AC POWER LOSS FOR SUPERCONDUCTING STRIPS OF ARBITRARY THICKNESS IN THE CRITICAL-STATE CARRYING A TRANSPORT CURRENT

The magnetic field and current distributions are computed numerically for a superconducting strip in the critical state with infinite length , but finite thickness and width. The width-to-thickness ratio is vari ed from 1 to 100, covering the range from square bars to thick films. For some intermediate aspect ratios the sheet (integrated over thickne ss) current shows a solution close to the 2D one determined by Norris. However, for large aspect ratios (> 10) the current and field distrib utions differ significantly from the 2D solution, because the Norris s olution does not take into account land thus does not shield) the tran sverse field parallel to the strip. Power loss exponents are calculate d and found to vary from roughly 3 in a square bar to 4 in a high aspe ct ratio thin strip. In particular in the thin strip case the power lo ss exponents are current dependent owing to the contribution of the lo ss caused by the transverse magnetic field. The maximum magnetic field s occurring are calculated.