Current distribution on the electrodes of MPD arcjets

Abstract

Current distribution on the electrodes of a conventional MPD arcjet without external magnetic field was calculated based on induction equation, with the assumption that the magnetic Reynolds number is small. The calculated result, which showed the influence of tensor conductivity, coincided fairly well with the corresponding experimental one. It was seen, however, that the current density near the cathode tip in experiment had a larger value than that in calculation. This discrepancy was explained tentatively as being the result of the occurrence of cathode spots. It is also suggested in this paper that the unfavorable current concentration at the cathode base can be suppressed by using a specially devised divided cathode.