Results of the European study on conductor joints for ITER coils

Abstract

The general design and the associated performance analysis of a joint proposed by the European Union for both ITER Central Solenoid and Toroidal Field coils are presented. Results of an extensive testing programme performed on subsize joints (scale US), including DC resistance and pulsed field losses measurements are given and discussed, as well as their interaction on the final joint design. Results of feasibility tests carried out on a full-size piece are also given. This study has finally led to the design of a full-size joint sample to be fabricated in industry and tested in specific laboratory test facilities.

Manufacture and test of NbTi subsize joint samples for the ITER poloidal field coils

“…value is coherent with previous results [5]. Concerning the PF1 sample, even if there is a little difference in joint void fraction (due to the difference in cos value), this cannot explain that the is found four times higher with Ni-unplated strands than with CuNi barrier strands.…”

“…Roughly taking into account the volumes involved in resistance calculation, we can give an approximate expression of the joint resistance [5]: (1) where is the minimum sole thickness, is the copper resistivity, is the contact resistivity between sole and strand outer surface, is a given thickness of strand-to-sole surface contact (0.1 mm, meaning for comparisons only), is the resistivity of the internal barrier and is the internal barrier thickness.…”

Fabrication of the first European full-size joint sample for ITER

“…A part of this bending could be also due to the differential thermal contraction between steelkopper and the Nb3Sn cable during the cool down from 650°C to 20"C, associated with the difference in stiffness between steel and copper. This phenomenon was not observed on subsize joints about 117 in section and about 1/3 in length [2]. The average deflection due to bending is about 4 mm at the box end, when it is only 1 mm at mid-length.…”

“…The European design proposal for the ITER joints has been based on extensive work carried out on subsize joints fabrication and tests as well as on theoretical modeling [l], [ 2 ] . The joints of the TFMC have been designed according to this concept [3].…”

Extensive Characterisation of Copper-clad Plates, Bonded by the Explosive Technique, for ITER Electrical Joints

“…By fabrication of twin terminals at both conductor ends, soldered together, the concept allows for the joints to be dismountable. Each terminal is manufactured by compacting the stripped cable end into a bimetallic box, machined from a copper-clad plate, bonded by the explosive technique (Ciazynski et al, 1996).…”