What can we learn of vortex dynamics from ³He investigations

A short review of basic modes of vortex motion in rotating superfluids is presented. Emphasis is put on slow vortex modes with characteristics times larger than the rotation period. The slow modes are signatures of the collective effects in vortex arrays. In ³He, because of the large normal viscosity, the slow vortex modes are available for experimental studies first of all as overdamped modes. Nevertheless, they are able to provide data on the key collective properties of the vortex arrays in rotating ³He, such as long range vortex interaction, vortex elasticity (linear tension and shear rigidity of the vortex lattice) and surface pinning. The experiments that have already been done or are expected to be done are discussed. Evidence has been already obtained that weak surface pinning in ³He is influenced by the vortex lattice shear rigidity like the collective pinning in superconductors. It is shown that experiments on vortex dynamics may give an experimental answer to the puzzle of the intrinsic orbital moment in ³He-A.