ENHANCED CRITICAL-CURRENT DENSITY IN MELT-TEXTURED YBCO VIA AU ION SURFACE IRRADIATION

We irradiated both side of bulk melt textured YBCO with 235 MeV Au ion s. The thickness of the specimens is significally larger than the pene tration range of the ions so that two surface layers of columnar defec ts are created. Critical current density enhancements were obtained in temperature and field ranges that are useful for applications. The bo undary between reversible and irreversible regime is shifted toward hi gher temperatures. At higher fields the increase of the relaxation rat e with temperature is less steep after irradiation. The general trends are independent of the thickness of the samples, at least in the rang e from 5% to 13% of volume affected by irradiation.