Chaotic patterns in a Josephson junction model

The effect of an applied rf signal on the dynamics of a large area Josephson junction is examined by means of a model based on the sine-Gordon equation. In particular the problem of characterizing spatiotemporal chaotic patterns induced by the external harmonic varying magnetic field is addressed. In general it is found that instantaneous spatiotemporal patterns, i.e., patterns confined to one period of oscillation of the external field correlates poorly. Also the correlation between instantaneous patterns and average patterns is poor. However, the correlation between patterns obtained as averages over, e.g., ten or more consecutive instantaneous spatiotemporal patterns is high. Furthermore, averaged spatiotemporal patterns obtained for different values of the magnetic field amplitude correlate well. The average potential and kinetic energies of spatiotemporal patterns are calculated. In general the energies in the chaotic regions are lower than in regions with periodic response.