Direction Change of the Force Action upon Conductor under Frequency Variation of the Acting Magnetic Field

The present work is dedicated to the description of the thin-walled conductor attraction effect by the pulse magnetic field. This phenomenon was displayed experimentally. The effect pointed out relates to the direction of the pulse magnetic fields energy practical usage for the different technologies in manufacture. In the scientific literature this direction is known as the magnetic pulse metal forming. A hypothesis about the physical essence of the displayed phenomenon is suggested

Electromagnetic wave scattering by a superconductor

The interaction between radiation and superconductors is explored in this paper. In particular, the calculation of a plane standing wave scattered by an infinite cylindrical superconductor is performed by solving the Helmholtz equation in cylindrical coordinates. Numerical results computed up to $\mathcal{O}(77)$ of Bessel functions are presented for different wavelengths showing the appearance of a diffraction pattern.Comment: 3 pages, 3 figure

Bulk and Surface Nanoscale Hole Density Inhomogeneity in HgBa2_2CuO4+δ_{4+\delta} and Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta} Cuprates

It is well established that the hole density in the prototypical superconductor La$_{2-x}$Sr$_x$CuO$_4$ is very inhomogeneous due to Sr-dopant induced disorder. On the other hand, until recently it is widely believed that the hole distribution in HgBa$_2$CuO$_{4+\delta}$ and Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ doped by interstitial oxygen is much more uniform. Recent nuclear magnetic resonance measurements indicate, however, that the charge inhomogeneity in HgBa$_2$CuO$_{4+\delta}$ is close to that in La$_{2-x}$Sr$_x$CuO$_4$. Calculations performed in the present paper confirm this observation. We also show that the charge inhomogeneity is most pronounced at the surface layer that can be probed by scanning tunneling microscope. Our simulations demonstrate that, despite having similar amplitudes of charge inhomogeneity, the hole mean free path in HgBa$_2$CuO$_{4+\delta}$ is substantially longer than that in La$_{2-x}$Sr$_x$CuO$_4$. The screening of Coulomb repulsion in HgBa$_2$CuO$_{4+\delta}$ is also stronger. These two reasons might explain the difference in superconducting critical temperatures between these two compounds.Comment: to appear in PRB, extended discussion of hole mean free pat

Pulsed Electromagnetic Attraction Processes for Sheet Metal Components

The work is dedicated to EMF attraction processes which can deform both ferromagnetic and non-ferromagnetic sheet metal materials (low carbon steels, stainless steels and aluminum alloys) using low frequency discharges. The analytical models of both tooling configurations are based upon the solution of Maxwell equations in axially symmetrical formulation. For ferromagnetic materials, the attraction effect is based upon magnetic forces prevailing over the Lorentz forces for low frequency discharges. For nonferromagnetic materials, the attraction forces are created by employing the auxiliary screen which attracts the sheet metal blank. The concept of attraction in this inductor system is based upon inducing currents flowing in the same directions in the screen and in the sheet metal blank. In addition to the analytical models, the described concepts are illustrated by the experimental results on attraction of sheet metal blanks employing a single turn inductor

Electrostatic interaction of a pointlike charge with a wormhole

A pointlike electric charge at rest is considered in the spacetime which is a wormhole connecting two otherwise Minkowskian spaces. The potential (i. e. a solution of the Maxwell equations) is split into two parts: one of them depends only on the value and location of the charge, while the other, on the contrary, does not change when the charge is quasistatically moved. Correspondingly, the former is interpreted as being generated by the charge, and the latter as being source-free. It is shown that all source-free potentials differ in the flux through the throat (no "multipoles without multipoles"), which enables one to interpret the flux as the "charge" of the wormhole in agreement with Wheeler's concept of "charge without charge". The potential generated by the charge differs from Coulomb's and thus a force (called "self-force") acts on the charge even in the absence of the source-free field. This force is found explicitly in the limit of vanishing throat length. The result differs from that obtained recently by Khusnutdinov and Bakhmatov.Comment: The published version: 1) the regularity is proven 2) the part is rewritten explaining where is the error in Khusnutdinov and Bakhmatov's resul

Numerical Simulation of Multicomponent Ion Beam from Ion Sources

A program library for numerical simulation of a multicomponent charged particle beam from ion sources is presented. The library is aimed for simulation of high current, low energy multicomponent ion beam from ion source through beamline and realized under the Windows user interface for the IBM PC. It is used for simulation and optimization of beam dynamics and based on successive and consistent application of two methods: the momentum method of distribution function (RMS technique) and particle in cell method. The library has been used to simulate and optimize the transportation of tantalum ion beam from the laser ion source (CERN) and calcium ion beam from the ECR ion source (JINR, Dubna)

ЭКСПЕРИМЕНТАЛЬНЫЕ ИССЛЕДОВАНИЯ РАСПРЕДЕЛЕНИЯ ТОКА НА ПОВЕРХНОСТИ ЛИСТОВОЙ ЗАГОТОВКИ В ЛИНЕЙНЫХ ИНСТРУМЕНТАХ МАГНИТНО-ИМПУЛЬСНОГО ПРИТЯЖЕНИЯ

