Plasma and Cathode Emission from a High Power Hydrogen Arcjet Thruster

Abstract : An experimental study of the measurement of cathode temperature, current distribution, and near-cathode electron number density in a high power hydrogen arcjet is presented. This study is motivated by the desire to better understand arc-electrode interactions in arcjet thrusters, which in many cases, is the main determinate of arcjet lifetime. Measurements such as these may also provide the needed boundary conditions for numerical arcjet simulations, presently under development. We describe in this paper the application of a non-intrusive in-situ measurement technique for on-axis, spectral imaging of the electrode region of arcjets, and the application of this technique to the measurement of the cathode and anode temperatures, cathode spot size, and current distribution in a 30kW hydrogen arcjet thruster. A relatively large field of view (twice the throat diameter) and high spatial resolution (9 micrometers) are achieved.