Mechanical Design and Structural Analysis for Lower Port Optics of ITER Divertor Impurity Monitor

Abstract

The Divertor Impurity Monitor (DIM) for ITER is a spectroscopic diagnostic that measures the parameters of impurities and isotopes of hydrogen in the divertor plasmas. The DIM systems are installed in upper port, equatorial port, lower port (LP) and the divertor cassette. The LP systems consist of the side-upper/lower optical systems and the central optical system. In the central system, the front-end optics (optical mirrors) are located under the divertor-dome and this optics is required to have a structure that can withstand extremely high thermal loads in terms of establishing a sensitive optical structure. This paper presents a mechanical design of the optics with taking manufacturability into account and structural integrity assessment according to ITER load conditions (thermal and electro-magnetic loads, etc.) and design criteria specified in the RCC-MR code. The mechanical design of the optics forms a box-shaped optics and the structural analysis results indicate the mirror box satisfies design criteria in the RCC-MR code, except for the inner support part interfacing with the divertor cassette.