New Research in Physics

Abstract Abstract A new modification to the Gilmore model is introduced to accurately simulate the effects of liquid shear and bulk viscosity and compressibility on the radial cavitation dynamics of a single bubble under a driving ultrasound field. Furthermore, in order to an accurate description of interior gas thermodynamics, a hydrochemical model, in which the heat and mass interchange across the bubble wall and also the chemical reactions are included, is used. The results of newly developed model are compared to those attained from the more practical Gilmore model. The simulations result for a single argon bubble in water show that neglecting the terms related to liquid viscosity and compressibility in the momentum conservation equation could affect the maximum temperature and pressure inside the bubble at the final moments of collapse. Under the conditions used in this study, the maximum pressure changes up %2. Moreover, the temporal evolution of water vapor particles meets the results obtained using the molecular dynamics simulation.

Abstract In this paper by substituting the dielectric tensor in the Maxwell’s equations and applying the boundary conditions in a longitudinally magnetized plasma-filled coaxial waveguide ,six hybrid field components for azimuthal symmetric mode are obtained.The dispersion relation,and power for electromagnetic waves propagating in the considered configuration are derived.We examine the acceleration of an injected external relativistic electron using radiation of a microwave source in the considered waveguide having an azimuthal symmetric mode.The trajectory,velocity components,total energy and kinetic energy of injected electron in the considered waveguide along propagating axis and hybrid field components are plotted.The obtained differential equations are numerically solved by fourth-order Runge–Kutta method and results are graphically presented.

Abstract In this study, the propagation of electromagnetic waves and band gap structure in a one-dimensional ternary plasma photonic crystal including collisional plasma taking into account of thermal velocity of the electrons is investigated. Each unit cell of the structure consists of dielectric I-plasma-dielectric II. Plasma is a dispersive medium, meaning that its refractive index depends on the frequency of the incident electromagnetic wave. This feature distinguishes plasma photon crystal from other common photon crystals. In present paper, by using transfer matrix method, the absorption and reflection intensities of the electromagnetic waves with TE polarization are studied when the wave normally and obliquely incident on the photonic crystal. The results of simulation show that by changing different parameters of the photonic crystal such as the thickness and temperature of the plasma layer, dielectric constant and thickness of the dielectric layers, the width, number and the location of band gaps can be purposefully adjusted and the absorption of incident waves can be controlled.

Abstract Supercapacitors as electrical energy storage systems are widely known devices and due to the complexity of these systems, the numerical simulation is a fundamental approach to investigate their charging mechanism. Geometric effects of the pore are important on the electrical capacitance properties of supercapacitors. In this paper, the effects of linear pores width on their ion-philic behaviors are investigated. For this purpose similar linear pore systems that only differ in the pores’ width are simulated by using the PLT algorithm implemented in CAVIAR. The systems are simulated at two different applied voltages: 0 and 2 V. It was shown that the width is an important factor, that is, a larger pore width shows more ion-philic behaviors.

Abstract The relativistic effects on the dust grain charging process and the dust grain electrical potential are investigated by taking into account the relativistic cross section by the orbit-limited motion (OLM) theory, a kinetic model and the relativistic Maxwellian distribution function for currents carried by ions and electrons. The calculations are applied by the numerical analyses to finding the dust grain electrical potential in the dust charging process. It is found that by increasing the dust grains density, dust particles are as a component from conventional multi-ionic plasma that shows the collective behavior. In addition to, it is indicated that the role of mass is more colorful than the ion temperature in the light plasma such as hydrogen versa the heavy plasma such as oxygen in relativistic regime. Moreover, it is showed that, as ions are closer to the ultra-relativistic range, the dust grain electrical potential is increased and the difference between the dust grain electrical potential in oxygen, helium and hydrogen plasmas become more and more.

Abstract In this project, we investigate the properties of old and young galaxies in different environments, based on SDSS sample in the local universe. In order to that, we extracted the cluster and void catalog that are brighter than 𝑀𝑟~−17 and located in 𝑧<0.04. We show that massive old galaxies in void and cluster environments have higher velocity dispersion. On the other hand, this trend cannot be seen for young galaxies, especially for lower mass. Also, old galaxies are smaller than young galaxies at the same stellar-mass for void and cluster environments. In both environments, the sersic-index is constant for the low mass regime of young galaxies but increases for massive old galaxies. Although there is tight relation between the color of young galaxies and stellar-mass in both environments, it remains constant for all range mass of old galaxies. This study shows that the properties of old and young galaxies in local universe are independent of environments.

Abstract Excitation of plasmons at the surface of the overdense plasma is responsible for the transition of the energy of electromagnetic waves in the plasma. The effects of the nonlinearities and dispersions are inevitable in the overdense plasma. In this article, it is investigated these effects on the excitation of the surface waves on the interface between the plasma and vacuum. Using the perturbation expansion, the equations are analytically solved up to the second order. By studying the dispersion relation, the conditions are obtained for the formation of the surface waves in both linear and second-order approximations. The results show that the dissipation effects have important outcomes on the dispersion relation and its consequences. Specifically, in the presence of these effects, the frequency regime suitable for the surface wave excitations becomes wider. At the second-order approximation, the dissipation effects lead to the excitation of the surface waves at lower frequencies.