Reduced Critical Current Anisotropy and Improved Critical Current Performance in a Combined Pinning Landscape Created by Proton and Silver Irradiation

Particle irradiation using light ions and heavy ions is found to be an effective method to introduce flux-pinning centers into REBCO films and coated conductors. The degree of enhanced critical current at various conditions depends upon the size, morphology, and orientation of ion tracks. Proton irradiation to the optimised fluence results in greater isotropic enhancement at lower temperatures, the enhancement decreases as temperature increases. Silver ion irradiation on the other hand gives a greater enhancement at higher temperature but limited to particular angular ranges. We compare the results of these two types of irradiation and then produce a mixed pinning landscape with a combination of the two. We find a nearly isotropic enhancement in I_c at lower temperatures and an enhancement about the c -axis direction, similar but broader than silver irradiation alone, at higher temperatures.