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

COMPASS team, TCV team, ASDEX-Upgrade team, EUROFusion MST Team, JET Contributors

Research output: Contribution to journalReview articlepeer-review

18 Scopus citations

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
StatePublished - Jan 2018
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2017 Instituto Superior Tecnico.

Funding

This work has been carried out within the framework of the EUROFusion Consortium and has received funding from the EURATOM research and training programme 2014– 2018 under grant agreement No 633053. IST activities also received financial support from “Fundação para a Ciência e Tecnologia” through project UID/FIS/50010/2013. A.E. Shevelev and E.M. Khilkevitch are grateful for financial support from the Ministry of Education and Science of the Russian Federation (Agreement No.14.619.21.0001, 15.08.2014, id RFMEFI61914X0001). The experiments on COMPASS were supported by the MEYS CR project No. LM2015045. The views and opinions expressed herein do not necessarily reflect those of the European Commission.

FundersFunder number
Horizon 2020 Framework Programme
Euratom Research and Training Programme633053
Ministerstvo Školství, Mládeže a TělovýchovyLM2015045
Fundação para a Ciência e a TecnologiaUID/FIS/50010/2013
Ministry of Education and Science of the Russian Federation15.08.2014, 14.619.21.0001

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