Repetitive single vortex-loop creation by a vibrating wire in superfluid He-3-B

Spectacular features are observed on the velocity-force characteristics of a vibrating wire resonator in superfluid He-3-B at ultralow temperatures. B oth plateaus and discontinuities are seen in the characteristics. The plate aus seem to have two separate critical velocities where first some "event" occurs, which causes the wire to lose energy and slow down, followed bpa se cond lower critical velocity where the event decouples. It is suggested tha t these events are due to vortex-loop creation at protuberances on the vibr ating wire. This opens up the possibility of controlling the creation of vo rticity through specially prepared protuberances.