Characterisation of a 30 a heaterless hollow cathode

A novel high-current heaterless hollow cathode (HHC) has been designed, constructed, and tested, with the developed system successfully demonstrating operation up to 30 A. This system overcomes the need for excessive ignition voltages or propellant pulsing, by utilising a reduced keeper orifice that enables ignition with <350 V, and nominal flow rates (<15 sccm). The system has also demonstrated full ignition in 50 seconds compared with conventional ignition, which can require more than 10 minutes; additionally, the system requires as little as 1/6th of the ignition energy compared to that of conventional designs. The HHC’s performance was characterised with operation tested in Xe, Kr and Ar. Optical pyrometry has allowed measurements of the emitter tip temperature of a HHC for the first time. Furthermore, the internal cathode-keeper plasma has been investigated using optical emission spectroscopy to determine the plasma electron density