Abstract
A zero-dimension plasma model of thermionic hollow cathodes is here derived. The equations of conservation of mass, current and power are solved within the insert and orifice regions. The model introduces some elements of novelty compared to prior literature such as the inclusion of the electron current collected on the orifice lateral walls, and ion and electron currents collected on the orifice plate walls in the overall balance equations. Estimation of the power deposited on walls due to electron and ion bombardment in both insert and orifice regions are performed, thus, enabling comparisons among different geometrical configurations and operating regimes. The model results are compared against published experimental data and a thorough investigation of the model response to variation of geometrical and operational condition of a sample cathode are presented. A power budget, which includes power consumption and power deposition, of a sample thermionic cathode is also discussed.