Electromagnetic and mechanical characterisation of ITER CS-MC conductors affected by transverse cyclic loading, part 2: Interstrand contact resistances

A special cryogenic press has been built to study the mechanical and electrical propel-ties of full-size ITER multistrand Nb3Sn cable-in-conduit conductor samples under transverse, mechanical loading. This simulates the transverse magnetic force that occurs when the conductors are used in a coil. The cryogenic press can transmit a variable (cyclic) force up to 650 kN/m to a cable section of 400 mm length at 4.2 K. The jacket is opened partly in order to transmit the force directly onto the cable. The various interstrand contact resistances (R-c's) between stands selected from sub-cables at different positions inside the cable are measured. A summary of the results obtained with up to several tens of full loading cycles is presented. The cables consist of six last stage sub-cables (petals) which are wrapped with an Inconel 600 ribbon. A significant increase of the intra-petal R-c after several cycles is observed. An opposite effect is noticed for the inter-petal R-c. Upon applying a load of 650 kN/m, the R-c drops for the intra-petal as well as for the inter-petal resistance with respect to zero load.