Orbital dynamics of 3He-A in the presence of a heat flow and a magnetic field

The equation of motion of the orbital axis l of 3He-A has been solved numerically for a situation in which the liquid is contained in the channel between two parallel planes when there is a flow of heat between the planes and a magnetic field applied perpendicular to them. For zero field it is found that the texture with l uniform and perpendicular to the planes is stable, but in addition there are time-dependent solutions satisfying the same boundary conditions. Also, precessing solitary wave solutions are found when l is constrained to have a direction on one plane opposite to that on the other. Application of a magnetic field destabilises the texture of uniform l and with increasing field a time-independent state in which l spirals, a state with time-dependent l and a state with l perpendicular to the field over most of the channel are found successively. The application of the computations to three-dimensional geometries and to the problem of persistent current decay through orbital motion is discussed. The computations provide a plausible explanation of some of the persistent orbital motions observed by Wheatley and collaborators. (author)