Experimental results of laser in vessel viewing system (LIVVS) for JET

Tokamak machines need inspection systems to detect damages on the plasma facing components. The equipment currently in use for in-vessel inspection is mainly based on CCD (charged coupled device) cameras that cannot withstand heavy radiation in vessel operating conditions. To overcome this limit, JET decided to investigate the possibility to replace the actual IVVS TV camera with a radiation-resistant viewing system. For this purpose, ENEA has proposed an amplitude modulated (AM) laser system. Consequently, a new laser-based inspection device (laser in vessel viewing system (LIVVS)) has been designed, developed and tested in ENEA Frascati Laboratories. The system takes in-vessel surface images, scanning the target using a laser beam deflection system installed at the bottom end of a probe, matching the JET mechanical constraints. Experimental results are presented showing the main characteristics of the system.