Scientists from the Laboratory of High Energy Physics at JINR and their colleagues from China presented the engineering design of a forced-flow cooling high temperature superconducting (HTS) cable for a SMES system with high current capacity. This system is used to ensure stable operation of superconducting magnets in accelerators, including the one at the NICA Complex.

Accelerator complexes, such as NICA being constructed at JINR, are equipped with superconducting magnets operating at 10 kA level, which require high performance SMES (Superconducting Magnetic Energy Storage) for energy compensation needed for stable operation. The SMES needs to be operated with several kA-level current carrying and kA/s current ramping rate. The AC loss heat deposition resulting from fast current ramping makes immersion cooling and conduction cooling methods inapplicable.

The scientists introduced the forced flowing cooling high temperature superconducting (HTS) CORC (Conductor on Round Core) cable used for the SMES system with high current capacity. To achieve better bending performance and control the ohmic loss in the mandrel of the CORC cable, they chose flexible metal conduit as the external mandrel and casing. It can form an internal cooling channel and outer channel at the same time, which can realise satisfactory cooling effect. In addition, the bending performance of the CORC with new type mandrel was studied, and related testing experiments at liquid nitrogen temperature zone were conducted.

The results show that the CORC cable with flexible metal conduit as mandrel has satisfactory bending performance, with practically no critical current degradation after bending and straightening. The pressure drop of the forced flow cooling based on this kind of CORC cable was found to meet the operation requirements of forced flow cooling. The SMES system based on the cable is being engineered and will be finished in 2024.

VBLHEP JINR Deputy Director Hamlet Khodzhibagiyan and head of a VBLHEP JINR sector Mikhail Novikov conducted the study in co-authorship with Chinese scientists.