| 1. |
- Joffrin, E., et al.
(författare)
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Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall
- 2019
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Forskningsöversikt (refereegranskat)abstract
- For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D-T mixtures since 1997 and the first ever D-T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D-T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D-T preparation. This intense preparation includes the review of the physics basis for the D-T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D-T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfven eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D-T campaign provides an incomparable source of information and a basis for the future D-T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.
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| 2. |
- Murari, A., et al.
(författare)
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A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
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Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
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| 3. |
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Overview of the JET results
- 2015
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 55:10
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Tidskriftsartikel (refereegranskat)
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| 4. |
- Bombarda, F., et al.
(författare)
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Runaway electron beam control
- 2019
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 1361-6587 .- 0741-3335. ; 61:1
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Krasilnikov, A., et al.
(författare)
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Evidence of 9 Be + p nuclear reactions during 2ω CH and hydrogen minority ICRH in JET-ILW hydrogen and deuterium plasmas
- 2018
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 58:2
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Tidskriftsartikel (refereegranskat)abstract
- The intensity of 9Be + p nuclear fusion reactions was experimentally studied during second harmonic (2ω CH) ion-cyclotron resonance heating (ICRH) and further analyzed during fundamental hydrogen minority ICRH of JET-ILW hydrogen and deuterium plasmas. In relatively low-density plasmas with a high ICRH power, a population of fast H+ ions was created and measured by neutral particle analyzers. Primary and secondary nuclear reaction products, due to 9Be + p interaction, were observed with fast ion loss detectors, γ-ray spectrometers and neutron flux monitors and spectrometers. The possibility of using 9Be(p, d)2α and 9Be(p, α)6Li nuclear reactions to create a population of fast alpha particles and study their behaviour in non-active stage of ITER operation is discussed in the paper.
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| 6. |
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- 2018
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 58:1
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Forskningsöversikt (refereegranskat)
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- 2018
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 58:9
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Tidskriftsartikel (refereegranskat)
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| 32. |
- Voitsekhovitch, I., et al.
(författare)
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Recent EUROfusion Achievements in Support of Computationally Demanding Multiscale Fusion Physics Simulations and Integrated Modeling
- 2018
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Ingår i: Fusion Science and Technology. - : Informa UK Limited. - 1536-1055 .- 1943-7641. ; 74:3, s. 186-197
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Tidskriftsartikel (refereegranskat)abstract
- © 2018, © 2018 The Authors. Published with license by Taylor & Francis Group, LLC. Integrated modeling (IM) of present experiments and future tokamak reactors requires the provision of computational resources and numerical tools capable of simulating multiscale spatial phenomena as well as fast transient events and relatively slow plasma evolution within a reasonably short computational time. Recent progress in the implementation of the new computational resources for fusion applications in Europe based on modern supercomputer technologies (supercomputer MARCONI-FUSION), in the optimization and speedup of the EU fusion-related first-principle codes, and in the development of a basis for physics codes/modules integration into a centrally maintained suite of IM tools achieved within the EUROfusion Consortium is presented. Physics phenomena that can now be reasonably modelled in various areas (core turbulence and magnetic reconnection, edge and scrape-off layer physics, radio-frequency heating and current drive, magnetohydrodynamic model, reflectometry simulations) following successful code optimizations and parallelization are briefly described. Development activities in support to IM are summarized. They include support to (1) the local deployment of the IM infrastructure and access to experimental data at various host sites, (2) the management of releases for sophisticated IM workflows involving a large number of components, and (3) the performance optimization of complex IM workflows.
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| 33. |
- Litaudon, X., et al.
(författare)
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EUROfusion-theory and advanced simulation coordination (E-TASC): programme and the role of high performance computing
- 2022
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 1361-6587 .- 0741-3335. ; 64:3
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Tidskriftsartikel (refereegranskat)abstract
- This paper is a written summary of an overview oral presentation given at the 1st Spanish Fusion High Performance Computer (HPC) Workshop that took place on the 27 November 2020 as an online event. Given that over the next few years ITER24 will move to its operation phase and the European-DEMO design will be significantly advanced, the EUROfusion consortium has initiated a coordination effort in theory and advanced simulation to address some of the challenges of the fusion research in Horizon EUROPE (2021-2027), i.e. the next EU Framework Programme for Research and Technological Development. This initiative has been called E-TASC, which stands for EUROfusion-Theory and Advanced Simulation Coordination. The general and guiding principles of E-TASC are summarized in this paper. In addition, an overview of the scientific results obtained in the pilot phase (2019-2020) of E-TASC are provided while highlighting the importance of the required progress in computational methods and HPC techniques. In the initial phase, five pilot theory and simulation tasks were initiated: towards a validated predictive capability of the low to high transition and pedestal physics; runaway electrons in tokamak disruptions in the presence of massive material injection; fast code for the calculation of neoclassical toroidal viscosity in stellarators and tokamaks; development of a neutral gas kinetics modular code; European edge and boundary code for reactor-relevant devices. In this paper, we report on recent progress made by each of these projects.
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| 34. |
- Lönnroth, J. -S, et al.
