Simulation of the plume of a magnetically enhanced plasma thruster with SPIS

Abstract

A three-dimensional fully kinetic particle-in-cell (PIC) simulation strategy has been implemented to simulate the acceleration stage of a magnetically enhanced plasma thruster (MEPT). The study has been performed with the open-source code Spacecraft Plasma Interaction Software (SPIS). The tool has been copiously modified to simulate properly the dynamics of a magnetized plasma plume. A cross-validation of the methodology has been done with Starfish, a two-dimensional open-source PIC software. Two configurations have been compared: (i) in the absence of a magnetic field and (ii) in the presence of a magnetic field generated by a coil with maximum intensity of 300 G at the thruster outlet. The results show a reduction of the plume divergence angle, an increase of ion speed and an increase of the specific impulse in the presence of the magnetic nozzle. The simulations presented in this study are representative of the operative conditions of a 50 W MEPT. Nonetheless, the methodology adopted can be extended to handle the magnetized plasma plume of several other types of thrusters such as electron cyclotron resonance and applied field magnetoplasmadynamic thrusters.

Different fluid strategies for the simulation of a Helicon Plasma Thruster

“…Moreover, the implementation of the energy equations for the heavy species will be considered to accurately predict the neutral temperature and heat fluxes. Finally, a comparison against the results obtained with a PIC-MCC [10,11] model will be performed as means of verification of the codes implementation, and a comparison of the models will be made with respect to experimental data taken from literature for validation purposes.…”

“…Many numerical methods have been used in literature for modelling plasma production and acceleration. The most important approaches are fluid, [5,7] kinetic, [7] Particle-In-Cell with Monte-Carlo Collisions (PIC-MCC), [8][9][10][11] and hybrid. [9,12] In the fluid approach, the particle distribution function is assumed (usually Maxwellian) and the plasma is described in terms of continuity, momentum, and energy equations.…”

Fully kinetic model of plasma expansion in a magnetic nozzle

“…Future work will involve iterative coupling of the PIC to the fluid model 3D-VIRTUS, developed to simulate the source region of such devices [15,27,56,57]. The boundary conditions will also be applied within the framework of a 3D PIC code [26] to assess the limitations of the 2D axisymmetric assumptions, and analyse the plume interactions with non-axisymmetric spacecraft bodies.…”

“…This method ensures that the system evolves self-consistently and inherently guarantees that, once at steady-state, the ion and electron currents are equal (I iB = −I eB ) at the open boundaries (III), and therefore also at the infinity. The initial value of φ ∞ (φ 0 ∞ ) is set according to the theoretical value obtained by assuming a current-free condition at the thruster outlet, the absence of a magnetic field, and electron energy conservation [26]. For the Maxwellian population given by equation ( 8), the analytical result is…”

“…Both fluid and kinetic continuum approaches must further make assumptions regarding the VDF, one of the main impact parameters in magnetised plasma expansion [24]. Hence, numerical studies need to be extended to fully kinetic [26][27][28][29] or fluid-kinetic [30] approaches if the dynamics of a MN want to be treated self-consistently. The fully kinetic Particle-in-Cell (PIC) method represents the numerical strategy with the lowest level of assumptions.…”