A xenon collisional-radiative model applicable to electric propulsion devices: I. Calculations of electron-impact cross sections for xenon ions by the Dirac B-spline R-matrix method

Abstract

A fully relativistic Dirac B-spline R-matrix (DBSR) method is applied to calculate the oscillator strengths and electron-impact excitation cross sections involving the 5s25p5, 5s5p6, 5p46s, 5p45d, 5p46p, and 5p47s states of a Xe+ ion. A fully relativistic approach is necessary for this problem, since the spin–orbit coupling is of the same order as electron correlations in the outer shells of Xe+. Also, there is a complex open-shell structure with strong term dependence in the one-electron orbitals. The oscillator strengths are also calculated and agree well with available experimental measurements. We select some important excitation cross sections out of the ground, metastable, and quasi-metastable states of Xe+ for the collisional-radiative (CR) model to be discussed and analyzed. The present paper is the first one of a series of studies on a CR model of xenon ions in plasma diagnosis and numerical simulations of Hall and ion thrusters. In subsequent papers, the cross-section data for the Xe+ ion, together with those for neutral Xe from our previous calculation, are used to build a comprehensive CR model for electric propulsion systems involving xenon. Furthermore, the predictions of this model will then be examined by experiments in both Hall and ion thrusters.