Particle-in-Cell Model of the NEXT Ion Engine at Three Throttling Conditions

Abstract

Between 2004 and 2007 a detailed PIC-MCC (particle-in-cell Monte Carlo collision) computer model was developed at Wright State University to numerically simulate the plasma discharge in an ion engine. This computer code has been used to model both the NSTAR and NEXT ion engines. Base case operating conditions have been analyzed for both of these engines. Comparisons were made between these base case computational results and experimental results. For both the NSTAR and NEXT engines, the results were generally within 30% with many quantities having better comparisons than this. It is the goal of this work to use this Wright State computational model to analyze a number of additional operating conditions of the NEXT ion engine. Specifically, results for three operating conditions are shown in this paper. These operating conditions are TL40, TL09 and TL01. For each of these operating conditions the particle number density distributions for the neutrals, first ions, second ions, primary electrons, and secondary electrons are shown. Plots of the electron temperature distributions are given. In addition, the ion and electron flows to seven different regions on the walls and grids of the discharge chamber are given, as well as the total beam current, the double to single current ratio in the beam current, the propellant utilization efficiency, the current to the solid portion of the screen grid, and the discharge current.