Natural frequency spectrum of a flat superconducting cable

A matrix method is used to investigate the current damping process in a flat superconducting cable. A discrete spectrum of natural frequencies is obtained, each determining the rate of exponential damping of the corresponding induced current. Although the number of natural frequencies increases as the size of the cable increases, their spectrum remains finite because the maximum and minimum frequencies tend to finite limits. An analysis is made of the induced currents for the limiting frequencies. It is shown that in the range of minimum natural frequencies the induced currents are long-lived long current loops. At high frequencies the distribution of the induced currents in cable layers is sinusoidal. Pis’ma Zh. Tekh. Fiz. 25, 42–47 (July 12, 1999)