Response of the imaging cameras to hard radiation during JET operation

• Published in: Fusion engineering and design 2017-11, Vol.123, p.669-673
• Main Authors: Huber, Alexander, Sergienko, Gennady, Kinna, David, Huber, Valentina, Milocco, Alberto, Mercadier, Laurent, Balboa, Itziar, Conroy, Sean, Cramp, Simon, Kiptily, Vasili, Kruezi, Uron, Lambertz, Horst Toni, Linsmeier, Christian, Matthews, Guy, Popovichev, Sergey, Mertens, Philippe, Silburn, Scott, Zastrow, Klaus-Dieter
• Format: Article
• Language: English
• Subjects: Camera; Camera cooling; CCd; Dark current; Digital cameras; Digital electronics; Digital imaging; Electronics; Fluence; Hot pixels; Ionizing radiation; Monte Carlo simulation; Neutrons; Nuclear power plants; Pixels; Radiation; Radiation damage; Sensors; Studies
• ISSN: 0920-3796; 1873-7196; 1873-7196
• DOI: 10.1016/j.fusengdes.2017.03.167

•The camera image sensors degrade with time mainly due to neutron radiation damage.•Cooling the sensor down to −20°C essentially reduced the effects of the radiation damage; no detectable degradation of the actively cooled sensors has been observed.•Uncooled cameras must be replaced once/year after neutron fluence ∼1.9–3.2×1012 n/cm2.•The generation of a significant amount of dynamic hot pixels was observed in the presence of hard radiation.•Failure of the electronics at fluence ∼2–4.0×109 n/cm2. The analysis of the radiation damage of imaging systems is based on all different types of analogue/digital cameras with uncooled as well as actively cooled image sensors in the VIS/NIR/MWIR spectral ranges. The Monte Carlo N-Particle (MCNP) code has been used to determine the neutron fluence at different camera locations in JET. An explicit link between the sensor damage and the neutron fluence has been observed. Sensors show an increased dark-current and increased numbers of hot-pixels. Uncooled cameras must be replaced once per year after exposure to a neutron fluence of ∼1.9–3.2×1012neutrons/cm2. Such levels of fluence will be reached after ≈14-22 ELMy H-mode pulses during the future D-T campaign. Furthermore, dynamical noise seen as a random pattern of bright pixels was observed in the presence of hard radiation (neutrons and gammas). Failure of the digital electronics inside the cameras as well as of industrial controllers is observed beyond a neutron fluence of about ∼4×109 neutrons/cm2. The impact of hard radiation on the different types of electronics and possible application of cameras during future D-T campaign is discussed.