Phase slip and phase-slip cascades in He4 superflow through a small orifice

The behavior of quantized vortex filaments subject to flow through an idealized orifice is investigated. Small loops nucleated at the wall are entrained and stretched by the diverging flow of the orifice, leading to individual phase-slip events. A macroscopic remanent vortex, however, can repeatedly give rise to a cascade of phase slips draining large amounts of energy from the flow field. © 1993 The American Physical Society.