Anisotropy and feedthrough in magneto-Rayleigh-Taylor instabilities

Summary form only given. The magneto-Rayleigh-Taylor instability (MRT) is important to peta-watt pulsed-power system development, wire-array z-pinches and magnetized target fusion, and equation-of-state studies using flyer plates or isentropic compression. It is also important to the study of the crab nebulae. In this paper, MRT in a finite slab is studied analytically using the ideal MHD model. The slab may be accelerated by an arbitrary combination of magnetic pressure and fluid pressure, thus allowing an arbitrary degree of anisotropy intrinsic to the acceleration mechanism. When the magnetic fields in different regions of the slab are assumed to be in different directions, the model may provide an analytically tractable approximation of MRT in a cylindrical liner containing a preheated fuel magnetized with an axial field. The effect of feedthrough in the finite slab is analyzed. The classical feedthrough solution obtained by Taylor in the limit of zero magnetic field, the single interface MRT solution of Chandrasekhar in the limit of infinite slab thickness, and Harris´ stability condition on purely magnetic driven MRT, are all readily recovered in the analytic theory as limiting cases. In general, we find that MRT retains robust growth if it exists. However, feedthrough may be substantially reduced if there are magnetic fields on both sides of the slab, and if the MRT mode invokes bending of the magnetic field lines.