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@ARTICLE{Huber:852577,
      author       = {Huber, Alexander and Kinna, D. and Huber, V. and Arnoux, G.
                      and Sergienko, G. and Balboa, I. and Balorin, C. and Carman,
                      P. and Carvalho, P. and Collins, S. and Conway, N. and
                      McCullen, P. and Drenik, A. and Jachmich, S. and Jouve, M.
                      and Linsmeier, Ch. and Lomanowski, B. and Lomas, P. J. and
                      Lowry, C. G. and Maggi, C. F. and Matthews, G. F. and Meigs,
                      A. and Mertens, Ph. and Nunes, I. and Price, M. and Puglia,
                      P. and Riccardo, V. and Rimini, F. G. and Widdowson, A. and
                      Zastrow, K.-D.},
      title        = {{R}eal-time protection of the {JET} {ITER}-like wall based
                      on near infrared imaging diagnostic systems},
      journal      = {Nuclear fusion},
      volume       = {58},
      number       = {10},
      issn         = {1741-4326},
      address      = {Vienna},
      publisher    = {IAEA},
      reportid     = {FZJ-2018-05489},
      pages        = {106021 -},
      year         = {2018},
      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.},
      cin          = {IEK-4},
      ddc          = {530},
      cid          = {I:(DE-Juel1)IEK-4-20101013},
      pnm          = {174 - Plasma-Wall-Interaction (POF3-174)},
      pid          = {G:(DE-HGF)POF3-174},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000441292500001},
      doi          = {10.1088/1741-4326/aad481},
      url          = {https://juser.fz-juelich.de/record/852577},
}