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

TY - JOUR

T1 - Physically principled reflection models applied to filtered camera imaging inversions in metal walled fusion machines

AU - Carr, M.

AU - ASDEX Upgrade Team

AU - JET contributors

AU - MAST-Upgrade Team

AU - EUROFusion MST1 Team

AU - Meakins, A.

AU - Silburn, S. A.

AU - Karhunen, J.

AU - Bernert, M.

AU - Bowman, C.

AU - Callarelli, A.

AU - Carvalho, P.

AU - Giroud, C.

AU - Harrison, J. R.

AU - Henderson, S. S.

AU - Huber, A.

AU - Lipschultz, B.

AU - Lunt, T.

AU - Moulton, D.

AU - Reimold, F.

N1 - This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details.

PY - 2019/4/19

Y1 - 2019/4/19

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85065546960&partnerID=8YFLogxK

U2 - 10.1063/1.5092781

DO - 10.1063/1.5092781

M3 - Article

C2 - 31043003

AN - SCOPUS:85065546960

SN - 0034-6748

VL - 90

SP - 043504

JO - The Review of scientific instruments

JF - The Review of scientific instruments

IS - 4

M1 - 043504

ER -