Real-time protection of the JET ITER-like wall based on near infrared imaging diagnostic systems

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en Huber, A. Kinna, D. Huber, V. Arnoux, G. Sergienko, G. Balboa, I. Balorin, C. Carman, P. Carvalho, P. Collins, S. Conway, N. McCullen, P. Drenik, A. Jachmich, S. Jouve, M. Linsmeier, Ch Lomanowski, B. Lomas, P. J. Lowry, C. G. Maggi, C. F. Matthews, G. F. Meigs, A. Mertens, Ph Nunes, I. Price, M. Puglia, P. Riccardo, V. Rimini, F. G. Widdowson, A. Zastrow, K. D. 2018-12-10T10:31:48Z 2018-12-10T10:31:48Z 2018-08-09
dc.identifier.citation Huber , A , Kinna , D , Huber , V , Arnoux , G , Sergienko , G , Balboa , I , Balorin , C , Carman , P , Carvalho , P , Collins , S , Conway , N , McCullen , P , Drenik , A , Jachmich , S , Jouve , M , Linsmeier , C , Lomanowski , B , Lomas , P J , Lowry , C G , Maggi , C F , Matthews , G F , Meigs , A , Mertens , P , Nunes , I , Price , M , Puglia , P , Riccardo , V , Rimini , F G , Widdowson , A & Zastrow , K D 2018 , ' Real-time protection of the JET ITER-like wall based on near infrared imaging diagnostic systems ' Nuclear Fusion , vol. 58 , no. 10 , 106021 . DOI: 10.1088/1741-4326/aad481 en
dc.identifier.issn 0029-5515
dc.identifier.issn 1741-4326
dc.identifier.other PURE UUID: dc5ff929-7658-4960-b381-dc916751ff5a
dc.identifier.other PURE ITEMURL:
dc.identifier.other PURE LINK:
dc.description | openaire: EC/H2020/633053/EU//EUROfusion
dc.description.abstract In JET with ITER-like wall (JET-ILW), the first wall was changed to metallic materials (tungsten and beryllium) [1] which require a reliable protection system to avoid damage of the plasma-facing components (PFCs) due to beryllium melting or cracking of tungsten owing to thermal fatigue. To address this issue, a protection system with real time control, based on imaging diagnostics, has been implemented on JET-ILW in 2011. This paper describes the design, implementation, and operation of the near infrared imaging diagnostic system of the JET-ILW plasma experiment and its integration into the existing JET-ILW protection architecture. The imaging system comprises eleven analogue CCD cameras which demonstrate a high robustness against changes of system parameters like the emissivity. The system covers about two thirds of the main chamber wall and almost half of the divertor. A real-time imaging processing unit is used to convert the raw data into surface temperatures taking into account the different emissivity for the various materials and correcting for artefacts resulting e.g. from neutron impact. Regions of interest (ROI) on the selected PFCs are analysed in real time and the maximum temperature measured for each ROI is sent to other real time systems to trigger an appropriate response of the plasma control system, depending on the location of a hot spot. A hot spot validation algorithm was successfully integrated into the real-time system and is now used to avoid false alarms caused by neutrons and dust. The design choices made for the video imaging system, the implications for the hardware components and the calibration procedure are discussed. It will be demonstrated that the video imaging protection system can work properly under harsh electromagnetic conditions as well as under neutron and gamma radiation. Examples will be shown of instances of hot spot detection that abort the plasma discharge. The limits of the protection system and the associated constraints on plasma operation are also presented. The real-time protection system has been operating routinely since 2011. During this period, less than 0.5% of the terminated discharges were aborted by a malfunction of the system. About 2%-3% of the discharges were terminated due to the detection of actual hot spots. en
dc.language.iso en en
dc.relation info:eu-repo/grantAgreement/EC/H2020/633053/EU//EUROfusion
dc.relation.ispartofseries Nuclear Fusion en
dc.relation.ispartofseries Volume 58, issue 10 en
dc.rights restrictedAccess en
dc.subject.other Nuclear and High Energy Physics en
dc.subject.other Condensed Matter Physics en
dc.subject.other 114 Physical sciences en
dc.title Real-time protection of the JET ITER-like wall based on near infrared imaging diagnostic systems en
dc.type A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä fi
dc.description.version Peer reviewed en
dc.contributor.department Forschungszentrum Jülich
dc.contributor.department JET
dc.contributor.department CEA
dc.contributor.department University of Lisbon
dc.contributor.department Max-Planck-Institut für Plasmaphysik
dc.contributor.department Koninklijke Militaire School - Ecole Royale Militaire
dc.contributor.department Department of Applied Physics
dc.contributor.department European Commission
dc.contributor.department EPFL Valais Wallis
dc.subject.keyword hot spots
dc.subject.keyword image processing
dc.subject.keyword imaging diagnostics
dc.subject.keyword JUVIL software
dc.subject.keyword real-time protection system
dc.subject.keyword Nuclear and High Energy Physics
dc.subject.keyword Condensed Matter Physics
dc.subject.keyword 114 Physical sciences
dc.identifier.urn URN:NBN:fi:aalto-201812106312
dc.identifier.doi 10.1088/1741-4326/aad481

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