DIRECTED WAVE-PROPAGATION IN RANDOM-MEDIA - SUPERDIFFUSION AND PHASE-TRANSITION

We study a class of classical wave-propagation phenomena in which a multiply scattered wave in a random medium is directed along a certian spatial direction. Such a situation arises in the random scattering systems in which the scattering potential is slowly varying in the z direction. In 2D, we find a superdiffusive transverse displacement of the center of the transmitted beam 14, while the width of the beam scales as with 12. In 3D, we find a transition: for weak disorder, while v0.46 and v0.66 for strong disorder. 1990 The American Physical Society © 1990 The American Physical Society.