Electro-Mechanical Connection System for ITER In-vessel Magnetic Sensors

Several hundreds of magnetic sensors will be located within the ITER vacuum vessel, in a hostile environment characterized by severe neutron irradiation and plasma heat loads that represent a concern for the reliability and durability of the sensors. The in-vessel magnetic sensors are therefore conceived to be attached to the inner surface of the vacuum vessel through a connection system which allows a potential replacement by means of a suitable Remote Handling (RH) system. This paper presents the preliminary design of the "In-Vessel Magnetic platform", which represents a subsystem of the magnetic diagnostics formed by all the components necessary for guaranteeing the thermo-mechanical interface of the actual magnetic sensors with the vacuum vessel, their protection and the electrical connection to the in-vessel wiring for the transmission of the detected signal with a minimum level of noise. The design has been developed in order to comply with several functional requirements: the mechanical attachment to vacuum vessel; the electrical connection to the in-vessel wiring; an efficient heat transfer to vacuum vessel; the installation and replacement by means of RH system; the housing of metrology features for post-installation control; the ECH radiation shielding. Significant effort has been dedicated to investigate and develop a proper CAD model, integrated within the ITER In-Vessel configuration model, caring for the geometrical compliance with the Blanket modules (modified in order to accommodate the magnetic sensors in suitable grooves) and the RH compatibility. Thorough thermo-mechanical and electro-magnetic fem analyses have been performed to demonstrate the reliability of the system in standard and off-normal operating conditions.