Title: Surface Erosion of Plasma-Facing Materials Using an Electrothermal Plasma Source and Ion Beam Micro-Trenches

Abstract

Erosion characteristics of tungsten-alternative plasma-facing materials (PFMs) were tested under high heat flux conditions in the electrothermal plasma source facility at Oak Ridge National Laboratory. The PFMs of interest are high-purity β-3C chemical vapor deposition silicon carbide (SiC) and the MAX phases Ti₃SiC₂ and Ti₂AlC [MAX = chemical formula M_n+1AX_n, where M is an early transition metal (such as Ti or Ta), A is an A-group element (such as Si or Al), and X is carbon or nitrogen]. Additionally, an erosion analysis method was developed using a combination of focused ion beam microscopy and scanning electron microscopy, carving micro-trench geometries into polished sample surfaces. Samples of SiC, Ti₃SiC₂, and Ti₂AlC were exposed to the electrothermal plasma source alongside tungsten and monocrystalline silicon. Samples were exposed to a Lexan polycarbonate (C₁₆H₁₄O₃) electrothermal plasma stream in a He environment, at a specified impact angle, with infrared camera diagnostics. Edge localized mode–relevant heat fluxes of 0.9 to 1 GW/m² over 1-ms discharges were generated on the target surfaces. Tungsten samples exhibited pronounced melt-layer formation and deformation, with measured molten pits 2 to 10 μm in diameter and melt-layer depths of up to 7 μm deep. Surface erosion rates for Ti₃SiC₂ and Ti₂AlC rangedmore » from 80 to 775 μm/s and 85 to 470 μm/s, respectively. Both MAX phases exhibited extreme surface fracture and material ejection, with damage depths past 4 μm for Ti₂AlC and 11 μm for Ti₃SiC₂. Lastly, SiC displayed the best performance, in one case surviving 15 consecutive electrothermal plasma exposures with an average erosion rate of about 29 μm/s and no surface fracturing. SiC erosion rates ranged from 23 to 128 μm/s.« less

Authors:

Coburn, Jonathan D.  ^[1];

• Search DOE PAGES for author "Coburn, Jonathan D."
• Search DOE PAGES for ORCID "0000-0001-5618-0483"

Gebhart, T. E.  ^[2];

• Search DOE PAGES for author "Gebhart, T. E."
• Search DOE PAGES for ORCID "0000-0001-8259-6095"

Parish, Chad M.  ^[2];

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• Search DOE PAGES for ORCID "0000-0003-1209-7439"

Unterberg, Ezekial  ^[2];

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• Search DOE PAGES for ORCID "0000-0003-1353-8865"

Canik, John  ^[2];

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• Search DOE PAGES for ORCID "0000-0001-6934-6681"

Barsoum, M W.  ^[3];

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• Search DOE PAGES for ORCID "0000-0001-7800-3517"

Bourham, Mohamed  ^[1]

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• Search DOE PAGES for ORCID "0000-0002-7206-2361"

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+ Show Author Affiliations

1. North Carolina State Univ., Raleigh, NC (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. Drexel Univ., Philadelphia, PA (United States)

Publication Date:

Wed Jun 19 00:00:00 EDT 2019

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Fusion Energy Sciences (FES)

OSTI Identifier:

1528684

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Fusion Science and Technology

Additional Journal Information:

Journal Volume: 75; Journal Issue: 7; Journal ID: ISSN 1536-1055

Publisher:

American Nuclear Society

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Plasma-facing material; ion beam; MAX phase ceramics; silicon carbide; erosion