Influence of superthermal electrons on obliquely propagating ion-acoustic solitons in magnetized plasmas

Abstract

The effect of superthermal electrons, modeled by a Lorentzian velocity distribution function, on the oblique propagation characteristics of linear and nonlinear ion-acoustic waves in an electron-ion plasma in the presence of a uniform external magnetic field is investigated. First, the linear dispersion relations of the fast and slow modes are obtained. It is shown that the superthermal electrons make both modes propagate with smaller phase velocities. Then, the Korteweg-de Vries equation describing the propagation of nonlinear slow and fast ion-acoustic waves is derived. It is shown that the presence of superthermal electrons has a significant influence on the nature of magnetized ion-acoustic solitons. That is, for a larger population of the superthermal electrons, the soliton velocity of both modes in the laboratory frame significantly decreases and the soliton are slimmer, and on approaching the Maxwellian limit, the width becomes maximum.

Effect of Dust Grains on Dust-Ion-Acoustic KdV Solitons in Magnetized Complex Plasma with Superthermal Electrons

“…1 and 2 that by increasing the population of the superthermal electrons (smaller j), both of modes propagate with smaller phase velocity in comparison with the Maxwellian plasma (similar to the results of [30]). Figure 3 shows the changes of coefficients a; b with j for different q.…”

“…In order to obtain a better insight into the role of the dusts and superthermal electrons on the nature of DIA solitary waves, we perform a numerical simulation of the velocity, u, of DIA solitary waves and their width. Figure 5 depicts the normalized soliton velocity versus j for u fm ¼ u sm ¼ 0:1 and h ¼ 0:7 rad: As seen from this figure, the presence of superthermal electrons, for both modes, is that for a larger population of superthermal electrons (smaller j) the soliton velocity significantly decreases [30]. Also for larger q, (Fig.…”

“…Figure 6a exhibits, in the absence of dusts, q = zi, for larger population of superthermal electrons (smaller j) the soliton width is smaller [30,32] but Fig. 6b and c indicate for 2\j\3 (that dark solitons are propagated), for larger j; the soliton width becomes larger but for j 1 3 (that bright solitons are propagated) for larger j; the solitons become slimmer and on approaching the Maxwellian limit the width becomes near its minimum.…”

“…In both of figures, for the larger population of superthermal electrons (smaller j), the coefficient of the dispersive term of the KdV equation, b; becomes smaller and consequently the solitons have to be much slimmer [30]. Figure 4 depicts the influence of the charge state of ions, zi, on the coefficients a; b for fixed q = 2zi.…”

“…5b, c), the DIA waves have been faster [32,33] and the velocity of DIA soliton in the Maxwellian limit (j [ 15) is supersonic for both modes, but the soliton velocity of the slow mode is always subsonic when the dust grains are absent (i.e. q = zi) [30].…”