Stable long-term operation of superconducting current-feeder system for the LHD

A superconducting (SC) current-feeder system is used as the current transmission lines for the experimental fusion device, LRD. It consists of nine flexible SC bus lines with total length of 497 m, and nine pairs of gas-cooled current leads. To avoid the propagation of the ice on the leads, the temperature of the terminals had been kept in the range between 5 and 20 degrees C by the heaters. The measured voltage drops of all leads were less than 20 mV. The liquid helium levels of the leads and the sub-cooler tank will equalize by the siphon method. The total time of the coil excitations exceeds 3000 hours. We have demonstrated successfully that the SC current-feeder system was stable and easy to handle, and is useful for the SC experimental fusion device

Development and tests of a flexible superconducting bus-line for the Large Helical Device

A flexible superconducting bus-line is proposed as an electrical feeder between the superconducting coils of the Large Helical Device (LHD) and the device\u27s power supplies. The bus-line consists of superconducting cables and a cryogenic flexible transfer-line. A specially developed aluminum stabilized NbTi/Cu compacted strand cable satisfies requirements for large current capacity, high stability, high reliability and flexibility. A full-scale model with a length of 20 m was designed and constructed to investigate the feasibility and performance of the superconducting bus-line. Its fabrication, transportation, installation, cooling and excitation tests were successfully carried out. The bus-line was very stable and could be excited up to 40 kA (rated current is 30 kA) without a quench. The stability, current distribution and heat load were also measure