Kinetic insights into thrust generation and electron transport in a magnetic nozzle

Axisymmetric fully kinetic particle-in-cell simulations are carried out to study the expansion of plasma in a propulsive magnetic nozzle (MN). The simulation results reveal that the MN can boost the total thrust while the on-axis ion acceleration may be suppressed, demonstrating the necessity of including two-dimensional effects if the propulsive performance is the primary concern. The magnetic thrust resulting from the interaction of azimuthal electric current with the applied magnetic field is identified as the only source of enhancing the plasma plume thrust. It is found that the role of electron transport, in connection with the stress tensor, cannot be neglected in fluid modeling. The electron transport effects will induce a paramagnetic drift current and thus undermine the propulsive performance of MN.