Simulation of Divertor Performance in ST40 Under Dynamic Double-Null Plasmas

Erin Joy Capdos Tinacba; Jake Nichols; Travis Gray; Chris Marsden; Elena Vekshina; Xin Zhang

doi:10.1109/TPS.2026.3661891

Simulation of Divertor Performance in ST40 Under Dynamic Double-Null Plasmas

Erin Joy Capdos Tinacba
, Jake Nichols
, Travis Gray
, Chris Marsden
, Elena Vekshina
, Xin Zhang

Power Exhaust and Particle Control

Research output: Contribution to journal › Article › peer-review

Abstract

A power fraction model was implemented for the simultaneous prediction of 3-D surface temperature evolution at all four divertor targets in near-double-null (DN) tokamak configurations, which is especially important for compact high-field devices that may not have the ability to dissipate large amounts of power on the high-field side. Evaluating the power-sharing between the four divertor strike points in a disconnected DN configuration is important for understanding the overall power balance, as well as for optimizing the power exhaust performance and prolonging the survivability of the plasma facing components (PFCs). This power-sharing is typically evaluated in terms of the separation between the primary and secondary separatrices at the outboard midplane, it dR sep. The Heat flux Engineering Analysis Toolkit (HEAT) is coupled with Brunner's power fraction model to simulate the deposited heat flux and resultant temperature change on 3-D divertor targets in a dynamic DN (DDN) pulse operation in ST40, a high-field spherical tokamak. The simulation results showed that with DDN operation, the operation time has significantly increased compared with single-null geometry configurations.

Original language	English
Pages (from-to)	2820-2825
Number of pages	6
Journal	IEEE Transactions on Plasma Science
Volume	54
Issue number	6
DOIs	https://doi.org/10.1109/TPS.2026.3661891
State	Published - Jun 1 2026

Funding

ACKNOWLEDGMENT This manuscript has been authored by UTB, LLC, under contract DE0AC0500OR22725 with the US Department of Energy (DOE) and U.S. DOE CRADA NFE-19-07769. The US ernmentvgo retains and the ,publisher by accepting the article for publication, wledgesackno that the US ernmentvgo retains a e,vxclusinone paid-up, ocable,virre orldwidew license to publish or reproduce the published form of this manuscript, or wallo others to do so, for US ernmentvgo purposes. DOE will videpro public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (https: access-plan). The authors thank Jack Llvo from ORNL for his significant insights and advice on the .p Rdve 30 September 2025; visedre 28 December 2025; accepted 2 February 2026. This orkw asw supported in part by UTB, LLC, with the U.S. Department of Energy (DOE) under Contract DEAC0500OR22725; and in part by U.S. DOE CRADA under Grant NFE-19-07769. The wviere of this article asw arranged by Senior Editor M. K.vo Erin Joy Capdos Tinacba.) Erin Joy Capdos T, Jake Nichols, and Tsa Gray are with Oak Ridge National L,a Oak Ridge, TN 37830 USA (e-mail: [email protected]). Chris Marsden, Elena V, and Xin Zhang are with Tk Energy Ltd., O14 4SD Oxfordshire, U.K. Color ersionsv of one or more figures in this article are ailableva at //doi.org /10.1109/TPS.2026.3661891. Digital Object Identifier 10.1109 /TPS.2026.3661891

Keywords

Fusion
ST40
heat flux calculation
power balance

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10.1109/TPS.2026.3661891

Cite this

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title = "Simulation of Divertor Performance in ST40 Under Dynamic Double-Null Plasmas",

abstract = "A power fraction model was implemented for the simultaneous prediction of 3-D surface temperature evolution at all four divertor targets in near-double-null (DN) tokamak configurations, which is especially important for compact high-field devices that may not have the ability to dissipate large amounts of power on the high-field side. Evaluating the power-sharing between the four divertor strike points in a disconnected DN configuration is important for understanding the overall power balance, as well as for optimizing the power exhaust performance and prolonging the survivability of the plasma facing components (PFCs). This power-sharing is typically evaluated in terms of the separation between the primary and secondary separatrices at the outboard midplane, it dR sep. The Heat flux Engineering Analysis Toolkit (HEAT) is coupled with Brunner's power fraction model to simulate the deposited heat flux and resultant temperature change on 3-D divertor targets in a dynamic DN (DDN) pulse operation in ST40, a high-field spherical tokamak. The simulation results showed that with DDN operation, the operation time has significantly increased compared with single-null geometry configurations.",

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AU - Zhang, Xin

PY - 2026/6/1

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N2 - A power fraction model was implemented for the simultaneous prediction of 3-D surface temperature evolution at all four divertor targets in near-double-null (DN) tokamak configurations, which is especially important for compact high-field devices that may not have the ability to dissipate large amounts of power on the high-field side. Evaluating the power-sharing between the four divertor strike points in a disconnected DN configuration is important for understanding the overall power balance, as well as for optimizing the power exhaust performance and prolonging the survivability of the plasma facing components (PFCs). This power-sharing is typically evaluated in terms of the separation between the primary and secondary separatrices at the outboard midplane, it dR sep. The Heat flux Engineering Analysis Toolkit (HEAT) is coupled with Brunner's power fraction model to simulate the deposited heat flux and resultant temperature change on 3-D divertor targets in a dynamic DN (DDN) pulse operation in ST40, a high-field spherical tokamak. The simulation results showed that with DDN operation, the operation time has significantly increased compared with single-null geometry configurations.

AB - A power fraction model was implemented for the simultaneous prediction of 3-D surface temperature evolution at all four divertor targets in near-double-null (DN) tokamak configurations, which is especially important for compact high-field devices that may not have the ability to dissipate large amounts of power on the high-field side. Evaluating the power-sharing between the four divertor strike points in a disconnected DN configuration is important for understanding the overall power balance, as well as for optimizing the power exhaust performance and prolonging the survivability of the plasma facing components (PFCs). This power-sharing is typically evaluated in terms of the separation between the primary and secondary separatrices at the outboard midplane, it dR sep. The Heat flux Engineering Analysis Toolkit (HEAT) is coupled with Brunner's power fraction model to simulate the deposited heat flux and resultant temperature change on 3-D divertor targets in a dynamic DN (DDN) pulse operation in ST40, a high-field spherical tokamak. The simulation results showed that with DDN operation, the operation time has significantly increased compared with single-null geometry configurations.

KW - Fusion

KW - ST40

KW - heat flux calculation

KW - power balance

UR - https://www.scopus.com/pages/publications/105031650175

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JO - IEEE Transactions on Plasma Science

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ER -

Simulation of Divertor Performance in ST40 Under Dynamic Double-Null Plasmas

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