Abstract
This paper describes an arcjet thruster using a segmented cathode with a protection-gas
channel to reduce electrode erosion. In the future, inter-orbit massive transports are mandatory
to build large-scale space platforms, and hence, necessitates large thrust electric propulsion.
Arcjet thrusters, which have relatively high thrust-to-power ratio with middle-class specific
impulse of 600 s for hydrazine propellant, are one of the promising propulsion devices. However, intense Joule heat deteriorates the cathode to reduce the lifetime of the thruster. Hence, the authors propose to apply segmented cathodes and hydrocarbon protection gas to the arcjet thrusters in order to suppress the electrode damage and extend the lifetime. Hydrocarbon will produce carbon layers on the cathode surface, which would protect the cathode. In this study, segmented-cathode type arcjet thruster was prototyped to check whether the electrode loss will be reduced by the use of segmented-cathode. For safety, nitrogen was used as a tentative alternative to the hydrocarbon cathode protection gas since hydrocarbon could produce carbon monoxide gas in the arc discharge. Tests showed that the cathode erosion per energy was reduced from 0.24 to 0.1 ug/kJ by supplying the cathode-protection gas to the hollow cathode.
