SURFACE-ROUGHNESS EFFECT ON SURFACE IMPEDANCE OF SUPERCONDUCTORS

The measured values of microwave surface resistance and reactance of a superconductor have generally three contributions from (1) the intrin sic properties, (2) the internal defects, and (3) the external surface roughness. In this paper, we formulate the increased factor of surfac e resistance and reactance of superconductors using Morgan's square-gr ooves model and with the consideration that the current flows along th e irregular surface. Numerical results obtained using a finite differe nce method are presented together with fitted closed-form formulas.