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Simulation of the SPARC plasma boundary with the UEDGE code

Journal Article · · Nuclear Fusion
 [1];  [1];  [2];  [3];  [4];  [1];  [4];  [1];  [1];  [1]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Commonwealth Fusion Systems, Cambridge, MA (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
+ Show Author Affiliations
Here in this work, the UEDGE edge transport code is used to examine conditions in the SPARC divertor and edge plasma for various levels of carbon impurity and power from the core (PSOL). A double-null magnetic configuration is simulated assuming up-down symmetry in geometry and physics. The anomalous heat and particle transport coefficients are tuned to match empirical predictions for SPARC's midplane density profiles, target plate heat flux profiles, and inner/outer divertor power sharing. Convective transport is included on the low-field side, while on the high-field side the transport is modeled as purely diffusive. Hydrogen neutrals are modeled as a fluid with inertial effects, and a carbon impurity is included using the fixed-fraction model. We find that detachment induced by impurity seeding could significantly reduce the heat flux to the divertor surfaces in the SPARC tokamak. At PSOL = 28 MW (the value predicted for SPARC's full-power H-mode scenario) cases with both divertor legs detached were obtained with a carbon impurity fraction between 0.3%–1.4%, far below Zeff limits for SPARC. When the plasma in the outer leg is detached, the peak heat flux density perpendicular to the target plate is below 1 MW m-2, electron and ion temperatures are less than 1.5 eV, and momentum detachment is observed. However, the detachment state is found to be sensitive to the side-wall boundary conditions, the level of neutral pumping, and the target plate tilt. Finally, a broadly similar SOLPS simulation of SPARC is used to assess the appropriateness of the simpler impurity and neutral models used in UEDGE.
Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Fusion Energy Sciences (FES); Commonwealth Fusion Systems; SPARC Fellowship Fund; Samuel W. Ing Memorial Fund
Contributing Organization:
SPARC Team
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
1820706
Alternate ID(s):
OSTI ID: 23129811
Journal Information:
Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 8 Vol. 61; ISSN 0029-5515
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English

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70 PLASMA PHYSICS AND FUSION TECHNOLOGY