Inference of molecular divertor density from filtered camera analysis of molecularly induced Balmer line emission during detachment in JET L-mode plasmas

Karhunen, J.; Holm, A.; Lomanowski, B. A.; Solokha, V.; Aleiferis, S.; Carvalho, P.; Groth, M.; Lawson, K. D.; Meigs, A. G.; Shaw, A.

doi:10.1088/1748-0221/17/01/c01032

Inference of molecular divertor density from filtered camera analysis of molecularly induced Balmer line emission during detachment in JET L-mode plasmas

Journal Article · Mon Jan 10 00:00:00 EST 2022 · Journal of Instrumentation

DOI:https://doi.org/10.1088/1748-0221/17/01/c01032· OSTI ID:1860559

Karhunen, J. ^[1]; Holm, A. ^[2]; Lomanowski, B. A. ^[3]; Solokha, V. ^[2]; Aleiferis, S. ^[4]; Carvalho, P. ^[5]; Groth, M. ^[2]; Lawson, K. D. ^[6]; Meigs, A. G. ^[6]; Shaw, A. ^[6]

Univ. of Helsinki (Finland)
Aalto Univ., Otaniemi (Finland)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
National Centre for Scientific Research, Athens (Greece)
Inst. of Superior Tecnico (IST), Lisbon (Portugal)
Culham Science Centre, Abingdon (United Kingdom). Culham Centre for Fusion Energy (CCFE)

Here a previously presented Monte Carlo method for estimating local plasma conditions in 2D based on intensity ratios of deuterium Balmer D_α, D_γ and D_ε lines was amended to consider also the D_α and D_γ emission contributions arising from molecular processes. The obtained estimates were used to infer the molecular divertor density with the help of the molecular databases of EIRENE. The method was benchmarked against EDGE2D-EIRENE simulations and observed to reproduce the molecularly induced emission fractions and the molecular divertor densities primarily within 25% of the references. Experimental analysis of a JET L-mode density scan suggested molecularly induced D_α and D_γ contributions of up to 60–70% and 20%, respectively, during the process of detachment. The independent estimates of the molecular divertor density inferred from the obtained molecularly induced D_α and D_γ intensities agree within uncertainties with each other. Both estimates show the molecular density increasing up to approximately 1.0–2.0 x 10²⁰ m^-3 at the outer strike point in deep detachment with its ratio to the local electron density agreeing with EDGE2D-EIRENE predictions within the scatter of the experimental data.

View Accepted Manuscript (DOE)

Research Organization:: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Organization:: Euratom Research and Training Programme; USDOE Office of Science (SC)

Grant/Contract Number:: AC05-00OR22725

OSTI ID:: 1860559

Journal Information:: Journal of Instrumentation, Journal Name: Journal of Instrumentation Journal Issue: 01 Vol. 17; ISSN 1748-0221

Publisher:: Institute of Physics (IOP)Copyright Statement

Country of Publication:: United States

Language:: English

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