High-current Electric Discharge Research Articles

Influence of a laser intensity on EUV brightness and ion speed from a laser-assisted discharge-produced plasma

Laser-assisted discharge-produced plasma (LDP) is one of the ways to generate extreme ultraviolet (EUV) light used in the semiconductor manufacturing processes. This light source uses a pulsed laser and a high-current pulsed electrical discharge to make a high-temperature and high-density tin plasma. One of two rotating disk electrodes, of which surfaces are coated by liquid tin (Sn), is irradiated by the laser to produce tin plasma. The plasma propagates from one electrode (cathode) to the other (anode) and ignites an electrical breakdown between the electrodes. The low-inductance circuit connected to the electrodes provides a current of approximately 15 kA and 150 ns to the tin plasma. The plasma implodes due to its own magnetic pressure, and EUV radiation is emitted from the resultant hot and dense plasma. High-speed ions are also emitted from the plasma and limit the lifetime of the mirror used to collect the EUV light. We need to maximize the light emission and minimize the ion emission. The role of the laser is essential in the LDP EUV source not only to ignite the discharge but also to condition the initial plasma. It influences EUV energy, EUV brightness, and emitted ion speed distribution of the plasma. The experiment suggested that laser intensity higher than 25 GW/cm2 produced high EUV brightness and low emitted ion speed.

HVHC-ESD-Induced Oxygen Vacancies: An Insight into the Phenomena of Interfacial Interactions of Nanostructure Oxygen Vacancy Sites with Oxygen Ion-Containing Organic Compounds.

The challenging environmental chemical and microbial pollution has always caused issues for human life. This article investigates the detailed mechanism of photodegradation and antimicrobial activity of oxide semiconductors and realizes the interface phenomena of nanostructures with toxins and bacteria. We demonstrate how oxygen vacancies in nanostructures affect photodegradation and antimicrobial behavior. Additionally, a novel method with a simple, tunable, and cost-effective synthesis of nanostructures for such applications is introduced to resolve environmental issues. The high-voltage, high-current electrical switching discharge (HVHC-ESD) system is a novel method that allows on-the-spot sub-second synthesis of nanostructures on top and in the water for wastewater decontamination. Experiments are done on rhodamine B as a common dye in wastewater to understand its photocatalytic degradation mechanism. Moreover, the antimicrobial mechanism of oxide semiconductors synthesized by the HVHC-ESD method with oxygen vacancies is realized on methicillin- and vancomycin-resistant Staphylococcus aureus strains. The results yield new insights into how oxygen ions in dyes and bacterial walls interact with the surface of ZnO with high oxygen vacancy, which results in breaking of the chemical structure of dyes and bacterial walls. This interaction leads to degradation of organic dyes and bacterial inactivation.

Computational and Experimental Modeling in Magnetoplasma Aerodynamics and High-Speed Gas and Plasma Flows (A Review)

This paper provides an overview of modern research on magnetoplasma methods of influencing gas-dynamic and plasma flows. The main physical mechanisms that control the interaction of plasma discharges with gaseous moving media are indicated. The ways of organizing pulsed energy input, characteristic of plasma aerodynamics, are briefly described: linearly stabilized discharge, magnetoplasma compressor, capillary discharge, laser-microwave action, electron beam action, nanosecond surface barrier discharges, pulsed spark discharges, and nanosecond optical discharges. A description of the physical mechanism of heating the gas-plasma flow at high values of electric fields, which are realized in high-current and nanosecond (ultrafast heating) electric discharges, is performed. Methods for magnetoplasma control of the configuration and gas-dynamic characteristics of shock waves arising in front of promising and advanced aircraft (AA) are described. Approaches to the control of quasi-stationary separated flows, laminar–turbulent transitions, and static and dynamic separation of the boundary layer (for large PA angles of attack) are presented.

Studies of initiation and quenching of extensive high-current discharges

The system has been developed for initiating and quenching the arc discharges by means of moving apart the initially closed electrodes at a variable speed. The experimental studies of the extensive high-current electric arc discharges were performed in the atmospheric air. By means of optimizing the process of moving apart the electrodes and matching their sizes and shapes, it is possible to increase up to ten times the length of the stably burning high-current arc without using the external magnetic field for its stabilization.

