Performance assessment of long-legged tightly-baffled divertor geometries in the ARC reactor concept
Name
Wigram_2019_Nucl._Fusion_59_106052.pdf
Description
Published version
Size
8.8 MB
Format
Adobe PDF
Checksum (MD5)
ac391d5f0224cbd21afb467ff08d11a5
Author(s)
Labombard, Brian
Kuang, A. Q.
Golfinopoulos, Theodore
Terry, J.L.
Whyte, D.G.
Date Issued
September 2019
Journal
Nuclear fusion
Publisher
IOP Publishing
Citation
Wigram, M.R.K., et al., "Performance assessment of long-legged tightly-baffled divertor geometries in the ARC reactor concept." Nuclear fusion 59, 10 (2019): no. 106052 doi: 10.1088/1741-4326/AB394F ©2019
Version
Final published version
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 longlegged 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 (∼1.4λ [subscript]q [subcript]∥) between main and divertor X-point magnetic flux surfaces. Even greater potential reductions are identified for reducing separations to ∼1λ [subscript]q [subscript]∥ 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 λ [subscript]q [subcript]∥ of 0.4 mm. ©2019
MIT Department
Massachusetts Institute of Technology. Plasma Science and Fusion Center
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Creative Commons Attribution 3.0 unported license
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DOI of Published Version
https://doi.org/10.1088/1741-4326/AB394F
