Electrode Erosion of Arc Heater by Emission Spectroscopy

Abstract

Emission spectroscopy was conducted in a miniature arc heater in China Aerodynamics Research and Development Center to study the erosion of water-cooled copper electrode due to the high-temperature environment. With a 2-mm-diam viewpoint, emission signal of plasma torch at the exit of the nozzle was collected. Three tests were implemented under different conditions with arc currents of 400, 600, and 800 A. Temperature under each condition was determined as $4680\pm 300$ , $4560\pm 300$ , and $4650\pm 300\mathrm{K}$ . By absolute irradiance calibration, the number density of copper atoms in the flowfield was determined; combined with the estimate of the plasma torch volume and the flow velocity, the erosion rate of copper electrode was given. Apparently, the erosion rate increases with the raise of the current, as shown in the result. Based on experience and the results of previous studies by other researchers, the value of the erosion rate is reliable, which verified a new approach with optical method to investigate the electrode erosion of arc-heated facilities.