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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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2020-12
Major/Subject
Mcode
Degree programme
Language
en
Pages
Series
Nuclear Materials and Energy, Volume 25
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.
Description
| openaire: EC/H2020/633053/EU//EUROfusion
Keywords
Camera tomography, Detachment, Divertor physics, Divertor spectroscopy, Fusion
Other note
Citation
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 , vol. 25 , 100831 . https://doi.org/10.1016/j.nme.2020.100831