Transitional Behavior of MPD Arcjet Operation

Abstract

The thrust and discharge voltage of a quasisteady MPD arcjet have been measured, with emphasis on the transitional characteristics from the propellant over-fed to starved condition and from aerodynamic to electromagnetic acceleration. From the anode and cathode potential measurements, the transition into the starved condition was found to be preceded slightly by the transition of acceleration process when the discharge current was increased. At the beginning of the electromagnetic acceleration, the thrust became unstable. This was attributable to radial current expansion toward the outer anode region. At higher discharge current, the flow pattern settled and the quasisteady state was restored.