ElectricaI Resistance and ac Losses in Superconductors

Some recent informations about the resitive and ac behaviors of superconductors are briefly reviewed， which are essentially due to the motion of quantized magnetic flux or vortex lines under the applied e1ectric and magnetic fie1ds. A1though the situations are complicated， the mechanisms involved for these behaviors are summarized in different ways; (i) the fluxflow， (ii) the f1ux creep， (iii) the hysteresis loss， (iv) the eddy-current loss， (v) the skin effect，and/or (vi) the surface impedance. It is of importance to take account of the pinning and depinning effects on the f1ux motion. Furthermore， the geometry of the applied static and oscillatory magnetic fie1ds， as well as these strengths re1ative to the characteristic critica1 fie1ds HCl and Hc2' are considered to p1ay an important role for the mechanisms to be distinguishe