Large Current Pulses Research Articles

Measurement of pulse current during high voltage tests using Rogowski coil with non-inverting integrator

The work is devoted to the development and modelling of the system of pulse current measurement during high-voltage tests and experiments. The proposed measurement system is based on the application of Rogowski coil with non-inverting integrator. The results of numerical modelling of the developed current measurement system are compared with the results of application of a low-inductance shunt resistor, Rogowski coil with passive RC-integrator and Rogowski coil with inverting active integrator in similar measurement systems. Various standard pulse currents including steep edge pulse (1/20 µs), large amplitude current pulse (4/10 µs), lightning pulse current (8/20 µs), switching pulse current (30/80 µs), and 1-3 ms pulse currents are modelled for the comparative test. From the simulation results, it follows that the developed Rogowski coil with the proposed non-inverting integrator has sufficiently high accuracy in a wide frequency band overlapping the frequency band of standard pulse currents in high-voltage tests.

ВПЛИВ З’ЄДНУВАЛЬНОГО ВИСОКОВОЛЬТНОГО КАБЕЛЮ НА СТРУМИ І НАПРУГИ У ПРИСТРОЇ ІМПУЛЬСНОГО БАР’ЄРНОГО РОЗРЯДУ

The article is devoted to the study of the connecting cable influence, as an element with distributed parameters between the pulsed generator and discharge chamber in the electrical complex based on pulsed barrier discharge, to the values of currents and voltages in the system. Based on experimental studies and modeling, it has been established that the currents at different ends of the cable differ significantly from each other, which is due to the large value capacitive pulsed charging current of the cable. It has been established that during the barrier discharge, a correctly measured pulse current has significantly shorter duration than pulse of voltage. During the electrical discharge, a feature of the dependence of the current at the input to the cable is the appearance of an additional local maximum, of much smaller amplitude with a time shift equal to the time the electromagnetic wave movement along the cable. It has been shown that the use of the connecting cable of increased length makes it possible to increase the voltage between the electrodes of two times in comparison with the voltage at the cable input, without taking into account the voltage drop across the internal resistance of the generator when the cable length no less than twice the path length that the electromagnetic wave moves during the time from start of the pulse to maximum value generator pulse. References 16, figures 7.

Design, construction and test of a prototype coil with demountable CuBe joints for pulsed table-top tokamaks

In a classic small tokamak, the magnetic confinement is achieved by toroidal coils that fit into a donut-shape mechanical structure. To facilitate their handling and maintenance as well as the access to various auxiliaries components, their design has evolved toward a modular configuration. For such demountable design, it is important to guarantee the electrical continuity of the winding of the coil across the modular parts through electrical contacts. The resulting joints rely on pressure and specific materials to transfer high current densities at a good mechanical stability and manageable losses. In the present work, a prototype of a circular demountable toroidal field coil (CDTFC) was designed and built to test some technical choices to be used in the final coils of a table-top tokamak referred to as TPM-1U. For this small tokamak, the magnet wires to wind the toroidal coils should be able to handle large pulsed currents in the tens of thousands of Amperes whereas the coil joints should handle a peak current density of at least 75 kA/cm2. The case study here is the TPM-U1 table-top tokamak. Its conceptual design is recalled and mechanical and magnetic details of the demountable coil prototype are provided. For the experimental test, the contacts were slightly pressed using a custom-made contact assembly and current pulses between 4 kA and 8 kA were fedto the coil prototype. The degradation of the joint was visually estimated by assessing the amount of micro-melting, plastic deformation and oxidation appearing at the interface between the materials in contact. It is shown that the selected AWG-04 magnet wire is appropriate for carrying kiloAmpere range pulsed currents and that the CuBe contacts are able to withstand current densities larger than the specification, up to 263 kA/cm2, under low contact pressures of a few mega-Pascal simplifying their handling. Some technical choices have been probed on a prototype coil yielding a generic sequence of tasks to build and test mechanically and electromagnetically demountable coils and their joints.

