Frequency dependence of the electromagnetic-field-induced resistance of a phase-slip line

The resistance of a high-frequency phase-slip line (an ac PSL) in a wide tin film has been experimentally investigated as a function of the external irradiation frequency. It is shown that the behavior of the descending branch of the nonmonotonic frequency dependence of the ac PSL resistance agrees well with the theoretical predictions. The behavior of the ascending branch of this frequency dependence is associated with the nonlinear relaxation processes of the population imbalance of the branches of the quasi-particle spectrum under conditions of microwave pumping at irradiation frequencies greater than the inverse charge-imbalance relaxation time. Comparisons are carried out with the analogous dependences for high-frequency phase-slip centers in narrow channels. The dependences of the penetration depth of a variable longitudinal electric field into a superconductor on the frequency and mean free path of the electrons when they are scattered at impurities are obtained.