A Theoretical Approach to the Investigation of Electrostatic Plasma Waves in Laser Pulse Interaction with Hypothetical Nonuniform Quantum Electron–Positron Magnetoplasma

Electrostatic plasma waves (EPWs) in a nonuniform quantum electron–positron magnetoplasma in the presence of ponderomotive force of laser have been studied using low-frequency and WKB approximations. Effects of the initial quantities and their transverse gradients and the effect of laser ponderomotive force on the plasma waves have been investigated. We indicate that the ponderomotive force, as regards its direction, has a significant effect on the plasma waves, and their instability rate in the parallel direction, so that, increasing the magnitude of this force increases the group and phase velocities of these waves and their instability rates. Also, the parallel plasma waves have been affected directly by amounts of initial number density and streaming velocity but, their dependence on the amount of external magnetic field is only, via the ponderomotive force. Our results indicate that in the quantum state, the additional correction terms in ponderomotive force can lead to a modification in the instability rate, and the plasma waves velocities. In the perpendicular direction, the transverse gradient of the external magnetic field was the only operant factor in the propagation of the EPWs, and it causes the waves become unstable. Also, their instabilities are affected by the magnetic field, number density, and their transverse gradients.