  We investigate experimentally a deterministic underdamped Josephson vortex
ratchet -- a fluxon-particle moving along a Josephson junction in an asymmetric
periodic potential. By applying a sinusoidal driving current one can compel the
vortex to move in a certain direction, producing average dc voltage across the
junction. Being in such a rectification regime we also load the ratchet, i.e.,
apply an additional dc bias current I_dc (counterforce) which tilts the
potential so that the fluxon climbs uphill due to the ratchet effect. The value
of the bias current at which the fluxon stops climbing up defines the strength
of the ratchet effect and is determined experimentally. This allows us to
estimate the loading capability of the ratchet, the output power and
efficiency. For the quasi-static regime we present a simple model which
delivers simple analytic expressions for the above mentioned figures of merit.

Superconductivity;Chaotic Dynamics;Pattern Formation and Solitons;Exactly Solvable and Integrable Systems