Electrodynamic Acceleration Research Articles

The Use of Boron Fibers and Particles for Creating Functionally Graded Material Based on Ti64 Using the Laser Additive Manufacturing Method

This work presents a study on the additive manufacturing of functionally graded metal-ceramic materials based on Ti64 with boron fibers and particles. For the first time, the phase composition of the obtained composite was investigated using synchrotron radiation. It was shown that during laser exposure and in situ synthesis, boron dissolves in the titanium matrix, forming secondary compounds such as TiB and TiB2. An increase in the microhardness of the formed material compared to the titanium alloy was established. High-speed impact tests on the Ti64-B samples were conducted using an electrodynamic mass accelerator. It was shown that the use of boron fibers in the metallic matrix reduces the depth of the crater created during impact testing by 40% compared to the Ti64 reinforcement-free coating.

Investigation of the Resistance to High-Speed Impact Loads of a Heterogeneous Materials Reinforced with Silicon Carbide Fibers and Powder.

Pioneering studies on the additive manufacturing of a cermet heterogeneous material using SiC ceramic fiber were carried out. Unique studies of the damage staging (cratering) and the transition to the destruction of the formed material during high-speed impact created with the help of an electrodynamic mass accelerator have been carried out. It has been shown that the use of ceramic fiber in a metal matrix reduces the impact crater depth by 22% compared to material with ceramic particles. For the first time, the phase composition of the resulting composite was studied using synchrotron radiation. It was shown that, as a result of laser exposure, silicon carbide SiC is dissolved in the titanium matrix with the formation of secondary compounds of the TiC and Ti5Si3C types. It has been established that the use of SiC ceramic fibers leads to their better dissolution, in contrast to the use of SiC ceramic particles, with the formation of secondary phase compounds, and to an increase in mechanical characteristics.

FIELD DISTORTION ARRESTERS WITH IMPROVED TIME LIMITS FEATURES AND INCREASED RELIABILITY

The article considers the features of the design of four-channel rail arresters with field distortion with improved time characteristics and presents the results of studies of their time characteristics. The need for these studies is associated with the widespread use of such dischargers in capacitive energy storage devices that serve as power sources for electrodynamic mass accelerators. At the present stage of the development of science and technology, the use of such accelerators is the most promising for creating experimental stands for modeling in laboratory conditions the processes of high-speed interaction of structural elements of aircraft with particles of different masses and different origins. According to the operating conditions of the experimental stands, in a wide range of changes in both particle masses and interaction velocities, the amplitude values of currents through the low-inductive load of the mass accelerator can vary from kiloamperes to several megamperes at acceleration times from units to hundreds of microseconds. With this in mind, capacitive energy storage devices are performed in a multi-module design. Each module of a capacitive energy storage device is switched to the load by its own switch. To expand the range of operation of the spark gap of the storage device, to obtain the time characteristics of the spark gap with small delay times, to exclude the probability of spontaneous operation of the spark gap, and to provide the stability of the discharge formation during parallel operation of the switches, the designs of four-channel rail spark gaps with field distortion with improved characteristics were developed, their experimental and theoretical studies were carried out.
 
 The results of the conducted studies show that the smallest value of the delay time and, accordingly, the spread of the delay time are obtained for a spark gap with field distortion with two control electrodes.
 
 It is shown that the obtained analytical expressions presented in the article and the empirical expression calculated for a spark gap with a field distortion with two control electrodes make it possible to determine the values of threshold voltages and delay times, taking into account the statistical delay time and the time of discharge formation.
 
 The value of the threshold voltage is determined, at which the process of direct transformation of the streamer into a spark discharge with high conductivity followed by a breakdown of the interelectrode gap is observed.
 
 The dependences of the static voltage on the pressure in the inner chamber of the spark gap with field distortion with improved time characteristics are given. It is shown that at a certain distance between the main electrodes at a pressure of 0,3-0,5 MPa, the arresters operate with a margin of electrical strength when the static breakdown voltage is 1,5-2 times higher than the operating voltage applied to the electrodes of the gas gap of the arrestor. This eliminates the possibility of spontaneous triggering of the dischargers of the capacitive energy storage.

About the Limitation for the Plasma Motion Velocity in Electrodynamic Accelerator

About the Limitation for the Plasma Motion Velocity in Electrodynamic Accelerator

Using a Current Shunt for the Purpose of High-Current Pulse Measurement.

