Environment-resistive coating for the thin-film-based superconducting fault-current limiter Ag/Au-Ag/YBa2Cu3O7/CeO2/Al2O3

We have studied environment-resistive coatings (ERC) for the thin-film-based superconducting fault-current limiter (SFCL) Ag/Au-Ag/YBa2Cu3O7/CeO2/Al2O3. We evaluated nine candidate ERC materials by two accelerating-environment tests, and revealed that the shellac- and the fluorine-resin have a high environmental resistance. Especially, the shellac resin almost completely protected Jc of an element exposed to 60 °C saturated water vapor for 2 h (3.4->3.2 MA/cm2). We also performed a practical operation test of SFCL using an element half covered by shellac, and found that the ERC does not diminish the current limiting properties similarly to the previous results of the Teflon-coated SFCL [1].