L-shell electron excitations of Mg- through O-like tungsten ions

Abstract

Electron impact excitations from ground state L shell viz. n = 2 → n = 3 transitions in Mg-like W62+, Na-like W63+, Ne-like W64+, F-like W65+ and O-like W66+ ions have been considered. A fully relativistic distorted wave (RDW) theory has been used to calculate the excitation cross-sections for an electric and magnetic dipole, as well as for the quadrupole transitions for these ions, which were observed recently in the measurements taken from an electron-beam-ion trap (EBIT-I) at the Livermore laboratory. We have performed calculations in the electron impact energy range from a threshold excitation energy of up to 60 keV. Our results, where possible, have been compared with the few previous theoretical calculations that are available. Analytic fits to our calculated excitation cross-sections have also been done for plasma modeling purposes. Our calculated cross-sections have been further employed to obtain the linear polarization of the photon emissions for dipole-allowed transitions due to the decay of the electron impact excited anisotropic states to the ground state for all five of the tungsten ions that are considered in the present work.

E1, M1, E2 transition energies and probabilities of W54+ions

“…A collisional-radiative model was applied to explain the observed spectrum. An MCDF calculation with restricted electron correlation effects on the 3d-3p transitions was presented by Dipti et al; they also calculated the electron impact excitation cross section and polarization degree [12].…”

“…During recent decades, several studies have been performed to provide the theoretical and experimental values of W 54+ ions [5][6][7][8][9][10][11][12]. Safronova et al calculated the magnetic dipole (M1) and electric quadrupole (E2) transitions between the multiplets of the ground state configuration ([Ne]3s 2 3p 6 3d 2 ) of W 54+ using the relativistic many-body perturbation theory (RMBPT) [7].…”

Fusion-Related Ionization and Recombination Data for Tungsten Ions in Low to Moderately High Charge States

“…Within the frame of the tungsten collisions project reviewed in this communication, processes described by Equations (1)- (5) were studied for selected charge states by experiments which were partially accompanied by theory. In addition to information about the collision processes listed above, cross sections and rate coefficients for charge transfer ( [18,19] and references therein), electron-impact excitation ( [20,21] and references therein) together with spectroscopic information ( [22] and references therein) on tungsten ions in all charge states are needed for plasma diagnostics. Spectroscopic observations and further collisional data are becoming available now and are summarized in several contributions to the present Special Issue of ATOMS on "Atomic Data for Tungsten".…”

Electron Impact Excitation of Extreme Ultra-Violet Transitions in Xe7–Xe10 Ions

“…This ensures the quality of the target ion's wavefunctions that are crucial in determining the accuracy of the scattering parameters. Moreover, the RDW method has been successfully implemented in the previous work on a variety of targets from closed to open-shell systems and neutral atoms to multiply or highly charged ions atoms/ions [25][26][27][28][29][30]. It has also been found that using RDW cross sections in a collisional radiative (CR) model provides plasma parameters that are in better agreement with the measurements [31][32][33][34].…”