Arc-jets and impulse facilities have been extensively used to investigate the flow physics of planetary re-entry, but they each address different aspects of re-entry flow-fields. This work presents a conceptual design of a dual-facility setup, utilising an arc-jet as a model preheating device in the impulse test facility. This novel preheating apparatus will replicate realistic ablation coupling effects in hypervelocity flows. This paper outlines the major challenges and key considerations for the system integration of arc-jet in the T6 Stalker Tunnel. A small-scale arc-jet facility, OPG1, is currently being developed at the University of Oxford to test the plasma generator, model movement system, and sub-components for the expansion tube testing. Analyses were performed to examine the thermal and structural loads on the model movement system exposed to both plasma and hypervelocity flow. The results showcased that the model movement system will effectively serve dual-facility operations.

A small-scale thermal arc-jet facility based on a 21.5 kW tungsten inert gas welding power supply has been developed. The design and simulations are presented here. The plasma generator is situated inside a vacuum vessel forming an Argon plasma with a mass flow rate of approximately 0.2 g/s. The vessel is evacuated by a series of pumps providing sufficient suction to keep the vessel below 125 Pa during continuous operation. The system is designed with regards to heat transfer and vacuum performance with the goal of keeping component temperatures pressures below critical values to prevent material failure and enable adequate vacuum. The thermal design of the plasma generator includes a water cooling circuit which keeps the copper anode below melting temperatures. A viscous reacting 2D axisymmetric simulation is carried out using Eilmer4 simulating the nozzle flow including the stagnation chamber and the free jet impinging onto a 40 mm diameter sphere-cone model. The simulations predict a maximum heat flux on the model surface of approximately 800 kW/m 2 when a plasma total temperature of 7400 K is assumed.

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