Giga-Gauss scale quasistatic magnetic field generation in an 'escargot' target

A simple setup for the generation of ultra-intense quasistatic magnetic fields, based on the generation of electron currents with a predefined geometry in a curved 'escargot' target, is proposed and analysed. Particle-In-Cell simulations and qualitative estimates show that giga-Gauss scale magnetic fields may be achieved with existent laser facilities. The described mechanism of the strong magnetic field generation may be useful in a wide range of applications, from laboratory astrophysics to magnetized ICF schemes.Comment: Submitted to PRL. arXiv admin note: text overlap with arXiv:1409.524

A plasma solenoid driven by an Orbital Angular Momentum laser beam

A tens of Tesla quasi-static axial magnetic field can be produced in the interaction of a short intense laser beam carrying an Orbital Angular Momentum with an underdense plasma. Three-dimensional "Particle In Cell" simulations and analytical model demonstrate that orbital angular momentum is transfered from a tightly focused radially polarized laser beam to electrons without any dissipative effect. A theoretical model describing the balistic interaction of electrons with laser shows that particles gain angular velocity during their radial and longitudinal drift in the laser field. The agreement between PIC simulations and the simplified model identifies routes to increase the intensity of the solenoidal magnetic field by controlling the orbital angular momentum and/or the energy of the laser beam

Gain of electron orbital angular momentum in a direct laser acceleration process

Three-dimensional "particle in cell" simulations show that a quasistatic magnetic field can be generated in a plasma irradiated by a linearly polarized Laguerre-Gauss beam with a nonzero orbital angular momentum (OAM). Perturbative analysis of the electron dynamics in the low intensity limit and detailed numerical analysis predict a laser to electrons OAM transfer. Plasma electrons gain angular velocity thanks to the dephasing process induced by the combined action of the ponderomotive force and the laser induced-radial oscillation Similar to the "direct laser acceleration," where Gaussian laser beams transmit part of its axial momentum to electrons, Laguerre-Gaussian beams transfer a part of their orbital angular momentum to electrons through the dephasing process

Landau damping in thin films irradiated by a strong laser field

The rate of linear collisionless damping (Landau damping) in a classical electron gas confined to a heated ionized thin film is calculated. The general expression for the imaginary part of the dielectric tensor in terms of the parameters of the single-particle self-consistent electron potential is obtained. For the case of a deep rectangular well, it is explicitly calculated as a function of the electron temperature in the two limiting cases of specular and diffuse reflection of the electrons from the boundary of the self-consistent potential. For realistic experimental parameters, the contribution of Landau damping to the heating of the electron subsystem is estimated. It is shown that for films with a thickness below about 100 nm and for moderate laser intensities it may be comparable with or even dominate over electron-ion collisions and inner ionization.Comment: 15 pages, 2 figure

Melting Point and Lattice Parameter Shifts in Supported Metal Nanoclusters

The dependencies of the melting point and the lattice parameter of supported metal nanoclusters as functions of clusters height are theoretically investigated in the framework of the uniform approach. The vacancy mechanism describing the melting point and the lattice parameter shifts in nanoclusters with decrease of their size is proposed. It is shown that under the high vacuum conditions (p<10^-7 torr) the essential role in clusters melting point and lattice parameter shifts is played by the van der Waals forces of cluster-substrate interation. The proposed model satisfactorily accounts for the experimental data.Comment: 6 pages, 3 figures, 1 tabl

Сравнительное исследование электроискровых покрытий, полученных с использованием электродов TiC–NiCr и TiC–NiCr–Eu2O3

The study covers coatings obtained on 40Kh steel substrates by electro-spark deposition (ESD) using TiC–NiCr and TiC–NiCr– Eu2O3 electrodes. Coatings were deposited by the Alier-Metal 303 unit in argon environment under the normal pressure using direct and opposite polarity. The structure, elemental and phase composition of electrodes and coatings were studied using X-ray phase analysis, scanning electron microscopy, energy dispersive spectroscopy, glow discharge optical emission spectroscopy, and optical profilometry. Mechanical and tribological properties of coatings were determined by nanoindentation and testing according to the «pin-disk» scheme including high-temperature conditions in the range of 20–500 °C. The tests conducted include abrasive wear tests using the Calowear tester, impact resistance tests using the CemeCon impact tester, and tests for gas and electrochemical corrosion resistance. Test results showed that electrodes contain titanium carbide, nickel-chromium solid solution, and europium oxide in case of a doped sample. Coatings exhibit the same phase composition but solid solution is formed on the iron base. Coatings with the Eu2O3 additive do not differ significantly in structural characteristics, hardness, friction coefficient, and exceed the base coatings in terms of their abrasive resistance, repeated impact resistance, heat and corrosion resistance. There was an increase in impact resistance by 1.2–2.0 times, a decrease in corrosion current by more than 20 times, and an oxidation index by almost 2 times during the transition to doped coatings.Исследованы покрытия, полученные на подложках из стали 40Х методом электроискрового легирования с использованием электродов TiC–NiCr и TiC–NiCr–Eu2O3. Покрытия наносились с помощью установки «Alier-Metal 303» в среде аргона при нормальном давлении в режиме прямой и обратной полярности. Структура, элементный и фазовый составы электродов и покрытий были изучены посредством рентгенофазового анализа, растровой электронной микроскопии, энергодисперсионной спектроскопии, оптической эмиссионной спектроскопии тлеющего разряда и оптической профилометрии. Механические и трибологические свойства покрытий определялись методом наноиндентирования и путем испытаний по схеме «стержень–диск», в том числе при повышенных температурах в диапазоне 20–500 °С. Проведены исследования на абразивный износ с использованием прибора «Calowear-tester», стойкость к динамическим воздействиям с помощью установки «CemeCon impact-tester» и стойкость к газовой и электрохимической коррозии. Полученные результаты показали, что электроды содержат карбид титана, твердый раствор никеля в хроме и оксид европия в случае допированного образца. Покрытия также включали данные фазы, однако твердый раствор формировался на основе железа. Покрытия с добавкой Eu2O3 по структурным характеристикам, твердости, коэффициенту трения существен- но не отличались, а по стойкости к абразивному износу и к циклическим ударным нагрузкам, жаро- и коррозионной стойкости превосходили базовые покрытия. Наблюдались увеличение стойкости к ударным нагрузкам в 1,2–2,0 раза, понижение тока коррозии более чем в 20 раз и уменьшение показателя окисления почти в 2 раза при переходе к допированным покрытиям