Construction readiness of combined CCT demonstrator

The construction readiness of the combined CCT demonstrator based on a rope of 6 twisted NbTi strands around one copper core strand has been presented. 

The document summarizes the assembly process of the demonstrator magnet with detailed 3D illustrations, and listing the main components (conductor, formers, envelope tube, end plates, and splice box) and the main procedures (winding, impregnation and mechanical assembly). The conductor is a rope (6 NbTi strands+1 copper core) with a double braid of polyester, fully characterized in terms of critical current, high voltage and splice measurements, and ready for the final production and delivery to CIEMAT (Madrid, Spain).

The former material is aluminium-bronze, chosen due to its low electrical conductivity and favourable manufacturing properties, allowing a minimum rib thickness of 0.4 mm. The outermost envelope tube of the magnet system provides mechanical support, serves as a container for wax impregnation, and is made of aluminum-bronze, while glass-fiber reinforced PEEK end plates secure and lock the tubes, with cables guided axially to a splice box for impregnation.

The report describes the winding tests and the improvements for superconducting ropes, including the need for rounded groove edges, temporary clamps, and increased insulation for successful winding in the final magnet formers. The use of wax impregnation is considered, highlighting its effectiveness in preventing quenches and describing the impregnation process within the magnet itself, aided by a polyester braid to prevent voids.

The assembly procedure involves winding two layers of 2x7 ropes on inner and outer formers, testing insulation, adding support for layer transition, installing the envelope tube, end plates, and splice box, making rope joints and voltage taps, and concluding with wax impregnation and cleanup.

Finally, the readiness table provides an overview of the construction status, indicating that the conductor and end plates are ready for construction, with some components like the envelope tube and splice box being in a medium readiness state, while winding and impregnation are generally prepared, and assembly readiness is medium with the inter-layers and second layer surfaces to be defined.