Instability of AB interfaces of different shapes in rotating 3He

Abstract In our experiments on rotating superfluid 3 He the interface between the A and B phases is stabilized in a magnetic field. With decreasing current in the barrier magnet, the shape of the interface changes from almost flat and perpendicular to the sample axis to a ring of A phase which coats the outer sample boundary, with B phase in the center. The influence of the shape of the interface on the critical velocity of its shear-flow instability is investigated.