Low-Frequency Electrostatic Oscillations in Non-uniform Electron–Positron, Electron–Positron-Ion, and Electron–Ion Plasmas in the Presence of Ponderomotive Force

Abstract

Low-frequency electrostatic oscillations in three electron–positron, electron–positron-ion, and electron–ion quantum non-uniform magnetoplasmas in the presence of the ponderomotive force of the short pulse laser have been investigated in a comparative mode. According to the investigations, the oscillations in the direction parallel to the external magnetic field, where the plasmas are uniform in this direction, behave in the same way to a great extent in the three plasmas. In this direction, the oscillations are mostly influenced by the ponderomotive force of the laser, and in the absence of this force, they propagate stably with a constant phase and group velocities. In the presence of this force, the oscillations become unstable, and by the increase of this force, the instability rate and also the group and phase velocities of the oscillations increase. In the perpendicular direction, the oscillations indicate different behaviors in each of the three plasmas, and they are strongly affected by the number density, external magnetic field, and their transverse gradients. In this direction, the transverse gradient of the external magnetic field is the necessary condition for propagation of plasma waves in the electron–positron plasma, and also in the electron–ion plasma when the amount of ion charge is equal to the electron charge. However, in the electron–positron-ion plasma, due to the lack of charge symmetry, this condition is not necessary for perpendicular propagation.