Axial momentum gains of ions and electrons in magnetic nozzle acceleration

Abstract

Fully kinetic simulations of magnetic nozzle acceleration were conducted to investigate the axial momentum gains of ions and electrons with electrostatic and Lorentz forces. The axial momentum gains per ion and electron are directly calculated from the kinetics of charged particles, indicating that electrons in the magnetic nozzle obtain the net axial momentum by the Lorentz force, even though they are decelerated by the electrostatic force. Whereas ions are also accelerated by the electrostatic force, the axial momentum gain of electrons increases significantly with increasing magnetic field strength and becomes dominant in the magnetic nozzle. In addition, it is clearly shown that the axial momentum gain of electrons is due to the electron momentum conversion from the radial to the axial direction, resulting in a significant increase in the thrust and exhaust velocity.

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

“…The boundary conditions of the electrostatic field are Dirichlet boundary conditions at the right and top boundaries (ϕ 0) and the Neumann boundary conditions at the left and bottom boundaries (zϕ/zn 0 with z/zn being the normal derivative), where ϕ is the potential. Note that the Dirichlet boundary conditions generate the sheath near the right and top boundaries, as shown in our previous paper [30].…”

“…We have employed two-dimensional (x-y) and bidirectional calculation models to reduce the calculation cost [19,30]. Although bidirectional thrusters are different from the common thruster, they are proposed for space debris removal [31].…”

“…The plasma kinetics in the thruster is analyzed using particle-in-cell and Monte Carlo collisions (PIC-MCC) techniques. Details of the calculation model and simulation method were given in previous papers [19,30,32,33], and a brief description is written in this paper.…”

Vector resolved energy fluxes and collisional energy losses in magnetic nozzle radiofrequency plasma thrusters

“…We have employed two-dimensional ( -) and bidirectional calculation model to reduce the calculation cost [15,26]. Although bidirectional thrusters are different from the common thruster, they are proposed for the space debris removal [27].…”

“…The plasma kinetics in the thruster is analyzed using particle-in-cell and Monte calro collisions (PIC-MCC) techniques. Details of the calculation model and simulation method were given in previous papers [15,26,28,29], and a brief description is written in this paper.…”