A High-Precision Flat-Top Pulsed Power Supply Topology Based on SFPFN and Active Coupled Inductor Filter

This study presents a power supply topology capable of generating a large current pulse with a long flat-top duration and a high output voltage. The proposed topology is based on the sequentially fired pulse forming network (SFPFN) and the active coupled inductor filter. The SFPFN generates the primary inaccurate current pulse, and the filter then shapes the current to achieve accurate output. In order to achieve the required accuracy, a novel active coupled inductor filter is proposed which consists of a switched-mode compensator, an auxiliary thyristor pair, a DC bias capacitor, and a coupled inductor. It is designed to deviate most of the voltage and current stress to the coupled inductor, the auxiliary thyristor pair, and the DC bias capacitor, thus reducing the semiconductor devices requirements of the switched-mode compensator. Experimental results based on a 335 A low-power prototype verified the capability of the proposed topology to produce high-precision current pulses and the potential to be generalized to high-power scenarios.

A generalized physical principle of development of plasma channel of a high-voltage pulse spark discharge in a dielectric

Goal. Development of the generalized physical principle of development of plasma channel of a high-voltage electrical pulse spark discharge in the homogeneous dielectric of the different aggregate state. Methodology. Basis of physical optics, theoretical electrical engineering, electrophysics bases of technique of high-voltage and large pulse currents, bases of high-voltage pulse technique and measuring technique. Results. Development of physical principle of development of plasma channel of an electric pulse spark discharge is executed in a homogeneous gas dielectric on the applied example of the use in calculations and experiments of the double-electrode discharge system (DEDS) with a long air interval, testing action of standard interconnect аperiodic pulse of high-voltage of temporal shape of Tm/Тd≈200 μs/1990 μs of positive polarity. The generalized formula is got for the calculation of total length of lc of the real way of development of an pulse spark discharge in an air dielectric, which allowed to formulate the offered physical principle in the following kind: «The plasma channel of an pulse spark discharge in a gas dielectric spreads from one of its points to other after a way length of lc, providing the least falling on it of electric voltage of Uc». It is shown that this principle in the first approaching can be applied and to the homogeneous liquid and hard dielectrics. Comparison of the developed physical principle of distribution of plasma channel of an electrical spark discharge is executed in a dielectrical environment with fundamental Fermat physical principle (a law) for distribution of light in an optically transparent environment, which specifies on mathematical likeness and closeness on destiny of these physical principles. Calculation estimations of falling of electric voltage of Uc on total length of lc of the real zigzag way of development in the air dielectric of DEDS a «edge-plane» with the least length of its discharge interval of lmin=1,5 m is presented, that a value Uc does not exceed 9 % from the experimental level of aggressive voltage of Umd≈611,6 кV in this DEDS for the аperiodic pulse of voltage of Tm/Тd≈200 μs/1990 μs. It is set that the estimated time of td advancement of leader channel of electric pulse discharge in air DEDS (lmin=1,5 m) on its real way total length of lc≈1,53 m makes td≈15,3 μs, and experimental duration of cut of Tdc of the indicated аperiodic impulse of voltage utilized in experiments, characterizing time of short circuit by the plasma channel of discharge of air interval in DEDS, appears equal Тdc≈td≈17 μs. Originality. The generalized physical principle of development of plasma channel of a high-voltage electrical pulse spark discharge is first developed in the homogeneous dielectric of the different aggregate state. Practical value. Application in electrical engineering practice and high-voltage pulse technique of the offered principle of distribution in the dielectrics of plasma channel of an pulse spark discharge will allow to develop both new and to perfect the existent methods of computer design of electro-discharge processes in the gas, liquid and hard insulation of different high-voltage electrical power engineering and electrophysics devices, directed on the increase of reliability of their operation.

A power efficient actively shielded two-channel transverse MRI gradient coil numerical design

Large and fast electrical current pulses are typically applied to conventional single-channel transverse MR gradient coils. However, these pulses result in a significant amount of power losses and heating of the coils. Previously, we presented a cylindrical multi-channel Z-gradient coil design that has better power efficiency compared to the single-channel design. In this work, we further investigate the DC power advantage for a two-channel actively-shielded transverse cylindrical gradient coil over the single-channel design. The conventional coil quadrants are radially divided into two sections, one for each channel, for both the primary and shielding surfaces. The symmetric inner sections of both the primary and shielding coils are assigned to the first channel, while the outer enclosing sections for each quadrant are assigned to the second channel. Discrete wire design is employed, where quasi-elliptic functions are used to parameterize the turns of each section. The coil geometric parameters, section size, number of turns, and turn locations are used as the design optimization parameters. The coils are optimized to maximize the coil’s efficiency while keeping the linearity error less than 10% and the shielding ratio above 85%. The design procedure is employed to design both the single and two-channel transverse gradient coils for comparison. Eleven different two-channel configurations having different section sizes were investigated. Results show that the power used to drive the most power-efficient two-channel coil is less than that of the single-channel design by ∼25%. Moreover, the two-channel configuration showed slightly better shielding efficiency.

