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

Badnell, N. R. and Spruck, K. and Krantz, C. and Novotný, O. and Becker, A. and Bernhardt, D. and Grieser, M. and Hahn, M. and Repnow, R. and Savin, D. W. and Wolf, A. and Müller, A. and Schippers, S. (2016) Recombination of W19+ ions with electrons : absolute rate coefficients from a storage-ring experiment and from theoretical calculations. Physical Review A - Atomic, Molecular, and Optical Physics. ISSN 1050-2947 (In Press)

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Abstract

Experimentally measured and theoretically calculated rate coefficients for the recombination of W19+ ([Kr] 4d10 4f9) ions with free electrons (forming W18+) are presented. At low electron-ion collision energies, the merged-beams rate coefficient is dominated by strong, mutually overlapping, recombination resonances as already found previously for the neighboring charge-state ions W18+ and W20+. In the temperature range where W19+ 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 ADAS 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.