ON SMALL PERTURBATIONS OF STATIONARY STATES IN A NONLINEAR NONLOCAL MODEL OF A JOSEPHSON-JUNCTION

The problem of weak perturbations of steady states in a Josephson junc tion is considered in the strong coupling limit, when the Josephson le ngth lambda(J) is smaller than the London depth lambda(L). This proble m reduces to a nonlocal eigenvalue problem with periodic or localized potential. An infinite set of eigenfrequencies and corresponding eigen modes of perturbations is found in explicit form for two different kin ds of steady-state periodic structures and for a localized formation, corresponding to an isolated magnetic Josephson vortex.