Electrically function-switchable magnetic domain-wall memory.

Versatile memory is strongly desired for end users, to protect their information in the information era. In particular, bit-level switchable memory that can be switched from rewritable to read-only function would allow end users to prevent important data being tampered with. However, no such switchable memory has been reported. We demonstrate that the rewritable function can be converted into read-only function by applying a sufficiently large current pulse in a U-shaped domain-wall memory, which comprises an asymmetric Pt/Co/Ru/AlOx heterostructure with strong Dzyaloshinskii-Moriya interaction. Wafer-scale switchable magnetic domain-wall memory arrays on 4-inch Si/SiO2 substrate are demonstrated. Furthermore, we confirm that the information can be stored in rewritable or read-only states at bit level according to the security needs of end users. Our work not only provides a solution for personal confidential data, but also paves the way for developing multifunctional spintronic devices.

Nucleation and Growth Mode of Solid Electrolyte Interphase in Li-Ion Batteries.

The solid electrolyte interphase (SEI) is regarded as the most important yet least understood component in Li-ion batteries. Considerable effort has been devoted to unravelling its chemistry, structure, and ion-transport mechanism; however, the nucleation and growth mode of SEI, which underlies all these properties, remains the missing piece. We quantify the growth mode of two representative SEIs on carbonaceous anodes based on classical nucleation theories and in situ atomic force microscopy imaging. The formation of inorganic SEI obeys the mixed 2D/3D growth model and is highly dependent on overpotential, whereby large overpotential favors 2D growth. Organic SEI strictly follows the 2D instantaneous nucleation and growth model regardless of overpotential and enables perfect epitaxial passivation of electrodes. We further demonstrate the use of large current pulses during battery formation to promote 2D inorganic SEI growth and improve capacity retention. These insights offer the potential to tailor desired interphases at the nanoscale for future electrochemical devices.

Портативный нейтронный генератор на лазерно-плазменном ионном диоде с магнитной изоляцией

The article presents a new experimental portable pulsed neutron generator based on a laser-plasma ion diode with magnetic insulation and the results of the first experiments. The laser-plasma diode makes it possible to obtain large ion current pulses that generate high-intensity neutron radiation. The source of optical radiation was a pulsed neodymium-doped yttrium aluminum garnet laser with a wavelength of 1064 nm, a pulse energy of up to 0.7 J, and a duration of ~10 ns. The ion beam is accelerated by an Arkadiev-Marx pulsed voltage generator with a voltage amplitude of up to 250 kV, a duration of up to 1.5 µs, and an energy of up to 160 J. Neutrons were generated using the reaction d(d,n)3He. A neutron yield of 2·107 neutron/pulse was obtained.

Influence of single-pulse and high-amplitude current on springback and mechanical properties of AA5052 aluminum alloy sheets

Springback is a key challenge in quasi-static (QS) stamping, which seriously affects the forming accuracy of aluminum alloy. A multi-pulse and low-amplitude current is widely used to reduce the springback of aluminum alloys. However, the increase in workpiece of current severely affects the material performance. Herein, a single-pulse and high-amplitude current is employed to eliminate springback of V-shaped parts in a short time (<500 μs). With an increase in discharge voltage, the springback of V-shaped parts decreases. Compared with QS stamping, the average values of yield strength and tensile strength decrease by 9.2% and 1.2%, while the average values of elongation increases by 18.9% after discharge under 10 kV. The increase in temperature of tensile specimen is found to be 5.6 °C at 10 kV. Thus, the thermal effect caused by a pulse current renders a small influence on the properties of V-shaped components. Moreover, the texture and microstructure before and after discharge are studied using electron backscattered diffraction electron backscattered diffraction and transmission electron microscopy measurements. Briefly, the grain size increases and texture strength decreases under the influence of pulse current. Also, dislocation entanglement at grain boundaries is reduced, compromising the strength and springback effect. This study provides experimental and theoretical bases for eliminating springback of Al alloys with a large pulse current. • The springback of the V-shaped parts is completely eliminated in the presence of pulse current, corresponding to a discharge voltage of 10 kV. • The influence of single-pulse and high-amplitude current on the material mechanical properties and microstructure is analyzed. • The yield strength and tensile strength decrease after discharge treatment, whereas the elongation increases. • After pulse current treatment, the proportion of low-angle grain boundaries (LAGBs) decreased, as well as the dislocation density at grain boundaries and intercrystalline regions was reduced.

