Impact of ELM control techniques on tungsten sputtering in the DIII-D divertor and extrapolations to ITER
- General Atomics, San Diego, CA (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Univ. of California, San Diego, CA (United States)
- Univ. of Wisconsin, Madison, WI (United States)
- Univ. of Toronto, ON (Canada)
The free-streaming plus recycling model (FSRM) has recently been developed to understand and predict tungsten gross erosion rates from the divertor during edge localized modes (ELMs). In this work, the FSRM was tested against the experimental measurements of W sputtering during ELMs, conducted via fast neutral tungsten (WI) spectroscopy. Good agreement is observed using a variety of controlling techniques, including gas puffing, neutral beam heating, and plasma shaping to modify the pedestal stability boundary and, thus, the ELM behavior. ELM mitigation by pellet pacing was observed to strongly reduce W sputtering by flushing C impurities from the pedestal and reducing the divertor target electron temperature. No reduction of W sputtering was observed during the application of resonant magnetic perturbations (RMPs), in contrast to the prediction of the FSRM. Potential sources of this discrepancy are discussed. Lastly, the framework of the FSRM is utilized to predict intra-ELM W sputtering rates in ITER. It is concluded that W erosion during ELMs in ITER will be caused mainly by free-streaming fuel ions, but free-streaming seeded impurities (N or Ne) may increase the erosion rate significantly if present in the pedestal at even the 1% level. Impurity recycling is not expected to cause critical W erosion in ITER due to the very low target electron temperature.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); General Atomics, San Diego, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- Grant/Contract Number:
- AC05-00OR22725; FC02-04ER54698; FG02-07ER54917; SC0013911; AC04-94AL8500; AC05-06OR23100
- OSTI ID:
- 1561609
- Alternate ID(s):
- OSTI ID: 1525522; OSTI ID: 1569625
- Journal Information:
- Physics of Plasmas, Vol. 26, Issue 6; Conference: 60. Annual Meeting of the APS Division of Plasma Physics, Portland, OR (United States), 5-9 Nov 2018; ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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