A novel acoustic lens in superfluid /sup 3/He

Abstract

The authors propose a novel scheme to achieve focusing of sound waves in superfluid /sup 3/He. This scheme exploits the magnetic field dependence of the superfluid phase diagram and the difference in the sound propagation characteristics of the A- and B-phases. Central to the scheme is the dispersion caused by the sound wave's strong interaction with order-parameter collective modes that exist in the B-phase. Details of a magnet that will be used to achieve such a lens are presented.<>