Development of an 11-channel multi wavelength imaging diagnostic for divertor plasmas in MAST Upgrade

X. Feng*, A. Calcines, R. M. Sharples, B. Lipschultz, A. Perek, W. A.J. Vijvers, J. R. Harrison, J. S. Allcock, Y. Andrebe, B. P. Duval, R. T. Mumgaard

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Divertor detachment and alternative divertor magnetic geometries are predicted to be promising approaches to handle the power exhaust of future fusion devices. In order to understand the detachment process caused by volumetric losses in alternative divertor magnetic geometries, a Multi-Wavelength Imaging (MWI) diagnostic has recently been designed and built for the Mega Amp Spherical Tokamak Upgrade. The MWI diagnostic will simultaneously capture 11 spectrally filtered images of the visible light emitted from divertor plasmas and provide crucial knowledge for the interpretation of observations and modeling efforts. This paper presents the optical design, mechanical design, hardware, and test results of an 11-channel MWI system with a field of view of 40°. The optical design shows better than 5 mm FWHM spatial resolution at the plasma on all 11 channels across the whole field of view. The spread of angle of incidence on the surface of each filter is also analyzed to inform the bandwidth specification of the interference filters. The results of the initial laboratory tests demonstrate that a spatial resolution of better than 5 mm FWHM is achieved for all 11 channels, meeting the specifications required for accurate tomography.

Original languageEnglish
Article number063510
Number of pages5
JournalReview of Scientific Instruments
Issue number6
Early online date9 Jun 2021
Publication statusE-pub ahead of print - 9 Jun 2021

Bibliographical note

Funding Information:
We would like to thank the CfAI Netpark engineering team for their support during the construction of the MWI system. We acknowledge financial support from EPSRC Grant No. EP/N024109/1. This work was carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom Research and Training Programme 2014–2018 and 2019–2020 under Grant Agreement No. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.

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