STABILITY AND SAFETY ESTIMATES AND TESTS OF A SUPERCONDUCTING BUS-LINE FOR LARGE-SCALE SUPERCONDUCTING COILS

We have been developing a flexible superconducting bus-line as a unit electrical feeder between large-scale superconducting coils and their power supplies away from the coils. The designed superconducting bus-l ine consists of a pair of +/- aluminum stabilized NbTi/Cu compacted st rand cables and a coaxial four-channel transfer line. A full-scale mod el of the SC bus-line (20 m long) has been constructed and tested succ essfully up to 40 kA without a quench under the short-circuit conditio n. Stability tests were also done by inducing a forced quench with hea ters. A minimum propagation current larger than 32.5 kA was confirmed. Thus, the bus-line was cryogenically stabilized at the rated current of 30 kA. We have examined the test results and evaluated the stabilit y and safety margins of this bus-line. The design criteria for a super conducting bus-line are also shown for large-scale superconducting coi ls with operating current as a parameter.