Design of the room temperature insulation breaks for ITER correction coil feeders

Abstract

The room temperature insulation breaks (RTIBs) for the International Thermonuclear Experimental Reactor (ITER) project insulate the helium (He) outlets of the High Temperature Superconducting (HTS) current leads in the feeders, which can be at up to 30 kV, from the grounded pipework returning the gas to the liquefier plant. Gaseous He at RT is particularly vulnerable to electrical breakdown, requiring an additional design effort as compared to that for cryogenic IBs with more than hundred times denser cryogenic He. To satisfy the working requirements, stainless steel (SS) pipes and glass fiber reinforced plastic (GFRP) were used to develop the RTIBs for the ITER Correction Coil (CC) feeders. Electrical and mechanical analyses of the RTIBs using finite element models were performed. In particular, the electric field distribution along the helium gas path and possible de-bonding or shear failure of the composite were investigated. In this paper, the results of the analysis are discussed. Further experiments indicate the designed RTIB can satisfy the functional require-ments.