Analysis of the failure mode of surge protector under multi-pulse lightning strikes and its mechanism

This paper proposes a special disconnector for surge protector (SPD) with the ability to pass large pulse currents under multiple pulses, which has been verified to solve the problem of SPD fire and combustion under multiple pulses in engineering applications. The safety problem caused by the lightning strike failure of SPD has always been a difficult research point in low-voltage power distribution systems, especially the failure mechanism under multi-pulse lightning strike is still unclear. In this paper, the multi-pulse lightning generator is used to simulate the multi-pulse lightning current to carry out the SPD lightning impulse test. The results show that the SPD will have short-circuit breakdown and fire and combustion under multi-pulse lightning strikes, mainly because the continuous pulses will generate energy superposition, and the built-in disconnector and external disconnector fuses and circuit breakers cannot effectively cooperate with the SPD, and there is a protection blind spot. As a result, the SPD cannot be quickly detached at the moment of a short circuit. Based on the thermal effect of multi-pulse lightning strikes, a multi-pulse SPD special disconnector is designed, which can effectively solve the problem of lightning strike ignition of SPD under multi-pulse lightning strikes, and is of great significance to the lightning protection safety of low-voltage power distribution systems.

Multi-Channel, Actively Shielded, Power Efficient MRI Z-Gradient Cylindrical Coil Design Using Target-Field Method

Gradient coils are essential for MRI where fast and large electrical current pulses are typically applied to conventional, single-channel gradient coils, particularly for high-performance gradient applications. However, these pulses result in significant power losses and heating of the coil. We investigate the design of power-efficient multi-channel Z-gradient coils operating in the conventional mode comparing them to conventional single-channel coils designed using similar dimensions and alike DC performance characteristics. The power-efficiencies of thirteen different two-channel configurations having various section lengths for two different dimensions are analyzed. The current density of each section is approximated by Fourier series expansion where a linear equation relating the desired target field and current density is formulated and then solved. A stream function is derived from the obtained current density and then used to extract the final winding patterns of each section using a particular track width and a specific number of turns. The design process involves optimizing the current driving each channel, the distribution of coil windings, and the section size. Similarly, the performance of three-channel coils is also investigated. Results show that a power dissipation reduction of 17-28% and ~23% can be achieved using two- and three-channel coils, respectively. Moreover, we showed that multi-channel coils may have a slightly better shielding efficiency compared to conventional coils. A new methodology for designing two- and three-channel coils is presented where an advantage in terms of power efficiency can be gained depending on design parameters, coil’s dimensions, number of turns, and other metrics.

Destruction of polymer insulation and threshold amplitudes of current pulses of different temporal shapes for electric wires and cables in the low- and high-current circuits of pulse power engineering, electrical engineering and electronic devices

