Abstract
Thermal protection system (TPS) is essential for the re-use of space vehicles. An arc-heated plasma wind tunnel has been developed for dynamic oxidation testing of TPS materials. In order to improve the certainty of stable operation of the arc-heated plasma wind tunnel and for a longer operating time, optimization of the nitriding treatment of the zirconium surface was carried out. The zirconium cathode surface was nitrided at 1200-1400°C at a nitrogen flow rate of 800 ml/min, and a uniform nitride film with a thickness of 10-30 μm was successfully produced. Using the fabricated cathodes, the arc-heated wind tunnel achieved a stable operation for one hour. The arc spot was stabilized at a single location for all cathodes fabricated under different conditions. It is considered that the continuous formation of ZrN solid solution at the arc spot on the electrode surface during arc discharge contributed to the stable operation of the arc-heated plasma wind tunnel for a longer operation time.
https://ror.org/04dt6bw53 
