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@ARTICLE{Brezinsek:844180,
      author       = {Brezinsek, S. and Laengner, M. and Coenen, J. W. and
                      O’Mullane, M. G. and Pospieszczyk, A. and Sergienko, G.
                      and Samm, U.},
      title        = {{S}pectroscopic determination of inverse photon
                      efficiencies of {W} atoms in the scrape-off layer of
                      {TEXTOR}},
      journal      = {Physica scripta},
      volume       = {T170},
      issn         = {1402-4896},
      address      = {Bristol},
      publisher    = {IoP Publ.},
      reportid     = {FZJ-2018-01632},
      pages        = {014052 -},
      year         = {2017},
      abstract     = {Optical emission spectroscopy can be applied to determine
                      in situ tungsten particle fluxes from erosion processes at
                      plasma-facing materials. Inverse photon efficiencies convert
                      photon fluxes of WI and WII line transitions into W and
                      ${{\rm{W}}}^{+}$ particle fluxes, respectively, dependening
                      on the local plasma conditions. Experiments in TEXTOR were
                      carried out to determine effective conversion factors for
                      different WI and WII transitions with the aid of WF6
                      injection into deuterium scrape-off layer plasmas in the
                      electron temperature T e range between
                      ${T}_{{e}}=20\,\mathrm{eV}$ and ${T}_{{e}}=82\,\mathrm{eV}$.
                      The inverse photon efficiencies or so-called effective
                      $\tfrac{S}{{XB}}$-values have been determined for WI lines
                      at $\lambda =400.9\,\mathrm{nm}$, 429.5 nm, 488.7 nm, 498.3
                      nm, and 522.5 nm as well as for WII at $\lambda
                      =434.6\,\mathrm{nm}$ and compared with theoretical
                      calculations from the ADAS data base. Moreover, a
                      multi-machine scaling for the $\tfrac{S}{{XB}}$-value in the
                      range of T e between $2...100\,\mathrm{eV}$ has been
                      determined for the most prominent WI line at $\lambda
                      =400.9\,\mathrm{nm}$ to
                      $\tfrac{S}{{XB}}({T}_{{e}})=53.63-56.07\times
                      {e}^{(0.045\times {T}_{{e}}[\mathrm{eV}])}$ considering
                      experimental data from TEXTOR, ASDEX Upgrade, PSI and
                      PISCES. Comparison with ADAS calculations for the same
                      transition reveal a good qualitative agreement with the
                      dependence on T e , but an underestimation of ADAS
                      calculations of less than 25\% over the full covered range
                      of experimentally accessible T e in the multi-machine
                      scaling. A good agreement within the experimental
                      uncertainties is found between TEXTOR and ADAS
                      $\tfrac{S}{{XB}}$-values for WI at $\lambda
                      =429.5\,\mathrm{nm}$ and $\lambda =488.7\,\mathrm{nm}$
                      whereas an underestimation of up to a factor two of ADAS
                      values for WI at $\lambda =522.5\,\mathrm{nm}$ and $\lambda
                      =498.3\,\mathrm{nm}$ was measured. Potentially, reasons for
                      the discrepancy are an overestimation of applied ionisation
                      rate coefficients in ADAS for neutral W and a stronger
                      electron dependence n e for these transitions.},
      cin          = {IEK-4},
      ddc          = {530},
      cid          = {I:(DE-Juel1)IEK-4-20101013},
      pnm          = {174 - Plasma-Wall-Interaction (POF3-174)},
      pid          = {G:(DE-HGF)POF3-174},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000414120500052},
      doi          = {10.1088/1402-4896/aa8a45},
      url          = {https://juser.fz-juelich.de/record/844180},
}