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

Henderson, S. S.; Bernert, M.; Brida, D.; Cavedon, M.; David, P.; Dux, R.; Février, O.; Jacquet, P.; Järvinen, Aaro; Kallenbach, A.; Karhunen, Juuso; Kirov, K.; Komm, Michael; Lennholm, M.; Lomanowski, Bart; Lowry, C.; McDermott, R.; Meigs, Andrew; Reimerdes, H.; Sun, H.; Thomas, B.

doi:10.1088/1741-4326/ad3970

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

Journal Article · Thu Apr 18 04:00:00 EDT 2024 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/ad3970· OSTI ID:2438745

^[1]; Bernert, M. ^[2]; ^[2]; ^[3]; ^[2]; Dux, R. ^[2]; ^[4]; Jacquet, P. ^[1]; ^[5]; ^[2]; Karhunen, Juuso ^[5]; Kirov, K. ^[1]; ^[6]; Lennholm, M. ^[1]; ^[7]; Lowry, C. ^[1]; ^[2]; Meigs, Andrew ^[1]; ^[4]; ^[1] more »

UK Atomic Energy Authority (UKAEA), Culham (United Kingdom)
Max Planck Institute for Plasma Physics, Garching (Germany)
University of Milan-Bicocca (Italy)
Ecole Polytechnique Federale Lausanne (EPFL) (Switzerland)
VTT Technical Research Centre of Finland (Finland)
Czech Academy of Sciences (CAS), Prague (Czech Republic). Institute of Plasma Physics
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Building on prior analysis of ASDEX Upgrade (AUG) experiments (Henderson et al 2023 Nucl. Fusion63 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.

View Accepted Manuscript (DOE)

Research Organization:: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Organization:: USDOE Office of Science (SC)

Contributing Organization:: EUROfusion Tokamak Exploitation; ASDEX Upgrade Team; JET Contributors

Grant/Contract Number:: AC05-00OR22725

OSTI ID:: 2438745

Journal Information:: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 6 Vol. 64; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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