Electron-impact excitation and ionization of W 3+ for the determination of tungsten influx in a fusion plasma

C P Ballance, S D Loch, M S Pindzola, D C Griffin

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19 Citations (Scopus)

Abstract

Tungsten will be employed as a plasma facing material in the ITER fusion reactor under construction in Cadarache, France; therefore, there is a significant need for accurate electron-impact excitation and ionization data for the ions of tungsten. We report on the results of extensive calculations of ionization and excitation for W 3+ that are intended to provide the atomic data needed for the determination of impurity influx diagnostics of tungsten in several existing tokamak reactors. The electron-impact excitation rate coefficients for this study were determined using the relativistic R -matrix method. The contribution to direct electron-impact ionization was determined using the distorted-wave approximation, the accuracy of which was verified by an R -matrix with pseudo states calculation. Contributions to total ionization from excitation autoionization were also generated from the relativistic R -matrix method. These results were then employed to calculate values of ionization per emitted photon, or SXB ratios, for four carefully selected spectral lines; these data will allow the determination of impurity influx from tungsten facing surfaces. For the range of densities of importance in the edge region of a tokamak reactor, these SXB ratios are found to be nearly independent of electron density but vary significantly with electron temperature.
Original languageEnglish
Pages (from-to)055202
Number of pages17
JournalJournal of Physics B: Atomic, Molecular and Optical Physics
Volume46
Issue number5
DOIs
Publication statusPublished - 19 Feb 2013
Externally publishedYes

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