Modeling deep slot divertor concepts at DIII-D using SOLPS-ITER with drifts

R. Maurizio; A. W. Leonard; A. G. McLean; M. W. Shafer; P. C. Stangeby; D. Thomas; J. H. Yu

doi:10.1016/j.nme.2022.101356

Modeling deep slot divertor concepts at DIII-D using SOLPS-ITER with drifts

R. Maurizio, A. W. Leonard, A. G. McLean, M. W. Shafer, P. C. Stangeby, D. Thomas, J. H. Yu

Advanced Tokamak Physics

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

2 Scopus citations

Abstract

A staged divertor program is currently under discussion to advance DIII-D research on core-edge integration. One phase could address optimization of power and particle exhaust, and supporting modeling of several slot divertor options is underway, including variations in wall baffling, slot depth and divertor leg length. This paper focuses on the role of slot depth to achieve highly dissipative (detached) divertor conditions, in both B_T directions. For ion B×∇B into the divertor and P_SOL= 4 MW, SOLPS-ITER finds that increasing the slot depth from 18 to 50 cm reduces the upstream separatrix electron density needed to detach by 15%, due to increased divertor radiation. A dedicated run of the EIRENE neutral transport code, in which neutrals are launched from the outer target and followed until ionization, finds that neutral leakage is strongly reduced in the deep slot compared to the shallow slot, explaining the increased divertor radiation and, thus, lower detachment density threshold. Reversing the B_T direction cools and densifies the plasma in the slot, such that both slot options are detached at all simulated densities. As for the opposite B_T direction, the deep slot has lower target temperature compared to the shallow slot, as a result of lower neutral leakage. Increasing the depth of a slot divertor is, therefore, beneficial to achieve highly dissipative divertor conditions for both field directions. Additional modeling will build on these results to evaluate whether an increased slot depth can also improve trapping of low-Z radiating impurities.

Original language	English
Article number	101356
Journal	Nuclear Materials and Energy
Volume	34
DOIs	https://doi.org/10.1016/j.nme.2022.101356
State	Published - Mar 2023

Funding

The authors would like to thank the entire DIII-D Divertor Science and Innovation team for their help and constructive discussions. This material is based upon work supported by the U.S. Department of Energy , Office of Science, Office of Fusion Energy Sciences, using the DIII-D National Fusion Facility, a DOE Office of Science user facility, under Award(s) DE-FC02-04ER54698 and DE-AC05-00OR22725. The authors would like to thank the entire DIII-D Divertor Science and Innovation team for their help and constructive discussions. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, using the DIII-D National Fusion Facility, a DOE Office of Science user facility, under Award(s) DE-FC02-04ER54698 and DE-AC05-00OR22725. This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

Funders	Funder number
United States Government
U.S. Department of Energy
Office of Science	DE-AC05-00OR22725, DE-FC02-04ER54698
Fusion Energy Sciences

Keywords

DIII-D
Detachment
Divertor
SOLPS-ITER
Slot divertor

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.nme.2022.101356

Cite this

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title = "Modeling deep slot divertor concepts at DIII-D using SOLPS-ITER with drifts",

abstract = "A staged divertor program is currently under discussion to advance DIII-D research on core-edge integration. One phase could address optimization of power and particle exhaust, and supporting modeling of several slot divertor options is underway, including variations in wall baffling, slot depth and divertor leg length. This paper focuses on the role of slot depth to achieve highly dissipative (detached) divertor conditions, in both BT directions. For ion B×∇B into the divertor and PSOL= 4 MW, SOLPS-ITER finds that increasing the slot depth from 18 to 50 cm reduces the upstream separatrix electron density needed to detach by 15%, due to increased divertor radiation. A dedicated run of the EIRENE neutral transport code, in which neutrals are launched from the outer target and followed until ionization, finds that neutral leakage is strongly reduced in the deep slot compared to the shallow slot, explaining the increased divertor radiation and, thus, lower detachment density threshold. Reversing the BT direction cools and densifies the plasma in the slot, such that both slot options are detached at all simulated densities. As for the opposite BT direction, the deep slot has lower target temperature compared to the shallow slot, as a result of lower neutral leakage. Increasing the depth of a slot divertor is, therefore, beneficial to achieve highly dissipative divertor conditions for both field directions. Additional modeling will build on these results to evaluate whether an increased slot depth can also improve trapping of low-Z radiating impurities.",

keywords = "DIII-D, Detachment, Divertor, SOLPS-ITER, Slot divertor",

author = "R. Maurizio and Leonard, {A. W.} and McLean, {A. G.} and Shafer, {M. W.} and Stangeby, {P. C.} and D. Thomas and Yu, {J. H.}",

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doi = "10.1016/j.nme.2022.101356",

language = "English",

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AU - Leonard, A. W.

AU - McLean, A. G.

AU - Shafer, M. W.

AU - Stangeby, P. C.

AU - Thomas, D.

AU - Yu, J. H.

PY - 2023/3

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AB - A staged divertor program is currently under discussion to advance DIII-D research on core-edge integration. One phase could address optimization of power and particle exhaust, and supporting modeling of several slot divertor options is underway, including variations in wall baffling, slot depth and divertor leg length. This paper focuses on the role of slot depth to achieve highly dissipative (detached) divertor conditions, in both BT directions. For ion B×∇B into the divertor and PSOL= 4 MW, SOLPS-ITER finds that increasing the slot depth from 18 to 50 cm reduces the upstream separatrix electron density needed to detach by 15%, due to increased divertor radiation. A dedicated run of the EIRENE neutral transport code, in which neutrals are launched from the outer target and followed until ionization, finds that neutral leakage is strongly reduced in the deep slot compared to the shallow slot, explaining the increased divertor radiation and, thus, lower detachment density threshold. Reversing the BT direction cools and densifies the plasma in the slot, such that both slot options are detached at all simulated densities. As for the opposite BT direction, the deep slot has lower target temperature compared to the shallow slot, as a result of lower neutral leakage. Increasing the depth of a slot divertor is, therefore, beneficial to achieve highly dissipative divertor conditions for both field directions. Additional modeling will build on these results to evaluate whether an increased slot depth can also improve trapping of low-Z radiating impurities.

KW - DIII-D

KW - Detachment

KW - Divertor

KW - SOLPS-ITER

KW - Slot divertor

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Modeling deep slot divertor concepts at DIII-D using SOLPS-ITER with drifts

Abstract

Funding

Keywords

UN SDGs

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