Electrical Explosion Of Conductors Research Articles

МЕТОДЫ МАГНИТНО-ИМПУЛЬСНОЙ СВАРКИ (ОБЗОР)

The article presents the features of various methods of pulsed welding in the solid phase using magnetic pressure according to a scheme with normal loading. A scheme of magnetic-pulse welding, implemented through electrical discharge cleaning without oblique impact, is described. Magnetic pressure is used for forming and welding. The authors proposed an original scheme for producing enclosing structures from dissimilar alloys by preheating the assembled unit in a vacuum, followed by crimping through the transmitting medium «shell» with an inductor according according to the «crimp» scheme. To obtain joints of the «rod-sheet» type in a heterogeneous combination of materials and structures of different thicknesses, the authors proposed to carry out a sequential connection of a magnetic hammer with the parts being welded, which allows synchronizing the process of thermal and force effects on the surfaces being welded. Various schemes for mating parts to be welded have been developed, including those using powder compositions as a connecting element. To implement the presented technological processes, universal special technological discharge-pulse equipment has been created, which makes it possible to implement the processes of welding, stamping, pressing, crimping, electric explosion of conductors and electrohydropulse processing of materials.

Calculation of Stresses Initiated by an Electrical Explosion of Conductors in a Composite Thick-Walled Cylinder

Calculation of Stresses Initiated by an Electrical Explosion of Conductors in a Composite Thick-Walled Cylinder

COMBINED HYDRODYNAMIC INSTABILITIES AND THEIR ROLE IN THE FORMATION OF MICRO- AND NANOSTRUCTURES OF MATERIALS UNDER PLASMA INFLUENCES

The formation of micro- and nanostructures in titanium alloys subjected to combined treatment, including exposure to heterogeneous plasma flows and subsequent modification of the surface layer by a low-energy high-current electron beam, was studied. It is established that the main mechanism for the formation of structural-phase states of the micro and nanoscale range under the influence of plasma flows created by an electric explosion of conductors is the joint manifestation of Kelvin-Helmholtz and Rayleigh-Taylor instabilities at the interface of the media. It is shown that the maximum growth rate of disturbances with acceleration of the second layer g = 5 ×109 m/s2 and a transverse velocity of 0 m/s falls on the wavelength λm = 6.76 µm. If the velocity value of the second layer is u0 = 10 m/s, then λm = 6.23 µm, and at u0 = 50 m/s ‒ λm = 1.24 μm. The mechanism of formation of micro- and nanostructures during subsequent electron beam processing is a combined thermo-evaporative, concentration- capillary and thermoelectric instability. It is shown that if the influence of the concentration gradient, thermoelectric and evaporative effects is not taken into account, the maximum value of the growth rate will be observed at a wavelength of 113 µm. Taking into account thermoelectric phenomenon leads to a decrease in the value of λm to 48 μm. It is established that at the value of the thermoelectric coefficient γ = 0.1 V/K, the maximum growth rate is observed at λm = 300 nm.

Retracted Article: Calculation of stresses initiated by electrical explosion of conductors in a composite thick-walled cylinder

This paper has been formally retracted on ethical grounds because the article contains extensive and repeated instances of plagiarism. The authors are responsible for this mistake and apologise for it. Request approved by the proceedings Editor and the Publisher on September 13, 2023.

Retraction Note: Calculation of stresses initiated by electrical explosion of conductors in a composite thick-walled cylinder

This paper has been formally retracted on ethical grounds because the article contains extensive and repeated instances of plagiarism. The authors are responsible for this mistake and apologise for it. Request approved by the proceedings Editor and the Publisher on September 13, 2023.

