2016 Articles

Recombination of W19+ ions with electrons: Absolute rate coefficients from a storage-ring experiment and from theoretical calculations

Badnell, N. R.; Spruck, K.; Krantz, C.; Novotny, Oldrich; Becker, A.; Bernhardt, D.; Grieser, M.; Hahn, Michael; Repnow, R.; Savin, Daniel Wolf; Wolf, A.; Muller, A.; Schippers, S.

Experimentally measured and theoretically calculated rate coefficients for the recombination of W 19 + ( [ Kr ] 4 d 10 4 f 9 ) ions with free electrons (forming W 18 + ) are presented. At low electron-ion collision energies, the merged-beam rate coefficient is dominated by strong, mutually overlapping, recombination resonances as already found previously for the neighboring charge-state ions W 18 + and W 20 + . In the temperature range where W 19 + is expected to form in a collisionally ionized plasma, the experimentally derived recombination rate coefficient deviates by up to a factor of about 20 from the theoretical rate coefficient obtained from the Atomic Data and Analysis Structure database. The present calculations, which employ a Breit–Wigner redistributive partitioning of autoionizing widths for dielectronic recombination via multi-electron resonances, reproduce the experimental findings over the entire temperature range.Experimentally measured and theoretically calculated rate coefficients for the recombination of W 19 + ( [ Kr ] 4 d 10 4 f 9 ) ions with free electrons (forming W 18 + ) are presented. At low electron-ion collision energies, the merged-beam rate coefficient is dominated by strong, mutually overlapping, recombination resonances as already found previously for the neighboring charge-state ions W 18 + and W 20 + . In the temperature range where W 19 + is expected to form in a collisionally ionized plasma, the experimentally derived recombination rate coefficient deviates by up to a factor of about 20 from the theoretical rate coefficient obtained from the Atomic Data and Analysis Structure database. The present calculations, which employ a Breit–Wigner redistributive partitioning of autoionizing widths for dielectronic recombination via multi-electron resonances, reproduce the experimental findings over the entire temperature range.