AC loss reduction of YBCO coated conductors by multifilamentary structure

The large cross-sectional aspect ratio of YBCO coated conductors leads to a large magnetization loss in an AC transverse magnetic field. In this work, the magnetization loss of a multifilamentary YBCO coated conductor was studied experimentally. A 100 Trim length of striated multifilamentary YBCO coated conductor was prepared where the conductor and filaments were 10 mm wide and 0.4 mm wide, respectively. Striations in the sample were accomplished by laser ablation. The magnetization loss of this striated conductor as well as a reference non-striated conductor was measured in AC transverse magnetic fields normal to the conductor at various frequencies. The measured magnetization loss of the 100 mm striated conductor was less than 9% of the measured loss of the non-striated conductor at f = 11.3 Hz and H/H-cc = 8.8 (H-cc = I-c/piw(c); I-c: critical current, w(c): conductor width). Even though the coupling loss component increases the magnetization loss in the striated conductor, the AC loss reduction by striation is still apparent even at 171.0 Hz. The transverse resistance between filaments estimated by a four-probe measurement was 38 muOmega for 1 m at 80 K. The coupling length estimated using this transverse resistance is much longer than the sample length even at 171.0 Hz, suggesting that the filaments in the striated conductor are far from 'completely coupled' or 'saturated'.