Purpose. The purpose of the present work consists in the characteristics experimental determination of the pulsed current transverse distribution on the surface of a sheet non-magnetic metal between the point contacts of the power source with different geometry of their connection under operating frequencies variation. Methodology. The measurements were carried out using methods based on the known positions of electromagnetism. The simulating low-voltage equipment was used, as well as high-voltage power sources with a high level of the stored energy. Numerical processing of the measurement results was carried out using standard programs from the «Wolfram Mathematica» package. Results. The space-temporal shapes of the pulsed current density transverse distribution on the surface of the sheet blank were obtained and analyzed. It is established that the degree of transverse current concentration in sheet metal relative to the center of the system in the operating frequency range of ~ 1.8…22 kHz depends very little on its temporal characteristics. It was found that the level of the transverse current concentration in the conditionally allocated band connecting the contacts of connection depends significantly on the ratio of the width of this band and the transverse dimensions of the contact connection. Moreover, the smallest current is concentrated in a strip whose width is much less than the distance between the contacts (£ 11…16 %). Originality. For the first time, the numerical estimates degree of the current transverse concentration are obtained and the dependence of this parameter on the temporal characteristics of the current, as well as on the method of connecting the power source contacts, is established. Practical value. The research results will allow creating the new more efficient linear tools of magnetic-pulsed attraction of sheet metals, based on the force interaction of conductors with unidirectional currents. Целью работы является экспериментальное определение характеристик поперечного распределения плотности импульсных токов разной частоты на поверхности листового немагнитного металла между точечными контактами источника мощности при различной геометрии их подключения. Методика. Измерения проводились с помощью методов, основанных на известных положениях электромагнетизма. Использовалось модельное низковольтное оборудование, а также высоковольтные источники мощности с высоким уровнем запасаемой энергии. Численная обработка результатов измерений проводилась с помощью стандартных программ из пакета «Wolfram Mathematica». Результаты. Получены и проанализированы пространственно-временные формы поперечного распределения плотности импульсного тока на поверхности листовой заготовки. Научная новизна. Впервые получены численные оценки степени поперечной концентрации тока и установлена зависимость данного параметра от временных характеристик тока, а также от способа подключения контактов источника мощности. Практическое значение. Результаты исследований позволяют создавать новые более эффективные линейные инструменты магнитно-импульсного притяжения листовых металлов, основанные на силовом взаимодействии проводников с однонаправленными токами

ЭКСПЕРИМЕНТАЛЬНЫЕ ИССЛЕДОВАНИЯ РАСПРЕДЕЛЕНИЯ ТОКА НА ПОВЕРХНОСТИ ЛИСТОВОЙ ЗАГОТОВКИ В ЛИНЕЙНЫХ ИНСТРУМЕНТАХ МАГНИТНО-ИМПУЛЬСНОГО ПРИТЯЖЕНИЯ

Purpose. The purpose of the present work consists in the characteristics experimental determination of the pulsed current transverse distribution on the surface of a sheet non-magnetic metal between the point contacts of the power source with different geometry of their connection under operating frequencies variation. Methodology. The measurements were carried out using methods based on the known positions of electromagnetism. The simulating low-voltage equipment was used, as well as high-voltage power sources with a high level of the stored energy. Numerical processing of the measurement results was carried out using standard programs from the «Wolfram Mathematica» package. Results. The space-temporal shapes of the pulsed current density transverse distribution on the surface of the sheet blank were obtained and analyzed. It is established that the degree of transverse current concentration in sheet metal relative to the center of the system in the operating frequency range of ~ 1.8…22 kHz depends very little on its temporal characteristics. It was found that the level of the transverse current concentration in the conditionally allocated band connecting the contacts of connection depends significantly on the ratio of the width of this band and the transverse dimensions of the contact connection. Moreover, the smallest current is concentrated in a strip whose width is much less than the distance between the contacts (£ 11…16 %). Originality. For the first time, the numerical estimates degree of the current transverse concentration are obtained and the dependence of this parameter on the temporal characteristics of the current, as well as on the method of connecting the power source contacts, is established. Practical value. The research results will allow creating the new more efficient linear tools of magnetic-pulsed attraction of sheet metals, based on the force interaction of conductors with unidirectional currents. Целью работы является экспериментальное определение характеристик поперечного распределения плотности импульсных токов разной частоты на поверхности листового немагнитного металла между точечными контактами источника мощности при различной геометрии их подключения. Методика. Измерения проводились с помощью методов, основанных на известных положениях электромагнетизма. Использовалось модельное низковольтное оборудование, а также высоковольтные источники мощности с высоким уровнем запасаемой энергии. Численная обработка результатов измерений проводилась с помощью стандартных программ из пакета «Wolfram Mathematica». Результаты. Получены и проанализированы пространственно-временные формы поперечного распределения плотности импульсного тока на поверхности листовой заготовки. Научная новизна. Впервые получены численные оценки степени поперечной концентрации тока и установлена зависимость данного параметра от временных характеристик тока, а также от способа подключения контактов источника мощности. Практическое значение. Результаты исследований позволяют создавать новые более эффективные линейные инструменты магнитно-импульсного притяжения листовых металлов, основанные на силовом взаимодействии проводников с однонаправленными токами