Influence of film width and magnetic field orientation on AC loss in YBCO thinfilm

Abstract

Three YBCO thin films on sapphire substrate with widths of 3, 5, and 10 mm wereprepared, and their AC loss characteristics were studied experimentally. The total AC lossdissipated in samples carrying AC transport current in an AC transverse magnetic field wasmeasured by an electromagnetic method. The total AC loss in YBCO film isproportional to the film width and the perpendicular magnetic field component, acomponent of the transverse magnetic field that is perpendicular to the film wide face.Reduction of the film width and/or the perpendicular magnetic field component is anessential means of decreasing the total AC loss. When plotting the total AC lossdivided by film width against the perpendicular magnetic field component, curvesfor various film widths and field angles almost agree with each other. The totalAC loss can be estimated by analytical expressions except in an intermediaterange of the perpendicular magnetic field component. The experimental resultsindicate two engineering approaches for reducing the total AC loss in YBCO film:decreasing the film width and decreasing the perpendicular magnetic field component.Findings have shown empirically that decreasing the film width and decreasingsinα,where α is the field angle, are equivalently effective in reducing the total AC loss.