Radiometric force in dusty plasmas

A radiofrequency glow discharge plasma, which is polluted with a certain number of dusty grains, is studied. In addition to various dusty plasma phenomena, several specific colloidal effects should be considered. We focus on radiometric forces, which are caused by inhomogeneous temperature distribution. Aside from thermophoresis, the role of temperature distribution in dusty plasmas is an open question. It is shown that inhomogeneous heating of the grain by ion flows results in a new photophoresis like force, which is specific for dusty discharges. This radiometric force can be observable under conditions of recent microgravity experiments.Comment: 4 pages, amsmat

Ultrashort optical pulse propagation in terms of analytic signal

We demonstrate that ultrashort optical pulses propagating in a nonlinear dispersive medium are naturally described through incorporation of analytic signal for the electric field. To this end a second-order nonlinear wave equation is first simplified using a unidirectional approximation. Then the analytic signal is introduced, and all nonresonant nonlinear terms are eliminated. The derived propagation equation accounts for arbitrary dispersion, resonant four-wave mixing processes, weak absorption, and arbitrary pulse duration. The model applies to the complex electric field and is independent of the slowly varying envelope approximation. Still the derived propagation equation posses universal structure of the generalized nonlinear Schrdinger equation (NSE). In particular, it can be solved numerically with only small changes of the standard split-step solver or more complicated spectral algorithms for NSE. We present exemplary numerical solutions describing supercontinuum generation with an ultrashort optical pulse

Ultrashort Optical Pulse Propagation in terms of Analytic Signal

We demonstrate that ultrashort optical pulses propagating in a nonlinear dispersive medium are naturally described through incorporation of analytic signal for the electric field. To this end a second-order nonlinear wave equation is first simplified using a unidirectional approximation. Then the analytic signal is introduced, and all nonresonant nonlinear terms are eliminated. The derived propagation equation accounts for arbitrary dispersion, resonant four-wave mixing processes, weak absorption, and arbitrary pulse duration. The model applies to the complex electric field and is independent of the slowly varying envelope approximation. Still the derived propagation equation posses universal structure of the generalized nonlinear Schrödinger equation (NSE). In particular, it can be solved numerically with only small changes of the standard split-step solver or more complicated spectral algorithms for NSE. We present exemplary numerical solutions describing supercontinuum generation with an ultrashort optical pulse

Formation and stabilisation of single current filaments in planar dielectric barrier discharge

In the experimental part we report on a typical bifurcation scenario of the current distribution in the discharge plane of a planar dielectric barrier discharge system. Increasing the amplitude $\hat U$ of the sinusoidal driving voltage after breakdown a large number of dynamic solitary filaments is observed and the subsequent decrease of $\hat U$ results in a pronounced hysteresis with decreasing number of filaments. In this way isolated single stationary filaments can be generated. In the theoretical part the latter are modeled by a reaction-drift-diffusion equation that is solved in three dimensional space numerically without any fitting procedure. As a result we obtain well defined stationary filaments of which size an shape essentially are independent of the initial conditions and having a width and an amplitude that agree with experiment rather well. On the basis of the numerical results we consider mechanisms of filament stabilisation. This includes the discussion of the well known surface charges as well as an additional focusing effect of volume charges

From Optical Rogue Waves to Optical Transistors

We demonstrate that nonlinear wave interaction between fundamental solitons with surrounding dispersive waves in a nonlinear optical fiber leads to intermittent giant waves with all typical signatures of rogue waves. The underlying physical mechanism is based on the concept of the so-called optical event horizon and is naturally given in the supercontinuum generation process. Moreover, one can use this mechanism in a deterministic way to make an all-optical control of light pulses possible. This is a natural way to optical transistors

From Optical Rogue Waves to Optical Transistors

We demonstrate that nonlinear wave interaction between fundamental solitons with surrounding dispersive waves in a nonlinear optical fiber leads to intermittent giant waves with all typical signatures of rogue waves. The underlying physical mechanism is based on the concept of the so-called optical event horizon and is naturally given in the supercontinuum generation process. Moreover, one can use this mechanism in a deterministic way to make an all-optical control of light pulses possible. This is a natural way to optical transistors

Weather Modification in Georgia: Past, Present, Prospects for Development

Analysis of scientific and practical works on the artificial impact on the weather in Georgia in the past and at the present time (combating hailstorms, regulating the thunderstorm activity of clouds, artificial precipitation, etc.). The prospects for further development of these works are discussed