Vortex pinning in superfluid helium

A formalism for determining the behavior of vortex filaments in the presence of pinning sites is presented. As an initial application, the properties of a single quantized vortex terminating on a geometrically simple pinning site and subject to pure superflow are investigated. It is found that there exists a critical velocity above which the vortex decouples from the pinning site by a nonlinear, discontinuous process arising from its interaction with the nearby boundaries. No evidence of a vortex-mill mechanism is observed. © 1981 The American Physical Society.