A Kinetic Model of the Ionization Layer within an Electron Cyclotron Resonance Plasma Cathode

An Electron Cyclotron Resonance (ECR) plasma cathode utilizes resonant microwave heating within a magnetic field to generate a plasma from a working gas. Electrons may be extracted from this plasma for a variety of applications, ranging from space propulsion to plasma etching. The inclusion of an orifice plate in combination with an applied voltage allows for the formation of a region with enhanced ionization from which more electrons can be extracted. A kinetic model of the formation of this enhanced ionization region in the vicinity of the orifice is presented in this work, detailing both the formation mechanisms, as well as sensitivity to varying operating parameters. Additionally, electron emission enhancement associated with the formation of the ionization layer is quantified for the purpose of maximizing extractable current from the device. The simulations were carried out using the EDIPIC code [https://github.com/PrincetonUniversity/EDIPIC-2D], and the modeling results are validated against experimental data obtained from ECR device operation.