Comparison of reduced model predictions for divertor detachment onset and reattachment timescales in ASDEX Upgrade and JET experiments

S.S. Henderson; M. Bernert; D. Brida; M. Cavedon; P. David; R. Dux; O. Février; P. Jacquet; Aaro Järvinen; A. Kallenbach; Juuso Karhunen; et al.; JET Contributors; ASDEX Upgrade Team; EUROfusion Tokamak Exploitation Team

doi:10.1088/1741-4326/ad3970

Comparison of reduced model predictions for divertor detachment onset and reattachment timescales in ASDEX Upgrade and JET experiments

S.S. Henderson^*, M. Bernert, D. Brida, M. Cavedon, P. David, R. Dux, O. Février, P. Jacquet, Aaro Järvinen, A. Kallenbach, Juuso Karhunen, et al., JET Contributors, ASDEX Upgrade Team, EUROfusion Tokamak Exploitation Team

^*Corresponding author for this work

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

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Abstract

Building on prior analysis of ASDEX Upgrade (AUG) experiments (Henderson et al 2023 Nucl. Fusion 63 086024), this study compares simple analytical formula predictions for divertor detachment onset and reattachment timescales in JET experiments. Detachment onset primarily scales with divertor neutral pressure, impurity concentration, power directed to the targets, machine size, and integral perpendicular power decay length. JET experiments, focusing on seeding mixtures of Ne and Ar, align with the detachment onset predictions. Radiation efficiencies among the impurities show good agreement with the model predictions, contrasting with AUG observations which suggested higher efficiency for Ar and lower efficiency for Ne. The time taken to re-ionise the neutral volume in front of the outer target in fully detached divertor conditions was measured following both abrupt increases in injected neutral beam power and, separately, cutting of the impurity gas flow. Re-ionisation of the neutrals occurs within approximately 1 s on JET, which aligns with the simple model prediction derived from AUG data. While the AUG results are not new, their comparison with the JET results enhances understanding, reinforcing confidence in using simple models to predict future reactor scenarios.

Original language	English
Article number	066006
Number of pages	10
Journal	Nuclear Fusion
Volume	64
Issue number	6
DOIs	https://doi.org/10.1088/1741-4326/ad3970
Publication status	Published - Jun 2024
MoE publication type	A1 Journal article-refereed

Funding

This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No. 101052200\u2014EUROfusion) and from the EPSRC (Grant No. EP/W006839/1). The Swiss contribution to this work has been funded by the Swiss State Secretariat for Education, Research and Innovation (SERI). To obtain further information on the data and models underlying this paper please contact PublicationsManagerukaea.uk. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission or SERI. Neither the European Union nor the European Commission nor SERI can be held responsible for them.

Keywords

ASDEX Upgrade
divertor detachment
divertor reattachment
impurity seeding
JET
model validation

UN SDGs

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

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10.1088/1741-4326/ad3970Licence: CC BY

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Henderson, S. S., Bernert, M., Brida, D., Cavedon, M., David, P., Dux, R., Février, O., Jacquet, P., Järvinen, A., Kallenbach, A., Karhunen, J., et al., JET Contributors, ASDEX Upgrade Team, & EUROfusion Tokamak Exploitation Team (2024). Comparison of reduced model predictions for divertor detachment onset and reattachment timescales in ASDEX Upgrade and JET experiments. Nuclear Fusion, 64(6), Article 066006. https://doi.org/10.1088/1741-4326/ad3970

@article{1c82788f40324bd382c725d18679bf9e,

title = "Comparison of reduced model predictions for divertor detachment onset and reattachment timescales in ASDEX Upgrade and JET experiments",

abstract = "Building on prior analysis of ASDEX Upgrade (AUG) experiments (Henderson et al 2023 Nucl. Fusion 63 086024), this study compares simple analytical formula predictions for divertor detachment onset and reattachment timescales in JET experiments. Detachment onset primarily scales with divertor neutral pressure, impurity concentration, power directed to the targets, machine size, and integral perpendicular power decay length. JET experiments, focusing on seeding mixtures of Ne and Ar, align with the detachment onset predictions. Radiation efficiencies among the impurities show good agreement with the model predictions, contrasting with AUG observations which suggested higher efficiency for Ar and lower efficiency for Ne. The time taken to re-ionise the neutral volume in front of the outer target in fully detached divertor conditions was measured following both abrupt increases in injected neutral beam power and, separately, cutting of the impurity gas flow. Re-ionisation of the neutrals occurs within approximately 1 s on JET, which aligns with the simple model prediction derived from AUG data. While the AUG results are not new, their comparison with the JET results enhances understanding, reinforcing confidence in using simple models to predict future reactor scenarios.",

keywords = "ASDEX Upgrade, divertor detachment, divertor reattachment, impurity seeding, JET, model validation",

