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Pedestal origin and extrapolation of high-density small edge-localised-modes peak parallel energy fluence in ITER and SPARC

Year: 2026
Type: article
Abstract: Experimental analysis and simulations with the BOUT++ code show that small edge-localised modes (ELMs) in reactor-relevant high-density regimes originate in a region close to the separatrix and only marginally perturb the pedestal structure. The measured divertor peak parallel energy fluence ( ε ∥,peak ) for a database of small ELM scenarios in DIII-D and ASDEX Upgrade can be reproduced, within 40 % accuracy on average, if an ad hoc modification of the Eich peak parallel ELM energy fluence model is applied to account for the small ELM pedestal birth location. This allows for first-order extrapolation of small-ELM divertor ε ∥,peak to ITER and SPARC, resulting in values that satisfy the nominal melting threshold of tungsten monoblocks of 12 MJ m −2 . The findings reported in this study, both via modelling and direct measurements, constitute a step forward in assessing small ELMs in high edge-collisionality scenarios as a viable plasma regime for the operation of next-generation fusion machines.
DOI: 10.1017/s0022377826101433
Authors: Renato Perillo, Charles Lasnier, Jose Boedo, Thomas Eich, Zeyu Li, Andreas Redl, Filipp Khabanov, Claudio Marini, Adam McLean, Fenton Glass, Timo Ravensbergen, Rabel Rizkallah, Dmitry Rudakov, Peter Traverso, the DIII-D Team, the ASDEX Upgrade Team
Institutions: University of California San Diego, Lawrence Livermore National Laboratory, Commonwealth Fusion Systems (United States), General Atomics (United States), University of Wisconsin–Madison, ITER, Oak Ridge Associated Universities
Language: English
Open Access status: hybrid
Estimated APC paid: $3,550
Awards: G14554683, G2145270357, G222768804, G2285105350, TAS::89 0227::TAS RECOVERY ACT - DIII-D EDGE PHYSICS AND DISRUPTIONS, G2660421919, G333530719, DIII-D EDGE PHYSICS AND DISRUPTIONS, G3696093938, BEHAVIOR AND DYNAMICS OF MULTIFIELD TURBULENCE IN TOKAMAK PLASMAS, THE DIII-D NATIONAL FUSION PROGRAM AND ADVANCED FUSION TECHNOLOGY RESEARCH AND DEVELOPMENT, BEHAVIOR AND DYNAMICS OF MULTIFIELD TURBULENCE IN TOKAMAK PLASMAS, G574795485, BEHAVIOR AND DYNAMICS OF MULTIFIELD TURBULENCE IN TOKAMAK PLASMAS, THE DIII-D NATIONAL FUSION PROGRAM AND ADVANCED FUSION TECHNOLOGY RESEARCH AND DEVELOPMENT, TAS::89 0227::TAS RECOVERY ACT - DIII-D EDGE PHYSICS AND DISRUPTIONS, G7473577905, THE DIII-D FUSION RESEARCH PROGRAM AND ADVANCED FUSION TECHNOLOGY RESEARCH AND DEVELOPMENT
OpenAlex ID: W7143783027
FWCI: 2.976
Cites: 52
Cited by: 1
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