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

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

JET Contributors

Power Exhaust and Particle Control

Research output: Contribution to journal › Article › peer-review

8 Scopus citations

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
Journal	Nuclear Materials and Energy
Volume	25
DOIs	https://doi.org/10.1016/j.nme.2020.100831
State	Published - Dec 2020

Funding

This work has been 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.

Keywords

Camera tomography
Detachment
Divertor physics
Divertor spectroscopy
Fusion

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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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 = "{JET Contributors} and 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",

note = "Publisher Copyright: {\textcopyright} 2020",

year = "2020",

month = dec,

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

language = "English",

volume = "25",

journal = "Nuclear Materials and Energy",

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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 - JET Contributors

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.

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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U2 - 10.1016/j.nme.2020.100831

DO - 10.1016/j.nme.2020.100831

M3 - Article

AN - SCOPUS:85097167990

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

Abstract

Funding

Keywords

UN SDGs

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