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Nucleation of vortices in units of one quantum has been observed with c.w. NMR in a rotating cylinder filled with 3He-B. During acceleration a new vortex is created each time the counterflow velocity at the perimeter reaches a critical value vc(T, p). The measured vc resembles the calculated velocity vcb(T, p) of the bulk superflow instability, but is smaller by a factor with power law dependence on the superfluid coherence length. This indicates that a nucleation event takes place whenever the flow exceeds vcb locally at the nucleation site and the nucleation barrier vanishes.

Exponentially damped relaxation with a time constant (1 ÷ 3) min after perturbation of steady rotation has been discovered in rotating 3He-B, using NMR techniques. The effect represents an overdamped collective mode of the vortex array, governed by vortex tension and pinning. Elastic-shear deformation of the array is found to influence pinning, but does not contribute in the bulk liquid. The presence of shear elasticity provides the first evidence for crystalline order of a vortex array in 3He.

Negative ion mobility in rotating 3He-B at magnetic fields H 0.1 T has been measured along the common direction of H and the rotation axis Ω. When Ω > 0, we observed an increase of mobility, which originates from a reorientation of the anisotropic energy gap. The increase can be understood quantitatively only if soft vortex cores, predicted by Sonin, are assumed. Their size was found to be on the order of the magnetic Healing length ξH.