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Generation of compressional Alfvénic rogue and solitary waves in magnetohydrodynamic plasmas is investigated. Dispersive effect caused by non-ideal electron inertia currents perpendicular to the ambient magnetic field can balance the nonlinear steepening of waves leading to the formation of a soliton. The reductive perturbation method is used to obtain a Korteweg-de Vries (KdV) equation describing the evolution of the solitary wave. The height of a soliton is proportional to the soliton speed 'U' and inversely proportional to plasma 'β' (ratio of plasma thermal pressure to pressure of the confining magnetic field) and the width of soliton is proportional to the electron inertial length. KdV equation is used to study the nonlinear evolution of modulationally unstable compressional Alfvénic wavepackets via the nonlinear Schrödinger equation. The characteristics of rogue wave influenced by plasma 'β' and the electron inertial length are described. [ABSTRACT FROM AUTHOR]

Particle simulations and a pseudopotential method were used to study ion-acoustic solitary waves in a plasma composed of Boltzmann electrons and kinetic beam ions. Pseudopotential theory was first applied to determine how ion-acoustic solitary waves can exist in a two-component plasma. Then, particle simulations were carried out, wherein ion-acoustic solitary waves were excited by modulating the bias grid voltage in a double plasma model. For the modulation, the potential of the grid bias was rapidly decreased, such that hump-type ion-acoustic solitary waves with good Gaussian shape were excited one after another, forming a train of waves. The simulation also showed that the phase velocities of ions decrease sharply when the solitary wave occurs, which indicates that the solitary ion-acoustic wave is excited via the inverse Landau damping process. [ABSTRACT FROM AUTHOR]

The existence condition for bump and dip type, as well as double layer (DL), solutions of electrostatic solitary waves (ESWs) in a nonthermal electron plasma with heavy ions is investigated by a pseudopotential method. It is found that the nonthermality of electrons determines the existence of the DL solution and that the amplitude of ESWs is enhanced by the density of heavy ions. When the heavy ion density is beyond a certain critical value, ESWs and DLs cannot exist. It is also found that both the lower and upper critical Mach numbers are reduced by the presence of heavy ions. [ABSTRACT FROM AUTHOR]

Coulombic expansion of an atomic cluster can significantly affect the growth of stimulated Raman backscattering in cluster embedded plasmas. The pulse attenuation and the collisional absorption occur during the early phase of cluster expansion, competing against each other in determining the Raman threshold intensity in a cluster plasma. The threshold laser intensities estimated for various wave numbers of the electron plasma waves are found to be consistent with the previous result [P. K. Tiwari et al., Phys. Plasmas 14, 103101 (2007)]: Collisional threshold intensities are to be of 1∼105 W/cm2 at the electron-ion collisional frequency ≈1013 s-1, and the pulse attenuated threshold intensities are to be of ∼1013 W/cm2 for short pulse length ∼20 fs. The pulse attenuation and collisional absorption of Raman threshold intensities are found to be inversely proportional to both the pulse duration and attenuation length. [ABSTRACT FROM AUTHOR]

A high intensity laser short pulse causes rapid tunnel ionization of an inhomogeneous gas. The tunnel ionization of the gas causes a defocusing of the laser pulse. The electron experiences an unequal ponderomotive force due to the trailing and rising part of the laser pulse, hence, gains net energy. The net acquired electron energy is reduced due to the inhomogeneity in gas density. If the accelerated electrons are targeted to a low-Z material nucleus, the electron-positron pair will be created via a trident process. [ABSTRACT FROM AUTHOR]