface interaction effects.