Title: Modeling of deuterium and carbon radiation transport in MAST-U tokamak advanced divertors

Abstract

Modest effects of deuterium and carbon radiation opacity in the Super-X and snowflake divertor plasmas are predicted for MAST Upgrade tokamak with core plasma input power 2.5–5 MW and plasma current 1 MA. The radiation transport modeling is based on the SOLPS-EIRENE and UEDGE code divertor plasma predictions. Two radiation transport models are used: one is based on a full radiation transport equation implemented in the radiation transport and collisional-radiative code CRETIN (without feedback on the background plasma), and another is an internal self-consistent UEDGE model with ionization, recombination, and heating rates corrected for Ly_α line trapping based on the escape probability model implemented in CRETIN. In MAST-U, the Super-X and snowflake divertor plasmas are predicted to reach detached regimes at lower upstream densities than the standard divertor, and the conclusion still holds with radiation transport effects included. At neutral densities m^-3, modest Ly_α deuterium line trapping with optical depths 10–15 is predicted in the Super-X divertor. Divertor plasmas are optically thin to other Lyman and Balmer lines, as well as to strong C III and C IV lines that are responsible for most of divertor radiated power. Insignificant changes (within a few percent) to divertor deuterium ionization and recombinationmore » rates are found. Radiation fluxes on outer divertor target are modified within a factor of 2–3 when the radiation transport is accounted for, and a similar variation is found due to the line shape models that define the absorption and emission line profiles in the radiation transport modeling. The predicted Lyman and Balmer spectral intensities are significantly modified due to radiation trapping. A measurement of divertor radiation transport effects is discussed using the Ly_β/Ba_α line ratio. In the snowflake divertor configuration, divertor plasmas are found to be optically thin to Lyman series lines within a large range of parameter variations that include upstream density, divertor transport coefficients, and magnetic configurations. Finally, modest radiation transport effects are only found in a few cases with strongest divertor transport and magnetic configurations closest to the ideal snowflake configuration, however, the plasma background models that were used are yet to be validated with an experiment.« less

Authors:

Soukhanovskii, V. A.  ^[1];

• Search DOE PAGES for author "Soukhanovskii, V. A."
• Search DOE PAGES for ORCID "0000-0001-5519-0145"

Khrabry, A. I.  ^[1];

• Search DOE PAGES for author "Khrabry, A. I."
• Search DOE PAGES for ORCID "0000-0002-2855-7148"

Scott, H. A.  ^[1];

• Search DOE PAGES for author "Scott, H. A."
• Search DOE PAGES for ORCID "0000-0002-6686-9134"

Rognlien, T. D. ^[1]; Moulton, D. ^[2]; Harrison, J. R.  ^[2]

• Search DOE PAGES for author "Harrison, J. R."
• Search DOE PAGES for ORCID "0000-0003-2906-5097"

---

+ Show Author Affiliations

1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2. Culham Science Centre, Abingdon (United Kingdom). Culham Centre for Fusion Energy (CCFE), EURATOM/UKAEA Fusion Association

Publication Date:

Wed Apr 20 00:00:00 EDT 2022

Research Org.:

Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Fusion Energy Sciences (FES); Engineering and Physical Sciences Research Council (EPSRC)

OSTI Identifier:

1863677

Report Number(s):

LLNL-JRNL-829727
Journal ID: ISSN 0029-5515; 1045841; TRN: US2305636

Grant/Contract Number:  

AC52-07NA27344; EP/P012450/1

Resource Type:

Accepted Manuscript

Journal Name:

Nuclear Fusion

Additional Journal Information:

Journal Volume: 62; Journal Issue: 6; Journal ID: ISSN 0029-5515

Publisher:

IOP Science

Country of Publication:

United States

Language:

English

Subject:

74 ATOMIC AND MOLECULAR PHYSICS