A model of a damped dc-driven long Josephson junction (LJJ) with periodically installed microresistors or microshorts (microshunts), or crossed by a periodic chain of Abrikosov vortices, is considered. A maximum value of the bias current density admitting pinned states of a fluxon and a minimum value admitting free motion of a fluxon are found, the latter being an improtant generalization of the well-known result of McLaughlin and Scott. For LJJ's with a sinusoidal profile of the inhomogeneity, a current-voltage characteristic is obtained in an explicit form.

• Received 21 March 1988

DOI:https://doi.org/10.1103/PhysRevB.38.9242