Net versus gross erosion of silicon carbide in DIII-D divertor
- Univ. of California, San Diego, CA (United States)
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- General Atomics, San Diego, CA (United States)
- Chinese Academy of Sciences (CAS), Hefei (China)
- Univ. of Toronto, ON (Canada)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Gross and net erosion rates of silicon from silicon carbide (SiC) coatings were measured in the divertor of DIII-D under well diagnosed reactor-relevant plasma conditions. Amorphous and crystalline SiC coatings on graphite with thickness of ~80 nm and ~250 μm, respectively, were exposed near an attached outer strike point of lower single null L-mode plasmas using the Divertor Material Evaluation System (DiMES). Plasma density and electron temperature near the center of the coatings were ne ~ 4 × 1019 m-3 and T e ~ 23 eV. Gross erosion of Si from all samples was measured spectroscopically using the Si II 636 nm line. It was found to be a factor of ~4 higher for the amorphous coatings compared to the crystalline one. The thin amorphous coatings allowed measurements of net Si erosion with Rutherford backscattering. Net average Si erosion rate of ~3 × 1016 cm-2 s-1 was measured on the amorphous coatings with toroidal extent of 1 mm, where, according to ERO code modeling, the local redeposition of Si was about 30%. Using this rate, spectroscopic measurements, measured D+ ion fluxes, and corrections from ERO-OEDGE modeling, effective SXB coefficient for the Si II 636 nm line of ~52 and Si sputtering yield of ~0.017 Si/D were calculated. Finally, deuterium retention on SiC coatings was measured by 2.5 MeV 3He nuclear reaction analysis at 0.5–2.5 × 1017 atoms cm-2, consistent with retention due to implantation into a surface undergoing net erosion.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA); National Natural Science Foundation of China (NSFC)
- Grant/Contract Number:
- AC05-00OR22725; FG02-07ER54917; FC02-04ER54698; NA0003525; AC52-07NA27344; SC0018423; 11861131010; 11675218
- OSTI ID:
- 1832712
- Alternate ID(s):
- OSTI ID: 1860688
- Report Number(s):
- LLNL-JRNL-830756; TRN: US2216761
- Journal Information:
- Physica Scripta, Vol. T171, Issue T171; ISSN 0031-8949
- Publisher:
- IOP PublishingCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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