Radiation induced dynamics of the Galactic halo

We show results of numerical simulations of a three component plasma consis ting of electrons, ions and dust with external gravitation and radiation fi elds. We perform simulation runs, starting from an analytic halo equilibriu m, balancing pressure, gravitational, and radiative forces. Within these th e equilibrium is perturbed by the radiation of a typical OB-star associatio n. The perturbation has a total energy input of 10(7) L-. and a duration of 30 Myrs. After switching off the perturbation, the simulations are continu ed to further investigate the dynamics induced. We start with a self consistent one-fluid MHD model without background magn etic field and show for an asymmetric case that the system approaches a new equilibrium after switching on the perturbation. Later it relaxes into the starting configuration again, when the additional radiation is turned off. We then show, first by including a disk-parallel magnetic field and then b y redoing the simulations with a full three-fluid code, the influence of ma gnetic fields and species separation on the plasma dynamics. With our compu tations we demonstrate that these features can be important for the explana tion of the structures of galactic halos and large scale mass flows.