Chaotic dynamics of Josephson equation driven by constant dc and ac forcings

The chaotic dynamics of a Josephson equation driven by constant de and ac c urrent forcing with a shifted phase is investigated. We at first study whet her there exist multiple saddle points with nontransverse homoclinic or het eroclinic orbits for unperturbed equation. Secondly, we obtain threshold fo r the existence of chaos by using Meinikov's method, and the threshold is i nfluenced by the shifted phase. Finally some numerical results are reported in order to prove theoretical predictions. (C) 2001 Elsevier Science Ltd. All rights reserved.