Goal. Development of engineering method for settlement of threshold amplitudes Impk of single-pulse current ip(t) of different temporal shapes for electric wires and cables with polyethylene (PET), polyvinylchloride (PVC) and rubber (R) half-length insulation, used in modern pulsed power engineering, electrical engineering and electronics in their low- and high-current circuits. Methodology. Basis of the theoretical and applied electrical engineering, electrical power engineering, electrophysics bases of technique of high-voltage and large pulsed currents, bases of low- and high-current electronics, measuring technique, electromagnetic compatibility and standardization. Results. Development of engineering method is executed on close calculation determination of threshold amplitudes Impk of single-pulse axial-flow current ip(t) of different temporal shapes for electric wires and cables with copper (aluminum) current-carrying parts and PET, PVC and R half-length insulation, used in the ow- and high-current circuits of pulsed electrical power engineering, electrical engineering and electronics. Electrothermal resistibility of half-length insulation of the examined cable and wire products (CWP), proper maximum to the possible temperatures of heating of current-carrying and insulating parts of the probed wires and cables and shutting out the offensive of the phenomenon destruction in the indicated insulation of CWP, was fixed based on this method. Calculation analytical correlations are obtained for finding in probed CWP of threshold numeral values of Impk amplitudes of pulses of current ip(t), time-varying both on aperiodic dependence of type τf/τp with duration of their front τf and duration of their pulses τp and by law of exponential attenuation sinewave. It is shown that at Imp&gt;Impk destruction of their half-length insulation, resulting in the decline of service life of CWP, will come from the thermal overheat of current-carrying parts of the examined electric wires and cables. The examples of practical application of the offered method are resulted upon settlement for a radiofrequency coaxial cable RC 50-4-11 with middle sizes is easily soiled with continuous PET insulation of threshold amplitudes of Impk of standard aperiodic pulses of current ip(t) from nano-, micro- and millisecond temporal ranges of shape of τf/τp=5 ns/200 ns, τf/τp=10 μs/350 μs and τf/τp=7 ms/160 ms. It is shown that with the proper growth of parameter τp&gt;&gt;τf for flow on a continuous copper tendon and split copper shell of radiofrequency coaxial cable RC 50-4-11 with middle sizes is easily soiled indicated homopolar pulses of current ip(t) substantial diminishing of their threshold amplitudes of Impk (with 531,2 кА for the nanosecond pulse of current of type 5 ns/200 ns to 1.84 кА for the millisecond impulse of current of type of 7 ms/160 ms takes place). Originality. An engineering method is first developed for close settlement of threshold numeral values of Impk amplitudes of single-pulse axial-flow current ip(t) of arbitrary peak-temporal parameters for electric wires and cables with copper (aluminum) current-carrying parts and PET, PVC and R half-length insulation. Practical value. Application in electrical engineering practice of the offered engineering method for determination of threshold amplitudes Impk of the indicated pulses of axial-flow current ip(t) for the probed electric wires and cables will allow considerably to increase service life of examined CWP.

Computational modelling of structural batteries accounting for stress-assisted convection in the electrolyte

Structural batteries consist of carbon fibres embedded in a porous structural battery electrolyte (SBE), which is composed of two continuous phases: a solid polymer skeleton and a liquid electrolyte containing Li-salt. In this paper we elaborate on a computational modelling framework to study the electro-chemo-mechanical properties of such structural batteries while accounting for the combined action from migration as well as stress-assisted diffusion and convection in the electrolyte. Further, we consider effects of lithium insertion in the carbon fibres, leading to insertion strains. The focus is placed on how the convective contribution to the mass transport within the SBE affects the general electro-chemo-mechanical properties. The numerical results indicate that the convective contribution has only minor influence on the multifunctional performance when the mechanical loading is caused by constrained deformation of constituents during electro-chemical cycling. However, in the case of externally applied mechanical loading that causes severe deformation of the SBE, or when large current pulses are applied, the convective contribution has noticeable influence on the electro-chemical performance. In addition, it is shown that the porosity of the SBE, which affects the effective stiffness as well as the mobility and permeability, has significant influence on the combined mechanical and electro-chemical performance.

Preliminary experimental study on the mechanisms of explosion-electric coupling

Electric energy is one of the most widely used forms of energy. It is valuable to couple electric energy with an explosion to boost detonation performance. The phenomenon of electric energy enhancing an explosion is referred to herein as explosion-electric coupling (EEC) by the author. An experimental device was designed to explore this phenomenon, and the device was equipped with measuring devices to collect data related to the electric and detonation characteristics of explosives. Trinitrotoluene and aluminized explosives were selected as test explosives and pressed into flat and cylindrical charges. Thus, different kinds of explosives with different shapes were able to be studied. The change of the current-voltage curve of the EEC was analyzed, and the process of the EEC was divided into three stages: explosion initiation, detonation growth, and steady-state detonation propagation. The results showed that the enhanced pressure of the von Neumann spike varied with the explosive type, the same as for the increase of the detonation velocity. However, the increased pressure of the Chapman-Jouguet point mattered for the shape of the explosive charges. According to the features of the electrical characteristics and the increases of the detonation properties, a hypothesis was proposed to explain how the electric energy affected the explosion. The external electric field and the large pulse current were two forms of electric energy that influenced the explosion, and these forms of electric energy had different effects on different detonation properties.

