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Title: Numerical assessment of the new V-shape small-angle slot divertor on DIII-D

Abstract

The small-angle slot (SAS) divertor of the DIII-D tokamak, and its upcoming upgrade, the V-shape small-angle slot (SAS-V) divertor, are numerically investigated using the SOLPS-ITER code package, including the effect of particle drifts, for a range of plasma density, heating power, strike point position in the slot, and for both magnetic field directions. The simulations show that the electron temperature near the strike point is reduced in SAS-V compared to SAS, for both magnetic field directions, such that SAS-V achieves divertor detachment at a lower value of the outboard mid-plane separatrix electron density. The detachment threshold is lower because the V-shape focuses recycling neutrals on the V-end, densifying and cooling the plasma in the slot. At sufficiently high density, the V-shape also reduces the radial gradient of the temperature profile at the target, which in turns reduces the radial electric field and the E × B drift velocities, further densifying and cooling the plasma in the slot and leading to detachment. The V-shape effect, however, is reduced for higher heating power. With more heating power, the detachment density increases, reducing the ionization mean free path of recycled neutrals, which therefore become less sensitive to target shape changes. This suggests thatmore » in a fusion reactor, where the heating power is high, optimization of the divertor target shape needs to be combined with other strategies to lower the detachment density, such as in-slot injection of low-Z impurities.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3];  [4]; ORCiD logo [4]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [5]; ORCiD logo [4]; ORCiD logo [4]; ORCiD logo [6]; ORCiD logo [4]; ORCiD logo [7]; ORCiD logo [6]
  1. Oak Ridge Associated Univ., Oak Ridge, TN (United States); General Atomics, San Diego, CA (United States)
  2. Southwestern Inst. of Physics, Chengdu (China)
  3. Oak Ridge Associated Univ., Oak Ridge, TN (United States)
  4. General Atomics, San Diego, CA (United States)
  5. Univ. of Toronto, ON (Canada)
  6. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  7. General Atomics, San Diego, CA (United States); Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1830231
Alternate Identifier(s):
OSTI ID: 1842602
Report Number(s):
DOE-GA-54698
Journal ID: ISSN 0029-5515; TRN: US2216445
Grant/Contract Number:  
FC02-04ER54698; AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 61; Journal Issue: 11; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; DIII-D; SOLPS-ITER; slot divertor

Citation Formats

Maurizio, R., Du, H., Gallo, A., Guo, H. Y., Leonard, A., Ma, X., Sinclair, G., Stangeby, P., Thomas, D. M., Wang, H., Wilcox, R. S., Yu, J. H., Casali, L., and Shafer, M. W. Numerical assessment of the new V-shape small-angle slot divertor on DIII-D. United States: N. p., 2021. Web. doi:10.1088/1741-4326/ac27c8.
Maurizio, R., Du, H., Gallo, A., Guo, H. Y., Leonard, A., Ma, X., Sinclair, G., Stangeby, P., Thomas, D. M., Wang, H., Wilcox, R. S., Yu, J. H., Casali, L., & Shafer, M. W. Numerical assessment of the new V-shape small-angle slot divertor on DIII-D. United States. https://doi.org/10.1088/1741-4326/ac27c8
Maurizio, R., Du, H., Gallo, A., Guo, H. Y., Leonard, A., Ma, X., Sinclair, G., Stangeby, P., Thomas, D. M., Wang, H., Wilcox, R. S., Yu, J. H., Casali, L., and Shafer, M. W. Fri . "Numerical assessment of the new V-shape small-angle slot divertor on DIII-D". United States. https://doi.org/10.1088/1741-4326/ac27c8. https://www.osti.gov/servlets/purl/1830231.
@article{osti_1830231,
title = {Numerical assessment of the new V-shape small-angle slot divertor on DIII-D},
author = {Maurizio, R. and Du, H. and Gallo, A. and Guo, H. Y. and Leonard, A. and Ma, X. and Sinclair, G. and Stangeby, P. and Thomas, D. M. and Wang, H. and Wilcox, R. S. and Yu, J. H. and Casali, L. and Shafer, M. W.},
abstractNote = {The small-angle slot (SAS) divertor of the DIII-D tokamak, and its upcoming upgrade, the V-shape small-angle slot (SAS-V) divertor, are numerically investigated using the SOLPS-ITER code package, including the effect of particle drifts, for a range of plasma density, heating power, strike point position in the slot, and for both magnetic field directions. The simulations show that the electron temperature near the strike point is reduced in SAS-V compared to SAS, for both magnetic field directions, such that SAS-V achieves divertor detachment at a lower value of the outboard mid-plane separatrix electron density. The detachment threshold is lower because the V-shape focuses recycling neutrals on the V-end, densifying and cooling the plasma in the slot. At sufficiently high density, the V-shape also reduces the radial gradient of the temperature profile at the target, which in turns reduces the radial electric field and the E × B drift velocities, further densifying and cooling the plasma in the slot and leading to detachment. The V-shape effect, however, is reduced for higher heating power. With more heating power, the detachment density increases, reducing the ionization mean free path of recycled neutrals, which therefore become less sensitive to target shape changes. This suggests that in a fusion reactor, where the heating power is high, optimization of the divertor target shape needs to be combined with other strategies to lower the detachment density, such as in-slot injection of low-Z impurities.},
doi = {10.1088/1741-4326/ac27c8},
journal = {Nuclear Fusion},
number = 11,
volume = 61,
place = {United States},
year = {Fri Oct 08 00:00:00 EDT 2021},
month = {Fri Oct 08 00:00:00 EDT 2021}
}

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