Dispersion Relation In Two-fluid Magnetohydrodynamics And Its Applications To Propagating Waves In Stratified Solar Atmosphere

EUV(Extreme Ultra-Violet)wave is characterized as a large-scale disturbances phenomenon emanated from the solar eruption source and can propagate globally in the solar corona,whose physical nature has been controversial for almost 20 years.Accord-ing to one leading theory,the EUV wave is a fast magnetoacoustic wave,as the coronal counterpart of Moreton wave in the chromosphere.However,observations have shown that EUV wave differs significantly from Moreton wave in both velocity and lifetime.To reconcile these differences,we here propose the wave characteristics of a two-fluid MHD model with partly ionization in the stratified solar atmosphere,and its dispersion relation is systematically analyzed.Through analysing its dispersion relation systemat-ically,we can obtain the solutions of Alfven wave,sound wave,fast and slow magne-toacoustic waves.The solved imaginary part of wave frequency is negative,indicating that these waves will be damped by the collision between the neutral and ionized gases.But the solved real part indicates the collision causes little change in these waves prop-agation velocities.By building some physics quantities models,including the magnetic field,temperature,the ionized ratio and collision frequency models,we can obtain the propagating characteristics of fast magnetoacoustic wave in stratified solar atmosphere.Because the chromosphere has the lower ionization rate and the stronger magnetic fields than the corona,the velocities of Moreton are much higher than those of EUV waves.The results can also solve the problem that the chromospheric fast-mode waves ve-locities in one-fluid MHD model are much lower than the Moreton waves velocities.In contrast to the chromospheric waves damped strongly by the collision,the coronal waves in the fully ionized corona are able to propagate longer and farther.Our results turn out to be consistent with the observations and support the previous theory that fast magnetoacoustic waves account for both EUV and Moreton waves in the different layers of solar atmosphere.