Analysis of linear branches in the I- characteristics of Josephson junctions

Resistive branches have often been observed in the current-voltage characteristics of long Josephson junctions. In the present paper we perform a systematic numerical analysis of the generation of these branches when an external magnetic field is applied to the junctions. We show that the linear branches exist only over a limited voltage interval which is determined quantitatively. We also clarify to what extent the linear branches can be attributed to flux-flow effects.