Runaway electron beam generation and mitigation during disruptions at JET-ILW

Reux, C.; Plyusnin, Victor F.; Alper, B.; Alves, D.; Базылев, Б.; Belonohy, É.; Boboc, A.; Brezinsek, S.; Coffey, I.; Decker, J.; Drewelow, P.; Devaux, S.; Vries, P. C. de; Fil, A.; Gerasimov, S.; Giacomelli, L.; Jachmich, S.; Khilkevitch, E.; Kiptily, V.; Kosłowski, R.; Kruezi, U.; Lehnen, M.; Lupelli, I.; Lomas, P. J.; Manzanares, A.; Aguilera, A. Martín de; Matthews, G. F.; Mlynář, J.; Nardon, E.; Nilsson, Emelie; Thun, C. Perez von; Riccardo, V.; Saint‐Laurent, F.; Shevelev, A.; Sips, G.; Sozzi, C.; Contributors, Jet

doi:10.1088/0029-5515/55/9/093013

Cited by 114 publications

(137 citation statements)

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“…This I p reduction is imputable to the very large post-TQ plasma resistance [8] and induces a toroidal driving electric field. At the end of the CQ, disruptive runaway beams may be observed via a slowly decaying I p which correlates with different radiation measurements such as: synchrotron, soft and hard X-rays, gamma and neutron emissions [2,9]. The disruption runaway phase, which is not systematically seen in experiments, is known as runaway plateau [2,9] and can last up to few hundreds of milliseconds.…”

Section: Introductionmentioning

confidence: 92%

“…In tokamak plasmas, fast electrons are said to run away when collision effects are not capable to compensate the electron acceleration induced by a driving electric field [4]. Highly energetic runaway electron (RE) beams are sometimes experimentally observed during plasma disruptions with possible harmful consequences for the reactor first wall [2]. Indeed, a plasma facing component (PFC) struck by RE might suffer damages due to the deposition of high heat loads [2].…”

Section: Introductionmentioning

confidence: 99%

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Electron acceleration in a JET disruption simulation

et al. 2018

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Runaways are suprathermal electrons having sufficiently high energy to be continuously accelerated up to tens of MeV by a driving electric field [1]. Highly energetic runaway electron (RE) beams capable of damaging the tokamak first wall can be observed after a plasma disruption [2]. Therefore, it is of primary importance to fully understand their generation mechanisms in order to design mitigation systems able to guarantee safe tokamak operations. In a previous work, [3], a test particle tracker was introduced in the JOREK 3D non-linear MHD code and used for studying the electron confinement during a simulated JET-like disruption. It was found in [3] that relativistic electrons are not completely deconfined by the stochastic magnetic field taking place during the disruption thermal quench (TQ). This is due to the reformation of closed magnetic surfaces at the beginning of the current quench (CQ). This result was obtained neglecting the inductive electric field in order to avoid the unrealistic particle acceleration which otherwise would have happened due to the absence of collision effects. The present paper extends [3] analysing test electron dynamics in the same simulated JET-like disruption using the complete electric field. For doing so, a simplified collision model is introduced in the particle tracker guiding center equations. We show that electrons at thermal energies can become RE during or promptly after the TQ due to a combination of three phenomena: a first REs acceleration during the TQ due to the presence of a complex MHD-induced electric field, particle reconfinement caused by the fast reformation of closed magnetic surfaces after the TQ and a secondary acceleration induced by the CQ electric field.

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Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Electron acceleration in a JET disruption simulation

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“…Another topic on which progress remains to be done is RE suppression. For example, recent results on JET 15 suggest that MGI may prevent REs only if the gas reaches the plasma before the formation of a runaway beam. This seems inconsistent with a strategy based on two successive material (gas or pellets) injections, the first one to mitigate the thermal loads and the second one to suppress REs, as is envisaged for ITER.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional non-linear magnetohydrodynamic modeling of massive gas injection triggered disruptions in JET

et al. 2015

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Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication Citation for published version (APA):Fil, A., Nardon, E., Hoelzl, M., Huijsmans, G. T. A., Orain, F., Becoulet, M., ... . Threedimensional non-linear magnetohydrodynamic modeling of massive gas injection triggered disruptions in JET. Physics of Plasmas, 22, 062509-1/18. DOI: 10.1063/1.4922846 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Three-dimensional non-linear magnetohydrodynamic modeling of massive gas injection triggered disruptions in JET JOREK 3D non-linear MHD simulations of a D 2 Massive Gas Injection (MGI) triggered disruption in JET are presented and compared in detail to experimental data. The MGI creates an overdensity that rapidly expands in the direction parallel to the magnetic field. It also causes the growth of magnetic islands (m=n ¼ 2=1 and 3/2 mainly) and seeds the 1/1 internal kink mode. O-points of all island chains (including 1/1) are located in front of the MGI, consistently with experimental observations. A burst of MHD activity and a peak in plasma current take place at the same time as in the experiment. However, the magnitude of these two effects is much smaller than in the experiment. The simulated radiation is also much below the experimental level. As a consequence, the thermal quench is not fully reproduced. Directions for progress are identified. Radiation from impurities is a good candidate. V C 2015 AIP Publishing LLC.[http://dx

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“…To provide energy distributions of fast electrons and ions in tokamak plasmas based on gamma-ray measurements, a spectrum deconvolution code DeGaSum has been developed at the Ioffe Institute [67]. The code was applied to get the energy distributions of runaway electrons in experiments at FT-2 [68,69], TUMAN-3M [70], JET [71] and ASDEX-Upgrade [72]. Examples of a hard x-ray spectrum recorded during an Ohmic TUMAN-3M discharge and the runaway electron distribution function reconstructed with the DeGaSum code are shown in figure 22.…”

Section: 1npa and Grsmentioning

confidence: 99%

Tokamak research at the Ioffe Institute

et al. 2019

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Recent research at three small tokamaks with different parameters located at the Ioffe Institute-the spherical tokamak Globus-M, the large aspect ratio tokamak FT-2 and the compact tokamak TUMAN-3M-are reviewed. This overview covers energy confinement (Globus-M and FT-2), L-H transition (TUMAN-3M and FT-2), Alfvén waves (Globus-M and TUMAN-3M), ion cyclotron emission (TUMAN-3M), major plasma discharge disruption (Globus-M) and scrape-off layer (Globus-M) studies. A full-f global gyrokinetic modeling benchmark using synthetic diagnostics in FT-2 is described. Anomalous absorption and emission in electron cyclotron resonance heating experiments due to the parametric excitation of localized upper hybrid waves are analyzed theoretically. Progress in the development of the neutral particle analysis, gamma-ray spectrometry and divertor Thomson scattering combined with laser-induced fluorescence diagnostics for ITER is discussed. The status of the new Globus-M2 spherical tokamak is reported.

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Runaway electron beam generation and mitigation during disruptions at JET-ILW

Cited by 114 publications

References 49 publications

Electron acceleration in a JET disruption simulation

Electron acceleration in a JET disruption simulation

Three-dimensional non-linear magnetohydrodynamic modeling of massive gas injection triggered disruptions in JET

Tokamak research at the Ioffe Institute

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