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Title: Performance assessment of long-legged tightly-baffled divertor geometries in the ARC reactor concept

Abstract

Extremely intense power exhaust channels are projected for tokamak-based fusion power reactors; a means to handle them remains to be demonstrated. Advanced divertor configurations have been proposed as potential solutions. Recent modelling of tightly baffled, long-legged divertor geometries for the divertor test tokamak concept, ADX, has shown that these concepts may access passively stable, fully detached regimes over a broad range of parameters. The question remains as to how such divertors may perform in a reactor setting. To explore this, numerical simulations are performed with UEDGE for the long-legged divertor geometry proposed for the ARC pilot plant conceptual design - a device with projected heat flux power width (λq||) of 0.4 mm and power exhaust of 93 MW - first for a simplified Super-X divertor configuration (SXD) and then for the actual X-point target divertor (XPTD) being proposed. It is found that the SXD, combined with 0.5% fixed-fraction neon impurity concentration, can produce passively stable, detached divertor regimes for power exhausts in the range of 80-108 MW - fully accommodating ARC's power exhaust. The XPTD configuration is found to reduce the strike-point temperature by a factor of ~10 compared to the SXD for small separations (~1.4λq||) between main and divertormore » X-point magnetic flux surfaces. Even greater potential reductions are identified for reducing separations to ~1λq|| or less. The power handling response is found to be insensitive to the level of cross-field convective or diffusive transport assumed in the divertor leg. By raising the separatrix density by a factor of 1.5, stable fully detached divertor solutions are obtained that fully accommodate the ARC exhaust power without impurity seeding. To our knowledge, this is the first time an impurity-free divertor power handling scenario has been obtained in edge modelling for a tokamak fusion power reactor with λq|| of 0.4 mm.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
DOE Contract Number:  
SC0014264; AC52-07NA27344
Research Org.:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center; Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE National Nuclear Security Administration (NNSA)
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
OSTI Identifier:
1881477
DOI:
https://doi.org/10.7910/DVN/NMVUFS

Citation Formats

Wigram, Michael Robert Knox, LaBombard, Brian, Umansky, Maxim V., Kuang, Adam Q., Golfinopoulos, Theodore, Terry, Jim L., Brunner, Daniel, Rensink, Marvin E., Ridgers, Christopher P., and Whyte, Dennis G. Performance assessment of long-legged tightly-baffled divertor geometries in the ARC reactor concept. United States: N. p., 2020. Web. doi:10.7910/DVN/NMVUFS.
Wigram, Michael Robert Knox, LaBombard, Brian, Umansky, Maxim V., Kuang, Adam Q., Golfinopoulos, Theodore, Terry, Jim L., Brunner, Daniel, Rensink, Marvin E., Ridgers, Christopher P., & Whyte, Dennis G. Performance assessment of long-legged tightly-baffled divertor geometries in the ARC reactor concept. United States. doi:https://doi.org/10.7910/DVN/NMVUFS
Wigram, Michael Robert Knox, LaBombard, Brian, Umansky, Maxim V., Kuang, Adam Q., Golfinopoulos, Theodore, Terry, Jim L., Brunner, Daniel, Rensink, Marvin E., Ridgers, Christopher P., and Whyte, Dennis G. 2020. "Performance assessment of long-legged tightly-baffled divertor geometries in the ARC reactor concept". United States. doi:https://doi.org/10.7910/DVN/NMVUFS. https://www.osti.gov/servlets/purl/1881477. Pub date:Wed Jun 03 00:00:00 EDT 2020
@article{osti_1881477,
title = {Performance assessment of long-legged tightly-baffled divertor geometries in the ARC reactor concept},
author = {Wigram, Michael Robert Knox and LaBombard, Brian and Umansky, Maxim V. and Kuang, Adam Q. and Golfinopoulos, Theodore and Terry, Jim L. and Brunner, Daniel and Rensink, Marvin E. and Ridgers, Christopher P. and Whyte, Dennis G.},
abstractNote = {Extremely intense power exhaust channels are projected for tokamak-based fusion power reactors; a means to handle them remains to be demonstrated. Advanced divertor configurations have been proposed as potential solutions. Recent modelling of tightly baffled, long-legged divertor geometries for the divertor test tokamak concept, ADX, has shown that these concepts may access passively stable, fully detached regimes over a broad range of parameters. The question remains as to how such divertors may perform in a reactor setting. To explore this, numerical simulations are performed with UEDGE for the long-legged divertor geometry proposed for the ARC pilot plant conceptual design - a device with projected heat flux power width (λq||) of 0.4 mm and power exhaust of 93 MW - first for a simplified Super-X divertor configuration (SXD) and then for the actual X-point target divertor (XPTD) being proposed. It is found that the SXD, combined with 0.5% fixed-fraction neon impurity concentration, can produce passively stable, detached divertor regimes for power exhausts in the range of 80-108 MW - fully accommodating ARC's power exhaust. The XPTD configuration is found to reduce the strike-point temperature by a factor of ~10 compared to the SXD for small separations (~1.4λq||) between main and divertor X-point magnetic flux surfaces. Even greater potential reductions are identified for reducing separations to ~1λq|| or less. The power handling response is found to be insensitive to the level of cross-field convective or diffusive transport assumed in the divertor leg. By raising the separatrix density by a factor of 1.5, stable fully detached divertor solutions are obtained that fully accommodate the ARC exhaust power without impurity seeding. To our knowledge, this is the first time an impurity-free divertor power handling scenario has been obtained in edge modelling for a tokamak fusion power reactor with λq|| of 0.4 mm.},
doi = {10.7910/DVN/NMVUFS},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2020},
month = {6}
}

Works referencing / citing this record:

Performance assessment of long-legged tightly-baffled divertor geometries in the ARC reactor concept
journal, September 2019