Filamentation of the surface plasma layer during the electrical explosion of conductors in strong magnetic fields

A model has been considered to describe the development of a surface discharge over a conductor electrically exploding in a strong magnetic field. A simulation performed using this model has shown that in the initial stage of the conductor explosion, a plasma layer of several tens of micrometers thick with an electron temperature of several electronvolts is formed on the metal surface. Based on the theory of small perturbations, the development of thermal filamentation instabilities that form in the surface plasma layer has been analyzed. The characteristic growth rates and wavelengths of these instabilities have been determined. The theoretical results were compared with the results of experiments performed on the ZEBRA generator (providing load currents of amplitude about 1 MA and rise time about 100 ns) and on the MIG generator (providing load currents of amplitude about 2 MA and rise time about 100 ns). For the conditions implemented with these generators, the filamentation model gives rise times of thermal filamentation instabilities of tens of nanoseconds at characteristic wavelengths of the order of 100 μm. These values are in good agreement with experimental data, which indicates the adequacy of both the surface discharge development model and the filamentation model.

Experiments on plasma dynamics of electrical wire explosion in air

Besides a typical high-density plasma source, electrical explosion of conductors is also indispensable in switches, nanomaterial synthesis, shock-wave sources, etc. In this paper, an experimental study regarding plasma dynamics of electrical wire explosions (μs-timescale) is presented, with spatiotemporal resolved diagnostics. Pure Cu/Ni wire and Cu-Ni alloy wire were used and compared. The alloy wire usually has a higher resistivity, resulting in a higher initial energy deposition (heating) rate. Abel inverse transformation indicated that the plasma radiation focussed on the outer region of the discharge channel for the alloy wire. In addition, the metallic vapour determined by the material properties had a considerable influence on the plasma process and resulting nanomaterials. In particular, both transverse and axial-layered structures were observed in alloy wire vapour. In addition, for the first time, the expanding arc-like plasma of explosion products was understood and examined from aspects of material properties and energy relaxation. The later stage of wire explosion resembled the state of regular metal vapour arcs under 1 MPa pressure. Finally, the core factor for the fast energy deposition stage of wire explosion was ascertained. Correlations between pre-exposition circuit parameters and post-explosion dynamic effects were found, which is significant for practical applications.

ИМПУЛЬСНЫЙ ВЫСОКОВОЛЬТНЫЙ ИСТОЧНИК НАПРЯЖЕНИЯ НА БАЗЕ ДВУХСПИРАЛЬНОГО МАГНИТОКУМУЛЯТИВНОГО ГЕНЕРАТОРА С УЛУЧШЕННЫМИ ХАРАКТЕРИСТИКАМИ

Relevance The paper proposes an original design of a high-voltage electromechanical two-spiral voltage source based on a magnetic accumulation generator (MAG) and a voltage multiplier with improved characteristics. In the multiplier, with the help of special switches, the addition of all voltages arising from the electrical explosion of conductors in separate inductive energy storage devices connected in parallel to the magnetic accumulation generator is carried out. A mathematical model and the results of mathematical modeling of the operation of the voltage source are presented, the calculated ratios will find application for practical use. In the course of the work, methods of the theory of electric circuits, magnetic field, elements of mathematical analysis and the theory of electrical oscillatory processes (beating, resonance, etc.) in complex circuits were used. As a result, a ratio is obtained that determines the maximum value of the beat frequency between two electrical circuits connected by a weak capacitive coupling, creating a magnetic accumulation generator with high microwave radiation and with the possibility of its regulation. The results of the work will be used in power engineering (an ice control unit, a shunt reactor to increase the power factor, etc.), mechanical engineering, medicine (cardiology), military equipment, etc. In the future, it is planned to use the obtained results of work in the direction of studying the use of a pulsed electromagnetic field for dewatering and desalting oil, which will lead to an increase in the efficiency of existing installations in practice. Aims of research Development of the design of a high-voltage electromechanical two-spiral voltage source based on a magnetic accumulation generator and a voltage multiplier with improved characteristics, theoretical and experimental studies with subsequent conclusions and recommendations. Studies of the proposed double-spiral MAG and the development of an event for its further practical application. Research methods Methods of mathematical modeling, research and testing of high voltage equipment. Results A pilot design of a high-voltage electromechanical two-spiral voltage source based on a magnetic accumulation generator and a voltage multiplier with improved characteristics is proposed, calculated ratios with experimental research and proposals for implementation in individual industries and testing laboratories are obtained on the basis of the created mathematical model. Keywords: magnetic accumulation generator, multiplier, electric explosion, simulation, liner, double-spiral solenoid, oscillatory process

