Effect of reflections on 2D tomographic reconstructions of filtered cameras and on interpreting spectroscopic measurements in the JET ITER-like wall divertor

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Effect of reflections on 2D tomographic reconstructions of filtered cameras and on interpreting spectroscopic measurements in the JET ITER-like wall divertor. / Karhunen, J.; Carr, M.; Harrison, J. R.; Lomanowski, B.; Balboa, I.; Carvalho, P.; Groth, M.; Huber, A.; Matthews, G. F.; Meakins, A.; Silburn, S.

In: Review of Scientific Instruments, Vol. 90, No. 10, 103504, 01.10.2019, p. 1-11.

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Karhunen, J. ; Carr, M. ; Harrison, J. R. ; Lomanowski, B. ; Balboa, I. ; Carvalho, P. ; Groth, M. ; Huber, A. ; Matthews, G. F. ; Meakins, A. ; Silburn, S. / Effect of reflections on 2D tomographic reconstructions of filtered cameras and on interpreting spectroscopic measurements in the JET ITER-like wall divertor. In: Review of Scientific Instruments. 2019 ; Vol. 90, No. 10. pp. 1-11.

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@article{f4cf844a3b754bbf85c246ab6732d4c3,
title = "Effect of reflections on 2D tomographic reconstructions of filtered cameras and on interpreting spectroscopic measurements in the JET ITER-like wall divertor",
abstract = "Considering reflections from metallic wall surfaces in generation of tomographic reconstructions of the tangentially viewing, visible-range spectroscopic divertor cameras in JET has been observed to yield enhanced spatial accuracy and significant reduction of emission artifacts in experimentally resolved 2D line emission distributions. Neglection of reflections in the tomography process was found to lead to overestimation of the emission near the wall surfaces by up to a factor of 4, as well as to formation of bright emission artifacts between the main emission regions and the wall surfaces, comprising locally up to 50{\%} of the emission. Mimicking divertor spectroscopy measurements by integrating the tomographic reconstructions along vertical lines-of-sight implies that reflections comprise 15{\%}-25{\%} of the observed line-integrated emission peaks. The spatial differences in the reflection contribution between the different lines-of-sight are less pronounced than in the 2D reconstructions due to the dominance of the brightest emission regions through which the spectroscopic lines-of-sight pass. However, postprocessing EDGE2D-EIRENE simulations using the CHERAB code and synthetic spectroscopy suggests a decrease of the spectroscopically inferred divertor electron temperature by up to 75{\%}, when redistribution of the observed light due to reflections is considered.",
author = "J. Karhunen and M. Carr and Harrison, {J. R.} and B. Lomanowski and I. Balboa and P. Carvalho and M. Groth and A. Huber and Matthews, {G. F.} and A. Meakins and S. Silburn",
note = "| openaire: EC/H2020/633053/EU//EUROfusion",
year = "2019",
month = "10",
day = "1",
doi = "10.1063/1.5118885",
language = "English",
volume = "90",
pages = "1--11",
journal = "Review of Scientific Instruments",
issn = "0034-6748",
number = "10",

}

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TY - JOUR

T1 - Effect of reflections on 2D tomographic reconstructions of filtered cameras and on interpreting spectroscopic measurements in the JET ITER-like wall divertor

AU - Karhunen, J.

AU - Carr, M.

AU - Harrison, J. R.

AU - Lomanowski, B.

AU - Balboa, I.

AU - Carvalho, P.

AU - Groth, M.

AU - Huber, A.

AU - Matthews, G. F.

AU - Meakins, A.

AU - Silburn, S.

N1 - | openaire: EC/H2020/633053/EU//EUROfusion

PY - 2019/10/1

Y1 - 2019/10/1

N2 - Considering reflections from metallic wall surfaces in generation of tomographic reconstructions of the tangentially viewing, visible-range spectroscopic divertor cameras in JET has been observed to yield enhanced spatial accuracy and significant reduction of emission artifacts in experimentally resolved 2D line emission distributions. Neglection of reflections in the tomography process was found to lead to overestimation of the emission near the wall surfaces by up to a factor of 4, as well as to formation of bright emission artifacts between the main emission regions and the wall surfaces, comprising locally up to 50% of the emission. Mimicking divertor spectroscopy measurements by integrating the tomographic reconstructions along vertical lines-of-sight implies that reflections comprise 15%-25% of the observed line-integrated emission peaks. The spatial differences in the reflection contribution between the different lines-of-sight are less pronounced than in the 2D reconstructions due to the dominance of the brightest emission regions through which the spectroscopic lines-of-sight pass. However, postprocessing EDGE2D-EIRENE simulations using the CHERAB code and synthetic spectroscopy suggests a decrease of the spectroscopically inferred divertor electron temperature by up to 75%, when redistribution of the observed light due to reflections is considered.

AB - Considering reflections from metallic wall surfaces in generation of tomographic reconstructions of the tangentially viewing, visible-range spectroscopic divertor cameras in JET has been observed to yield enhanced spatial accuracy and significant reduction of emission artifacts in experimentally resolved 2D line emission distributions. Neglection of reflections in the tomography process was found to lead to overestimation of the emission near the wall surfaces by up to a factor of 4, as well as to formation of bright emission artifacts between the main emission regions and the wall surfaces, comprising locally up to 50% of the emission. Mimicking divertor spectroscopy measurements by integrating the tomographic reconstructions along vertical lines-of-sight implies that reflections comprise 15%-25% of the observed line-integrated emission peaks. The spatial differences in the reflection contribution between the different lines-of-sight are less pronounced than in the 2D reconstructions due to the dominance of the brightest emission regions through which the spectroscopic lines-of-sight pass. However, postprocessing EDGE2D-EIRENE simulations using the CHERAB code and synthetic spectroscopy suggests a decrease of the spectroscopically inferred divertor electron temperature by up to 75%, when redistribution of the observed light due to reflections is considered.

UR - http://www.scopus.com/inward/record.url?scp=85073599826&partnerID=8YFLogxK

U2 - 10.1063/1.5118885

DO - 10.1063/1.5118885

M3 - Article

VL - 90

SP - 1

EP - 11

JO - Review of Scientific Instruments

JF - Review of Scientific Instruments

SN - 0034-6748

IS - 10

M1 - 103504

ER -

ID: 38292777