A High Performance Cathode Heater for Hall Thrusters, Phase II

The current state-of-the-art co-axial swaged tantalum (Ta) heaters use magnesium oxide (MgO) insulators, which limits their operation to temperatures well below 1300ºC to prevent undesirable chemical reactions between Mg and Ta and heater failure. This program will develop a new ceramic insulator that is chemically compatibility with Ta and has high thermal stability at temperatures of 1300ºC-1600ºC for swaged heaters for BaO-impregnated and LaB6 hollow cathodes. In Phase I, we demonstrated the new ceramic insulators can be used in swaged Ta heaters for BaO-impregnated cathodes that operate at 1100ºC-1300ºC. In Phase II, we will further develop the new ceramic insulator for use in LaB6 hollow cathode heaters that operate at 1600ºC. We will develop an extrusion process to fabricate ceramic insulators with high dimensional tolerances at low cost and fabricate a prototype swaged coaxial heaters in collaboration with a heater manufacturer. Performance mapping and heater testing will be carried out in collaboration with an end-user aerospace company. More »