Direct and remote measurements of a hollow cathode discharge

Results are presented from measurements made on a hollow cathode generated plasma using direct and remotely located probes. Based on previous life tests where erosion was seen on hollow cathode assembly components, it is necessary to understand the plasma flow field downstream of hollow cathodes. Experiments have been performed where large amplitude plasma potential oscillations were seen from measurements made using a floating emissive probe (potentials ranging from 20 V to 85 V within a 34 V discharge). In addition to the emissive probe, results are presented from a direct measurement triple Langmuir probe. Also, a remotely located electrostatic analyzer (ESA) was used to measure the energy of ions produced within the plasma.