Measurement of LaB6 hollow cathode emitter region temperature and plasma characteristics

Hollow cathodes are widely used as electron sources in electric propulsion systems owing to their high electron generation efficiency. Research findings allude to the significant impact of the temperature and plasma characteristics of the emitter region of a hollow cathode, which supplies thermionic electrons, on its operation. However, these characteristics are not yet fully understood. The objective of this study is to investigate these characteristics under different orifice diameters and operating conditions. The emitter temperature increased with the discharge current for both orifice diameters. The electron density was higher downstream for larger orifice diameters. The emitter temperature was compared with the orifice temperature and was found to be lower than the latter for smaller orifices.