Characterization of diamagnetism inside an ECR thruster with a diamagnetic loop

Abstract

The plasma-induced magnetic field in an electron cyclotron resonance plasma thruster is measured non-intrusively by means of a diamagnetic loop that encloses the plasma flow. The calibration process is described, and parasitic currents in the thruster walls and plasma oscillations are identified as the dominant sources of uncertainty. The integrated magnetic flux is seen to depend on the applied power and less significantly on the mass flow rate. The effect of the diamagnetic loop radius is also studied by testing two loops of different diameters. To estimate the perpendicular electron pressure in the plasma from the loop measurements, two plasma beam models, 1D and 2D, are used. While both models give similar results for the small loop, they differ significantly for the large loop, showing the relevance of 2D effects when a large diamagnetic loop is used.

Physics of E × B discharges relevant to plasma propulsion and similar technologies

“…Instead, the divergent MN is an electromagnetic device from the momentum point of view: magnetic thrust is achieved thanks to the diamagnetic drift developing on electrons [367], [369], [370], [371], [372]. These drifts form azimuthal current loops, of diamagnetic character, which induce a magnetic field acting on the thruster coils [373], [429], [430]. This coil/plasma configuration is equivalent to the basic setup of two wire loops with counterstreaming electric currents (of different magnitude), which repel each other, as shown in Fig.…”

Impact of the Microwave Coupling Structure on an Electron-Cyclotron Resonance Thruster

“…Therefore, it could lead to a robust, easy to operate, and lowcost propulsion system. The ECRT research is active on several fronts: thruster development [3,4], thruster system development [5], diagnostics development [6], and simulation [7,8].…”

Commentary: On helicon thrusters: Will they ever fly?

“…For a RF power of ∼1 kW, the thrust with no magnetic field is ∼3-4 mN, whereas the total thrust is larger than 10 mN for a magnetic field strength of ∼700 G corresponding to an electric power of less than 1 kW consumed by the solenoid. The thrust increase is caused by momentum conversion which results from the Lorentz force in the magnetic nozzle, as previously investigated in analytical [5], numerical [6,7], and experimental studies [8][9][10]. Therefore, applying the magnetic field is more effective than increasing the RF power.…”