Physically principled reflection models applied to filtered camera imaging inversions in metal walled fusion machines

M. Carr*, A. Meakins, S. A. Silburn, J. Karhunen, M. Bernert, C. Bowman, A. Callarelli, P. Carvalho, C. Giroud, J. R. Harrison, S. S. Henderson, A. Huber, B. Lipschultz, T. Lunt, D. Moulton, F. Reimold

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

10 Citations (Scopus)
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Abstract

Ray-tracing techniques are applied to filtered divertor imaging, a diagnostic that has long suffered from artifacts due to the polluting effect of reflected light in metal walled fusion machines. Physically realistic surface reflections were modeled using a Cook-Torrance micro-facet bi-directional reflection distribution function applied to a high resolution mesh of the vessel geometry. In the absence of gonioreflectometer measurements, a technique was developed to fit the free parameters of the Cook-Torrance model against images of the JET in-vessel light sources. By coupling this model with high fidelity plasma fluid simulations, photo-realistic renderings of a number of tokamak plasma emission scenarios were generated. Finally, a sensitivity matrix describing the optical coupling of a JET divertor camera and the emission profile of the plasma was obtained, including full reflection effects. These matrices are used to perform inversions on measured data and shown to reduce the level of artifacts in inverted emission profiles.

Original languageEnglish
Article number043504
Pages (from-to)1-12
Number of pages12
JournalReview of Scientific Instruments
Volume90
Issue number4
DOIs
Publication statusPublished - 1 Apr 2019
MoE publication typeA1 Journal article-refereed

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