We present here analytical arguments and numerical evidence for the existence of net directional motion of highly discrete sine-Gordon kinks under ac forces of zero average. We have also characterized the depinning of the oscillating kink under those circumstaWe present here analytical arguments and numerical evidence for the existence of net directional motion of highly discrete sine-Gordon kinks under ac forces of zero average. We have also characterized the depinning of the oscillating kink under those circumstances, and analyzed the instability mechanisms of the phase-locked running solutions. Possible experimental relevance of this phenomenon in circular arrays of Josephson junctions is discussed.[+][-]
