Coherence imaging spectroscopy at Wendelstein 7-X for impurity flow measurements

Perseo, Valeria; Gradic, Dorothea; König, Ralf; Ford, Oliver P.; Killer, Carsten; Grulke, Olaf; Ennis, David A.

doi:10.1063/1.5126098

Title: Coherence imaging spectroscopy at Wendelstein 7-X for impurity flow measurements

Journal Article · 01 January 2020 · Review of Scientific Instruments

DOI: https://doi.org/10.1063/1.5126098 · OSTI ID:1802585

^[1];

^[2]; König, Ralf ^[2];

^[2];

^[2]; Grulke, Olaf ^[2]; Ennis, David A. ^[3]

Max-Planck-Institut für Plasmaphysik, Greifswald (Germany); Max-Planck-Institut für Plasmaphysik, 17491 Greifswald, Germany
Max-Planck-Institut für Plasmaphysik, Greifswald (Germany)
Auburn Univ., Auburn, AL (United States)

In the last decade, Coherence Imaging Spectroscopy (CIS) has shown distinctive results in measuring ion flow velocities in the edge of magnetically confined plasma devices. Its 2D spatially resolved measurement capabilities and its high optical throughput are ideal for investigating the impurity behavior in the complex 3D magnetic island topology edge of Wendelstein 7-X (W7-X). However, a highly precise and stable calibration method is required for a reliable diagnostic operation. A new level of precision and stability has been achieved for the two CIS systems installed at W7-X with the use of a new calibration source, a continuous tunable laser commercially available only since 2015. A specific prototype model was successfully adapted to the challenging requirements of W7-X, granting high accuracy (±0.01 pm) and flexibility (spectral range: 450–650 nm) in the wavelength calibration required for measuring low-Z impurity ion flow velocities. These features opened up new investigation possibilities on temperature stability and wavelength response of the CIS components, allowing to fully characterize and validate the W7-X systems. The CIS diagnostic was operational throughout the last W7-X experimental campaign. Measured velocities on the order of ~20–30 km/s were observed, corroborated by comparisons with measurements with Mach probes.

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Research Organization:: Auburn Univ., AL (United States); Univ. of Wisconsin, Madison, WI (United States)

Sponsoring Organization:: Euratom; USDOE Office of Science (SC)

Contributing Organization:: W7-X Team

Grant/Contract Number:: SC0014210; SC0014529

OSTI ID:: 1802585

Journal Information:: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 1 Vol. 91; ISSN 0034-6748

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

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