Prospects of X-ray imaging spectrometers for impurity transport: Recent results from the stellarator Wendelstein 7-X (invited)

A. Langenberg*, N. A. Pablant, Th Wegner, P. Traverso, O. Marchuk, T. Bräuer, B. Geiger, G. Fuchert, S. Bozhenkov, E. Pasch, Olaf Grulke, F. Kunkel, C. Killer, D. Nicolai, G. Satheeswaran, K. P. Hollfeld, B. Schweer, T. Krings, P. Drews, G. OffermannsA. Pavone, J. Svensson, J. A. Alonso, R. Burhenn, R. C. Wolf

*Corresponding author for this work

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Abstract

This paper reports on the design and the performance of the recently upgraded X-ray imaging spectrometer systems, X-ray imaging crystal spectrometer and high resolution X-ray imaging spectrometer, installed at the optimized stellarator Wendelstein 7-X. High resolution spectra of highly ionized, He-like Si, Ar, Ti, and Fe as well as H-like Ar have been observed. A cross comparison of ion and electron temperature profiles derived from a spectral fit and tomographic inversion of Ar and Fe spectra shows a reasonable match with both the spectrometers. The also measured impurity density profiles of Ar and Fe have peaked densities at radial positions that are in qualitative agreement with the expectations from the He-like impurity fractional abundances, given the measured temperature profiles. Repeated measurements of impurity decay times have been demonstrated with an accuracy of 1 ms via injection of non-recycling Ti, Fe, and Mo impurities using a laser blow-off system.
Original languageEnglish
Article number10G101
JournalReview of Scientific Instruments
Volume89
Issue number10
Number of pages7
ISSN0034-6748
DOIs
Publication statusPublished - 2018

Cite this

Langenberg, A., Pablant, N. A., Wegner, T., Traverso, P., Marchuk, O., Bräuer, T., Geiger, B., Fuchert, G., Bozhenkov, S., Pasch, E., Grulke, O., Kunkel, F., Killer, C., Nicolai, D., Satheeswaran, G., Hollfeld, K. P., Schweer, B., Krings, T., Drews, P., ... Wolf, R. C. (2018). Prospects of X-ray imaging spectrometers for impurity transport: Recent results from the stellarator Wendelstein 7-X (invited). Review of Scientific Instruments, 89(10), [10G101]. https://doi.org/10.1063/1.5036536