Measurement of high-current pulses is crucial in some special applications, e.g., electrodynamic accelerators (EA) and converters. In such cases, the current shunts have limitations concerning the frequency bandwidth. To overcome the problem, a method based on the shunt mathematical model is proposed. In the method, the solution of ordinary differential equations for the RL circuit is carried out in order to obtain the real current shape. To check the method, as a referee, a Rogowski coil dedicated to measuring high-current pulses was used. Additionally, the measurement results were compared with the mathematical model of the tested power supply system. Measurements were made for the short power supply circuit, which allows eliminating the nonlinearity. The calculations were carried out using a circuit model. In order to obtain the parameters of the shunt (resistance and inductance), it was modeled using an ANSYS/Q3D Extractor software. Comparison of calculation and measurement results confirms the correctness of our method. In order to compare results, the normalized root mean square error (NRMSE) was used.

Thermalization of the plasma arising during counter collision of high-energy plasma flows in a longitudinal magnetic field

This work is devoted to the study of thermalization of plasma created by head-on collisions of high-energy plasma flows in a longitudinal magnetic field of 0.5–2 T. Hydrodynamic flows contained the energy of 200 kJ with velocities from 2 × 107 to 4 × 107 cm/s and ion density from 2 × 1015 to 4 × 1015 cm−3 were created inside the 2MK-200 facility by two electrodynamic plasma accelerators equipped by a system of pulsed gas injection. Nitrogen, neon and their mixtures with hydrogen and deuterium were implemented as working gases. A process of plasma creating was investigated by near-wall magnetic probes situated in different parts of the interaction chamber. Temporal evolution of the plasma electron temperature had been traced by x-ray photodiodes covered by different filters. It was discovered that the plasma electron temperature changed insignificantly during 6–8 μs after it reached the maximum value, which means that it ionization state can be considered as quasi-stationary.

Study of Friction Force in Electrodynamic Rail Accelerator: Experiment and Interpretation Using FEM Modelling

The paper presents experimental data and a model of an electromagnetic rail accelerator. The model includes an equivalent circuit, magnetic field in the system and movement of the projectile (that is solved separately) which is computed numerically. The main results are compared with our experimental data and friction force during acceleration is evaluated.

Multivariate calculations of the electrodynamic linear accelerator with a permanent magnet support

Multivariate calculations of the electrodynamic linear accelerator with a permanent magnet support

Counter Collision of High-Energy Plasma Flows in a Longitudinal Magnetic Field

In the paper, experimental results concerning the dynamics of the counter interaction of high-energy plasma flows in a magnetic field with an induction of up to 2 T are presented and discussed. Plasma flows with velocities (2–4) × 107 cm/s, ion density (2–4) × 1015 cm–3, and energy content of 70–100 kJ were formed by two electrodynamic coaxial accelerators with pulsed gas injection. Nitrogen and neon, as well as their mixtures with deuterium, were used as working gases. A description of the 2MK-200 facility, where the experiments were carried out, and diagnostic equipment are presented. Experimental results obtained in various operating modes of the facility are reported and discussed.

Моделирование электромагнитного поля в ускорителях рельсового типа в отсутствие внешнего кожуха

A mathematical model of an electrodynamic rail-type accelerator without an ideal casing is constructed. A computational algorithm for the numerical solution of the problem is created. To simulate the electromagnetic field corresponding to an unlimited region, methods for specifying artificial boundary conditions have been developed. These methods are based on Green's basic integral formula and the law of Bio — Savard — Laplace. To conduct computational experiments based on the algorithm, software has been developed. The results of solving the model problem testify to the correctness and effectiveness of the developed software for studying the process of acceleration of macrobodies in the channel of a rail-type electrodynamic accelerator.

Influence of dry frictional heating on acceleration disruption in a railgun with a metal armature

The main problem associated with the realization of the concept of the electrodynamic accelerator with a metal armature (MA) is the complexity of providing metal contact MA/rail at the velocity over 1 km/s. Here, a complex of physical phenomena is analyzed, which leads to the destruction of the metal contact of the rail/armature due to its melting and the ignition of an electric arc. A mathematical model of the dry frictional heating of the contact zone is formulated and its analytical solutions are obtained using fractional calculus. The criterion of no melting of the contact zone is derived. The generalization of the experimental data showed that to ensure the metal contact, the choice of rail and armature materials is a dilemma. A possible way to resolve this dilemma has been proposed.

