EROSION AND PASSIVATION OF ELECTRODES OF A MAGNETOPLASMADYNAMIC THRUSTER

The erosion of the electrodes in a low powered steady state magnetopla smadynamic thruster is described. The environment experienced by rite electrodes in this device is harsh, lending to high cathode erosion ra tes and, when operating with propellants containing oxygen, passivatio n of the anode. The erosion of the electrodes is often cited as the li fetime limiting feature of magnetoplasmadynamic thrusters, and can als o interfere with the operation of these devices when they are used for non-propulsive applications. The cathode erosion was investigated usi ng analysis of the surface structure, theoretical evaporation predicti ons, scanning electron microscopy (SEM), energy dispersive spectroscop y, (EDS), and metallographic examinations of the crystal structure. Th e passivation of the anode was investigated using SEM and EDS techniqu es. From this work suggestions for reducing the erosion rate are made. A plasma coating application of this device for materials deposition is also suggested.