On confinement and plasma acceleration from a small ECR plasma source

Abstract

<p>Electron Cyclotron Resonance (ECR) is a technique to create high density, low temperature plasmas that do not depend on a cathode, like arc discharges and are therefore easier to maintain and have a longer lifespan. The use of the Electron Cyclotron Resonance (ECR) for electron heating for Magnetic Nozzle (MN) thrusters have recently received increased interest, as they have been shown to provide improved thrust efficiency up to 16 % at only 30 W input power. Such performance make such thrusters viable for use on small, e.g. Cubesat, spacecraft. <p>An ECR plasma source similar to that described by Jarrige et al. (2017), was recently installed in a 30 cm diameter and 60 cm long cylindrical chamber at UiT. This source is grounded, as opposed to the previously described one, which is shielded from ground. The source consists of a cylindrical sleeve antenna of diameter 2.6 cm, and was operated at 10 -20 W, at mass flow rates from 0.2 –0.8 mg/s, which result in pressures ranging from 0.08 –0.3 Pa. High-resolution radial profiles of plasma parameters were obtained by means of Langmuir, ion energy analyzer and Mach probes, at two different axial positions 20 cm and 50 cm from the source, i.e. in the far plume of the source. The configurations were i) a monotonous expanding magnetic field, ii) a bottle-shaped magnetic field, and iii) a nearly homogeneous magnetic field with straight lines.