Simulation of Quasistationary Electromagnetic Fields in Regions Containing Disconnected Conducting Subregions

Methods for a numerical solution of Maxwell's equations in the quasistationary aproximation in a region with multiply connected conducting subregions were discussed. The case of nontrivial operator kernel was explored. The methods for finding the solution of the linear algebraic equations system were analyzed. The method of introducing a "fictional armature" was offered as alternative method for searching [retrieving] a normal solution of linear algebraic equations. Results of computational experiments were presented. The study was carried out on the example of calculation for electrodynamic acceleration process in the railgun channel

A Digital Model of the Electrodynamic Acceleration Process in a Coil Gun Devic

The subject of this paper is an analysis of the process of applying kinetic energy to a projectile made from a non-magnetic, electrically conductive material and placed inside of an inductance coil live with alternating current. A digital model of an acceleration system was built, comprising a high-current coil and a cylindrical projectile located inside of the coil. Analytical formulas of the three-dimensional distribution of the axial and radial components of the magnetic field generated by the coil were applied [5]. The mathematical model described herein included the projectile and coil three-dimensional system (with the dimensions and distribution of the coil turns), the parameters of the power supply system and their variations, caused by the energy input to the projectile (and including the variation of: coupling coefficient, pulsation, coefficient of attenuation, inductance, and resistance), and the balance of momentum of the projectile and coil system. A system of equations which depicted the projectile and coil system (the law of electromagnetic induction, the Biot-Savart law, electric-to-kinetic energy transfer, and the balance of momentum of the projectile and coil system) was solved with numerical methods.

High-Power X-Ray Line Radiation of the Plasma Produced in a Collision of High-Energy Plasma Flows

Results are presented from experimental studies of a pulsed source of soft X-ray (SXR) emission with photon energies in the range of 0.4–1 keV and an output energy of 2–10 kJ. SXR pulses with a duration of 10–15 μs were generated in collisions of two plasma flows propagating toward one another in a longitudinal magnetic field. The plasma flows with velocities of (2–4) × 107 cm/s and energy contents of 70–100 kJ were produced by two electrodynamic coaxial accelerators with pulsed gas injection. Nitrogen and neon, as well as their mixtures with deuterium, were used as working gases. The diagnostic equipment is described, and the experimental results obtained under different operating conditions are discussed. In particular, X-ray spectroscopy was used to study the high-temperature plasma produced in a collision of two plasma flows. The observed intensities of spectral lines are compared with the results of detailed kinetic calculations performed in a steady-state approximation. The calculations of the nitrogen and neon kinetics have shown that the electron temperature of a nitrogen plasma can be most conveniently determined from the intensity ratio of the resonance lines of He- and H-like nitrogen ions, while that of a neon plasma, from the intensity ratio between the resonance line of He-like Ne IX ions and the 3p−2s line of Li-like Ne VIII ions. In the experiments with plasma flows containing nitrogen ions, the electron temperature was found to be ≈120 eV, whereas in the experiments with plasma flows containing neon ions, it was 160–170 eV.

Analysis of an iron-core and ironless railguns powered sequentially

PurposeThe purpose of this paper is to calculate and measure transients for two different constructions of electrodynamic accelerators (ironless and iron-core) supplied by a three-section power system (three capacitor banks). The optimization of power supply parameters (switch-on times and capacitances of individual sections) in terms of system efficiency has been carried out.Design/methodology/approachCalculations have been carried out using a field-circuit model. For three-dimensional magnetostatic analysis, the Maxwell software and finite element method (FEM) were used, while for circuit model, the Matlab/Simulink software was implemented. For optimization of the supply system parameters, the genetic algorithm was used. The mathematical models were verified experimentally by using the original laboratory stand.FindingsThe efficiency of the system is much higher in case of iron-core accelerator. In both cases, the results obtained for optimized supply settings are only slightly better than those obtained by simultaneously switching on the thyristors and for symmetrical capacity division.Research limitations/implicationsDue to the presented field-circuit model, eddy currents in rails have been neglected. In the field model, there was no possibility to combine current flow calculations with moving of the projectile.Originality/valueUsing the presented filed-circuit model, both electrical and mechanical transients could be calculated with sufficient precision. Thus, it could be used in the optimization of supply system. The solution time is low compared with the solution time of the transient field model.

Transient Analysis of a Railgun with Permanent Magnets Support

Abstract The calculation and measurement results of transients for an electrodynamic accelerator with permanent magnet support have been presented in this paper. The calculations have been made using the magnetostatic model in the Maxwell software, as well as using a Matlab/Simulink transient model. The waves of mechanical parameters (projectile velocity and acceleration, force) and electric ones (excitation current and capacitor voltage) have been analyzed for different supply conditions (voltage value, capacitance). The efficiency and projectile energy have been studied as well. The mathematical models have been verified experimentally using the original laboratory stand. A good conformity between calculation and measurement results has been obtained.