Surface discharge during electrical explosion of conductors in strong magnetic fields

In experiments on the electrical explosion of conductors in rapidly growing mega-Gaussian magnetic fields, it was found that at the initial stage of the explosion, “hot spots” up to 500 pieces/mm2 were recorded on the surface. At a later stage, a plasma layer was formed on the surface of the conductor, in which filaments, that is, current channels, were formed. In this work, on the basis of the ecton theory, a model of the development of a surface discharge is constructed. The model makes it possible to estimate, firstly, the magnitude of the current flowing through the surface plasma, and secondly, the thickness of the plasma layer.

Electrical Explosion of Conductors to Produce Nanosized Carbides and to Apply Functional Coatings

An analytical review of recent studies in the field of electrical explosion of conductors (EEC) has been performed to select modes and conditions of high-resistivity EEC, which is used to produce functional wear-resistant hard-alloy carbide coatings containing refractory metals, their carbides, and nanocarbon particles. The influence of the environment in which the EEC is carried out on the composition of the products obtained is analyzed. The influence of the conductor’s electric explosion modes in gaseous carbon-containing media on the synthesis of refractory metal carbides is considered. The problems of producing the functional composite coatings of metal surfaces are also discussed.

METHOD FOR MEASURING THE PRESSURE OF A SHOCK-ACOUSTIC WAVE OF AN ELECTRIC EXPLOSION OF A CONDUCTOR IN A DISCHARGE CHAMBER WITH A CONDENSED ENVIRONMENT

An electric explosion of conductors, as well as an electric discharge as a whole, is a poorly studied unique phenomenon that is widely used both in basic scientific research and in various technological processes, which determines the relevance of further studies of ongoing processes. In this paper, we consider the methods and carry out calibration procedures to determine the value of the conversion coefficient for a piezoelectric pressure transducer with a reactive acoustic waveguide made of non-Newtonian fluid material. Designs of calibration plants are shown, the principle of which is based on the method of falling load and the interaction of parallel currents. The results of recording and measuring the pressure of a shock acoustic wave (SAW) generated by an electric explosion of a metal conductor of a ring-shaped geometry in a closed space of conical geometry with a condensed (aqueous) medium are presented. The discharge current and the voltage drop across the exploding flat ring foil (EEFRF) were recorded by the Rogowski belt and voltage divider, respectively. The pressure pulse of the acoustic shock wave was recorded by a piezoelectric pressure transducer. The electrical signals were recorded with a GDS-810 S digital two-beam storage oscilloscope. The amplitude value of pressure was estimated by plastic deformation of the plate sensor in the form of a round thin plate with clamped edges.

Features of treatment of metal surface layers by pulsed plasma jets formed during electrical explosion of conductors

The results analysis of the experimental studies obtained by the methods of modern physical materials science of metals and alloys surface layers after electroexplosive alloying and coating is presented.

Loading, Deformation, and Destruction of Cylindrical Samples of Polymethylmethacrylate and Fluoroplastic Using an Electric Explosion of Conductors

In this paper, we present the results of experimental studies of loading, deformation, and destruction of cylindrical samples of polymethylmethacrylate and fluoroplastic using an electric explosion of conductors at various loading rates. The analysis of the propagation of cylindrical stress waves in the samples, which is related to the formation and evolution of cracks, is carried out. Based on the fractographic analysis of fracture surfaces, the destruction mechanisms are compared, and the features of the main deformation processes are revealed.

