Beam emission spectroscopy diagnostic design and capabilities for two-dimensional turbulence measurement on Wendelstein 7-X
POSTER
Abstract
Turbulence transport is found to play a significant role in heat and particle confinements on Wendelstein 7-X (W7-X). A beam emission spectroscopy (BES) diagnostic is designed for studying 2D plasma turbulence dynamics at r/a∼0.5-1 by measuring the localized Doppler-shifted Balmer-alpha emission (n=3→2) from neutral heating beams on W7-X. We report the recent status of the diagnostic design, including optical assembly, detector platform, and the optical throughput. The field-aligned sightlines of BES is arranged to satisfy the constraints of the 3D magnetic topology and nearly radial heating beams while maintaining the sufficient Doppler shift to isolate the beam emission manifold on W7-X. The sightline grid with 1.4 cm spacing is evaluated to be sensitive to ion-scale turbulence with k⊥ρi≦0.4 at r/a=0.75 in the post-pellet regime of W7-X. We report on point spread function (PSF) calculations for a BES sightline grid in a variety of magnetic configurations and operational regimes of W7-X. Finally, the BES capabilities for 2D ion-scale turbulence measurements are summarized, the plan for in-situ calibration and experimental measurement on W7-X is foreseen.
*Supported by U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences Award Np. DE-SC0019009. This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No 101052200 — EUROfusion). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them.
Presenters
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Xiang Han
- University of Wisconsin - Madison
- University of Wisconsin