Dynamics and criteria of CFRP destruction by lightning currents

The article discusses a promising conductive composite material such as carbon-plastic. This material has significant strength, not inferior to metal, has a low specific weight and has interesting electrophysical characteristics. For a wider use of the material in various structural products, it is necessary to consider its unique characteristics. The work is devoted to the study of the conductive properties of carbon fiber under the influence of lightning currents and the development of criteria for its destruction. Based on two models of destruction of CFRP by lightning currents, a theoretical analysis of its destruction has been carried out. The first model considered the composite material as a continuous medium with anisotropic-conducting properties. The solution of the Laplace equation with the Neumann boundary conditions made it possible to find the distribution of current densities over the material and theoretically determine the radius and depth of damage. The second model, the layered structure model, took into account the structure of real CFRP. The dynamics of layer-by-layer destruction is considered on the basis of the equivalent circuit of carbon fiber reinforced plastic, which takes into account the longitudinal and transverse resistivity of the composite. The distributions of the radial current density along the radius and depth of the material are constructed and the analysis of the spreading of currents at various degrees of material anisotropy is carried out. Strong anisotropy, leading to the release of total energy in the first layer. Destruction of the upper layer changes the distribution of currents in the rest of the layers. The results of numerical modeling of layer-by-layer destruction of CFRP for five layers are presented. The process of destruction under the action of large current pulses is considered. The fracture criteria for various degrees of material anisotropy are obtained and refined. The resulting formulas contain values that are reproduced in the experiment. The calculation results are in good agreement with experiment. In conclusion, it is concluded that the criteria are applied to predict the effects of lightning and optimize lightning protection at the design stage of an aircraft.

The characteristics of ion wind thruster based on dielectric barrier discharge in near space

The experimental results show that when the pressure is constant, with the increase of power, the thrust-power ratio of the thruster decreases, and the wind speed and thrust increase, but the increase rate gradually decreases and finally tends to be stable；When the pressure is 5.5 kPa, The rate of increase in thrust decreases the slowest, that is, the thruster has the maximum thrust potential at 5.5 kPa, and when the input power is greater than 75 W, the relative maximum thrust can be generated, reaching 14.8 μN; At the same time, with the increase of input power, the thrust - power ratio increases first and then decreases; When the input power is constant in the range of 15–65 W, as the air pressure increases, the wind speed decreases, and the thrust and thrust-power ratios all have local extremes, that is, when the air pressure is 8 kPa, it reaches the regional maximum, the maximum is 12.7 μN and 0.45 μN/W, respectively, at 16 kPa, it reaches the minimum value of the area, and the minimum is 4 μN and 0.14 μN/W, respectively. By comparing the discharge images under different atmospheric pressures, it can be concluded that the thrust generated by the accelerated collision of particles with a single short-time large current pulse is less than that generated by the accelerated collision of ions with a long-time small high-frequency pulse discharge, and the particle collision probability is the main reason affecting the wind speed; Meanwhile, with the increase of input power, the “virtual electrode” formed by the accumulation of positive ion space charge reduces the increase rate of wind speed and thrust.

ANALYSIS OF CHARACTERISTICS AND POSSIBILITIES OF HIGH-VOLTAGE COMPLEX SCIENTIFIC-&amp;-RESEARCH PLANNING-&amp;-DESIGN INSTITUTE «MOLNIYA» OF NTU «KHPI» FOR THE TESTS OF OBJECTS OF ENERGY, ARMAMENT, AVIATION AND SPACE-ROCKET TECHNIQUE ON ELECTRIC SAFETY AND EMC

