Investigation On The Properties Of Nonlinear Waves In Magnetized Plasmas

Plasma is a matter state, which exists extensively in the universe. With the continuous development of nonlinear physics, a growing number of investigators are interested in the investigation of nonlinear properties of plasmas. Some magnetized plasma models are considered, and the properties of solitons, shocks, and head-on between two solitary waves are investigated. The research contents and the obtained results are as follows:1. The nonlinear properties of magnetoacoustic solitary waves (MASWs) are investigated in magnetized pair ion-electron (PIE) plasmas. The three-fluid collisionless electromagnetic model is considered and the reductive perturbation method is employed to derive the Korteweg-de Vries equation for MASWs in PIE plasmas. It is found that the system under consideration admits compressive solitary structures. The effects of magnetic field intensity, plasma number density and negative ions concentration on MASWAs are studied. This study may have relevance to nonlinear wave formation and the propagation of pair ion plasmas containing electron impurities.2. Nonlinear properties of magnetoacoustic waves are investigated in magnetized pair-ion plasmas with dust impurity. Three-fluid collisionless magnetohydrodynamic model is considered and reductive perturbation method is employed to derive KdV equation for magnetoacoutic solitary waves (MASWs). The effects of the charge number of dust particles, magnetic field, and plasma number density on MASWs are studied. It is found that by increasing the value of magnetic field intensity, both amplitude and width of solitary wave increase for positively charged dust particles. The amplitude of the solitary wave increases as the dust charge number is raised, while the width of the structure almost remains the same. However, both the amplitude and width of the solitary wave decrease by increasing positive ions number density.3. The properties of magnetoacoustic shock waves are investigated in magnetized quantum electron-positron-ion plasmas. The three-fluid magnetized quantum magnetohydrodynamic model is considered to derive the KdVB equation for magnetoacoustic shock waves by employing reductive perturbation method. It is found that the system under consideration admits shock waves structures. The effects of the magnetic field intensity, number density ratio of positronto ion, electrons number density, and kinematic viscosity on MASWs structure are investigated. It is found that the strength of shock increases with the increase of magnetic field firstly, It is found that the variation of the magnetic field and number density have same effects on the structure of shock waves. It is also shown that the strength and velocity of shock decrease with the increase of the number density of positrons to ions δ, however, the strength and velocity of shock increase significantly with the increase of kinematic viscosity of ion. The investigation may be useful for understanding of formation and propagation of magnetocoustic shock waves in dense electron-positron-ion magnetoplasma.4. We present the first study of the head-on collision between two electron acoustic solitary waves (EASWs) in magnetized quantum plasma consisting of electrons, positrons, and ions, using the extended Poincare-Lighthill-Kou (PLK) method, we obtain the Korteweg-de Vries equations, the phase shifts and the trajectories after the head-on collision of the two EASWs. It is found that the phase shifts are significantly affected by the values of the quantum parameter H, the ion to electron number density ratio δ, the electron cyclotron to electron plasma frequency ratio a and the obliqueness θ (direction of propagation)5. The properties of head-on collisions of two ion-acoustic solitary waves (IASWs) in magnetized plasmas with nonextensive electrons and positrons are studied unsing the extended Poicare-Lighthill-Kuo (PLK) method. The effects of the ion gyro-frequency to ion plasma frequency ratio, the positrons to ions number density ratio, the electrons temperature to positrons temperature ratio, and the nonextensive parameter q on the phase shifts are studied. It is shown that these factors fignificantly modify the phase shifts. It is useful for understanding the collective phenomena of space plasma with nonextensiv electons and positrons.