Numerical investigation of parameter dependent discharge characteristics in a low power radio frequency plasma thruster with magnetic nozzle

Radio-frequency plasma thrusters with magnetic nozzles are promising candidates for micro-satellite propulsion because of their electrode-free configuration, compact structure, and wide operating flexibility. However, for low-power RF plasma thrusters, the parameter-dependent discharge characteristics under different magnetic-field and operating conditions still require further clarification from an engineering design perspective. In this study, a two-dimensional axisymmetric multiphysics fluid model is established for the RPT-1 discharge chamber to investigate the effects of magnet position, magnetic field strength, xenon flow rate, and RF power on plasma density and electron temperature. The results show that the magnet position produces a non-monotonic influence on plasma parameters, which is associated with the spatial matching between the magnetic-confinement region and the RF power-coupling region. Within the investigated range, increasing the magnetic field strength from 0.05 T to 0.30 T increases the outlet-center plasma density from approximately 7.76×1018 m-3 to 7.79×1018 m-3, while the electron temperature rises slightly from about 3.265 eV to 3.267 eV. Increasing the xenon flow rate from 5 sccm to 10 sccm enhances the axial plasma density inside the discharge chamber but decreases the outlet-center plasma density by approximately 45% and reduces the electron temperature from about 3.28 eV to 2.95 eV due to enhanced collisional energy loss and reduced ionization efficiency near the outlet. In contrast, increasing RF power from 50 W to 150 W significantly enhances both plasma density and electron temperature owing to stronger electron heating and ionization. The present work focuses on engineering-oriented parameter trends based on a fluid description rather than fully kinetic plasma dynamics, and the results provide useful guidance for magnetic-field arrangement and operating-parameter selection in low-power RF plasma thrusters.