Purpose. Implementation of analysis of basic technical descriptions and new possibilities of separate electric options of unique high-voltage electrical engineering complex Scientific-&-Research Planning-&-Design Institute «Molniya» of NTU «KhPI», intended for testing objects of industrial energy (IE) on electric safety, action on them of standard storm and interconnect pulses of voltage (current), and also objects of armament and military technique (OAMT), aviation (AT) and space-rocket (SRT) technique on electromagnetic compatibility (EMC) and resistibility at direct action on them of the rationed pulses of current of artificial lightning and row of no-spread temporal functions of pulses of current (high-voltage). Methodology. Basis of the applied electrical engineering, electroenergy and electromechanics, electrophysics bases of technique of high-voltage and large pulse currents, bases of the applied instrument-making, high-voltage measuring technique and standardization. Results. Description of basic technical descriptions and new possibilities of component parts of unique high-voltage electrical engineering complex Scientific-&-Research Planning-&-Design Institute «Molniya» of NTU «KhPI», intended for testing different objects of IE on electric safety, their resistibility to direct (indirect) action of standard aperiodic storm and interconnect pulses of voltage (current), and also OAMT, AT and SRT on EMC and resistibility to lightning at a direct action on them of the rationed pulses of current of artificial lightning. It is shown that these tests can be conducted in accordance with the requirements of normative documents of the USA of SAE ARP| 5412: 2013, SAE ARP 5414: 2013, SAE ARP 5416: 2013, RTCA DO-160G: 2011, military Standards of the USA of MIL-STD-464C: 2010, MIL-STD-461G: 2015, Standards of NATO AECTP-500: 2016, AECTP-250: 2014, International Standards of IEC 62305-1: 2010, IEC 61024-1: 1990 and intergovernmental Standard GOST 1516.2-97 on the domestic high-voltage options of type of UITOM-1, GTM-10/350, GKIN-2, TI-CS115 (NCS08), TI-CS116 (NCS09), G-NCS10, MV 1000 and IK-1U with the rationed descriptions. Examples and results of tests of row of technical objects are resulted on indicated high-voltage little- and heavy-current electric options. Originality. First in a complex kind basic technical descriptions and proof-of-concept possibilities of unique high-voltage electrical equipment of Scientific-&-Research Planning-&-Design Institute «Molniya» of NTU «KhPI» are presented, being in Ukraine head organization in area of development, creation and practical application of the indicated high-voltage technique in behalf of domestic industries of IE, airplane and rocket production, and also defense industries of industry. Practical value. Application of the described domestic high-voltage proof-of-concept electrical equipment at tests on electric safety, EMC and resistibility to lightning of different objects of IE, OAMT, AT and SRT will be instrumental in the increase of reliability of their functioning in the conditions of striking (destabilizing) action on them of powerful electromagnetic hindrances of natural and artificial origin.

Modular solid‐state pulse generator based on multi‐turn LTD

A modular solid-state pulse generator based on a multi-turn linear transformer driver (LTD) is designed for the application of pulse power techniques with a high voltage, large current and wide pulse width. The LTD adopts the method of multi-turn winding on the magnetic core, which can help to output pulses of wide width. The isolation of the power supply with windings in the same direction of the LTD modules is designed, and the isolation voltage of the magnetic cores is the working voltage of the LTD modules. A modular solid-state pulse generator based on the multi-turn LTD is developed, which is composed of 10 LTD modules. Each module consists of 18 energy storage capacitors, metal-oxide-semiconductor field-effect transistors and their driving circuits connected in parallel. The pulse generator can output pulses with parameters including a voltage ranging from 0 to 5000 V, a pulse current up to −500 A, and a pulse width ranging from 200 ns to 5 μs. When all modules work in synchronisation, rectangular pulses can be produced with a rise time of 30 ns and a fall time of 16 ns. If all modules are asynchronised, trapezoidal pulses are produced with adjustable step-like rising and falling edges. Moreover, a higher-voltage pulse can be achieved by increasing the number of LTD modules.

Preparation of boron nanoparticles by pulsed discharge of compacted powder

In this study, a low-cost and simple method for the preparation of B nanoparticles is described. Based on the pulsed wire discharge method, a large pulsed current was discharged through 10 mg of B micro-sized powder to form B nanoparticles in Ar gas. A small amount of Cu and C impurities was detected due to the material of the electrodes and the heat-shrinkable tube. The prepared B nanoparticles were of a crystalline phase and their sizes were estimated to be less than 100 nm. To the authors’ knowledge, this is the first realization of spherical crystalline B nanoparticles.