Erlangen 2018 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 12: Magnetic Confinement - Poster

P 12.5: Poster

Dienstag, 6. März 2018, 16:15–18:15, Redoutensaal

The Wendelstein 7-X Phase Contrast Imaging Diagnostic — •Adrian von Stechow¹, Olaf Grulke^1,3, Lukas-Georg Böttger^1,3, Eric Edlund², Miklos Porkolab², and The W7-X team¹ — ¹Max-Planck-Institut für Plasmaphysik — ²MIT Plasma Science and Fusion Center — ³Technical University of Denmark

The Wendelstein 7-X stellarator (W7-X) is in its second operation phase with full divertor geometry. W7-X is highly optimized to minimize neoclassical transport and designed to run steady state, and is thus the first stellarator in which the role of turbulent transport can be quantitatively assessed at reactor relevant parameters. These results feed back to ongoing modeling activities which predict ion temperature gradient and trapped electron modes that fundamentally differ in their scaling and spatial distribution from those observed in tokamaks.

Quantitative characterization of turbulence requires a broad range of profile and fluctuation diagnostics, including a new phase contrast imaging (PCI) system that measures spatially resolved electron density fluctuations along a sight line through the plasma center. The project is a collaboration between the MIT PSFC and IPP. An overview of diagnostic features and capabilities and exemplary results of characteristic discharge features are presented. These include remote alignment and optical reconfiguration of the CO₂ laser system to cover a broad spatial range in real (50-110 mm) and k space (5-17 cm⁻¹), absolute k-space and relative amplitude calibration by means of an acoustic speaker array, and radial localization of measurements by selective beam masking.