Title: Evaluation of silicon carbide as a divertor armor material in DIII-D H-mode discharges

Abstract

Silicon carbide (SiC) represents a promising but largely untested plasma-facing material (PFM) for next-step fusion devices. In this work, an analytic mixed-material erosion model is developed by calculating the physical (via SDTrimSP) and chemical (via empirical scalings) sputtering yield from SiC, Si, and C. The Si content in the near-surface SiC layer is predicted to increase during D plasma bombardment due to more efficient physical and chemical sputtering of C relative to Si. Silicon erosion from SiC thereby occurs primarily from sputtering of the enriched Si layer, rather than directly from the SiC itself. SiC coatings on ATJ graphite, manufactured via chemical vapor deposition, were exposed to repeated H-mode plasma discharges in the DIII-D tokamak to test this model. The qualitative trends from analytic modeling are reproduced by the experimental measurements, obtained via spectroscopic inference using the S/XB method. Quantitatively the model slightly under-predicts measured erosion rates, which is attributed to uncertainties in the ion impact angle distribution, as well as the effect of edge-localized modes. After exposure, minimal changes to the macroscopic or microscopic surface morphology of the SiC coatings were observed. Compositional analysis reveals Si enrichment of about 10%, in line with expectations from the erosion model. Extrapolatingmore » to a DEMO-type device, an order-of-magnitude decrease in impurity sourcing, and up to a factor of 2 decrease in impurity radiation, is expected with SiC walls, relative to graphite, if low C plasma impurity content can be achieved. Furthermore, these favorable erosion properties motivate further investigations of SiC as a low-Z, non-metallic PFM.« less

Authors:

Abrams, Tyler  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-9605-6871"

Bringuier, Stefan A.  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-6753-1437"

Thomas, Dan M.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-1217-7773"

Sinclair, Gregory  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-4195-177X"

Gonderman, S. ^[1]; Holland, L. ^[1]; Rudakov, Dmitry L.  ^[2];

• Search DOE PAGES for author "Rudakov, Dmitry L."
• Search DOE PAGES for ORCID "0000-0002-5266-4269"

Wilcox, Robert S.  ^[3];

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• Search DOE PAGES for ORCID "0000-0003-1369-1739"

Unterberg, Ezekial A.  ^[3];

• Search DOE PAGES for author "Unterberg, Ezekial A."
• Search DOE PAGES for ORCID "0000-0003-1353-8865"

Scotti, Filippo  ^[4]

• Search DOE PAGES for author "Scotti, Filippo"
• Search DOE PAGES for ORCID "0000-0002-0196-9919"

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+ Show Author Affiliations

1. General Atomics, San Diego, CA (United States)
2. Univ. of California San Diego, La Jolla, CA (United States)
3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Publication Date:

Wed Apr 21 00:00:00 EDT 2021

Research Org.:

Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); General Atomics, San Diego, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division

OSTI Identifier:

1874541

Alternate Identifier(s):

OSTI ID: 1784024; OSTI ID: 1818709

Report Number(s):

LLNL-JRNL-836399
Journal ID: ISSN 0029-5515; 1055687; TRN: US2307125

Grant/Contract Number:  

AC52-07NA27344; FC02-04ER54698; AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Nuclear Fusion

Additional Journal Information:

Journal Volume: 61; Journal Issue: 6; Journal ID: ISSN 0029-5515

Publisher:

IOP Science

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY; DIII-D; silicon carbide; SiC; sputtering; erosion; plasma-materials interactions; divertor