A Study of Ion Thruster Optics through Particle Simulations and Evaluation of the Near Plume Plasma Properties

Abstract

A three-dimensional hybrid PIC-DSMC code is developed to simulate the physics of ion optics between an accelerator and a screen grid that are placed at the end of the discharge chamber of an ion thruster. Ions and neutrals are both represented with macro particles that have different weights. Electric potential is evaluated from the Gauss' Law that takes the form of the Poisson's equation, where the right hand side includes the net charge density evaluated at the computational grid nodes. The solution domain is a 30 o slice in cylindrical coordinates with symmetry boundary conditions at the radial and azimuthal boundaries. Macro particles are tracked with the Leapfrog algorithm. DSMC collisions are implemented for heavy species. A parametric study is performed to find the grid configuration that yields the best performance.

Evaluation of Ion Beam Behavior in 50 W Class RF Ion Thruster

“…The acceleration process of the ions and the divergence phenomenon of the ion beam through the grid system were investigated by PIC simulation featured in OverViz plasma simulation suite [16]. Numerical simulation helps to visualize the ion beam trajectory and provides the ion density distribution from which the divergence angle of the ion beam can be determined [17,18]. Figure 2 shows two different computational domains with corresponding boundary conditions.…”

Formation and neutralization of electric charge and current of an ion thruster plume

“…The flight heritage and success of GITs has led to the development of numerous and miscellaneous tools for their ion optics and plume simulation. Among the different existing models to simulate the ion beam extraction, formation and neutralization, the most successful are hybrid models [4][5][6][7][8][9][10], based on particle-in-cell (PIC) modeling of the ions, and fluid modeling of the electrons. Yet, there exist also full-PIC codes attempting to overcome the inherent limitations of the electrons fluid approach [11][12][13][14][15][16], with the corresponding computational burden and some yet unresolved modeling difficulties, such as the imposition of proper electron boundary conditions (with some existing proposals [17]) to avoid using too large simulation domains.…”