Impact of the plasma boundary on machine operation and the risk mitigation strategy on JET

Abstract This work examines the separatrix and Scrape-off-Layer (SOL) characteristics in three scenarios on JET: the Quasi-Continuous Exhaust (QCE) regime, the ITER Baseline scenario, and the X-point Radiator (XPR) regime. All three scenarios are potentially compatible with reactor operations, as they aim to provide power exhaust solutions through different approaches. The QCE regime is distinguished by its generally higher separatrix and SOL collisionality, associating with broader SOL width. These features, combined with the near-double-null (DNX) configuration, introduce several operational challenges on JET. The resulting broader SOL interacts with fast Beam neutrals, contributing to an unfavorable power load on local limiter. The heat load on the Upper Dump Plate Tiles in the QCE regime can be up to 5–6 times higher compared to the other scenarios. Additionally, the energy distribution shows a pronounced inner-outer asymmetry in QCE pulses, with the energy deposited on the outer limiter being up to four times higher than on the inner limiter. However, through careful operational planning and robust real-time protection system, the power loads were effectively managed within acceptable limits during QCE pulses, enabling successful scientific outcomes. As a result, the QCE regime serves as a case study to illustrate the critical need for integrating physics understanding, risk identification, operational strategies, and robust real-time protection to successfully implement new scenarios for fusion devices.

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Publication Details

Journal
Nuclear Fusion
Published
2025-05-20
DOI
https://doi.org/10.1088/1741-4326/addad7
Citations
1
Primary Topic
Fusion materials and technologies
Type
article
Field-Weighted Citation Impact
0.52

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Impact of the plasma boundary on machine operation and the risk mitigation strategy on JET

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Impact of the plasma boundary on machine operation and the risk mitigation strategy on JET

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article en
1 citations

Abstract

Abstract This work examines the separatrix and Scrape-off-Layer (SOL) characteristics in three scenarios on JET: the Quasi-Continuous Exhaust (QCE) regime, the ITER Baseline scenario, and the X-point Radiator (XPR) regime. All three scenarios are potentially compatible with reactor operations, as they aim to provide power exhaust solutions through different approaches. The QCE regime is distinguished by its generally higher separatrix and SOL collisionality, associating with broader SOL width. These features, combined with the near-double-null (DNX) configuration, introduce several operational challenges on JET. The resulting broader SOL interacts with fast Beam neutrals, contributing to an unfavorable power load on local limiter. The heat load on the Upper Dump Plate Tiles in the QCE regime can be up to 5–6 times higher compared to the other scenarios. Additionally, the energy distribution shows a pronounced inner-outer asymmetry in QCE pulses, with the energy deposited on the outer limiter being up to four times higher than on the inner limiter. However, through careful operational planning and robust real-time protection system, the power loads were effectively managed within acceptable limits during QCE pulses, enabling successful scientific outcomes. As a result, the QCE regime serves as a case study to illustrate the critical need for integrating physics understanding, risk identification, operational strategies, and robust real-time protection to successfully implement new scenarios for fusion devices.

Nuclear FusionVol. 65(7)
ITER (FR), National Agency for New Technologies, Energy and Sustainable Economic Development (IT), University of Padua (IT), Max Planck Institute for Plasma Physics (DE), Institute for the Science and Technology of Plasmas (IT), Universidad de Sevilla (ES)
Research Councils UK, Euratom Research and Training Programme
Openalex Percentile: Top 38%
Fusion materials and technologies
0.52
DOIOpen Access PDFOpenAlex
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