Development of a high current heaterless hollow cathode

Higher power in-space propulsion systems are increasingly been developed and utilised due to payload increases and mission demands. This requires higher current cathodes to match this demand, as such cathodes are increasingly adopting lanthanum hexaboride (LaB6) emitters due to the higher current density operation capabilities. However, LaB6 cathodes operate at higher temperatures compared with traditional barium oxide cathodes, due to the material’s relatively higher work function. Hence, this poses higher challenges to the heater technologies, which raise convention HCs to thermionic temperature. Here we present the development of a heaterless hollow cathode (HHC) system, which self-heats within only tens of seconds before nominal operation, and enables currents up to 30 A. Such that the system effectively removes the burden of the heater subcomponent. Within this work, the breakdown, cold (heating) discharge and nominal performance of the HHC have been characterised. In addition, optical emission spectroscopy is utilised to assess the relative erosion rates.