author = "S.S. Henderson and M. Bernert and D. Brida and M. Cavedon and P. David and R. Dux and O. F{\'e}vrier and P. Jacquet and Aaro J{\"a}rvinen and A. Kallenbach and Juuso Karhunen and K. Kirov and M. Komm and M. Lennholm and B. Lomanowski and C. Lowry and R. McDermott and A. Meigs and H. Reimerdes and H. Sun and B. Thomas and {et al.} and {JET Contributors} and {ASDEX Upgrade Team} and {EUROfusion Tokamak Exploitation Team}",

year = "2024",

month = jun,

doi = "10.1088/1741-4326/ad3970",

language = "English",

volume = "64",

journal = "Nuclear Fusion",

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Henderson, SS, Bernert, M, Brida, D, Cavedon, M, David, P, Dux, R, Février, O, Jacquet, P, Järvinen, A, Kallenbach, A, Karhunen, J, et al., JET Contributors, ASDEX Upgrade Team & EUROfusion Tokamak Exploitation Team 2024, 'Comparison of reduced model predictions for divertor detachment onset and reattachment timescales in ASDEX Upgrade and JET experiments', Nuclear Fusion, vol. 64, no. 6, 066006. https://doi.org/10.1088/1741-4326/ad3970

TY - JOUR

T1 - Comparison of reduced model predictions for divertor detachment onset and reattachment timescales in ASDEX Upgrade and JET experiments

AU - Henderson, S.S.

AU - Bernert, M.

AU - Brida, D.

AU - Cavedon, M.

AU - David, P.

AU - Dux, R.

AU - Février, O.

AU - Jacquet, P.

AU - Järvinen, Aaro

AU - Kallenbach, A.

AU - Karhunen, Juuso

AU - Kirov, K.

AU - Komm, M.

AU - Lennholm, M.

AU - Lomanowski, B.

AU - Lowry, C.

AU - McDermott, R.

AU - Meigs, A.

AU - Reimerdes, H.

AU - Sun, H.

AU - Thomas, B.

AU - et al.

AU - JET Contributors

AU - ASDEX Upgrade Team

AU - EUROfusion Tokamak Exploitation Team

PY - 2024/6

Y1 - 2024/6

N2 - Building on prior analysis of ASDEX Upgrade (AUG) experiments (Henderson et al 2023 Nucl. Fusion 63 086024), this study compares simple analytical formula predictions for divertor detachment onset and reattachment timescales in JET experiments. Detachment onset primarily scales with divertor neutral pressure, impurity concentration, power directed to the targets, machine size, and integral perpendicular power decay length. JET experiments, focusing on seeding mixtures of Ne and Ar, align with the detachment onset predictions. Radiation efficiencies among the impurities show good agreement with the model predictions, contrasting with AUG observations which suggested higher efficiency for Ar and lower efficiency for Ne. The time taken to re-ionise the neutral volume in front of the outer target in fully detached divertor conditions was measured following both abrupt increases in injected neutral beam power and, separately, cutting of the impurity gas flow. Re-ionisation of the neutrals occurs within approximately 1 s on JET, which aligns with the simple model prediction derived from AUG data. While the AUG results are not new, their comparison with the JET results enhances understanding, reinforcing confidence in using simple models to predict future reactor scenarios.

AB - Building on prior analysis of ASDEX Upgrade (AUG) experiments (Henderson et al 2023 Nucl. Fusion 63 086024), this study compares simple analytical formula predictions for divertor detachment onset and reattachment timescales in JET experiments. Detachment onset primarily scales with divertor neutral pressure, impurity concentration, power directed to the targets, machine size, and integral perpendicular power decay length. JET experiments, focusing on seeding mixtures of Ne and Ar, align with the detachment onset predictions. Radiation efficiencies among the impurities show good agreement with the model predictions, contrasting with AUG observations which suggested higher efficiency for Ar and lower efficiency for Ne. The time taken to re-ionise the neutral volume in front of the outer target in fully detached divertor conditions was measured following both abrupt increases in injected neutral beam power and, separately, cutting of the impurity gas flow. Re-ionisation of the neutrals occurs within approximately 1 s on JET, which aligns with the simple model prediction derived from AUG data. While the AUG results are not new, their comparison with the JET results enhances understanding, reinforcing confidence in using simple models to predict future reactor scenarios.

KW - ASDEX Upgrade

KW - divertor detachment

KW - divertor reattachment

KW - impurity seeding

KW - JET

KW - model validation

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U2 - 10.1088/1741-4326/ad3970

DO - 10.1088/1741-4326/ad3970

M3 - Article

AN - SCOPUS:85191253792

SN - 0029-5515

VL - 64

JO - Nuclear Fusion

JF - Nuclear Fusion

IS - 6

M1 - 066006

ER -

Comparison of reduced model predictions for divertor detachment onset and reattachment timescales in ASDEX Upgrade and JET experiments

Abstract

Funding

Keywords

UN SDGs

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