The Laser in Vessel Viewing System (IVVS) For ITER: Test Results on First Wall and Divertor Samples and New Developments

A prototype of the laser In Vessel Viewing and ranging System (IVVS) was developed at ENEA laboratories in Frascati. It is based on an amplitude modulated laser radar designed to withstand the severe ITER conditions. IVVS (In Vessel Viewing System) probe has been designed and built to perform sub-millimetric amplitude and range images inside ITER during maintenance procedure. This means that IVVS has to properly operate under UHV ( 10-9 mbar), HT (up to 200 oC), HB ( up to 6 T) and ? radiation ( up to 5 MGy total exposure). IVVS is foreseen to be introduced into ITER by means of a proper carrier through the Divertor Port. For economical reasons, the present probe has been designed to operate under room conditions using, as far as possible, materials/components, for the optics and the frame, expected to withstand ? radiation (fused silica, stainless steel, aluminium, etc). The most critical part of the system, the fiber optic optical encoder, was successfully tested in Mol, by SCK-CEN laboratories, under gamma irradiation at 15 KGy/h up to a dose of 2.47 MGy. The paper describes the first results of the characterization of the IVVS probe under room conditions at Frascati Labs. The characterization have been performing on a full scale mock-up of the first wall panel and of the divertor vertical target. The surfaces of these components are considered characteristics of several in-vessel components. Furthermore the paper discusses and describes new developments to increase the overall IVVS performances and functionality. (author)