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Title: Modelling the effect of divertor closure on detachment onset in DIII-D with the SOLPS code

SOLPS modelling has shown that divertor plasma detachment occurs at a lower upstream separatrix density in the more closed DIII-D upper divertor than the open lower divertor, demonstrating the utility of the divertor closure in widening the range of acceptable densities for adequate heat handling. To achieve reduced heat flux and erosion at the plasma-facing components, future devices will need to operate in at least partially detached divertor conditions . Two-dimensional fluid plasma models coupled to Monte Carlo neutral transport simulations, such as SOLPS, have been widely used to predict the onset of detachment. In modelling the DIII-D discharges, the cross-field transport coefficients are constrained to reproduce the experimental upstream profiles. The closed divertor has been modelled with the same input parameters of the open divertor, allowing a direct comparison of the target conditions in both geometries. SOLPS simulations indicate that a higher molecular density correlates strongly with lower electron temperatures. The increased closure of the upper divertor improves the trapping of neutrals, thereby reducing the power density deposited at the target and facilitating detachment, in agreement with experimental observations.
Authors:
ORCiD logo [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [4]
  1. Oak Ridge Associated Univ., Oak Ridge, TN (United States)
  2. Dalian Univ. of Technology, Dalian (China). School of Physics
  3. General Atomics, San Diego, CA (United States)
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-751782
Journal ID: ISSN 0863-1042; 936705
Grant/Contract Number:
AC52-07NA27344; FC02‐04ER54698; FC02-04ER54698; AC05-06OR23100
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
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; closure; detachment; divertor; SOLPS
OSTI Identifier:
1491633
Alternate Identifier(s):
OSTI ID: 1434964

Casali, L., Sang, C., Moser, A. L., Covele, B. M., Guo, H. Y., and Samuell, C.. Modelling the effect of divertor closure on detachment onset in DIII-D with the SOLPS code. United States: N. p., Web. doi:10.1002/ctpp.201700215.
Casali, L., Sang, C., Moser, A. L., Covele, B. M., Guo, H. Y., & Samuell, C.. Modelling the effect of divertor closure on detachment onset in DIII-D with the SOLPS code. United States. doi:10.1002/ctpp.201700215.
Casali, L., Sang, C., Moser, A. L., Covele, B. M., Guo, H. Y., and Samuell, C.. 2018. "Modelling the effect of divertor closure on detachment onset in DIII-D with the SOLPS code". United States. doi:10.1002/ctpp.201700215.
@article{osti_1491633,
title = {Modelling the effect of divertor closure on detachment onset in DIII-D with the SOLPS code},
author = {Casali, L. and Sang, C. and Moser, A. L. and Covele, B. M. and Guo, H. Y. and Samuell, C.},
abstractNote = {SOLPS modelling has shown that divertor plasma detachment occurs at a lower upstream separatrix density in the more closed DIII-D upper divertor than the open lower divertor, demonstrating the utility of the divertor closure in widening the range of acceptable densities for adequate heat handling. To achieve reduced heat flux and erosion at the plasma-facing components, future devices will need to operate in at least partially detached divertor conditions . Two-dimensional fluid plasma models coupled to Monte Carlo neutral transport simulations, such as SOLPS, have been widely used to predict the onset of detachment. In modelling the DIII-D discharges, the cross-field transport coefficients are constrained to reproduce the experimental upstream profiles. The closed divertor has been modelled with the same input parameters of the open divertor, allowing a direct comparison of the target conditions in both geometries. SOLPS simulations indicate that a higher molecular density correlates strongly with lower electron temperatures. The increased closure of the upper divertor improves the trapping of neutrals, thereby reducing the power density deposited at the target and facilitating detachment, in agreement with experimental observations.},
doi = {10.1002/ctpp.201700215},
journal = {Contributions to Plasma Physics},
number = 6-8,
volume = 58,
place = {United States},
year = {2018},
month = {4}
}