High-Voltage, High-Current Electrical Switching Discharge Synthesis of ZnO Nanorods: A New Method toward Rapid and Highly Tunable Synthesis of Oxide Semiconductors in Open Air and Water for Optoelectronic Applications.

A novel method of oxide semiconductor nanoparticle synthesis is proposed based on high-voltage, high-current electrical switching discharge (HVHC-ESD). Through a subsecond discharge in the HVHC-ESD method, we successfully synthesized zinc oxide (ZnO) nanorods. Crystallography and optical and electrical analyses approve the high crystal-quality and outstanding optoelectronic characteristics of our synthesized ZnO. The HVHC-ESD method enables the synthesis of ZnO nanorods with ultraviolet (UV) and visible emissions. To demonstrate the effectiveness of our prepared materials, we also fabricated two UV photodetectors based on the ZnO nanorods synthesized using the subsecond HVHC-ESD method. The UV-photodetector test under dark and UV light irradiation also had a promising result with a linear ohmic current-voltage output. In addition to the HVHC-ESD method's excellent tunability for ZnO properties, this method enables the rapid synthesis of ZnO nanorods in open air and water. The results demonstrate the preparation, highlight the synthesis of fine hexagonal-shaped nanorods under a second with controlled oxygen vacancies, and point defects for a wide range of applications in less than a second.

Guest Editorial Special Issue on High-Current Discharge Plasmas

An intention to organize this Special Issue was born at the International Congress on Energy Fluxes and Radiation Effects (EFRE), which is held every two years in Tomsk under the technical sponsorship of the IEEE. The Congress brings together four conferences, namely, the Symposium on High Current Electronics (SHCE), the Conference on Modification of Materials With Particle Beams and Plasma Flows (CMM), the Conference on Radiation Physics and Chemistry of Condensed Matter (RPC), and the Conference on New Materials and High Technologies (NMHT). Conferences have joined the Congress in different years, but the oldest one is SHCE, which was organized for the first time in 1973, four years before the establishment of the Institute of High Current Electronics (IHCE) in Tomsk. The Symposium on High Current Electronics anticipated the name of the Institute for High Current Electronics due to the fact that the scientific direction of the Institute was laid in the late 60s–early 70s of the last century by the scientific team headed by Prof. Gennady Mesyets, who organized IHCE, SHCE, and subsequently EFRE. The Congress covers a wide range of problems, from pulse power to nanoelectronics, but the unifying canvas is the high-energy impact on materials and environments. In 2020, EFRE Proceedings have published 302 conference papers that the reader can find in the IEEE Xplore digital library. This is why this Special Issue was not intended to publish extended versions of the four-page Congress papers. This special issue was open to the publication of articles by authors regardless of their participation in the EFRE community. The idea of the Special Issue was to collect and analyze the scientific and engineering interests of the community related to the plasma of high-current electric discharges.

On the stimulation of the de-excitation of nuclear isomers in plasma of a high-current electric discharge

The prospects of stimulated de-excitation of nuclear isomers (SDENI) with a trigger transition energy ∆E up to ∼ 1 keV in a plasma of a high-current electric discharge (HCED) with an electron temperature θ ∼ ∆E are discussed. An estimate of the probability of the SDENI process in plasma by the mechanism of nuclear excitation by electron capture (NEEC) is obtained. Themost promising for the SDENI study are isomers 229mTh (∆E ≈ 8 eV), 235mU (∆E = 76 eV), 110mAg (∆E = 1128 eV). To create an energy source most promising isomer is 186m Re (∆E is unknown) with a half-life of 2 × 105y, for which stimulated de-excitation in the laser plasma had beenalready observed at θ ∼ 1 keV.

