Vector Resolved Energy Fluxes and Collisional Energy Losses in Magnetic Nozzle Radiofrequency Plasma Thrusters

Energy losses in a magnetic nozzle radiofrequency plasma thruster are investigated to improve the thruster efficiency and are calculated from particle energy losses in fully kinetic simulations. The simulations calculate particle energy fluxes with a vector resolution including the plasma energy lost to the dielectric wall, the plasma beam energy, and the divergent plasma energy in addition to collisional energy losses. As a result, distributions of energy losses in the thruster and the ratios of the energy losses to the input power are obtained. The simulation results show that the plasma energy lost to the dielectric is dramatically suppressed by increasing the magnetic field strength, and the ion beam energy increases instead. In addition, the divergent ion energy and collisional energy losses account for approximately 4%–12% and 30%–40%, respectively, regardless of the magnetic field strength.

Numerical investigations of 2-D planar magnetic nozzle effects on pulsed plasma plumes

This paper presents a study of a novel type of magnetic nozzle that allows for three-dimensional (3-D) steering of a plasma plume. Numerical simulations were performed using Tech-X’s USim® software to quantify the nozzle’s capabilities. A 2-D planar magnetic nozzle was applied to plumes of a nominal pulsed inductive plasma (PIP) source with discharge parameters similar to those of Missouri S&T’s Missouri Plasmoid Experiment (MPX). Argon and xenon plumes were considered. Simulations were verified and validated through a mesh convergence study as well as comparison with available experimental data. Periodicity was achieved over the simulation run time and phase angle samples were taken to examine plume evolution over pulse cycles. The resulting pressure, velocity, and density fields were analysed for nozzle angles from 0° to 14°. It was found that actual plume divergence was small compared to the nozzle angle. Even with an offset angle of 14° for the magnetic nozzle, the plume vector angle was only about 2° for argon and less than 1° for xenon. The parameters that had the most effect on the vectoring angle were found to be the coil current and inlet velocity.

Experimental Characterization of the Capacitively Coupled RF-Plasma Thruster

A novel design of a neutralizer-free plasma thruster is proposed. This setup features a capacitively coupled RF discharge for plasma generation combined with a magnetic nozzle configuration for acceleration. Characteristics of the plasma plume and ions flux are investigated with the help of emissive probes and retarding potential analyzers (RPA). Essential parameters of the thruster like ions energy, ions flux, utilization efficiencies, and thrust are estimated. The investigated system produces a beam of ions accelerated to an energy of 10 eV when operated at power levels of ~20 W and a mass flow of 1.2 mg/s. The ion energy coincides with the potential drop in the plasma plume indicating that the acceleration takes place due the formation of an ambipolar electric field in the expanding plasma. The design is compared to the data available of other similar thrusters.