Gravitational-Wave Stochastic Background from Kinks and Cusps on Cosmic Strings

We compute the contribution of kinks on cosmic string loops to stochastic background of gravitational waves (SBGW).We find that kinks contribute at the same order as cusps to the SBGW.We discuss the accessibility of the total background due to kinks as well as cusps to current and planned gravitational wave detectors, as well as to the big bang nucleosynthesis (BBN), the cosmic microwave background (CMB), and pulsar timing constraints. As in the case of cusps, we find that current data from interferometric gravitational wave detectors, such as LIGO, are sensitive to areas of parameter space of cosmic string models complementary to those accessible to pulsar, BBN, and CMB bounds.Comment: 24 pages, 3 figure

On production and asymmetric focusing of flat electron beams using rectangular capillary discharge plasmas

A method for the asymmetric focusing of electron bunches, based on the active plasma lensing technique is proposed. This method takes advantage of the strong inhomogeneous magnetic field generated inside the capillary discharge plasma to focus the ultrarelativistic electrons. The plasma and magnetic field parameters inside the capillary discharge are described theoretically and modeled with dissipative magnetohydrodynamic computer simulations enabling analysis of the capillaries of rectangle cross-sections. Large aspect ratio rectangular capillaries might be used to transport electron beams with high emittance asymmetries, as well as assist in forming spatially flat electron bunches for final focusing before the interaction point.Comment: 16 pages, 7 figures, 1 tabl

Laser beam coupling with capillary discharge plasma for laser wakefield acceleration applications

One of the most robust methods, demonstrated up to date, of accelerating electron beams by laser-plasma sources is the utilization of plasma channels generated by the capillary discharges. These channels, i.e., plasma columns with a minimum density along the laser pulse propagation axis, may optically guide short laser pulses, thereby increasing the acceleration length, leading to a more efficient electron acceleration. Although the spatial structure of the installation is simple in principle, there may be some important effects caused by the open ends of the capillary, by the supplying channels etc., which require a detailed 3D modeling of the processes taking place in order to get a detailed understanding and improve the operation. However, the discharge plasma, being one of the most crucial components of the laser-plasma accelerator, is not simulated with the accuracy and resolution required to advance this promising technology. In the present work, such simulations are performed using the code MARPLE. First, the process of the capillary filling with a cold hydrogen before the discharge is fired, through the side supply channels is simulated. The main goal of this simulation is to get a spatial distribution of the filling gas in the region near the open ends of the capillary. A realistic geometry is used for this and the next stage simulations, including the insulators, the supplying channels as well as the electrodes. Second, the simulation of the capillary discharge is performed with the goal to obtain a time-dependent spatial distribution of the electron density near the open ends of the capillary as well as inside the capillary. Finally, to evaluate effectiveness of the beam coupling with the channeling plasma wave guide and electron acceleration, modeling of laser-plasma interaction was performed with the code INF&RNOComment: 11 pages, 9 figure

Non-adiabatic cluster expansion after ultrashort laser interaction

AbstractWe used X-ray spectroscopy as a diagnostic tool for investigating the properties of laser-cluster interactions at the stage in which non-adiabatic cluster expansion takes place and a quasi-homogeneous plasma is produced. The experiment was carried out with a 10 TW, 65 fs Ti:Sa laser focused on CO2 cluster jets. The effect of different laser-pulse contrast ratios and cluster concentrations was investigated. The X-ray emission associated to the Rydberg transitions allowed us to retrieve, through the density and temperature of the emitting plasma, the time after the beginning of the interaction at which the emission occurred. The comparison of this value with the estimated time for the "homogeneous" plasma formation shows that the degree of adiabaticity depends on both the cluster concentration and the pulse contrast. Interferometric measurements support the X-ray data concerning the plasma electron density

QUANTITATIVE ASSESSMENT OF THE INVESTMENT PROJECT CREATION OR RENOVATION TRANSPORT INFRASTRUCTURE

Summary. The paper proposes a method of determining the quantitative assessment of the investment project of reconstruction of the facility or transport infrastructure, taking into account the impact on both the vehicle and non-transport effect. Among the most significant socio- economic benefits of modernization and development of the road network of the federal and regional significance include: improving and improving and improving the social conditions of the population , increased economic activity , reduction of transport costs in the price of goods and services, reducing the negative impact of transport and road complex environment. Modelling of toxic pollutant emissions for the transport stream to optimize road to reconstruct existing infrastructure by minimizing environmental damage. Kinematic model of traffic flow, which allows to express the parameters of toxic pollution through directly observable quantities, based on the concept of cellular automata , augmented parameters governing the organization of traffic. Necessary to determine the parameters of motion so that the average flow rate was in the optimal range (60 - 90) km / h. Multicriteria optimization problem so requires collecting and analyzing vast and diverse information of the following types: topographic, demographic, social, economic, environmental, transport. As follows from the calculations, the doses of all types of toxic effects, per unit length of the road, increase significantly in the fall an average speed of traffic flow. Thus, modeling of toxic emissions transport stream allows one hand to optimize the traffic in the existing infrastructure and, on the other hand, to optimize the construction and reconstruction of infrastructure

INNOVATIVE MECHANISM FOR RENTAL HOUSING IN THE REGION (VORONEZH REGION)

Summary. One mechanism for addressing the housing problems of the population in the coming years could be the construction of rental (wage) housing. Pilot projects for the construction of rental housing implemented in many regions of Russia: Samara, Krasnodar, Novosibirsk, Kaluga, Nizhny Novgorod and Kemerovo regions, the Republic of Tatarstan. Thus, rental housing projects (tenements) are currently produced in Nizhny Novgorod, with the objectives of these projects are: the solution of social problems; legalization rental business premises; profit at the expense of rent; creation of new jobs; improving the city's infrastructure. These projects are realized in a some of regions of the country, influence on the realty market thus is insufficiently considered. In article methodical maintenance for creation of the housing intended for tenancy is offered. The system of the coefficients is developed, allowing characterizing various aspects of building of rental housing in region. These coefficients are divided into 4 categories: coefficients of availability of rental housing; coefficient of competitiveness of rental housing; the coefficients characterizing scales of construction of rental housing in region; coefficient of fillability of rental housing. The expediency building of rental housing in one of most dynamically developing regions - the Voronezh region is considered. Research suggests that the construction of rental housing in the region will not only provide a good opportunity to the people solving the housing problem, but is an essential resource and improve the region's competitiveness in the struggle for human resources

Discharge plasma formation in square capillary with gas supply channels

A comprehensive model of processes in a discharge capillary is required in order to obtain nominal parameters of a preformed plasma channel suitable for the laser wake-field acceleration. We present three-dimensional magnetohydrodynamics simulations of a hydrogen gas filling process and discharge plasma formation in a short square shaped capillary with gas supply channels. Time evolution of the gas pressure and the plasma density in the capillary channel for a chosen discharge current profile is analyzed. Performed simulations provide distributions of the electric current, the magnetic field, and the electron density along the whole channel, taking into account gas supply areas as well as areas outside of the capillary. Obtained results show that the presence of gas supplies leads to the inhomogeneous plasma density distribution along the capillary channel which has to be taken into account for generating an optimal laser-driven electron beam

Experimental and numerical studies of structure of cluster targets for femtosecond laser pulses

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