A volume-averaged plasma model for heaterless C12A7 electride hollow cathodes

Abstract

A volume-averaged hollow cathode plasma model is presented that serves as a preliminary design tool for orificed hollow cathodes. The plasma discharge volume is subdivided into two computational domains with separate sub-models that are used to determine the emitter and orifice region plasma parameters. The plasma model is coupled with a lumped node thermal model that uses power inputs from the plasma model to estimate the temperature distribution of the hollow cathode. The model has been implemented for conventional cylindrical emitter geometries and for novel disc-shaped emitters. A lanthanum hexaboride (LaB6) hollow cathode has been used to validate the cylindrical model results and shows good agreement with well-known trends of hollow cathodes and published model data, while a calcium aluminate electride (C12A7:e-) hollow cathode developed at Technische Universität Dresden (TUD) served as the basis for the disc configuration. The model results of the disc configuration are presented and discussed to identify trends and optimization potential for hollow cathodes using C12A7:e- emitters. The model results in combination with thermal measurements of the TUD hollow cathode indicate a work function of C12A7:e- in a hollow cathode plasma below 2 eV.

Solution of Orifice Hollow Cathode Plasma Model Equations by Means of Particle Swarm Optimization

“…Hall Effect Thrusters (HETs), Gridded Ion Thrusters (GITs), High Efficiency Multistage Plasma Thrusters (HEMPTs) [2]. A lot of computational tools, based on phenomenological models, also known as zero-dimensional (0D) or reduced-order models, aimed to predict OHCs' plasma properties and performances and useful to support their design, have been developed since '80s [3][4][5][6][7][8][9][10][11][12].…”

“…The equations that constitutes the most of the models presented in the open literature [5][6][7][9][10][11][12] are commonly iteratively solved to face with their own non-linear characteristic. Each author adopts a different approach.…”