Magnetized electron-positron plasmas, a new mode, stability conditions

In this paper, a set of two-fluids equations based on the quantum magnetic hydrodynamic model (QMHD) for electron-positron plasma were considered and the role of spin in different spin-spin, and spin-field interactions were briefly discussed. Furthermore, effects of density and heterogeneity in the equations were considered. For each of the two electron and positron fluids, the complete theory of spin-1/2 electron-positron quantum plasmas when electrons and positrons move with velocities much smaller than the speed of light was discussed. By considering the two regimes of non-spin and spin plasma separately, new dispersion relations was extracted and analyzed. We also examined the limits of weak and strong magnetic fields and the effect of spin polarization on ripple waves in plasma medium. Results show that the spin-current evolution in a magnetized plasma creates a new dispersion mode. The fast mode generates in the direction perpendicular to the direction of propagation of the waves. The speed of this mode is equal to the speed of the mode in the parallel direction plus an additional term that depends on the characteristics of the system. For high-density plasma, this correction is negligible, but for very low densities and weak magnetic fields, this effect is significant.