ANODE POWER DEPOSITION IN AN APPLIED-FIELD SEGMENTED ANODE MPD THRUSTER

Anode heat flux measurements of a water-cooled segmented anode applied-field MPD thruster were made to investigate anode heat transfer phenomena. Pure argon and argon-hydrogen mixtures were used as propellants for a variety of thruster currents, propellant mass flow rates, and axial applied magnetic field strengths. The thruster was operated in two modes: 1) with all four segments active, and 2) with two of the segments floating. The results of this work show that the heat flux to the anode increases monotonically with axial magnetic field strength and thruster current. Between 50-75% of the anode heat flux is transported by the current-carrying electrons. Convective and radiative heat transfer (primarily from the cathode radiation) account for the remaining portion of the power deposited to the anode. The addition of hydrogen to the argon propellant results in the reduction of the fraction of anode power deposited by the anode fall to a level equivalent to that of convection and radiation.