 The main problem encountered in deciphering the dynamics of the Jovian magnetosphere is the transport of heavy cold plasma from the Io torus at 6 "R"J to the outer magnetosphere at distances of more than 50 "R"J.The precise mechanism of this process is not known, but it is hypothesized to occur as a result of plasma diffusion due to interchange instability.The process is similar to the Rayleigh-Taylor instability in hydrodynamics.