Abstract
This paper describes the extensive progress that has been made in the understanding of tokamak pedestal physics since the 2007 publication of ‘Progress in the ITER Physics Basis’ (Ikeda 2007 Nucl. Fusion 47 E01-S500). It serves as Chapter 3 of the 2025 Nuclear Fusion Special Issue titled ‘On the Path to Tokamak Burning Plasma Operation’ (Campbell et al 2025 Nucl. Fusion). This review was compiled by the pedestal and edge physics (PEP) community affiliated with the International Tokamak Physics Activity organization. It attempts to collect in one place citations to the majority of published literature on the pedestal physics topics that will be most important for the operation of a future power producing burning plasma tokamak. These include citations to publications describing the physics of the pedestal plasmas in many operating tokamaks worldwide and the pedestal physics projections for several near-term future devices including ITER. Descriptions of experimental results, interpretive modeling and predictive extrapolations are integrated together and comprehensive references are provided. This review is organized around four primary technical sections, viz.: pedestal structure, edge localized mode (ELM) characteristics, ELM control and regimes without large ELMs. Key results from many of the references are described briefly and set into the tokamak burning plasma power plant context. In addition, different perspectives on pedestal physics topics that are currently under debate within the community are also described, to provide guidance on needs for future research. Finally, attempts are made to describe conclusions from all of this progress consistent with discussions by the pedestal physics community at this time. The goal of this review is to provide a useful reference document for pedestal physics researchers going forward toward operation of a burning tokamak fusion plasma.
| Original language | English |
|---|---|
| Article number | 053001 |
| Journal | Nuclear Fusion |
| Volume | 65 |
| Issue number | 5 |
| DOIs | |
| State | Published - May 1 2025 |
Funding
The information, data, or work presented herein was funded in part as follows: MEF and XQX by LLNL under US DOE Contract No. DE-AC52-07NA27344. PBS, LRB, AW by US DOE Contract DE-AC05-000R22725. CPS and AON by Columbia University under Grant Nos. DE-SC0021968 and DE-SC0022270, JH by MIT under US DOE Award No. DE-SC0014264 and FML by North Carolina State University under US DOE Awards Nos. DE-SC0024523 and DE-SC0023400. JK by Fiat Lux under US DOE Contract No. DE-SC0024592. EV gratefully acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant Agreement No. 805162). The information, data, or work by TZ is funded in part by National Magnetic Confinement Fusion Science Program of China under Grant No. 2022YFE03050003 and by ZL under Contract No. 2019YFE03090200. LF is supported by Vetenskapsrådet, under Grant No. 2023-04895. EdlL was partly supported by the PID2021-127727OB-I00 Grant funded by the Spanish Ministry of Science, Innovation and Universities. US and BL were supported in part by the Swiss National Science Foundation. GYP was supported by R&D Programs of ‘High Performance Tokamak Plasma Research & Development (EN2501-16)’ and ‘High Performance Fusion Simulation R&D (EN2541-11)’ through the Korea Institute of Fusion Energy (KFE) funded by the Government funds, Republic of Korea. SS has been funded in part by the EPSRC Energy Programme [Grant Number EP/W006839/1]. Work by MD, EW, WS, BV, PTL, TH, AC, and MH 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—EUROfusion). 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. Neither the European Union nor the European Commission can be held responsible for them. The views and opinions expressed herein do not necessarily reflect those of the ITER Organization. The author team would like to acknowledge the tremendous effort and help of the Guest Editors in charge of this chapter, Amanda Hubbard and Wolfgang Suttrop, and the entire team of guest editors for this Nuclear Fusion Special Issue. The authors also gratefully acknowledge the many contributions of Yongkyoon In to the coordination and guidance of the project as deputy-chair and chair of the PEP group, and significant support of Hyeon-Myeong Jeong to manuscript editing. In addition, we would like to thank all of the experts of the ITPA Pedestal and Edge Physics (PEP) topical group who have participated in discussions of this manuscript at PEP and other meetings over the last 4 years for their valuable comments and suggestions. In particular many thanks to M. Faitsch, and many of the co-authors for their careful reading of the manuscript and for their very useful comments. Finally the PEP community would like to acknowledge the seminal contributions of the late Marc Beurskens to the field of pedestal physics, and in particular to the understanding of pedestal structure in tokamaks. His development of comprehensive profiles of pedestal parameters in JET contributed to significant advancements in understanding of the physics processes that set the structure of the pedestal. The progress on research and development (R&D) described in this chapter focuses in general on tokamak burning plasma regimes but includes some topics of relevance specifically to ITER. In some cases, the latter underlying physics R&D activities were motivated by specific features of the ITER 2016 staged approach baseline (see [953, 954] for details). The new ITER baseline 2024 currently under elaboration, as introduced in [955], proposes modifications to several of these features (e.g. first wall material, heating and current drive mix, etc) Consideration of these developments will certainly be part of the already anticipated additional R&D beyond that described in this chapter. The information, data, or work presented herein was funded in part as follows: MEF and XQX by LLNL under US DOE Contract No. DE-AC52-07NA27344. PBS, LRB, AW by US DOE Contract DE-AC05-000R22725. CPS and AON by Columbia University under Grant Nos. DE-SC0021968 and DE-SC0022270, JH by MIT under US DOE Award No. DE-SC0014264 and FML by North Carolina State University under US DOE Awards Nos. DE-SC0024523 and DE-SC0023400. JK by Fiat Lux under US DOE Contract No. DE-SC0024592. EV gratefully acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant Agreement No. 805162). The information, data, or work by TZ is funded in part by National Magnetic Confinement Fusion Science Program of China under Grant No. 2022YFE03050003 and by ZL under Contract No. 2019YFE03090200. LF is supported by Vetenskapsrådet, under Grant No. 2023-04895. EdlL was partly supported by the PID2021-127727OB-I00 Grant funded by the Spanish Ministry of Science, Innovation and Universities. US and BL were supported in part by the Swiss National Science Foundation. GYP was supported by R&D Programs of ‘High Performance Tokamak Plasma Research & Development (EN2501-16)’ and ‘High Performance Fusion Simulation R&D (EN2541-11)’ through the Korea Institute of Fusion Energy (KFE) funded by the Government funds, Republic of Korea. SS has been funded in part by the EPSRC Energy Programme [Grant Number EP/W006839/1]. Work by MD, EW, WS, BV, PTL, TH, AC, and MH 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—EUROfusion). 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. Neither the European Union nor the European Commission can be held responsible for them. The views and opinions expressed herein do not necessarily reflect those of the ITER Organization.
Keywords
- ELM characteristics
- ELM control
- burning plasma
- edge pedestal structure
- regimes without large ELMs
- tokamak