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Title: 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 ( n e, sep, det.) is ~35% lower in SAS 2 than in the open configuration, with n e, sep, det. = 1.66 and 2.59 × 10 19 m -3, respectively. With drifts, the same ~35% difference remains, but detachment density for each configuration is shifted up by ~15%, giving n e, sep, det. = 1.94 and 2.99 × 10 19 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,more » 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.« less

Authors:
ORCiD logo [1];  [2];  [2];  [2]
  1. Univ. of Washington, Seattle, WA (United States)
  2. 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) (SC-24)
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. doi: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. doi: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 = {2018},
month = {6}
}

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Works referenced in this record:

Variation of particle exhaust with changes in divertor magnetic balance
journal, December 2005


Currents in the scrape-off layer of diverted tokamaks
journal, October 1989


The scaling of the heat flux width in DIII-D
journal, July 2013


Plasma edge and plasma-wall interaction modelling: Lessons learned from metallic devices
journal, August 2017


Presentation of the New SOLPS-ITER Code Package for Tokamak Plasma Edge Modelling
journal, January 2016

  • Bonnin, Xavier; Dekeyser, Wouter; Pitts, Richard
  • Plasma and Fusion Research, Vol. 11, Issue 0
  • DOI: 10.1585/pfr.11.1403102

High density operation for reactor-relevant power exhaust
journal, August 2015


Spectroscopic measurement of atomic and molecular deuterium fluxes in the DIII-D plasma edge
journal, July 2006

  • Hollmann, E. M.; Brezinsek, S.; Brooks, N. H.
  • Plasma Physics and Controlled Fusion, Vol. 48, Issue 8
  • DOI: 10.1088/0741-3335/48/8/009

Analysis of drift effects on the tokamak power scrape-off width using SOLPS-ITER
journal, November 2016


SOLPS analysis of neutral baffling for the design of a new diverter in DIII-D
journal, April 2017


Analytic description of the chemical erosion of graphite by hydrogen ions
journal, December 1996


Small angle slot divertor concept for long pulse advanced tokamaks
journal, February 2017


A Fusion Nuclear Science Facility for a fast-track path to DEMO
journal, October 2014


The new SOLPS-ITER code package
journal, August 2015


SOLPS modeling of the effect on plasma detachment of closing the lower divertor in DIII-D
journal, December 2016


Numerical modelling of high density JET divertor plasma with the SOLPS4.2 (B2-EIRENE) code
journal, September 2008


Contribution of $\vec {E}\times \vec {B}$ drifts and parallel currents to divertor asymmetries
journal, September 2012


Drifts, currents, and power scrape-off width in SOLPS-ITER modeling of DIII-D
journal, August 2017


An investigation of the secondary-electron emission of carbon samples exposed to a hydrogen plasma
journal, September 1987

  • Woods, M. E.; Hopkins, B. J.; Matthews, G. F.
  • Journal of Physics D: Applied Physics, Vol. 20, Issue 9
  • DOI: 10.1088/0022-3727/20/9/008

Modeling of detachment experiments at DIII-D
journal, August 2015