Study of applied magnetic field magnetoplasmadynamic thrusters with particle-in-cell and Monte Carlo collision. II. Investigation of acceleration mechanisms

Abstract

The particle-in-cell method previously described in paper (I) has been applied to the investigation of acceleration mechanisms in applied-field magnetoplasmadynamic thrusters. This new approach is an alternative to magnetohydrodynamics models and allows nonlocal dynamic effects of particles and improved transport properties. It was used to model a 100 kW, steady-state, applied-field, argon magnetoplasmadynamic thruster to study the physical acceleration processes with discharge currents of 1000–1500 A, mass flow rates of 0.025–0.1 g/s and applied magnetic field strengths of 0.034–0.102 T. The total thrust calculations were used to verify the theoretical approach by comparison with experimental data. Investigations of the acceleration model offer an underlying understanding of applied-field magnetoplasmadynamic thrusters, including the following conclusions: (1) swirl acceleration mechanism is the dominant contributor to the plasma acceleration, and self-magnetic, Hall, gas-dynamic, and swirl acceleration mechanisms are in an approximate ratio of 1:10:10:100; (2) the Hall acceleration produced mainly by electron swirl is insensitive to the change of externally applied magnetic field and shows only slight increases when the current is raised; (3) self-magnetic acceleration is normally negligible for all cases, while the gas-dynamic acceleration contribution increases with increasing applied magnetic field strength, discharge current, and mass flow rate.

2-D Extended Fluid Model of Applied-Field Magnetoplasmadynamic Thruster With Solid and Hollow Cathodes

“…3. The obtained CVCs correspond well with theoretical and experimental results [23], [28]. As it can be seen, the same currents are obtained at lower voltages in the case of hollow cathode.…”

“…Numerical simulations combined with theoretical analysis could become a powerful tool in optimization of thruster design, although great amounts of physical processes and external parameters that must be taken into account make it an uneasy task [24], [25]. MPD thruster is usually treated using plasma quasi-neutrality assumption [26]- [28], detailed description of boundary sheaths is omitted. The obtained results do not allow for making any justified assumptions concerning the lifetime of a simulated device, as most surface processes such as cathode erosion greatly depend on the value of cathode voltage drop.…”

Influence of Electron and Ion Thermodynamics on the Magnetic Nozzle Plasma Expansion

“…These qualities make them an interesting device to produce thrust in space. Currently, several advanced plasma thrusters, including the helicon plasma thruster [1], [2], [3] (HPT), the electron cyclotron resonance thruster [4] (ECRT), the applied-field magnetoplasmadynamic (AF-MPD) thruster [5], [6], [7], and the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) [8], employ an MN as their main acceleration stage.…”

Modeling of plasma processes in the slowly diverging magnetic fields at the exit of an applied-field magnetoplasmadynamic thruster

“…The whole simulation process must proceed based on electron-ion timescale, which requires millions of time-steps to reach the quasi-steady state. Taking some reasonable accepted acceleration methods, 21,22 the computation procedure can be significantly abbreviated based on the precondition that several relevant parameters be adjusted. Therefore, the way regarding plasma plume as representative particles makes it convenient to record all messages of kinetic movement so that many microscopic and macroscopic variables of passing plasma can be acquired in detail.…”

“…3,10 Considering the specific working conditions of propulsion units, a suitable computational model should be constructed so that various characteristics of plasma motion through magnetic nozzle can be demonstrated. As the PIC (particle-in-cell) method based on particle kinetic dynamics has successfully been applied and identified some key issues of AF-MPDT performances, 21,22 it is appropriate to pursue the present simulation process with relevant modifications. Specifically, this simulation work examines magnetic nozzle effects based on the AF-MPDT experimental results reported by NASA Lewis Research Center.…”