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@ARTICLE{Pablant:904064,
      author       = {Pablant, N. A. and Langenberg, A. and Alonso, J. A. and
                      Bitter, M. and Bozhenkov, S. A. and Ford, O. P. and Hill, K.
                      W. and Kring, J. and Marchuck, O. and Svensson, J. and
                      Traverso, P. and Windisch, T. and Yakusevitch, Y.},
      title        = {{C}orrection and verification of x-ray imaging crystal
                      spectrometer analysis on {W}endelstein 7-{X} through x-ray
                      ray tracing},
      journal      = {Review of scientific instruments},
      volume       = {92},
      number       = {4},
      issn         = {0034-6748},
      address      = {[S.l.]},
      publisher    = {American Institute of Physics},
      reportid     = {FZJ-2021-05634},
      pages        = {043530 -},
      year         = {2021},
      abstract     = {X-ray ray tracing is used to develop ion-temperature
                      corrections for the analysis of the X-ray Imaging Crystal
                      Spectrometer (XICS) used at Wendelstein 7-X (W7-X) and
                      perform verification on the analysis methods. The XICS is a
                      powerful diagnostic able to measure ion-temperature,
                      electron-temperature, plasma flow, and impurity charge state
                      densities. While these systems are relatively simple in
                      design, accurate characterization of the instrumental
                      response and validation of analysis techniques are difficult
                      to perform experimentally due to the requirement of extended
                      x-ray sources. For this reason, a ray tracing model has been
                      developed that allows characterization of the spectrometer
                      and verification of the analysis methods while fully
                      considering the real geometry of the XICS system and W7-X
                      plasma. Through the use of ray tracing, several important
                      corrections have been found that must be accounted for in
                      order to accurately reconstruct the ion-temperature
                      profiles. The sources of these corrections are described
                      along with their effect on the analyzed profiles. The
                      implemented corrections stem from three effects: (1) effect
                      of sub-pixel intensity distribution during de-curving and
                      spatial binning, (2) effect of sub-pixel intensity
                      distribution during forward model evaluation and generation
                      of residuals, and (3) effect of defocus and spherical
                      aberrations on the instrumental response. Possible
                      improvements to the forward model and analysis procedures
                      are explored, along with a discussion of trade-offs in terms
                      of computational complexity. Finally, the accuracy of the
                      tomographic inversion technique in stellarator geometry is
                      investigated, providing for the first time a verification
                      exercise for inversion accuracy in stellarator geometry and
                      a complete XICS analysis tool-chain.},
      cin          = {IEK-4},
      ddc          = {620},
      cid          = {I:(DE-Juel1)IEK-4-20101013},
      pnm          = {134 - Plasma-Wand-Wechselwirkung (POF4-134)},
      pid          = {G:(DE-HGF)POF4-134},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {34243399},
      UT           = {WOS:000639283800004},
      doi          = {10.1063/5.0043513},
      url          = {https://juser.fz-juelich.de/record/904064},
}