Page 152 - Fundamentals of Magnetic Thermonuclear Reactor Design

134 Fundamentals of Magnetic Thermonuclear Reactor Design

external thermal perturbations that may occur, for example, as a result of crack-
ing of the impregnating compound.
In ITER, the CICC is made of twisting sub-elements (sub-cables or ‘pet-
als’) separated by resistive barriers (stainless-steel wrap) (Fig. 5.12; Tables 5.6
and 5.7).
The barriers bring down the cable energy losses due to varying magnetic
fields (AC losses) without preventing current redistribution between the
elements. The central cooling channel significantly reduces the hydraulic
impedance of ITER conductors, which is important in view of the consid-
erable winding length. Due to the large strand, surface being cooled the
cable exhibits good stability against thermal disturbances caused by strand
movements and sub-cable friction even with the copper/non-copper ratio
of ∼1:1.
ITER superconducting cables were developed in 1987–2006 as part of an
extensive international collaboration. Cable design and configuration were cho-
sen so that the following stage-by-stage process can be followed:

l Superconducting cable pulling-through into a tight conduit (jacket) followed
by compacting to achieve the final dimension.

FIGURE 5.12 Superconducting cables (CICCs) for the ITER magnet system. (1) Supercon-
ducting and copper strands, (2) the central helix cooling channel, (3) steel band winding, (4) cable
jacket and (5) insulation. (Copyright ITER Organization, 2017).