Design of Thermocouple Connectors for ITER HNB Injectors

The connection of mineral insulated (MI) sensors to extension cables will occur through custom connectors for thermocouples installed on in-vessel components of the ITER Neutral Beam injectors. This in-vessel mating plug and socket design allows for maintenance and replacement of components with multiple and reliable signal connections. The connector design is based on previous experience on connectors procured for other fusion diagnostics. It is developed to house up to 63 metal-ceramic terminations of MI thermocouples, to shield signals from electromagnetic interference, and to isolate the sensor shield from the vessel avoiding ground loops. Furthermore, vacuum, nuclear radiation, and remote handling maintenance requirements were satisfied. The manufacturing feasibility of the connector design is verified considering machining operations, compatibility with standard crimp contact pins, and machinable glass-ceramic for realisation of insulation plates and bushes. The design is complemented by assembly verifications at the signal feedthrough interface and by alignment tolerance check to be specified for the procurement.