CRITICAL-STATE MODEL FOR HARMONIC-GENERATION IN A SUPERCONDUCTING MICROWAVE RESONATOR

A critical-state model is developed for the treatment of the nonlinear ac response of a superconducting coaxial-type transmission line. Anal ytical results are presented for the resistance and reactance as well as the response at overtone frequencies. Center conductors of both ell iptical and rectangular thin-film cross section are considered. The do minant response, in the case of the elliptical geometry, is found to b e independent of the aspect ratio of the ellipse. Significant differen ces are found between the elliptical and strip geometries. These diffe rences are due to the difference in-structure of the critical state in the two geometries. The model is applied to resonators with the assum ption that end effects can be neglected. Qualitative agreement is foun d with experimental results.