In recent years, using Sol-gel procedure for the purpose of laboratory and industrial synthesis of Nano-structures, and especially silica Nano-particles, has been significantly increased. In this research, silica particles were synthesized by Sol-gel procedure and their physical and chemical properties were studied by means of scanning electron microscopy (SEM), transmission electron microscopy...

The propagation of electron-acoustic waves (EAWs) in an unmagnetized plasma, comprising (r,q)-distributed hot electrons, cold inertial and stationary positive ions, is investigated. Both the unmodulated modulated EAWs, such as solitary waves, rogue (RWs), breathers are discussed. Sagdeev potential approach employed to determine existence domain electron acoustic structures study perfectly symme...

In the Plasma Beat Wave Accelerator, acceleration is achieved by a longitudinal electrostatic field produced as a result of charge separation generated by a plasma wave traveling close to the speed of light. The plasma wave in turn is produced by two colinear laser pulses whose amplitude is modulated so that the beat frequency matches the plasma frequency. Optical mixing and Raman forward scatt...

A fully relativistic treatment of Bernstein waves in an electron-positron pair plasma has remained too formidable a task, owing to the very complex nature of the problem. In this paper, we perform contour integration of the dielectric-response function and numerically compute the dispersion curves for a uniform magnetized relativistic electron-positron pair plasma. The behavior of the dispersio...

The nonresonant beat-wave excitation of relativistic plasma waves is studied in two-dimensional simulations and experiments. It is shown through simulations that, as opposed to the resonant case, the accelerating electric fields associated with the nonresonant plasmons are always in phase with the beat-pattern of the laser pulse. The excitation of such nonresonant relativistic plasma waves is s...

By making use of nonuniform magnetic fields, it is shown experimentally that control of helicon wave propagation can be achieved in a low pressure 0.08 Pa expanding plasma. The m=1 helicon waves are formed during a direct capacitive to wave mode transition that occurs in a low diverging magnetic field B0 3 mT . In this initial configuration, waves are prevented from reaching the downstream regi...

We show that a non-thermal electron distribution may change the nature of ion acoustic solitons. If the ions are assumed to respond as a fluid to perturbations in the potential, with no significant trapping in a potential well, then a thermal plasma only supports a solitary waves with a density peak. However, with a suitable distribution of non-thermal particles, solitary waves with both densit...

In this paper, by using a quantum hydrodynamic plasma model which incorporates the important quantum statistical pressure and electron diffraction force, we present the corrected plasmon dispersion relation for graphene which includes a k quantum term arising from the collective electron density wave interference effects (which  is integer and constant and k is wave vector). The longitudinal ...

The major goal of this group is to generate a basic understanding of various types of oscillations and waves in ionized gases that are relevant to problems in thermonuclear fusion and space research. The experimental and theoretical studies fall roughly into three main groups. a. Investigations of electromagnetic radiation emitted spontaneously by the plasma, because of thermal and nonthermal f...

The temporal evolution of drift-Alfv en waves in a plasma ow with homogeneous shear is studied as an initial value problem without the use of spectral expansion in time. It is shown that the conventional modal structure of the drift-Alfv en instability (as well as drift and Alfv en waves) pertains only in the initial stage of its evolution. For larger times, non-modal e ects due to the velocity...