title: A protection system for the JET ITER-like wall based on imaging             diagnostics.
abstract: The new JET ITER-like wall (made of beryllium and tungsten) is more fragile than             the former carbon fiber composite wall and requires active protection to prevent             excessive heat loads on the plasma facing components (PFC). Analog CCD cameras operating             in the near infrared wavelength are used to measure surface temperature of the PFCs.             Region of interest (ROI) analysis is performed in real time and the maximum temperature             measured in each ROI is sent to the vessel thermal map. The protection of the ITER-like             wall system started in October 2011 and has already successfully led to a safe landing             of the plasma when hot spots were observed on the Be main chamber PFCs. Divertor             protection is more of a challenge due to dust deposits that often generate false hot             spots. In this contribution we describe the camera, data capture and real time             processing systems. We discuss the calibration strategy for the temperature measurements             with cross validation with thermal IR cameras and bi-color pyrometers. Most importantly,             we demonstrate that a protection system based on CCD cameras can work and show examples             of hot spot detections that stop the plasma pulse. The limits of such a design and the             associated constraints on the operations are also presented.
authors.affiliation: Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon, United Kingdom.
authors.forename: G
authors.initials: G
authors.lastname: Arnoux
authors.forename: S
authors.initials: S
authors.lastname: Devaux
authors.forename: D
authors.initials: D
authors.lastname: Alves
authors.forename: I
authors.initials: I
authors.lastname: Balboa
authors.forename: C
authors.initials: C
authors.lastname: Balorin
authors.forename: N
authors.initials: N
authors.lastname: Balshaw
authors.forename: M
authors.initials: M
authors.lastname: Beldishevski
authors.forename: P
authors.initials: P
authors.lastname: Carvalho
authors.forename: M
authors.initials: M
authors.lastname: Clever
authors.forename: S
authors.initials: S
authors.lastname: Cramp
authors.forename: J-L
authors.initials: JL
authors.lastname: de Pablos
authors.forename: E
authors.initials: E
authors.lastname: de la Cal
authors.forename: D
authors.initials: D
authors.lastname: Falie
authors.forename: P
authors.initials: P
authors.lastname: Garcia-Sanchez
authors.forename: R
authors.initials: R
authors.lastname: Felton
authors.forename: V
authors.initials: V
authors.lastname: Gervaise
authors.forename: A
authors.initials: A
authors.lastname: Goodyear
authors.forename: A
authors.initials: A
authors.lastname: Horton
authors.forename: S
authors.initials: S
authors.lastname: Jachmich
authors.forename: A
authors.initials: A
authors.lastname: Huber
authors.forename: M
authors.initials: M
authors.lastname: Jouve
authors.forename: D
authors.initials: D
authors.lastname: Kinna
authors.forename: U
authors.initials: U
authors.lastname: Kruezi
authors.forename: A
authors.initials: A
authors.lastname: Manzanares
authors.forename: V
authors.initials: V
authors.lastname: Martin
authors.forename: P
authors.initials: P
authors.lastname: McCullen
authors.forename: V
authors.initials: V
authors.lastname: Moncada
authors.forename: K
authors.initials: K
authors.lastname: Obrejan
authors.forename: K
authors.initials: K
authors.lastname: Patel
authors.forename: P J
authors.initials: PJ
authors.lastname: Lomas
authors.forename: A
authors.initials: A
authors.lastname: Neto
authors.forename: F
authors.initials: F
authors.lastname: Rimini
authors.forename: C
authors.initials: C
authors.lastname: Ruset
authors.forename: B
authors.initials: B
authors.lastname: Schweer
authors.forename: G
authors.initials: G
authors.lastname: Sergienko
authors.forename: B
authors.initials: B
authors.lastname: Sieglin
authors.forename: A
authors.initials: A
authors.lastname: Soleto
authors.forename: M
authors.initials: M
authors.lastname: Stamp
authors.forename: A
authors.initials: A
authors.lastname: Stephen
authors.forename: P D
authors.initials: PD
authors.lastname: Thomas
authors.forename: D F
authors.initials: DF
authors.lastname: Valcárcel
authors.forename: J
authors.initials: J
authors.lastname: Williams
authors.forename: J
authors.initials: J
authors.lastname: Wilson
authors.forename: K-D
authors.initials: KD
authors.lastname: Zastrow