The azimuthal currents in the ion-driven magnetic nozzle

Ion-driven magnetic nozzles (Ti > Te) are designed as intrinsic parts of cutting-edge propulsive technologies such as variable specific impulse magnetoplasma rockets (VASIMRs) and applied -field magnetoplasmadynamic thrusters. Employing a two-dimensional axisym-metric particle-in-cell (PIC) code, in the ion-driven magnetic nozzle, the compositions and dis-tributions of azimuthal currents in different axial regions are investigated under various inlet ion temperatures Ti0 and found to differ dramatically from that in the electron-driven magnetic noz-zles. Previously reported to be all paramagnetic and vanishing under a high magnetic field, the azimuthal currents resulting from the E 3 B drift are shown to turn diamagnetic and sustain a considerable magnitude when Ti0 is considered. The previously reported profile of diamagnetic drift current is altered by the introduction of inlet ion temperature, and the paramagnetic part is significantly suppressed. Moreover, a wide range of paramagnetic currents appear downstream due to the inward detachment of ions, which can also be reduced by increasing inlet ion tem-perature. Albeit considered in this paper, the azimuthal currents resulting from grad-B and curvature drift are still negligible in all cases of interest. The magnitude of diamagnetic azimuthal currents increases with amplifying Ti0, indicating a clear physical image of energy transformation from ion thermal energy to the directed kinetic energy through electromagnetic processes in the magnetic nozzle. Additionally, the magnetic inductive strength also has notice-able impacts on the azimuthal currents, the current magnitude tends to decrease as the magnetic field increases, and over-increment of it may result in larger divergence angles and lower nozzle efficiency. 2022 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).