Behavior of magneto‐acoustic waves in a nonequilibrium subsonic disk MHD generator

Abstract

SUMMARYThe behavior of magneto-acoustic waves in a nonequilibrium subsonic disk MHD generator was examined. The solution of the sixth-order dispersion relation obtained by linearizing the set of MHD equations suggested that a magneto-acoustic wave which propagates at a velocity of u r − a (u r : radial fluid velocity, a: sound velocity) should be damped in subsonic flow. From time-dependent quasi-onedimensional simulations, it was verified that the pressure disturbance in the subsonic generator was damped at approximately the same rate as the value predicted by the linear theory. From a simplified analytical model, the mechanism of magneto-acoustic instability with fully ionized seed was discussed, and the damping criterion for the magneto-acoustic wave was clarified.