Speaker
Description
This report details the design of and results from a fast-switching, high power density HTS switch. The switch design initially used commercially available second generation HTS tapes, with later prototypes using thin films of YBCO on sapphire. The method used to switch into the off-state is through application of an AC magnetic field to the superconductor, causing any transport current to experience a dynamic resistance. The field also heats the superconductor causing the material to thermally quench but the recovery time back into the superconducting state can be very fast. Results show that second generation REBCO coated conductors can be used, but thin films of REBCO on thermally conducting, electrically insulating material such as sapphire have superior performance. Results showed that a 10mmx50mm, 300nm YBCO thin film on sapphire could provide an on-state IC of 90A and an off-state resistance of around 100mΩ. On-state to off-state transition time was less than 100µs and off-state to on-state transition time was less than 10ms. These results are promising for further development of a high power, fast-acting HTS power switching device for use in applications such as flux pumps or superconducting power converters. More broadly, switching thin films of HTS fast and controllably between superconducting and non-superconducting states is an interesting area of research which may yield further applications.
