Electron energy distribution and instabilities in electron beam generated ExB plasma*

Electron beam (e-beam) generated plasmas are promising for low pressure, low damage threshold material processing applications requiring efficient generation of ions and radical species [1,2]. The production of reactive species generated by electron impact is governed by the electron energy distribution function (EEDF). In this work, we investigate the EEDF and plasma parameters of a partially magnetized plasma generated by e-beam in low pressure (0.1-10 mTorr) argon. The e-beam (energy < 100 eV) is extracted from a negatively biased thermionic filament and injected at one end of a cylindrical vacuum chamber with applied axial magnetic field. The EEDF is measured using Langmuir probes, and plasma potential profiles and ion density oscillations are additionally characterized with emissive and ion probes respectively. Results indicate the presence of beam electrons with energy at roughly the applied cathode potential, as well as a group of warm electrons (10-30 eV). Analysis of results of these measurements and their comparison with PIC simulations will be presented.

[1]       Zhao F et al C G 2021 Carbon 177 244–51

[2]       Walton S G et al 2015 ECS J. Solid State Sci. Technol. 4 N5033–40