The effect of silver nanoparticles doped in PVA on the structural and optical properties of composite films is studied experimentally. Samples are PVA films of 0.14 mm thickness doped with different sizes and concentrations of silver nanoparticles. Structural properties are studied using X-ray diffraction and FTIR spectrum. Using the reflectance and transmittance of samples, the effect of doped nanoparticles and their concentration on optical parameters of PVA films include absorption coefficient, optical bandgap energy, complex refractive index, complex dielectric function, complex optical conductivity, and relaxation time is extracted and discussed. The dispersion of the refractive index of films in terms of the single oscillator Wemple-DiDomenico (WD) model is investigated and the dispersion parameters are calculated. Results show that by doping silver nanoparticles in PVA, number of Bragg’s planes in the structure of polymer and its crystallinity are increased noticeably. Ag–O bonds are formed in the films and the bandgap energy of samples is decreased. Calculations based on WD model confirm that by doping nanoparticles, the anion strength of PVA as a dielectric medium is decreased.

The nonlinear dust acoustic solitary waves in a dusty plasma with two nonthermal ion species at different temperatures is studied analytically. Using reductive perturbation method, the Kadomtsev-Petviashivili (KP) equation is derived, and the effects of nonthermal coefficient, ions temperature, and ions number density on the amplitude and width of soliton in dusty plasma are investigated. It is shown that the amplitude of solitary wave of KP equation diverges at critical points of plasma parameters. The modified KP equation is also derived, and from there, the soliton like solutions of modified KP equation with finite amplitude is extracted. Results show that generation of rarefactive or compressive solitary waves strongly depends on the number and temperature of nonthermal ions. Results of KP equation confirm that for different magnitudes of ions temperature (mass) and number density, mostly compressive solitary waves are generated in a dusty plasma. In this case, the amplitude of solitary wave is decreased, while the width of solitary waves is increased. According to the results of modified KP equation for some certain magnitudes of parameters, there is a condition for generation of an evanescent solitary wave in a dusty plasma.

Using a gas-jet flow, via the interaction between an ultrashort high-intensity laser pulse and plasma in the presence of a perpendicular external dc magnetic field, the short pulse radiation from a magnetized plasma wakefield has been observed. Different nozzles are used in order to generate different densities and gas profiles. The neutral density of the gas-jet flow measured with a Mach-Zehnder interferometer is found to be proportional to back pressure of the gas jet in the range of 1 to 8 atm. Strength of the applied dc magnetic field varies from 0 to 8 kG at the interaction region. The frequency of the emitted radiation with the pulse width of 200 ps (detection limit) is in the millimeter wave range. Polarization and spatial distributions of the experimental data are measured to be in good agreement with the theory based on the V(p)xB radiation scheme, where V(p) is the phase velocity of the electron plasma wave and B is the steady magnetic field intensity. Characteristics of the radiation are extensively studied as a function of plasma density and magnetic field strength. These experiments should contribute to the development of a new kind of millimeter wavelength radiation source that is tunable in frequency, pulse duration, and intensity.

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