Experimental characterization of a lanthanum hexaboride hollow cathode for five-kilowatt-class hall thrusters

A hollow cathode has been designed and tested at Sitael, Space Propulsion Business Unit (formerly Alta). A heaterless configuration has been selected to remove a single point of failure for the cathode, which is represented by the heater. To further improve the system reliability, a LaB6 emitter has been selected for the lack of specific activation procedures and the low sensitivity to impurities and air exposure. Tests were carried out by using xenon and krypton as propellants. Krypton was adopted to reduce on-ground development and qualification costs and the dependence on the volatile natural-resource market. The cathode showed a successful operation with both propellants in the investigated range of operating conditions, with a design expected to provide robustness and reliability in terms of ignition procedure, discharge parameters and steady-state temperatures.