High-power-density fault-current limiting devices using superconducting YBa2Cu3O7 films and high-resistivity alloy shunt layers

Switching of superconducting thin-film resistive fault-current limiting devices with alloy shunt layers was studied. Au-Ag alloy thin films, whose room-temperature resistivity is about six times higher than that of pure gold, were sputter deposited on YBa2Cu3O7 films on sapphire substrates with high critical current density of J(c)=3.05+/-0.05 MA/cm(2). A small sample, 5 mm wide and 40 mm long, had the capacity of a rated current of 32 A(rms) in normal operation and withstood a high voltage of 107 V-rms for 0.1 s after switching, resulting in a very high switching power density of similar to1.7 kVA/cm(2), which is more than four times higher than conventional devices using gold shunt layers. (C) 2004 American Institute of Physics.