Spectroscopic imaging of limiter heat and particle fluxes and the resulting impurity sources during Wendelstein 7-X startup plasmas

L Stephey; G A Wurden; O Schmitz; H Frerichs; F Effenberg; C Biedermann; J Harris; R König; P Kornejew; M Krychowiak; E A Unterberg; W7-X Team

doi:10.1063/1.4959274

Spectroscopic imaging of limiter heat and particle fluxes and the resulting impurity sources during Wendelstein 7-X startup plasmas

Rev Sci Instrum. 2016 Nov;87(11):11D606. doi: 10.1063/1.4959274.

Authors

L Stephey¹, G A Wurden², O Schmitz¹, H Frerichs¹, F Effenberg¹, C Biedermann³, J Harris⁴, R König³, P Kornejew³, M Krychowiak³, E A Unterberg⁴; W7-X Team³

Affiliations

¹ University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
² Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
³ Max-Planck-Institut für Plasma Physik, Wendelsteinstrasse 1, 17491 Greifswald, Germany.
⁴ Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.

PMID: 27910364
DOI: 10.1063/1.4959274

Abstract

A combined IR and visible camera system [G. A. Wurden et al., "A high resolution IR/visible imaging system for the W7-X limiter," Rev. Sci. Instrum. (these proceedings)] and a filterscope system [R. J. Colchin et al., Rev. Sci. Instrum. 74, 2068 (2003)] were implemented together to obtain spectroscopic data of limiter and first wall recycling and impurity sources during Wendelstein 7-X startup plasmas. Both systems together provided excellent temporal and spatial spectroscopic resolution of limiter 3. Narrowband interference filters in front of the camera yielded C-III and H_α photon flux, and the filterscope system provided H_α, H_β, He-I, He-II, C-II, and visible bremsstrahlung data. The filterscopes made additional measurements of several points on the W7-X vacuum vessel to yield wall recycling fluxes. The resulting photon flux from both the visible camera and filterscopes can then be compared to an EMC3-EIRENE synthetic diagnostic [H. Frerichs et al., "Synthetic plasma edge diagnostics for EMC3-EIRENE, highlighted for Wendelstein 7-X," Rev. Sci. Instrum. (these proceedings)] to infer both a limiter particle flux and wall particle flux, both of which will ultimately be used to infer the complete particle balance and particle confinement time τ_P.