An effective Xe+–Xe interaction potential for electric propulsion systems

Abstract

An effective Xe+–Xe interaction potential for electric propulsion systems is proposed based on both spin–orbit free interaction potentials and the screened-Coulomb potential. The model not only conforms with the potential obtained by an ab initio method at large internuclear distances but also matches well with the potential derived from experimental scattering data at short internuclear distances. The scattering angles and differential cross sections computed by the effective potential are in good agreement with those obtained by the Morse potential in low-energy regions and those via two screened-Coulomb potentials (the Ziegler–Biersack–Littmark and Zinoviev potential) in high-energy regions, respectively. To further validate the effective potential, a particle-in-cell method with a Monte Carlo collisions technique, coupled with a direct method for solving the scattering equation, was applied to simulate the collisions of 1500-eV and 7000-eV single-charged xenon ions with background xenon atoms in a test cell. The simulated currents on the inner cylinder, exit plate, exit orifice, and front plate are calculated by different potentials. Results show that the effective potential can give a good prediction of the Xe+–Xe elastic collisions in the wider energy region compared with the Morse, Ziegler–Biersack–Littmark, and Zinoviev potentials.