Нагружение, деформирование и разрушение цилиндрических образцов из полиметилметакрилата и фторопласта с использованием электрического взрыва проводников

The paper presents outcomes of the experimental study of mechanical loading, deformation and fracture of the cylindrical specimens of poly(methyl methacrylate) and fluoropolymer performed with the electric explosion of conductors with various rates of loading. Propagation of the cylindrical waves of mechanical loading through the sample analyzed and correlated with generation and evolution of the fractures. Comparison of main mechanisms of fracture based on the fractographic analysis performed. Leading features of the distortion processes revealed.

Synthesis of Bimetal Fe–Pb Janus Nanoparticles via the Electric Explosion of Iron and Lead Conductors

The present work shows the ability to synthesize bimetal Janus nanoparticles of immiscible iron and lead metals via the electric explosion of two conductors. The electric characteristics of the explosion of Fe and Pb conductors are studied, and the dispersion/phase composition of nanoparticles, as well as the elemental distribution in nanoparticles, is comprehensively analyzed. Finally, the mechanism of the formation of Fe–Pb Janus nanoparticles under the electric explosion of conductors is proposed as well.

Modeling of the initial stages of the formation of heterogeneous plasma flows in the electric explosion of conductors

The experimental and theoretical studies on scattering of electric explosion products in the end-type plasma accelerator are carried out. Using the method of high-speed imaging (106 shots per second), it is revealed that there are three zones in a heterogeneous plasma flow. Zone 1 is a plasma focus, in Zone 2 there is a 90° turn of a flow, whereas a plasma flow is parallel to the dielectric disk in Zone 3. Following the concepts of plasma scattering when exposed to magnetic and gas-dynamic pressure, a mathematical model is proposed and provides an adequate explanation of plasma motion in Zone 3. It comprises equations of laws of mass and conservation of momentum, as well as the first and second Kirchhoff's laws. The outcomes of modeling are in compliance with the experimental data. A numerical single-fluid magnetohydrodynamic model is developed for general description of formation and evolution of a plasma flow. It is based on Navier-Stokes and Maxwell's equations. The obtained patterns of plasma current distribution agree satisfactory with the results of high-speed imaging. They point at a jet in the central part of the electrode, which splits out with the distance from its surface.

Comparative analysis of characteristics of material damage at various load speeds by electric explosion of conductors

The results of experimentation on the destruction of cylindrical samples made from PMMA and fluoroplast with the help of electric explosion of conductor (EEC) at various loading speeds are presented. The character of fracture of PMMA and fluoroplast as a result of dynamic loading by exploding a conductor is analyzed.

Assignment of Appropriate Conditions for Synthesizing Tungsten Nanopowder by Electric Explosion of Conductors

The paper provides the results of experimental research into properties of tungsten nanopowders synthesized by electric explosion of a conductor in argon at various energies, put into the conductor when exploding. The authors have studied how the conditions of synthesizing the tungsten nanopowder influence on the average size of particles.

Effect of energy deposition rate on plasma expansion characteristics and nanoparticle generation by electrical explosion of conductors

The process of electrical explosion of metal conductors has been used to produce nano particles under normal atmospheric conditions. The impact of average rate of energy deposition, overheat factor on size distribution of particles and expansion characteristics of plasma generated from exploding conductors have been experimentally investigated. The particle size was characterized by TEM and XRD while expansion rate was measured using streak photography.The geometric mean diameter of size distribution was found to be influenced by rate of energy deposition in the conductors. It is observed that higher the rate of energy deposition, higher will be the expansion velocity, and smaller will be the size of particles formed.

Nonlinear diffusion waves in high magnetic fields

The nonlinear diffusion of a magnetic field and the large-scale instabilities arising upon an electrical explosion of conductors in a superstrong (2-3 MG) magnetic field were investigated experimentally on the MIG high-current generator (up to 2.5 peak current, 100 ns current rise time). It was observed that in the nonlinear stage of the process, the wavelength of thermal instabilities (striations) increased with a rate of 1.5-3 km/s.