Молния, Наука. Часть 1:Современный взгляд

Lightning can be defined as a transient, high-current (typically tens of kA) electric discharge in air whose length is measured in km. As for any discharge in air, lightning channel is composed of ionized gas, that is, of plasma, whose peak temperature is typically 30,000 K, about five times higher than the temperature of the surface of the Sun. Lightning was present on Earth long before human life evolved and it may even have played a crucial role in the evolution of life on our planet. The global lightning flash rate is some tens to a hundred km per second. Each year, some 25 million cloud-to-ground lightning discharges occur in the United States, and this number is expected to increase by about 50% due to global warming over the 21st century. Lightning initiates many forest fires, and over 30% of all electric power line failures are lightning related. Each commercial aircraft is struck by lightning on average once a year. A lightning strike to an unprotected object or system can be catastrophic. In the first part of the article, an overview of thunderclouds and their charge structure is given, basic lightning terminology is introduced, and different types of lightning (including the so-called rocket-triggered lightning) are described. For the most common negative cloud-to-ground lightning, main lightning processes are identified and the existing hypotheses of lightning initiation in thunderclouds are reviewed.

Молния, Наука. Часть 2: Ток и электромагнетизм

Lightning can be defined as a transient, high-current (typically tens of kA) electric discharge in air whose length is measured in km. As for any discharge in air, lightning channel is composed of ionized gas, that is, of plasma, whose peak temperature is typically 30,000 K, about five times higher than the temperature of the surface of the Sun. The global lightning flash rate is some tens to a hundred km per second. Lightning initiates many forest fires, and over 30% of all electric power line failures are lightning related. Each commercial aircraft is struck by lightning on average once a year. A lightning strike to an unprotected object or system can be catastrophic. In the first part [1] of the article, an overview of thunderclouds and their charge structure was given, and different types of lightning were described. The existing hypotheses of lightning initiation in thunderclouds were reviewed. In the second part of the article, current and electromagnetic signatures of lightning are characterized and the techniques to measure lightning electric and magnetic fields are discussed

X-ray radiation plasma of high-current electric discharge

The complex of diagnostic equipment intended for research of pulsed x-ray radiation of high-current electric discharge plasma is described. The diagnostic complex allows measurements in the energy range of x-ray quanta 1÷300 keV, the dynamic range of the complex 1012. The results of investigation of x-ray radiation of micropinchevy discharge plasma on the installation type of the "low-inductive vacuum spark" depending on the elemental composition of the anode material of the discharge system are presented. The dependence of the plasma parameters and the spectral composition of x-ray radiation on the elemental composition of the anode material of the discharge system is established. Experiments have shown that with the growth of the atomic charge of the nucleus Z of the anode material of the discharge system increases the electron temperature of the plasma Te.

Lightning strike resistance of an electrically conductive CFRP with a CSA-doped PANI/epoxy matrix

An analysis of a structural damage extent of a developed electrically conductive CFRP composite exposed to the high-current electrical discharges simulating lightning strikes was conducted in order to evaluate its ability of carrying on lightning electrical current and its damage resistance during lightning events. The composite was fully fabricated from organic compounds, i.e. electrically conductive polymer blend of polyaniline (PANI) doped with camphorsulfonic acid (CSA) and epoxy resin, and carbon fabric used both as a mechanical reinforcement as well as supporting electrical conductor for ensuring adequate electrical conductivity and mechanical properties. An investigation of lightning strike resistance was performed during high-voltage and high-current mode tests. For preliminary evaluation the resulting damage was examined using visual inspection. Furthermore, the ultrasonic testing and X-ray computed tomography were applied for evaluation of degradation mechanisms occurring during a typical lightning strike event. The obtained results show that the developed composite is characterized by good electrical conductivity and mechanical properties and may successfully resist high-current impulse discharges typical for lightning strike events. Therefore, the developed composite can be considered asa potential candidate for a lightning strike protection material in aircraft industry and other applications.

Formation of electric discharges above the free surface of a current-carrying liquid

The study is devoted to analysis of the formation of high-current electric discharges developing above the free surface of a liquid metal, deformed as a result of the interaction of the electric current passing through the liquid metal with the intrinsic magnetic field. We report on the electric characteristics of discharges and parameters of their initiation, consider the patterns of deformation of the free surface and the formation of electric discharges, describe the processes occurring in the system, and discuss the mechanism of cyclic formation of discharges above the liquid metal surface.

