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

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

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

Guided Electromagnetic Discharge Pulses Driven by Short Intense Laser Pulses: Characterisation and Modelling

Strong electromagnetic pulses (EMP) are generated from intense laser interactions with solid-density targets, and can be guided by the target geometry, specifically through conductive connections to the ground. We present an experimental characterization, by time- and spatial-resolved proton deflectometry, of guided electromagnetic discharge pulses along wires including a coil, driven by 0.5 ps, 50 J, 1e19 W/cm2 laser pulses. Proton-deflectometry data allows to time-resolve first the EMP due to the laser-driven target charging and then the return EMP from the ground through the conductive target stalk. Both EMPs have a typical duration of tens of ps and correspond to currents in the kA-range with electric-field amplitudes of multiple GV/m. The sub-mm coil in the target rod creates lensing effects on probing protons, due to both magnetic- and electric-field contributions. This way, protons of 10 MeV-energy range are focused over cm-scale distances. Experimental results are supported by analytical modelling and high-resolution numerical particle-in-cell simulations, unraveling the likely presence of a surface plasma, which parameters define the discharge pulse dispersion in the non-linear propagation regime