On the propagation of magneto-ionic rays in a shearing plasma

Abstract

Using the geometrical optics approximation, we give the behavior of fast and slow magneto-ionic rays passing through a plasma which possesses a differential shear. Depending upon the orientation of the ambient magnetostatic field with respect to the flow direction, it is shown that the effects of the shear can cause ray paths to propagateupstream ordownstream. The fact that in an homogeneous plasma the slow magneto-ionic wave has a group angle which is oppositely directed to its phase angle causes the slow rays to exhibit properties which are extremely curious relative to those obtaining for the fast rays — which are themselves interesting. We have done these calculations to show that the effects of velocity shear in an otherwise homogeneous plasma lead to interesting ray behaviors which, presumably, bear upon the more general question of magneto-ionic energy transport in inhomogeneous plasmas.