Development of the optical remote handling connector for ITER Divertor Operational Instrumentation

Abstract

Divertor Operational Instrumentation (DOI) measures mechanical, electromagnetics and thermal parameters of the ITER Divertor Cassettes. The maintenance of the Cassettes requires their periodic removal and replacement by remote handling tools. The remote handling connector (RHC) of the DOI includes electrical and optical connections for the instrumentation cables, which must be disconnected during maintenance. The available space for the DOI RHC design is limited and the environmental conditions inside the Vacuum Vessel include high vacuum 10^-5 Pa, high temperature up to 350 °C and neutron and gamma-ray irradiation up to 1 GGy by the end of ITER operation. The access of remote handling tools is limited in the operating space surrounding DOI RHC. A study of existing connectors designed for plasma diagnostics electrical cables indicated that the concepts could not be adapted as such for the DOI RHC. The main concerns were related to the increased limitation of space, and the need to incorporate optical contacts for the fiber-optic cables that should be aligned with high precision to minimize optical losses. A dedicated design was required and developed. A novel extending DOI RHC concept was selected as it minimizes the required design changes to the surrounding systems. The concept consists of a cassette socket with an extending link located on the Divertor Cassette and a permanently installed vacuum vessel socket. The concept relies on the actuation of linear motion by the bolting tools of Cassette Toroidal Mover (CTM) manipulator and the flexibility of the cabling during the actuation. A physical full-size mock-up of the DOI RHC was manufactured to test the design solutions. The functionality of the mechanical structure in regards to remote handling operations were tested at remote handling connector platform (RHCP) at VTT Tampere Finland. Suppliers of optical connectors and ferrules were contacted to discuss the requirements of DOI RHC and commercial off-the-shelf optical components. Since there is no commercially available solution for attaching the fiber to the ferrule which would meet the aforementioned requirements, initial soldering tests were performed. The developed DOI RHC design provides input to the following design phases.