A new purely growing instability in a strongly magnetized nonuniform pair plasma

Abstract

It is shown that a strongly magnetized nonuniform electron-positron (hereafter referred to as e-p or pair) plasma is unstable against low-frequency (in comparison with the electron gyrofrequency) electrostatic oscillations. For this purpose, a dispersion relation is derived by using the Poisson equation as well as the electron and positron continuity equations with the guiding center drifts for the electron and positron fluids. The dispersion relation admits a purely growing instability in the presence of the equilibrium density and magnetic field inhomogeneities. Physically, instability arises because of the inhomogeneous magnetic field induced differential electron and positron density fluctuations, which do not keep in phase with the electrostatic potential arising from the charge separation in our nonuniform pair plasmas.

On the instability of electrostatic waves in a nonuniform electron–positron magnetoplasma

“…2). Comparing to the recent work which has been done by Shukla and Shukla [17], the present model reveals two wave modes with different velocities. The inclusion of the electron temperature gradient (ETG) produces two stable wave modes, (31).…”

“…In order to investigate the low-frequency electrostatic waves in comparison with the electron gyrofrequency ω ce = eB 0 /mc, where e, m and c are the magnitude of the electron charge, the electron/positron mass and the speed of light in vacuum, respectively, we use the basic set of linearized continuity equations [16,17],…”

“…The plasma collective mode remains stable near the thermodynamic equilibrium state, while it becomes unstable for a non-equilibrium state due to the free energy source availability. There could be different types of free energy sources, such as the streaming of plasma particles [15][16][17], spatial variations of the equilibrium number density [15][16][17][18], the magnetic field [16,17] and the plasma temperature inhomogeneities [16,18,19]. Such gradients of the physical quantities can drive collective modes unstable [14].…”

“…Such gradients of the physical quantities can drive collective modes unstable [14]. For this purpose several authors have paid attention to explain the enhanced fluctuations which play a significant role in the anomalous transport phenomena such as heat transport across the external magnetic field lines [14][15][16][17][18][19][20]. For example, Shukla and Weiland [21] investigated the toroidal electron-temperature-gradient (ETG) driven electromagnetic drift waves.…”

“…Shukla et al [16] highlighted the combined effects of the ETG and parallel electron velocity gradient on electrostatic instabilities in a nonuniform magnetoplasma. Recently, Shukla and Shukla [17] presented a new purely growing instability in a nonuniform EP plasma with equilibrium density and magnetic field inhomogeneities.…”