Monopulse electrical discharge machining ablation drilling technology for Ti-6Al-4V titanium alloy

A high-current monopulse electrical discharge machining (EDM) discharge ablation technique (i.e., monopulse EDM ablation) to drill Ti-6Al-4V titanium alloy plates is proposed. The activated surface material that employs discharge energy as induced energy induces a dramatic combustion reaction with oxygen. Perforation under the monopulse discharge effect is achieved depending on ablation energy produced by the metal oxidation reaction. A system with a monopulse generator is established to perform a monopulse EDM ablation drilling experiment on Ti-6Al-4V titanium alloy. The mechanism is analyzed. Mechanism analysis indicates that the process of monopulse EDM ablation drilling generally has five stages, namely, monopulse discharge and formation of the activated area, violent oxidation of the discharge point, oxidation hindered by the oxide layer, transmissible ablation extension, and downward ablation layer by layer. Tests of via holes are performed to compare EDM drilling and monopulse EDM ablation drilling. Results show that perforation is achieved at 500 μs by monopulse EDM ablation drilling for a 10-mm thick titanium alloy plate. However, the machining efficiency of EDM drilling is low (the machining time is 160 s) and cannot meet the value required by high-efficiency machining. The technology can be applied to cutting Ti-6Al-4V titanium alloy plates.

Parameters of electrical discharges with liquid metal electrode

The paper describes investigations of formation of high current electrical discharges emerging under free surface of liquid metal in tasks of melting and mixing intensification with use of electrovortex flow control. Discharge electrical characteristics, parameters of its ignition, visualization pictures of free surface deformation are presented here. Mechanisms of formation of the discharge over the liquid metal are discussed.

Transient Response of an Oscillating Heat Pipe by a Pulsed Heating in a High Magnetic Field Environment

An experimental investigation of a compact, triple-layer oscillating heat pipe (OHP) has been conducted to determine the fast-transient heating effect on the heat transport capability of an OHP in a high magnetic field environment. The OHP has dimensions of 1.3 cm thick, 22.9 cm long, and 7.6 cm wide embedded with two-independent closed-loops forming three layers of channels. The OHP was directly clamped to a railgun system in a medium caliber launcher (MCL) and subjected to high current electric discharges occurring over several microseconds. The experimental results show that the OHP is capable of significantly reducing peak temperatures during a pulsed heating event over pure copper, even in the presence of relatively high magnetic fields.

Important problems of future thermonuclear reactors*

Abstract This paper concerns important and difficult problems connected with a design and construction of thermonuclear reactors, which have to use nuclear fusion reactions of heavy isotopes of hydrogen, i.e., deuterium (D) and tritium (T). There are described conditions in which such reactions can occur, and different methods of a high-temperature plasma generation, i.e., high-current electrical discharges, intense microwave pulses, and injection of energetic neutral atoms (NBI). There are also presented experimental facilities which can contain hot plasma for an appropriate period, and particularly so-called tokamaks. The second part presents the technical problems which must be solved in order to build a thermonuclear reactor, that might be used for energetic purposes. There are considered problems connected with a choice of constructional materials for a vacuum chamber, its internal parts, external windings generating a magnetic field, and necessary shields. The next part considers the handling of radioactive tritium; the using of alpha particles (4He) for additional heating of plasma; recuperation of hydrogen isotopes absorbed in the tokamak internal parts, and a removal of a helium excess. There is presented a scheme of a future thermonuclear power plant and critical comments on a road map which should enable the construction of an industrial thermonuclear reactor (DEMO).

