AM laser system (IVVS) for the ITER in vessel viewing and ranging

In vessel inspection (viewing and ranging) systems, able to withstand the International Thermonuclear Experimental Reactor (ITER) very severe operating conditions, are fundamental to check plasma facing components in order to properly program ordinary and extraordinary maintenance activities. In this field different schemes have been proposed during the EDA ITER phase each of them showing problems in ranging and/or in radiation hardening and/or in additional illumination source. For this reason ENEA proposed the Laser in Vessel Viewing and Ranging System (IVVS) based on an amplitude modulated (AM) laser beam. At the moment IVVS seems the only system under testing able to perform, at the same time, viewing&ranging under the ITER operating conditions. The IVVS testing is scheduled to be completed within 2002 at ENEAʹs Frascati Labs. The present paper includes the IVVS design principle and the main results of the optics scheme that is the essential and innovative part of the probe.