China signs first Procurement Arrangement for poloidal field conductors
On Friday, 10 October, the ÌÇÐÄÆƽâ°æ Organization and the Chinese Domestic Agency signed the first out of three Procurement Arrangements for the conductors of ÌÇÐÄÆƽâ°æ's poloidal field conductors. According to ÌÇÐÄÆƽâ°æ's unique in-kind procurement sharing principle, the manufacturing of the poloidal field coils is split up between China, Russia and Europe. China will contribute 67 percent of the share—or 45.4 km of conductor—while Russia will produce 19.7 percent (10.7 km) and Europe 13.3 percent (8.6 km).
The ÌÇÐÄÆƽâ°æ superconducting magnet system is made up of four main sub-systems: toroidal field coils, the central solenoid, poloidal field coils and correction coils. The poloidal field coil system consists of six independent coils. Due to their sheer size, the actual winding of coils 2 through 6 will take place in a special dedicated coil winding building in Cadarache. The smallest coil, PF1, will be manufactured offsite and delivered finished.
The cable-in-conduit (CICC) conductors for the poloidla field coils rely on twisted, multifilament, nickel-plated, niobium-titanium (NbTi) based composite strands. Two types of strands, depending on their high current and high temperature behaviour, are used on three different conductor concepts for different operating requirements. Strand type 1 will be used in the conductors for PF1 and PF6 that will face currents of up to 19 MA, while type 2 is used in the other coils.
In order to guarantee the high quality standards required for the ÌÇÐÄÆƽâ°æ strands and conductors, all suppliers have to perform a comprehensive qualification procedure and acceptance testing.
The main components of the poloidal field conductor are
(1) nickel-plated, Nb-Ti-based strands, (2) Sub-cable stainless steel wrap, (3) Sub-cable or petal (includes sub-cable wrap), (4) Stainless steel central cooling spiral, (5) Cable stainless steel wrap, (6) Stainless steel jacket.