Comparison of runaway electron generation parameters in small, medium-sized and large tokamaks - A survey of experiments in COMPASS, TCV, ASDEX-Upgrade and JET

V.V. Plyusnin (Corresponding Author), C. Reux, V.G. Kiptily, G. Pautasso, J. Decker, G. Papp, A. Kallenbach, V. Weinzettl, J. Mlynar, S. Coda, V. Riccardo, P. Lomas, S. Jachmich, A. E. Shevelev, B. Alper, E. Khilkevitch, Y. Martin, R. Dux, C. Fuchs, B. DuvalM. Brix, G. Tardini, M. Maraschek, W. Treutterer, L. Giannone, A. Mlynek, O. Ficker, P. Martin, S. Gerasimov, S. Potzel, R. Paprok, P.J. McCarthy, U. Kruezi, Antti Hakola, Leena Aho-Mantila, Juuso Karhunen, Antti Salmi, Tuomas Tala, Markus Airila, Seppo Koivuranta, Jari Likonen, Paula Sirén, , , ASDEX Upgrade Team, EUROfusion MST1 Team, JET Contributors

    Research output: Contribution to journalReview Articlepeer-review

    18 Citations (Scopus)

    Abstract

    This paper presents a survey of the experiments on runaway electrons (RE) carried out recently in frames of EUROFusion Consortium in different tokamaks: COMPASS, ASDEX-Upgrade, TCV and JET. Massive gas injection (MGI) has been used in different scenarios for RE generation in small and medium-sized tokamaks to elaborate the most efficient and reliable ones for future RE experiments. New data on RE generated at disruptions in COMPASS and ASDEX-Upgrade was collected and added to the JET database. Different accessible parameters of disruptions, such as current quench rate, conversion rate of plasma current into runaways, etc have been analysed for each tokamak and compared to JET data. It was shown, that tokamaks with larger geometrical sizes provide the wider limits for spatial and temporal variation of plasma parameters during disruptions, thus extending the parameter space for RE generation. The second part of experiments was dedicated to study of RE generation in stationary discharges in COMPASS, TCV and JET. Injection of Ne/Ar have been used to mock-up the JET MGI runaway suppression experiments. Secondary RE avalanching was identified and quantified for the first time in the TCV tokamak in RE generating discharges after massive Ne injection. Simulations of the primary RE generation and secondary avalanching dynamics in stationary discharges has demonstrated that RE current fraction created via avalanching could achieve up to 70-75% of the total plasma current in TCV. Relaxations which are reminiscent the phenomena associated to the kinetic instability driven by RE have been detected in RE discharges in TCV. Macroscopic parameters of RE dominating discharges in TCV before and after onset of the instability fit well to the empirical instability criterion, which was established in the early tokamaks and examined by results of recent numerical simulations.

    Original languageEnglish
    Article number016014
    JournalNuclear Fusion
    Volume58
    Issue number1
    DOIs
    Publication statusPublished - Jan 2018
    MoE publication typeA2 Review article in a scientific journal

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