The dynamics of accretion disks around neutron stars is at the ground of many relevant astrophysical phenomena, like the black holes formation or the generation of jets responsible for the gamma ray bursts emission. The extreme state reached by the material accreating around a very compact object, requires an accurate description of all the phenomena relevant in the corresponding dynamics, i.e. the plasma structure of the medium. It was recently shown that the details of plasma physics induce significant modification in the accretion disk dynamics with respect to a simple fluid analysis. The main difference consists of the relevant poloidal currents which arise in the magnetized plasma and generate, in turn, a non-negligible magnetic field. The application of the ideal MHD to this axisymmetric system leads therefore to the appearance of a crystal structure in the radial dependence of the disck observables. By other words, the poloidal currents provide a local fragmentation of the disk into to ring-like substructures.

The current investigation in this topic is mainly concentrated on including into this plasma representation of the disk a precise astrophysical characterization of the real matter. In this respect, particular attention is devoted to the study of the effects that shear-viscosity induce on the crystal structures. In fact, the differential rotation of the disk radial portions is associated to a significant contribution due to a viscous stress-tensor which generate a non-negligible force in the tangential direction (Dr R. Benini, Dr G. Montani, Dr. F. Zonca). Further investigation are also concerning effects produced by the degenerate state of the plasma disk. Such an effect is expected to be relevant in the drift waves dynamics inside the disk layer (Dr G. Imponente, Dr G. Montani).