Explosion Of Copper Wires Research Articles

The Potential of Wire Explosion in Nanoparticle Production in Terms of Reproducibility.

Aquasols produced by exploding copper wires represent complex systems in which identifying individual colloidal components poses challenges due to broad and multimodal size distributions and varying shares among oxidation states. To evaluate the reproducibility of copper wire explosion, the size distribution of metallic and oxidized colloidal components within the 10-300 nm diameter range was assessed. Classification of each individual particle into bins according to size and chemical composition was accomplished by reconstructing the recorded optical extinction spectra of three sols produced under identical conditions as the weighted sum of the extinction spectra of individual copper and copper-oxide particles, computed using Mie theory. Our spectrophotometry-based component analysis revealed differences in particle number concentrations of the mainly oxidized nanoparticles, corresponding to deviations observed in the ultraviolet portion of the extinction spectra. Notable uniformity was observed, however, in the number of metallic fine particles, consistent with agreement in spectral features in the visible range. Regarding mass concentration, practically no differences were observed among the three samples, with nano-to-fine ratios of copper particles agreeing within 0.45%. Despite the complex processes during explosion leading to limited reproducibility in the ratio of different copper oxidation states, very good reproducibility (54.2 ± 0.7%) was found when comparing the total copper content of the samples to the mass of the exploded copper wire.

Addressing the critical parameters for overdamped underwater electrical explosion of wire

Experimental and magnetohydrodynamic numerical simulation results and analysis of a μs- and sub-μs-timescale overdamped underwater electrical explosion of copper wires having different lengths and diameters are presented. For these explosions, ∼80% of the energy stored in the pulse generator is deposited into the wire during a time comparable or shorter than a quarter period of the underdamped discharge. It was found that the threshold values of the deposited energy density, energy density rate, and energy density per unit area, which satisfy overdamped discharge, depend on the wire parameters and on the timescale of the explosion. It was shown that the mechanism responsible for this is the process during which the wire experiences phase transitions to a low-ionized plasma, the resistivity of which is determined by the electron–neutral collision rate, which, in turn, depends on the wire radial expansion velocity, current density, and temperature.

The optical diagnosis of electrical wire explosion under a microsecond current pulse.

Electrical wire explosions have many applications in scientific research and industry. Optical diagnosis is a powerful method to clarify the evolutionary process of such explosions. In this paper, an experimental platform was established to diagnose the optical radiation of electrical wire explosions. A low-jitter trigatron switch and its trigger generator were designed to ensure accurate synchronization. The spatial-temporal evolution process and the self-emission spectrum of electrical explosion plasmas from different wires (copper and tantalum) were obtained and analyzed. The optical diagnosis results indicated that the electrical explosion of copper wire was mainly characterized by the inhomogeneity of partial ionization and the rapid expansion of the discharge channel. The spectrum in the early discharge stage of the copper wire electrical explosion was a continuum, and most of the self-radiation spectral lines belonged to Cu I or Cu II. At the later stage of the plasma dissipation process, the continuous spectrum gradually transformed into a line spectrum. The development of the tantalum wire discharge channel was relatively uniform, and the plasma was mainly established in the gas-liquid mixed phase channel of the tantalum wire. The self-emission spectrum of the tantalum wire was always continuous, and the absorption process of line spectrum radiation was distinct.

Spectroscopic quantification of the nanoparticle production efficiency of copper wire explosion

Wire explosion is a technically straightforward green method for nanoparticle production; however, the determination of polydisperse and multimodal particle size distribution and thereby the assessment of the efficiency of the process pose serious challenges. Fitting extinction spectra derived from the Mie theory to the measured extinction spectra of colloidal solutions produced by the explosion of copper wires of 70 μm diameter and 20 mm length by discharging a capacitor of 435 nF charged to voltages ranging from 4 to 12 kV in an aqueous environment allows for determining the size distribution of the particles in the 10–300 nm diameter range and provides information on their oxidation state as well. In underwater wire explosion of copper, the vast majority of the nanoparticles transforms into copper oxides already during the process. The size distribution remains bimodal throughout the whole charging voltage range investigated. The nanoparticles follow a lognormal size distribution with a mode at 30 nm, while the fine particle population extending from 100 to 300 nm in diameter is dominated by rather normally distributed copper droplets with modes at 160–170 nm. The energy injected into the wire controls the individual concentration of both the fine and nanoparticles with the modes and ranges remaining hardly affected. The number concentration of the nanoparticles increases monotonically with the energy, spanning more than one order of magnitude. The throughput assessed by the total mass of the nanoparticles divided by the total mass of all species identified in the sol within the 0–300 nm diameter range increases monotonically from 1% at 4 kV up to 41% at 12 kV, revealing that wire explosion can be optimized for efficient nanoparticle production.

