Flow of a fissioning gas in an outflow disk magnetohydrodynamic generator

Abstract

The influence of fissioning and magnetohydrodynamic (MHD) interaction on the steady, supersonic flow of a compressible, turbulent, weakly ionized, fissioning gas in an outflow disk MHD generator is investigated. The two-dimensional (r, z) MHD flow is modeled using the thin-layer Navier-Stokes equations with MHD and fission power density source terms and Maxwell's equations, simplified by the MHD approximations and by neglecting the induced magnetic field. Simple plasma physics transport property models are developed for the collisiondominated, weakly ionized plasma in which fission fragment induced ionization provides the dominant source of conduction electrons. The two-dimensional MHD solution methodology is used to characterize the effects of fission power density and variable applied magnetic induction levels on the spatial profiles of important generator variables. A comparison of the predictions of the two-dimensional MHD solver with those of a quasi-onedimensional Euler solver with MHD and fission source terms is used to discuss the relative influence of twodimensional effects on the generator flowfield and on performance levels. The low MHD interaction and generator performance levels predicted for the supersonic fissioning plasma suggest that the fission fragment induced ionization, by itself, is insufficient to effect the electrical conductivity levels needed for practical power generation in the outflow disk MHD generator configuration of this study.