RBED cross sections for the ionization of atomic inner shells by electron-impact

Abstract

The relativistic binary-encounter-dipole (RBED) model for electron-impact ionization of atoms combines classical binary-encounter theory and the asymptotic dipole interaction, which is based on the plane-wave Born approximation, with the only non-trivial ingredient being the optical oscillator strength (OOS). Due to the difficulty of obtaining accurate OOSs, the performance of the RBED model has so far not been fully assessed. In the present work we compare RBED inner-shell ionization cross sections (total and differential) of neutral atoms evaluated using three types of OOSs, namely an empirical power-law OOS, analytical hydrogenic OOSs and ab initio OOSs calculated numerically from self-consistent atomic potentials. We find that, compared to the distorted-wave Born approximation (DWBA), the RBED with either hydrogenic or numerical OOSs generally yields more accurate total cross sections (TCSs) than the RBED with the power-law OOS, especially for the most tightly bound shells. In the highly relativistic limit the RBED model does not recover the Bethe asymptotic behavior because of its different energy-dependent prefactor, hence we investigate an alternative prefactor which restores the correct Bethe asymptote. Finally, we suggest multiplying the RBED differential cross sections (DCSs) by the ratio of DWBA to RBED TCSs and verify that this renormalization improves the agreement with the DWBA DCSs.

Impact of a minority relativistic electron tail interacting with a thermal plasma containing high-atomic-number impurities

“…We note agreement within a factor of two of recent R-matrix theories at the peak of the cross section, and that unlike those reported in Ref. [35], normally such calculations are not extended into the relativistic regime of relevance here. The plasma physics impact established in this paper certainly points to the importance and urgency of such systematic first-principle cross section calculations.…”

“…Figure 2. ICS for lumped-average L-shell ionization of Ar.Comparison of our proposed approximate ICS is made against the non-relativistic result of Burgess and Chidichimo[33], and the relativistic results of Scofield[13] and Wang et al[35].…”

“…As T e varies from 10 keV to 1 eV, n e can vary greatly as a function of Z , but n RE is a fixed number that only depends on how much current the runaways need to carry. For ex- Comparison of our proposed approximate ICS is made against the non-relativistic result of Burgess and Chidichimo [33], and the relativistic results of Scofield [13] and Wang et al [35].…”

Impact of a minority relativistic electron tail interacting with a thermal plasma containing high-atomic-number impurities [Slides]

“…However, the online version of record will be different from this version once it has been copyedited and typeset. 31 , and the relativistic results of Scofield 13 and Wang et al 33 .…”

“…peak of the cross section, and that unlike those reported in Ref. 33 , normally such calculations are not extended into the relativistic regime of relevance here. The plasma physics impact established in this paper certainly points to the importance and urgency of such systematic first-principle cross section calculations.…”