Numerical Study of Inductively Coupled Plasma Cathode as an Alternative to Hollow Cathode in Space Propulsion Applications
by Sina Jahanbakhsh, Murat Celik

Hollow cathodes have been commonly used as the electron source and neutralizer for ion thrusters and other electric propulsion devices. These cathodes provide high electron cur- rents very efficiently. However, they have certain disadvantages such as high erosion rate of the insert material and poisoning due to impurities in the propellant gas. Also, due to the requirement of heating before operation, cathode turn on times can be significant. To address these issues, alternative electron source concepts are being considered. In this work, RF inductively coupled plasma cathode has been studied. RF cathodes are insert free elec- tron sources that use radio frequency fields to create plasma inside a chamber, and this plasma is used to extract electrons and neutralize thruster ion beam. This work presents the eort to numerically model the concepts of RF cathode. Using a commercial software, 2-D axisymmetric and 3-D geometry of RF cathode concepts are modeled. Changes in the electron number density inside discharge chamber and extracted electron current from the RF cathode are obtained for different values of mass ow rate, delivered RF power and bias voltage. Also, a parametric study is done in order to understand the effect of geometric parameters on the RF cathode operation.