Estimation of 2D distributions of electron density and temperature in the JET divertor from tomographic reconstructions of deuterium Balmer line emission

J. Karhunen; B. Lomanowski; V. Solokha; S. Aleiferis; P. Carvalho; M. Groth; H. Kumpulainen; K. D. Lawson; A. G. Meigs; A. Shaw; JET Contributors

doi:10.1016/j.nme.2020.100831

Estimation of 2D distributions of electron density and temperature in the JET divertor from tomographic reconstructions of deuterium Balmer line emission

J. Karhunen^*, B. Lomanowski, V. Solokha, S. Aleiferis, P. Carvalho, M. Groth, H. Kumpulainen, K. D. Lawson, A. G. Meigs, A. Shaw, JET Contributors

^*Corresponding author for this work

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Abstract

Estimates for 2D distributions of electron density, n_e, and temperature, T_e, have been obtained using reflection-corrected tomographic reconstructions of deuterium Balmer line emission in the JET divertor. The solutions are obtained by a two-dimensional Monte Carlo optimization model, based on intensity ratios of the Balmer D_α, D_γ and D_ε emission and the ADAS photon emission coefficients with additional constraints provided by line-integrated spectroscopic measurements of n_e and T_e. Synthetic benchmarks utilizing EDGE2D-EIRENE simulation outputs yield reproduction of reference n_e and T_e distributions within 25% with statistical error estimates of 5–15%. Experimental analysis of an L-mode n_e ramp shows extension and movement of the outer divertor high-n_e region with n_e,div up to 1.5 × 10²⁰ m⁻³ from the outer strike point to above the X-point and decrease of the divertor T_e to the range of 0.5–1.0 eV within 25% agreement with the line-integrated measurements. Comparison between the local estimates and their corresponding line integrals suggests underestimation of n_e and T_e by up to 75% and 50%, respectively, due to the geometric effects of line integration.

Original language	English
Article number	100831
Number of pages	7
Journal	Nuclear Materials and Energy
Volume	25
DOIs	https://doi.org/10.1016/j.nme.2020.100831
Publication status	Published - Dec 2020
MoE publication type	A1 Journal article-refereed

Keywords

Camera tomography
Detachment
Divertor physics
Divertor spectroscopy
Fusion

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10.1016/j.nme.2020.100831

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Karhunen, J., Lomanowski, B., Solokha, V., Aleiferis, S., Carvalho, P., Groth, M., Kumpulainen, H., Lawson, K. D., Meigs, A. G., Shaw, A., & JET Contributors (2020). Estimation of 2D distributions of electron density and temperature in the JET divertor from tomographic reconstructions of deuterium Balmer line emission. Nuclear Materials and Energy, 25, Article 100831. https://doi.org/10.1016/j.nme.2020.100831

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title = "Estimation of 2D distributions of electron density and temperature in the JET divertor from tomographic reconstructions of deuterium Balmer line emission",

abstract = "Estimates for 2D distributions of electron density, ne, and temperature, Te, have been obtained using reflection-corrected tomographic reconstructions of deuterium Balmer line emission in the JET divertor. The solutions are obtained by a two-dimensional Monte Carlo optimization model, based on intensity ratios of the Balmer Dα, Dγ and Dε emission and the ADAS photon emission coefficients with additional constraints provided by line-integrated spectroscopic measurements of ne and Te. Synthetic benchmarks utilizing EDGE2D-EIRENE simulation outputs yield reproduction of reference ne and Te distributions within 25% with statistical error estimates of 5–15%. Experimental analysis of an L-mode ne ramp shows extension and movement of the outer divertor high-ne region with ne,div up to 1.5 × 1020 m−3 from the outer strike point to above the X-point and decrease of the divertor Te to the range of 0.5–1.0 eV within 25% agreement with the line-integrated measurements. Comparison between the local estimates and their corresponding line integrals suggests underestimation of ne and Te by up to 75% and 50%, respectively, due to the geometric effects of line integration.",

keywords = "Camera tomography, Detachment, Divertor physics, Divertor spectroscopy, Fusion",