(författare)
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Integrated ELM modelling
- 2006
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Ingår i: Contributions to Plasma Physics. - : Wiley. - 0863-1042 .- 1521-3986. ; 46:7-9, s. 726-738
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a short overview of current trends and progress in integrated ELM modelling. First, the concept of integrated ELM modelling is introduced, various interpretations of it are given and the need for it is discussed. Then follows an overview of different techniques and methods used in integrated ELM modelling presented roughly according to physics approached in use and in order of increasing complexity. The paper concludes with a short discussion of open issues and future modelling requirements within the field of integrated ELM modelling.
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| 38. |
- Horacek, J., et al.
(författare)
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ELM temperature in JET and COMPASS tokamak divertors
- 2023
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 63:5, s. 056007-
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Tidskriftsartikel (refereegranskat)abstract
- Analysis of the divertor edge localized mode (ELM) electron temperature at a uniquely high temporal resolution (10(-5) s) was reported at the JET tokamak (Guillemaut et al 2018 Nucl. Fusion 58 066006). By collecting divertor probe data obtained during many dozens of ELMs, the conditional-average (CAV) technique yields surprisingly low peak electron temperatures, far below the pedestal ones (70%-99% reduction!) which we, however, question. This result was interpreted through the collisional free-streaming kinetic model of ELMs, by a transfer of most of the electron energy to ions, implying a high tungsten sputtering for unmitigated ELMs in future fusion devices like ITER. Recently, direct microsecond temperature measurements on the COMPASS tokamak, however, showed that the electron temperature peak of ELM filaments measured in the divertor is reduced by less than a third with respect to the pedestal one. This was further confirmed by a dedicated 1D particle-in-cell (PIC) simulation and tends to prove that the pedestal electrons can transfer only their parallel energy to ions (due to low collisionality), thus less than a third, as is predicted by the collisionless free-streaming model. This finding strongly contradicts the JET observations. We have therefore compared the CAV to the direct (microsecond) ball-pen and Langmuir probes measurements in COMPASS and found very good agreement between them. Revisiting the aforementioned JET CAV analysis indeed shows that the electron temperatures are much higher than previously reported, close to those predicted by the PIC simulation, and thus the ion energy seems to not significantly increase in the scrape-off layer.
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| 39. |
- Krlin, L., et al.
(författare)
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Anomalous impurity diffusion in models of tokamak edge plasma turbulence
- 2004
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Ingår i: Czechoslovak Journal of Physics. - 0011-4626 .- 1572-9486. ; 54:1-3, s. 157-163
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Tidskriftsartikel (refereegranskat)abstract
- Using a simple spatially periodical and stationary potential as a model of electrostatic tokamak edge plasma turbulence, we have found recently [1, 2] an anomalous impurity diffusion in this regime. In this contribution, we estimate this diffusion for a more general and realistic form of the potential, which is close to the Hasegawa-Wakatani (HW) potential. As an interesting consequence of the discussed dynamics, we present, possibility of radial electric field generation in the edge turbulence regime. This effect. might play a role in tokamak scenarios with transport barriers.
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| 40. |
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| 41. |
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| 42. |
- Panek, R., et al.
(författare)
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Anomalous ion diffusion and radial-electric-field generation in a turbulent edge plasma potential weakly correlated in time and space
- 2005
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Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; 72:4, s. 327-332
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Tidskriftsartikel (refereegranskat)abstract
- Using a simple model of tokamak-edge-plasma turbulence in the form of a spatially periodic and time-independent electrostatic potential, we have found recently a new type of anomalous impurity diffusion in this regime [1], [2]. In the present contribution, we estimate this diffusion in the test-particle approach for a real turbulent potential obtained in an experiment. A significant difference in the impurity dynannics between the Hamiltonian and drift approaches is observed. As an interesting consequence of these dynamics, the possibility of radial-electric-field generation in the turbulence regimes appears. This effect can be of importance in scenarios related to transport barriers.
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| 43. |
- Williams, Jeremy J., et al.
(författare)
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Understanding the Impact of openPMD on BIT1, a Particle-in-Cell Monte Carlo Code, through Instrumentation, Monitoring, and In-Situ Analysis
- 2024
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Ingår i: Euro-Par 2024: Parallel Processing Workshops: Euro-Par 2024 International Workshops, August 26–30, Madrid, Spain.
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Konferensbidrag (refereegranskat)abstract
- Particle-in-Cell Monte Carlo simulations on large-scale systems play a fundamental role in understanding the complexities of plasma dynamics in fusion devices. Efficient handling and analysis of vast datasets are essential for advancing these simulations. Previously, we addressed this challenge by integrating openPMD with BIT1, a Particle-in-Cell Monte Carlo code, streamlining data streaming and storage. This integration not only enhanced data management but also improved write throughput and storage efficiency. In this work, we delve deeper into the impact of BIT1 openPMD BP4 instrumentation, monitoring, and in-situ analysis. Utilizing cutting-edge profiling and monitoring tools such as gprof, CrayPat, Cray Apprentice2, IPM, and Darshan, we dissect BIT1's performance post-integration, shedding light on computation, communication, and I/O operations. Fine-grained instrumentation offers insights into BIT1's runtime behavior, while immediate monitoring aids in understanding system dynamics and resource utilization patterns, facilitating proactive performance optimization. Advanced visualization techniques further enrich our understanding, enabling the optimization of BIT1 simulation workflows aimed at controlling plasma-material interfaces with improved data analysis and visualization at every checkpoint without causing any interruption to the simulation.
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