The introduction of a virtual radial direction in axial-azimuthal PIC simulations of Hall Thrusters
Résumé
Hall Thrusters (HTs) are well-settled space propulsion systems that are nowadays largely
used in space missions. In recent years, the need of designing new thrusters has met the great
boost in computing capacities: several codes have been developed to guide the development of
future thrusters. Among them, particle-in-cell (PIC) codes adopt a kinetic description of the
plasma and efficiently describe the evolution of the discharge in an HT. In the present work, we
use a bi-dimensional PIC code to simulate the axial-azimuthal plane of such device. Starting
from the design of current thrusters, we coupled the PIC code with a model for a RLC filter
that damps the large Breathing Mode oscillations. We also introduced a simplified model of the
radial dimension, referred to as fake-r, in the 2D axial-azimuthal simulation: at each timestep
we remove from the simulation a number of particles corresponding to the Bohm flux at the
walls. Several fake-r thicknesses have been tested and their effect on some important plasma
parameters are discussed. We also verified that the chosen value for the azimuthal length in
PIC simulations has a significant impact on the discharge current evolution.