Investigation of a two-electrode gas switch with electrodynamical acceleration of spark channel in oscillatory regime of discharge

We have developed a compact gas switch intended for operation in oscillatory (low damping) regime of discharge. It is two-electrode switch with electrodynamic acceleration of a spark channel and a matched series injection trigger generator. A series inductance is employed for isolation of a trigger pulse from a surrounded circuit. Two operations regimes have been investigated, namely “fast” regime with current amplitude ~ 160 kA, total charge ~ 12 C, period of oscillations 60 μ s, full pulse length ~ 400 μ s and “slow” regime with current amplitude ~ 30 kA, total charge 18 C, period of oscillations 360 μ s, full pulse length ~ 3 ms. The spark gap can be triggered reliably from 16 to 50 kV (at 72 kV self-breakdown voltage). Time delay in firing was less than 35 ns at 1 ns jitter at 30 mm gap and 40 kV charging voltage. The spark gap is designed for 50 kV charging voltage, at a current up to 200 kA, and up to 20 C charge transfer. Arc motion and electrodes erosion in this spark gap have been investigated. The main results are as follows: the arc channel moves on ~ 18 cm in fast regime and ~ 25 cm in slow regime. Results of the switch operation in slow and fast regimes with operational voltage of 40 kV and stored energy 32 kJ promise to get high lifetime. In this paper we present design for the spark gap and trigger generator. Test bed schematics and results of the tests are also described.

Electrodynamic acceleration of thin plates at high current densities

Processes accompanying the electrodynamic acceleration of a thin plate liner at a high accelerating current density are investigated. In addition to determining the electrical characteristics, shadow filming of the plate profile was carried out during the acceleration and the deformation of the profile in the region of fixed attachment to the current leads was monitored. A new experimentally reproducible effect in which the plate splits into three separate fragments, which is explained by nonuniform overheating by the current of the plate’s cross section and the electrodynamics of the process, was found. It was detected that, on the acceleration of copper liners, the current sheath is separated from the metal body of the liner and diverges in two directions. The nature of this phenomenon has not yet been determined.

Influence of the power supply parameters on the projectile energy in the permanent magnet electrodynamic accelerator

The main objective of the research is to investigate, how the power supply parameters influence the kinetic energy of the movable element, called commonly a projectile or bullet. A calculation and measurement results of transient characteristics for an electrodynamic accelerator with permanent magnet support were presented in the paper. The calculations were made with using field-circuit model, which includes the parameters of the power supply, mass of the bullet and friction phenomenon. Characteristics of energy and muzzle velocity verso supply voltage (50 V to 350 V) and capacitance value (60 mF to 340.5 mF) were determined, as well. A measurement verification of selected points of calculation characteristics were carried out for investigated values of muzzle velocity. A good conformity between calculation and measurement results was obtained. Concluding, presented characteristics of the muzzle velocity and energy of the projectile vs. power supply parameters indicate, that accelerators could be used for fatigue testing of materials.

Nanostructured materials for magnetic biosensing.

Abstract Background Magnetic nanoparticles (MNPs) are at the leading edge of the field of biomedical applications and magnetic biosensing. Methods MNPs were fabricated by electrophysical methods of the laser target evaporation (LTE) and spark discharge with electrodynamic acceleration of plasma jumpers (SD). Synthesis of polyacrylamide hydrogel was done in the presence of Fe2O3 MNPs in different concentrations obtained by LTE. [FeNi/Ti]3/Cu/[Ti/FeNi]3/Ti multilayers for giant magnetoimpedance (GMI) based sensitive elements were prepared by rf-sputtering for testing a biosensor prototype. Results Iron oxide MNPs, ferrofluids, ferrofluids contacting with biological systems, synthetic ferrogels mimicking natural tissues – are the steps of the discussed in this work development of bionanomaterials. Thorough the structural and magnetic studies of a multilayered sensitive element, MNPs and ferrogels insure the complete characterization of biosensor prototype. The GMI responses were carefully evaluated in initial state and in the presence of ferrogel with known concentration of MNPs. SD MNPs had the smallest 5–8 nm size. This nanomaterial was characterized by large internal strains of the order of 25 × 10− 3, which can play an important role for the interaction with different biosystems. Conclusions Iron oxide MNPs were fabricated by LTE and SD methods. SD MNPs had the smallest 5–8 nm size and large internal strains of the order of 25 × 10− 3. Designed GMI biosensor prototype allowed precise evaluation of the stray field of the MNPs present in the ferrogel by evaluating the systematic changes of the GMI in a 20–400 MHz frequency range. General significance This work summarizes recent developments in the field of nanomaterials potentially applicable in magnetic biosensing.