Fluxon motion in one-dimensional Josephson junction arrays

Current-voltage (IV-) characteristics of linear and annular discrete arrays of underdamped small Josephson junctions with different values of single loop inductances are calculated numerically and compared with those obtained for continuum long Josephson junctions. The resonances between the moving fluxon and the linear waves caused by the array discreteness induce steps on the IV -curve which do not exist in the continuum case. The voltage position of the steps is found to be in good agreement with the kinematic approach based on the Frenkel-Kontorova model. Our results show that in Josephson fluxon devices the discreteness may lead to strong super-radiant emission of electromagnetic waves by moving fluxons.