author = "J. Karhunen and B. Lomanowski and V. Solokha and S. Aleiferis and P. Carvalho and M. Groth and H. Kumpulainen and Lawson, {K. D.} and Meigs, {A. G.} and A. Shaw and {JET Contributors}",

note = "| openaire: EC/H2020/633053/EU//EUROfusion ",

year = "2020",

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doi = "10.1016/j.nme.2020.100831",

language = "English",

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Karhunen, J, Lomanowski, B, Solokha, V, Aleiferis, S, Carvalho, P, Groth, M , Kumpulainen, H, Lawson, KD, Meigs, AG, Shaw, A & JET Contributors 2020, 'Estimation of 2D distributions of electron density and temperature in the JET divertor from tomographic reconstructions of deuterium Balmer line emission', Nuclear Materials and Energy, vol. 25, 100831. https://doi.org/10.1016/j.nme.2020.100831

TY - JOUR

T1 - Estimation of 2D distributions of electron density and temperature in the JET divertor from tomographic reconstructions of deuterium Balmer line emission

AU - Karhunen, J.

AU - Lomanowski, B.

AU - Solokha, V.

AU - Aleiferis, S.

AU - Carvalho, P.

AU - Groth, M.

AU - Kumpulainen, H.

AU - Lawson, K. D.

AU - Meigs, A. G.

AU - Shaw, A.

AU - JET Contributors

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

PY - 2020/12

Y1 - 2020/12

N2 - Estimates for 2D distributions of electron density, ne, and temperature, Te, have been obtained using reflection-corrected tomographic reconstructions of deuterium Balmer line emission in the JET divertor. The solutions are obtained by a two-dimensional Monte Carlo optimization model, based on intensity ratios of the Balmer Dα, Dγ and Dε emission and the ADAS photon emission coefficients with additional constraints provided by line-integrated spectroscopic measurements of ne and Te. Synthetic benchmarks utilizing EDGE2D-EIRENE simulation outputs yield reproduction of reference ne and Te distributions within 25% with statistical error estimates of 5–15%. Experimental analysis of an L-mode ne ramp shows extension and movement of the outer divertor high-ne region with ne,div up to 1.5 × 1020 m−3 from the outer strike point to above the X-point and decrease of the divertor Te to the range of 0.5–1.0 eV within 25% agreement with the line-integrated measurements. Comparison between the local estimates and their corresponding line integrals suggests underestimation of ne and Te by up to 75% and 50%, respectively, due to the geometric effects of line integration.

AB - Estimates for 2D distributions of electron density, ne, and temperature, Te, have been obtained using reflection-corrected tomographic reconstructions of deuterium Balmer line emission in the JET divertor. The solutions are obtained by a two-dimensional Monte Carlo optimization model, based on intensity ratios of the Balmer Dα, Dγ and Dε emission and the ADAS photon emission coefficients with additional constraints provided by line-integrated spectroscopic measurements of ne and Te. Synthetic benchmarks utilizing EDGE2D-EIRENE simulation outputs yield reproduction of reference ne and Te distributions within 25% with statistical error estimates of 5–15%. Experimental analysis of an L-mode ne ramp shows extension and movement of the outer divertor high-ne region with ne,div up to 1.5 × 1020 m−3 from the outer strike point to above the X-point and decrease of the divertor Te to the range of 0.5–1.0 eV within 25% agreement with the line-integrated measurements. Comparison between the local estimates and their corresponding line integrals suggests underestimation of ne and Te by up to 75% and 50%, respectively, due to the geometric effects of line integration.

KW - Camera tomography

KW - Detachment

KW - Divertor physics

KW - Divertor spectroscopy

KW - Fusion

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DO - 10.1016/j.nme.2020.100831

M3 - Article

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SN - 2352-1791

VL - 25

JO - Nuclear Materials and Energy

JF - Nuclear Materials and Energy

M1 - 100831

ER -

Estimation of 2D distributions of electron density and temperature in the JET divertor from tomographic reconstructions of deuterium Balmer line emission

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