Dense Plasma Focus - From Alternative Fusion Source to Versatile High Energy Density Plasma Source for Plasma Nanotechnology

The dense plasma focus (DPF), a coaxial plasma gun, utilizes pulsed high current electrical discharge to heat and compress the plasma to very high density and temperature with energy densities in the range of 1-10×1010 J/m3. The DPF device has always been in the company of several alternative magnetic fusion devices as it produces intense fusion neutrons. Several experiments conducted on many different DPF devices ranging over several order of storage energy have demonstrated that at higher storage energy the neutron production does not follow I4 scaling laws and deteriorate significantly raising concern about the device's capability and relevance for fusion energy. On the other hand, the high energy density pinch plasma in DPF device makes it a multiple radiation source of ions, electron, soft and hard x-rays, and neutrons, making it useful for several applications in many different fields such as lithography, radiography, imaging, activation analysis, radioisotopes production etc. Being a source of hot dense plasma, strong shockwave, intense energetic beams and radiation, etc, the DPF device, additionally, shows tremendous potential for applications in plasma nanoscience and plasma nanotechnology. In the present paper, the key features of plasma focus device are critically discussed to understand the novelties and opportunities that this device offers in processing and synthesis of nanophase materials using, both, the top-down and bottom-up approach. The results of recent key experimental investigations performed on (i) the processing and modification of bulk target substrates for phase change, surface reconstruction and nanostructurization, (ii) the nanostructurization of PLD grown magnetic thin films, and (iii) direct synthesis of nanostructured (nanowire, nanosheets and nanoflowers) materials using anode target material ablation, ablated plasma and background reactive gas based synthesis and purely gas phase synthesis of various different types of nanostructured materials using DPF device will discussed to establish this device as versatile tool for plasma nanotechnology.

Solution of the nonlinear (radiative) thermal conductivity equation for pulsed high-current electric discharges in dense gases

A model of the initial expansion stage of cylindrical pulsed high-current electric discharges in dense gases in the approximation of radiative thermal conductivity is proposed. Based on the uniform distribution of the plasma pressure in the discharge channel and its constancy at this stage, the partial difference equations (continuity, Euler, and nonlinear thermal conductivity equations) of this model are reduced to ordinary differential equations. The space-time dependences of the plasma temperature and density in the channel on initial parameters were determined from the solutions to these equations. These dependences are consistent with experimental data within experimental error.

Observation of Isolated Breakdown Lightning Flashes in a Tropical Region

The impact of lightning on humans and its threats on life and structures have encouraged the scientists to pursue study in this field. Lightning flash is a high current electric discharge that can be classified into five categories which are intra-cloud discharges, cloud to cloud, cloud to air, ground to cloud and cloud to ground discharges. Intra-cloud discharges have the main portion of the lightning flashes. The most damages and disturbances of lightning flashes are due to cloud to ground and ground to cloud flashes. The discharge phenomenon has various behaviors even in the same thunderstorm. The cloud to ground lightning discharge starts with preliminary breakdown pulses followed by leaders which cause return strokes. The subsequent strokes happen after the first return stroke in a typical lightning flash, but in few flashes the discharges do not lead to any subsequent strokes. This research investigates on these types of flashes which are called isolated breakdown lightning flashes, in Malaysia. The isolated breakdown flashes have rarely been seen in tropical regions compared with temperate areas. Among 150 selected waveforms on 9thMay 2013 in our measurement station, only 10 isolated lightning flashes were observed in our dataset, which make up less than 7% of total flashes in one thunderstorm.

Dynamics of shock waves appearing during pulsed high-current electric gas discharges. II. Regular polygonal shock waves with closed surface fronts

Dynamics of regular polygonal shock waves (SWs), generated at thin wire explosion, with a closed surface front and numbers of sides n = 3, 4, 5, 6, 8, 10, 12, and 16 in the plane of polygons is experimentally studied. Depending on the initial Mach number MPSW0 of such waves and the number n, two convergence modes are implemented: convergence with and without changes in the number of sides n. It is shown that the shape of the reflected wave front differs from the shape of the converging SW front for polygonal SWs with n ≥ 8, i.e., it becomes smooth. The number MPSW0 is determined depending on initial characteristics of an SW generator and gas. A significant amplification of such SWs with n ≥ 12 is observed near to the center of polygons; their maximum amplification is estimated.