Study of scaling law for particle-in-cell/Monte Carlo simulation of low-temperature magnetized plasma for electric propulsion

Abstract

Particle-in-cell/Monte Carlo collision (PIC/MCC) algorithms are an outstanding numerical method for predicting the kinetic characteristics of discharge plasma. However, heavy computational costs limit its application, especially in large-scale plasma simulations. To investigate the distribution properties of plasma in magnetoplasmadynamic (MPD) thrusters, we used a scale reduction method called scaling law to simplify and accelerate the PIC/ MCC simulation. In this method, the physical processes, including the particle motion and collisions, of discharge plasma remained unchanged, thereby preserving the similarity of the discharge system before and after scaling. On the basis of the scaling law, all the scaling schemes of the relevant physical quantities were obtained. We verified the scaling law by analysing the electron trajectories and densities in electromagnetic fields at different scaling factors. The scaling methodology shows great advantages in reducing the total computation and the time to achieve the convergence of the simulation. Therefore, the PIC/MCC model with the scaling law provides an efficient and in-depth understanding of the discharge plasma in MPD thrusters.

Numerical investigation of plasma behavior in a micro DC ion thruster using the particle-in-cell/Monte Carlo collision (PIC/MCC) method

“…It would be such a great computation expense to use extremely small grid spacing and time step to resolve the plasma Debye length and the electron plasma frequency. Due to the inherent characteristics of PIC-MCC method such as huge amount of calculation and long calculation time, there is a large volume of published studies describing the acceleration methods for PIC simulation such as self-similar scaling routine [46][47][48], reducing the mass of heavy particles [23], increasing the vacuum permittivity [48,49]. Yuan et al [50] investigated the effect of numerical acceleration techniques which provided critical suggestions for employing these techniques.…”

“…As a result, this method is used in this paper and we set the artificial permittivity value to be inflated by a factor of 10 2 so that the plasma Debye length is in the millimeter range rather than micron range. In addition, the electron plasma frequency decreases with the inflated artificial permittivity value, which means the time step we use can be relatively large as tens of picoseconds so as to speed up the convergence [47][48][49]51]. In this paper, a structured grid with a length of 1.5 × 10 −4 m is used, and the time step is 3 × 10 −11 s, which meets the requirements mentioned above.…”

Revealing the plasma confinement behavior of an axial ring cusp hybrid discharge in a miniature ion thruster using PIC/MCC simulation

“…Due to the inherent characteristics of PIC/MCC methods such as the huge amount of calculation and long calculation time, it is necessary to adopt acceleration approaches such as assuming an artificial permittivity [22][23][24]. There is a large volume of published studies describing the acceleration methods for PIC simulations such as self-similar scaling routine [32,33], reducing the mass of heavy particles [21], increasing the vacuum permittivity [33,34]. Yuan et al [35] investigated the effect of numerical acceleration techniques which provided critical suggestions for employing these techniques.…”

A Central-Cathode Electrostatic Thruster Featuring a High-Temperature Superconducting Applied Field Module

“…They also found that at an applied field strength of 0.1 T, F AF was approximately ten times larger than F GD or F Hall . Li et al also used a PIC-MCC model to investigate an AF-MPD thruster [98] [99]. They made the electrostatic assumption and derived a self-similar scaling law to reduce computation time.…”