Installation of the JET ITER-Like Wall (ILW)has brought on the need of a reliable protection system as too high a temperature of the plasma facing components (PFCs) can result in beryllium (Be) melting or thermal fatigue of tungsten (W). A proper temperature measurement relies on the knowledge of three different parameters of equal importance: the sensitivity of the camera sensor, the transmission factor of the optics used and the emissivity of the monitored PFCs. In this paper we first present the calibration process of a wide angle infrared (IR) camera, which has involved the capabilities of the remote handling for introducing a calibrated hot source into the JET vacuum vessel. Then, we describe how the PFCs equipped with embedded thermocouples have been used to assess the emissivity of both Be and W.

Preprint of Paper to be submitted for publication in Proceedings of the 40th EPS Conference on Plasma Physics, Espoo, Finland 1st July 2013 - 5th July 2013