Electron impact single ionization differential cross sections of W (6s), W (5d), W (5p) and W (4f)

Abstract

Electron-induced triple differential cross sections (TDCSs) have been obtained for the few outer sub-shells of tungsten atoms, namely W (6s), W (5d), W (5p) and W (4f). Tungsten and related materials have been recommended as the prime candidates for wall materials in fusion plasma devices. The electron-induced cross-section data are strongly required for the diagnostics and modeling of plasma in such devices. We observe that the trends of TDCSs obtained for the ionization of W (5d) sub-shells are very different from the TDCSs of W (6s), W (5p) and W (4f) in terms of binary and recoil peak locations as well as in the change of magnitude of TDCS with an increasing value of momentum transfer which is due to the open d-shell. The angle and energy-resolved cross-section data of tungsten atoms may be of vital importance in order to understand the spectroscopy of W atoms as wall materials as well as an impurity.

Calculation of Electron Impact Single Ionization TDCS of Tungsten Atoms at 200, 500 and 1000 eV

“…It is also worth mentioning that the energy range considered in the present investigation is suitable for plasma applications as the electron temperatures vary from a few hundred eV at the outside of the separatrix (scrape-off layer) down to a few eV in the vicinity of the divertor surfaces [19,29]. The separatrix is a boundary between confined plasma and external plasma.…”

“…Recently, electron-induced cross-sections of tungsten atoms have been reported for ionization [25] and ionization as well as excitation [26]. Very recently, electron-induced direct ionization cross-sections have been calculated for W atoms in variants of distorted wave [27,28] and modified BEB approaches [28] and differential cross-sections have been reported for the electron impact ionization of W atoms at 100 eV projectile energy [29]. The differential crosssection obtained for the energy and angle resolved conditions may be of further importance to understand the electron spectroscopy involved in fusion plasma [29,30].…”

“…Very recently, electron-induced direct ionization cross-sections have been calculated for W atoms in variants of distorted wave [27,28] and modified BEB approaches [28] and differential cross-sections have been reported for the electron impact ionization of W atoms at 100 eV projectile energy [29]. The differential crosssection obtained for the energy and angle resolved conditions may be of further importance to understand the electron spectroscopy involved in fusion plasma [29,30]. The kinetic modeling of discharges which have non-Maxwellian velocity distributions for electrons may be executed efficiently using differential cross-section data [31].…”

“…Earlier studies to calculate TDCS of W atoms [27,29] have been carried out at projectile energy 100 eV for various scattering angles and ejected electron energies. In this communication, we report the TDCS results obtained for the electron impact single ionization of W atoms at various projectile energies, i.e., 200, 500 and 1000 eV for ejected electron energy 2 eV and 10 eV for different scattering angles.…”