A New Liquid Hydrogen Based Superconducting Coil Test Rig to Measure AC Losses

Abstract

This paper presents the design, development, operation, and test capabilities of a proposed superconducting coil testbed to measure AC losses at the NASA Glenn Research Center. Superconducting AC losses are important in the design of electric stators and rotors, power transmission lines, transformers, fault current limiters, magnets, and superconducting energy storage (not batteries). The new liquid hydrogen based rig will allow superconducting coil testing across a wide range of test parameters, including injected current (0−3400 A), frequency (0–400 Hz), magnetic field up to 0.6 T, phase angle between induced voltage and injected current (−180–180°), coil coolant temperature (18–28K), and AC power loss (5–30W). While the target application of interest is 20K superconducting MgB2 (the only superconductor that can presently be made with low AC losses) stator coils for future electric machines, the rig can accommodate test articles with straight wire, tape, cables, coils of any shape, any allowable combination of superconducting wire and fluid (e.g. YBCO coils and liquid nitrogen), and AC or DC testing. The new spin rig builds upon an existing Air Force spin rig through a more flexible mode of fluid control, a wider gap space for test articles (up to 10.2 cm) for test articles, and can accommodate test articles over a wider range of operating temperatures (18–95K) using liquid hydrogen, gaseous helium, or liquid nitrogen as the working fluid, thus supporting direct-cooled machines below 77K.