Maxwellian rate coefficients for electron-impact ionization of W ²⁶⁺

Abstract

Excitation-autoionization (EA) and direct ionization (DI) Maxwellian rate coefficients (MRC) are presented for the levels of the ground configuration of the W26+ ion. The study of EA and DI cross sections is performed by applying the Dirac–Fock–Slater method within the level-to-level distorted-wave approximation including radiative damping. Excitations to the high-nl shells (n ≤ 25) are taken into account for the EA process. It is shown that electron-impact ionization from the different levels of the ground configuration produces a significant variation of MRC. Excitations to configurations with energy levels that straddle the ionization threshold play the main role in enhancing MRC for the highest level of the ground configuration. The difference of 40% among the EA MRC is determined for the levels of the ground configuration.

Electron-impact single ionization of the nitrogen atom

“…This is slightly lower than the value of 14.53 eV recommended by the National Institute of Standards and Technology (NIST; Kramida et al (2021)). A similar trend between the single-ionization thresholds calculated using the DFS approximation and those derived from the NIST data was obtained for other ions: Se 2+ (Konceviciūtė et al 2018), Se 3+ (Pakalka et al 2018;Koncevičiutė et al 2019), Fe 3+ (Kynienė et al 2019), W 25+ (Kynienė et al 2016), W 26+ (Kynienė et al 2015;Kynienė et al 2018), and W 27+ (Jonauskas et al 2015). The energy levels for the ground configuration of the N atom are compared to the NIST values in Table 1.…”

“…The theoretical cross-sections obtained for the 2 D and 2 P terms are higher than experimental ones by ∼40% and ∼60%, respectively, at the peak values. The convergence of the cross-sections for the indirect process must be evaluated in order to provide reliable data (Jonauskas et al 2015;Kynienė et al 2015;Kynienė et al 2016Kynienė et al , 2018. The EA channels corresponding to excitations from the 2s subshell up to shells with the principal quantum number n 10 are shown in Fig.…”

Maxwellian and non-Maxwellian rate coefficients of the tungsten ions: W46+–W55+

“…Hot electrons have been detected in various sources including tokamaks and other plasmas [16][17][18][19]. In this section, we explore the effects of hot electrons with non-Maxwellian EEDFs.…”

“…Zhang and Kwon studied the MRC of W 17+ ground state and compared with the previous CADW rate coefficients [8]. Then, the MRC for W 25+ and W 26+ from different levels of ground state were calculated by Kynienė et al [15,16]. However, the presence of strong electric and magnetic fields, as well as the existence of multiple particle species and complex reaction channels in plasmas, can all lead to deviations from the Maxwellian distribution of electrons and result in non-Maxwellian distributions in plasmas [17].…”