Latest progress in Hall thrusters plasma modelling

Abstract

In the last thirty years, numerical models have revealed different physical mechanisms involved in the Hall thruster functioning leading to a bridge between analytical prediction / empirical intuition and experiments. For this reason, modeling effort is continuously increasing in the domain of Hall Thrusters. Two basic approaches exist: one based on fluid/hybrid simulation where the distribution of electrons is assumed Maxwellian and the plasma inside the thruster, considered as quasineutral, is described with macroscopic quantities (density, velocity and energy); the second approach is based on kinetic description for charged particles where no approximation is made for the distribution of particles. Fluid or hybrid approaches offer the advantage of demanding low run times and computational resources. They are very useful to perform parametric studies but actually the anomalous phenomena responsible for electron transport across the magnetic field barrier have not been selfconsistently modeled. Kinetic approach is able to better capture phenomena originating on the Debye scale length like the lateral sheaths, ExB electron drift instability, important to explain the anomalous electron transport, but it requires very long run times. For this latter, the progress in computer science offers the advantage to describe conditions more and more close to the thruster operation. In this review, we will present the two approaches emphasizing on numerical schemes used with assumptions and approximations and on main results obtained. Future directions on the Hall thruster modeling will finally outlined.

Electric Propulsion Methods for Small Satellites: A Review

“…Predictive modelling of thruster erosion has yet to be achieved in this capacity [63]. The need for analytical models to study HT operation and provide predictive analytical frameworks continues to increase [64]. HT can be modelled under fluid or kinetic regimes and while 2D modelling of HTs has been achieved, 3D modelling using particle-in-cell monte carlo collisions (PIC MCC) remains difficult and heavily time consuming, often taking up to several months to complete [65].…”

Radial distribution of electrons rotation moment in hall effect and plasma-ion thrusters

“…The authors of papers [1,2] try to describe "nearthe-wall-conductivity" with the use of total electron collision frequency without a clear comment about this totality. Such comment is made in paper [3] as the momentum transfer frequency including electron-atom and electron-ion collisions are included, as well as effect of anomalous transport but without presenting a specific mathematical form for this frequency.…”

Numerical and Experimental Investigation of Longitudinal Oscillations in Hall Thrusters

“…Several advantages can be obtained with hybrid models that combine different approaches for different species within the same computational framework. Although complex methodologies are available and currently used to carry out 2D (see, for instance, [9][10][11][12][13][14][15][16][17][18]) or even 3D simulations (see, for instance, [19,20]) of Hall thruster discharges (see also [21,22] for recent reviews of the literature), 1D models are still very appealing for studying the fundamental mechanisms in the dynamics of the plasma discharge. Indeed, despite the unavoidable lower accuracy and prediction capabilities in comparison with more complex models, they are easier to handle and definitely cheaper from a computational viewpoint.…”