COMPRESSIBLE NORMAL-MODES OF A RESISTIVE NONUNIFORM PLASMA

The theory of resistive dissipation of linear compressible modes in a nonuniform plasma is presented in a unified way, following a normal mo de approach. The familiar modes of a homogeneous ideal plasma are show n to be substantially modified by the presence of the resistivity and nonuniformity. It is then argued that the most suitable criterion for mode identification is based on the asymptotic properties of the solut ions. The modes are then classified as ideal or resistive according to the asymptotic absence or presence of the resistivity. After a brief summary of the results from previous articles, made for the sake of co mpleteness, the article concentrates on the new results concerning the compressible ideal solutions, the only ones that exhibit a resonant b ehavior. The properties of the solutions are examined by treating an e xplicit example of a nonhomogeneous situation. It is shown that the na ture of the modes varies in the direction of nonuniformity, being esse ntially a fast mode in the asymptotic region, a slow mode in the vicin ity of the so-called cusp resonance, and an Alfvenic mode near the Alf venic resonance point.