MHD leaky waves in a layered plasma: I Theory

In a three layer compressible plasma we study MHD leaky waves described by Fourier modes of complex frequency. We follow a matrix method that yields f our transcendental dispersion relations. The roots (real or complex) make u p a spectrum of pseudomodes, consisting of a complicate set of infinite bra nches. We derive analytical properties that allow to study the topology of the spectrum, the conditions of existence of real and complex roots, the co ntacts and crossings of branches of different types, etc. Our results allow to analyze any particular case of interest.