Drift effects and up-down asymmetry in balanced double-null DIII-D divertor configurations
Abstract
In a preliminary design study for a small-angle slot (SAS) divertor configuration suitable for DIII-D double-null advanced tokamak (AT) plasmas, a conceptual “SAS 2” slot divertor configuration has been modelled with SOLPS-ITER. A balanced double-null equilibrium, representing an H-mode AT plasma, is employed, with 5 MW neutral beam input power. In simulations with fully recycling walls and no pumping, an up–down-symmetric open divertor geometry is compared with the SAS 2 configuration. In density scans without electric or magnetic drifts, the upstream separatrix electron density needed to achieve detachment at both target strike points (ne, sep, det.) is ~35% lower in SAS 2 than in the open configuration, with ne, sep, det. = 1.66 and 2.59 × 1019 m-3, respectively. With drifts, the same ~35% difference remains, but detachment density for each configuration is shifted up by ~15%, giving ne, sep, det. = 1.94 and 2.99 × 1019 m-3, respectively. Cryopumping is modelled for the SAS 2 divertor, and with a pump duct deep in the upper slot on the common-flux side, detachment density is shifted up by ~15–20%. Strong pumping in the upper slot delays detachment there compared with the lower slot, regardless of drift direction. This research sets themore »
- Authors:
-
[1];
- Univ. of Washington, Seattle, WA (United States)
- General Atomics, San Diego, CA (United States)
- Publication Date:
- Research Org.:
- General Atomics, San Diego, CA (United States); College of William and Mary, Williamsburg, VA (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- OSTI Identifier:
- 1617849
- Alternate Identifier(s):
- OSTI ID: 1457462
- Grant/Contract Number:
- FC02-04ER54698; SC0007880; SC0010434
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Contributions to Plasma Physics
- Additional Journal Information:
- Journal Volume: 58; Journal Issue: 6-8; Journal ID: ISSN 0863-1042
- Publisher:
- Wiley
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; advanced tokamak; DIII-D; divertor; double-null; small-angle slot (SAS)
Citation Formats
Meier, E. T., Covele, B., Guo, H. Y., and Thomas, D. M. Drift effects and up-down asymmetry in balanced double-null DIII-D divertor configurations. United States: N. p., 2018.
Web. doi:10.1002/ctpp.201700167.
Meier, E. T., Covele, B., Guo, H. Y., & Thomas, D. M. Drift effects and up-down asymmetry in balanced double-null DIII-D divertor configurations. United States. https://doi.org/10.1002/ctpp.201700167
Meier, E. T., Covele, B., Guo, H. Y., and Thomas, D. M. Tue .
"Drift effects and up-down asymmetry in balanced double-null DIII-D divertor configurations". United States. https://doi.org/10.1002/ctpp.201700167. https://www.osti.gov/servlets/purl/1617849.
@article{osti_1617849,
title = {Drift effects and up-down asymmetry in balanced double-null DIII-D divertor configurations},
author = {Meier, E. T. and Covele, B. and Guo, H. Y. and Thomas, D. M.},
abstractNote = {In a preliminary design study for a small-angle slot (SAS) divertor configuration suitable for DIII-D double-null advanced tokamak (AT) plasmas, a conceptual “SAS 2” slot divertor configuration has been modelled with SOLPS-ITER. A balanced double-null equilibrium, representing an H-mode AT plasma, is employed, with 5 MW neutral beam input power. In simulations with fully recycling walls and no pumping, an up–down-symmetric open divertor geometry is compared with the SAS 2 configuration. In density scans without electric or magnetic drifts, the upstream separatrix electron density needed to achieve detachment at both target strike points (ne, sep, det.) is ~35% lower in SAS 2 than in the open configuration, with ne, sep, det. = 1.66 and 2.59 × 1019 m-3, respectively. With drifts, the same ~35% difference remains, but detachment density for each configuration is shifted up by ~15%, giving ne, sep, det. = 1.94 and 2.99 × 1019 m-3, respectively. Cryopumping is modelled for the SAS 2 divertor, and with a pump duct deep in the upper slot on the common-flux side, detachment density is shifted up by ~15–20%. Strong pumping in the upper slot delays detachment there compared with the lower slot, regardless of drift direction. This research sets the stage for future modelling that would explore more sophisticated cryopumping configurations, and sensitivity of divertor performance to changes in magnetic balance and input power.},
doi = {10.1002/ctpp.201700167},
journal = {Contributions to Plasma Physics},
number = 6-8,
volume = 58,
place = {United States},
year = {Tue Jun 26 00:00:00 EDT 2018},
month = {Tue Jun 26 00:00:00 EDT 2018}
}
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