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's 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, heat load were also measured.