Design and Analysis of High Heat Flux Plasma-Facing Components for NSTX Upgrade

Khodak, Andrei; Loesser, Douglas; Messineo, Michael; Brooks, Arthur; Jaworski, Michael; Youchison, Dennis L.; Cook, Jason

doi:10.1109/tps.2020.3046229

Title: Design and Analysis of High Heat Flux Plasma-Facing Components for NSTX Upgrade

Abstract

The National Spherical Tokamak Experiment (NSTX) upgrade (NSTX-U) requirements lead to enhanced heat loads on plasma-facing components (PFCs) especially in the divertor regions, where normal heat flux density can reach up to 8 MW/m 2 . For these high heat flux (HHF) regions, the PFCs were redesigned, to use castellations which relieved the thermal stresses associated with high incident heat flux. Another design feature of HHF PFCs is the absence of front face mounting holes which create localized areas of high temperature and thermal stress concentrations. Optimized shaping of the front face of the HHF PFCs eliminates regions where the front face is perpendicular to the heat flux direction during normal helicity operation and spreads the heat load. A unique mechanism was designed to connect PFC tiles to the NSTX-U center stack casing using locking features accessible from the low heat flux regions. Isotropic graphite was selected as the HHF PFC tile material. Initial tile design parameters were accessed using analytical expressions for pulsed heat flux loading. A working prototype of the locking mechanism was created during the initial stages of the design to prove the concept performance. This article presents an overview of the divertor HHF PFC design andmore »« less

Authors:

^[1]; Loesser, Douglas ^[1]; Messineo, Michael ^[1]; Brooks, Arthur ^[1]; Jaworski, Michael ^[2];

^[3];

^[3]

Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:: Wed Jan 13 00:00:00 EST 2021

Research Org.:: Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:: USDOE

OSTI Identifier:: 1821921

Alternate Identifier(s):: OSTI ID: 1827567; OSTI ID: 1843723

Report Number(s):: LA-UR-18-31730
Journal ID: ISSN 0093-3813; TRN: US2214402

Grant/Contract Number:: AC02-09CH11466; 89233218CNA000001; AC05-00OR22725

Resource Type:: Accepted Manuscript

Journal Name:: IEEE Transactions on Plasma Science

Additional Journal Information:: Journal Volume: 49; Journal Issue: 2; Journal ID: ISSN 0093-3813

Publisher:: IEEE

Country of Publication:: United States

Language:: English

Subject:: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; high heat flux (HHF); numerical analysis; plasma-facing components (PFCs)

Citation Formats


                    Khodak, Andrei, Loesser, Douglas, Messineo, Michael, Brooks, Arthur, Jaworski, Michael, Youchison, Dennis L., and Cook, Jason. Design and Analysis of High Heat Flux Plasma-Facing Components for NSTX Upgrade.  United States: N. p., 2021. 
Web.  doi:10.1109/tps.2020.3046229.

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                    Khodak, Andrei, Loesser, Douglas, Messineo, Michael, Brooks, Arthur, Jaworski, Michael, Youchison, Dennis L., & Cook, Jason. Design and Analysis of High Heat Flux Plasma-Facing Components for NSTX Upgrade.  United States.  https://doi.org/10.1109/tps.2020.3046229

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                    Khodak, Andrei, Loesser, Douglas, Messineo, Michael, Brooks, Arthur, Jaworski, Michael, Youchison, Dennis L., and Cook, Jason. Wed .  
"Design and Analysis of High Heat Flux Plasma-Facing Components for NSTX Upgrade".  United States.  https://doi.org/10.1109/tps.2020.3046229.  https://www.osti.gov/servlets/purl/1821921.

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@article{osti_1821921,

  title        = {Design and Analysis of High Heat Flux Plasma-Facing Components for NSTX Upgrade},

  author       = {Khodak, Andrei and Loesser, Douglas and Messineo, Michael and Brooks, Arthur and Jaworski, Michael and Youchison, Dennis L. and Cook, Jason},

  abstractNote = {The National Spherical Tokamak Experiment (NSTX) upgrade (NSTX-U) requirements lead to enhanced heat loads on plasma-facing components (PFCs) especially in the divertor regions, where normal heat flux density can reach up to 8 MW/m 2 . For these high heat flux (HHF) regions, the PFCs were redesigned, to use castellations which relieved the thermal stresses associated with high incident heat flux. Another design feature of HHF PFCs is the absence of front face mounting holes which create localized areas of high temperature and thermal stress concentrations. Optimized shaping of the front face of the HHF PFCs eliminates regions where the front face is perpendicular to the heat flux direction during normal helicity operation and spreads the heat load. A unique mechanism was designed to connect PFC tiles to the NSTX-U center stack casing using locking features accessible from the low heat flux regions. Isotropic graphite was selected as the HHF PFC tile material. Initial tile design parameters were accessed using analytical expressions for pulsed heat flux loading. A working prototype of the locking mechanism was created during the initial stages of the design to prove the concept performance. This article presents an overview of the divertor HHF PFC design and the results of the thermal and structural analyses performed using ANSYS software. The results of the analyses cover normal operating conditions and disruptions which impose electromagnetic (EM) loads from eddy and halo currents. The 3-D, transient, nonlinear analyses took into account the temperature-dependent properties of the materials, friction interfaces between the parts, and variable electric properties of the parts and interfaces. The results confirm that the HHF PFC tiles remain within the allowable limits for the loads defined by the NSTX-U Recovery Project. In addition, tolerance stack up analyses were performed to ensure tile performance in the worst possible assembly configuration. Finally, the design process was completed successfully, and the NSTX HHF PFC tiles are currently in the production phase.},

  doi          = {10.1109/tps.2020.3046229},

  journal      = {IEEE Transactions on Plasma Science},

  number       = 2,

  volume       = 49,

  place        = {United States},

  year         = {Wed Jan 13 00:00:00 EST 2021},

  month        = {Wed Jan 13 00:00:00 EST 2021}

}

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Works referenced in this record:

Optimization of high heat flux components for DIII-D neutral beam upgrades
journal, September 2019

Khodak, Andrei; Zatz, Irving; Wang, Wenping
Fusion Engineering and Design, Vol. 146
DOI: 10.1016/j.fusengdes.2019.02.047

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Title: Design and Analysis of High Heat Flux Plasma-Facing Components for NSTX Upgrade

Abstract

Citation Formats

Optimization of high heat flux components for DIII-D neutral beam upgrades journal, September 2019

Optimization of high heat flux components for DIII-D neutral beam upgrades
journal, September 2019