Mechanisms of magnetoplasmadynamic arc jet acceleration processes

A unique type of electric discharge has been discovered and some of its characteristics investigated. The discharge occurs between an impulsively heated cathode and a ring anode in an enclosed test cell that has been evacuated to 10 to the (-8) power Torr. It is a non-self-sustaining discharge that lasts for tens of milli-seconds in which the current transitions rapidly (about 2 microsec.) from a discharge mode to a cathode electron emission controlled mode at a critical voltage, (about 2,000 V at an ambient pressure of 10 to the (-8) power Torr.). The discharge has an impedance of approximately 3,400 ohms which increases when a solenoidal magnetic field is applied. In many respects, the discharge observed in the test cell is ideal for application to the Space Electric Ram Jet concept.