Measurement of plasma flow and electron energy probability function in radio frequency plasma thruster with a magnetic cusp

Abstract

The use of a cusp magnetic field is studied to improve the thrust performance of small electrodeless radio frequency (RF) plasma thrusters based on a theoretical analysis of a magnetized inductively coupled plasma. In this type of thruster, electrons play a critical role in determining the thrust performance. The electron energy probability function (EEPF) and two-dimensional profiles of the plasma parameters in the cusp-type magnetic field RF thruster are investigated to characterize the plasma flow. Non-Maxwellian EEPFs were obtained, which correspond to the pressure and plasma potential profiles in the plasma plume. In addition, the axial ion velocity was measured, and the presence of ion flux in the downstream direction is revealed, indicating ideal ion acceleration.