Oblique collision of ion acoustic solitons in a relativistic degenerate plasma.

The interaction (oblique collision) of two ion acoustic solitons (IASs) in a magnetized relativistic degenerate plasma with relativistic degenerate electrons and non-degenerate cold ions is studied. The extended Poincaré-Lighthill-Kuo (PLK) method is used to obtain two Korteweg deVries (KdV) wave equations that describe the interacting IASs, then the phase shifts due to interaction are calculated. We studied influence of the fluid number density on the interaction process, interacting solitons phase shifts and also phase velocities. The introduced model is valid for astrophysical objects with high density matter such as white dwarfs, neutron stars, degenerate electrons gas in metals and laboratory degenerate plasma. An inverse proportionality between the phase shifts, phase velocity and the equilibrium electron fluid number density [Formula: see text] was established in the range [Formula: see text]. We found that the soliton waves get sharper (narrower) and higher with increasing the electrons fluid number density [Formula: see text], and hence less spacial occupying. The phase shifts and the phase velocity remain approximately unchanged in the range of [Formula: see text]. The impact of the obliqueness angle [Formula: see text] on the soliton interaction process is also studied.

Head-on collision of dust acoustic solitons in a nonextensive plasma with variable size dust grains of arbitrary charge.

The head-on collision of two dust acoustic solitons (DASs) in a nonextensive plasma with positive or negative dust grains fluid including the effect of dust size distribution (DSD) is studied. The phase shifts for the two solitons due to the collision are derived by applying the extended Poincaré-Lighthill-Kuo (PLK) method. The influences of the power law DSD and the nonextensivity of plasma particles on the characteristic properties of the head-on collision of DASs are analyzed. It is found that the phase shifts can vanish, only for the case of positive dust grains, for certain values and ranges of the dust grain radius and the entropic index of ions (q_{i}). Also, they undergo a cutoff in the range of q_{i}>1 for the subextensive distribution. A brief discussion of possible applications in laboratory and space plasmas is included.

Weakly nonlinear ion-acoustic excitations in a relativistic model for dense quantum plasma.

The dynamics of linear and nonlinear ionic-scale electrostatic excitations propagating in a magnetized relativistic quantum plasma is studied. A quantum-hydrodynamic model is adopted and degenerate statistics for the electrons is taken into account. The dispersion properties of linear ion acoustic waves are examined in detail. A modified characteristic charge screening length and "sound speed" are introduced, for relativistic quantum plasmas. By employing the reductive perturbation technique, a Zakharov-Kuznetzov-type equation is derived. Using the small-k expansion method, the stability profile of weakly nonlinear slightly supersonic electrostatic pulses is also discussed. The effect of electron degeneracy on the basic characteristics of electrostatic excitations is investigated. The entire analysis is valid in a three-dimensional as well as in two-dimensional geometry. A brief discussion of possible applications in laboratory and space plasmas is included.

Stability of three-dimensional dust acoustic waves in a dusty plasma with two opposite polarity dust species including dust size distribution.

Propagation of dust acoustic waves (DAWs) with the effect of power law dust size distribution (DSD) in a magnetized dusty plasma with opposite polarity dust is studied. Using a reductive perturbation method, a Zakharov-Kuznetsov equation appropriate for describing three-dimensional DAWs is derived. The compressive and rarefactive solitons are possible in the present model. Due to the DSD effect, a soliton with a smaller amplitude and width and a larger velocity is observed. The stability criterion for obliquely propagating DAWs in such plasma using small-k expansion method is investigated. The growth rate of instability is derived and analyzed under the effect of power law DSD. It is found that the growth rate of instability is strongly affected by the power law DSD. The relevance of these findings to space plasma phenomena is briefly discussed.