Effect of Current on Plasma Parameters Resulting from the Wires-Exploding Technique of Copper Material

In this research the diagnostic of optical emission spectroscopy from exploding copper wires have done for different current. By using Boltzman plot can be calculated the plasma electron temperature , and by using Stark broadening can be evaluated the electron density for different current of (75, 100 and 150)A with diameter 0.25 mm in deionized water. It was observed that the electron density decrease with an increasing the current from 75 A to 150 A while the electron temperatures increase for the same current. The plasma has a peak 652 nm corresponding to Hα line for .hydrogen .atoms which obtained from .optical emission spectrum (OES), the peaks belong to atomic copper lines. The plasma electron temperature related with emission line intensity and number .density with the formed copper nanoparticles size was studied.

Effect of Current on Plasma Parameters Resulting from the Wires-Exploding Technique of Copper Material

In this research the diagnostic of optical emission spectroscopy from exploding copper wires have done for different current. By using Boltzman plot can be calculated the plasma electron temperature , and by using Stark broadening can be evaluated the electron density for different current of (75, 100 and 150)A with diameter 0.25 mm in deionized water. It was observed that the electron density decrease with an increasing the current from 75 A to 150 A while the electron temperatures increase for the same current. The plasma has a peak 652 nm corresponding to Hα line for .hydrogen .atoms which obtained from .optical emission spectrum (OES), the peaks belong to atomic copper lines. The plasma electron temperature related with emission line intensity and number .density with the formed copper nanoparticles size was studied.

Metal vapor content of an electric arc initiated by exploding wire in a model N2 circuit breaker: simulation and experiment

A conductive wire can explode by rapidly heating it to vaporization temperature by flowing a current through it. This process is utilized to generate high-temperature high-density plasmas. The temperature and pressure distributions at the time of the explosion are not easily measured. Moreover, the amount of metal vapor from the wire that remains within the arcing area is unknown. This work presents the whole-process model of a single-wire electrical explosion from solid-state to plasma formation. For this purpose, the voltage drop and resistance of the exploding copper wire in solid-state are simulated through a zero-dimensional thermo-electrical model. Then, compressible Euler equations are implemented with nodal discontinuous Lagrange shape functions in a one-dimensional model to compute the flow of the generated copper vapor (due to the wire explosion) in surrounding nitrogen gas. The aim is to calculate the distributions of pressure, density, velocity, temperature, and mass flow along the cylindrical shock waves to estimate the arc’s copper/nitrogen mixture ratio in free burning and nozzle constricted arcs. This mixture ratio is used to calculate the precise percentage of the metal vapor in the arcing area and to calculate Townsend growth coefficients utilizing to estimate the streamer breakdown of the mixture. The simulation results show good agreement with the experimental results in terms of the temporal evolution of the plasma channel boundary, the shock front speed estimation as well as the arc voltage magnitude numerically calculated deploying the extracted mixture percentage from this study, manifesting the validity of the model. It shows that despite the low-pressure studies, the exploding wire method is not suitable for circuit breakers employing supercritical fluids as the insulation.

Study on Ignition Mechanism and Shockwave Characteristics of Nitramine Powders Ignited by Microsecond Exploding Wire Plasma

Based on high pulsed power technology, electrical explosion is increasingly utilized to generate shock waves with high pressure. To further magnify the shock wave pressure, we have proposed a novel technique by using energetic materials ignited by the plasma of microsecond wire explosion. Organic derivatives of nitramide, termed nitroamines, are widely used as powerful and relatively insensitive explosives. In this paper, we investigated the shockwave characteristics of nitramine (RDX and HMX) powders ignited by exploding copper wire (diameter 0.3 mm and length 60 mm). With charge voltage of 24 kV and powder mass about 6.0 g, the most evident experimental results suggested that the RDX load possessed higher peak pressure of 11.38 MPa and larger areal impulse of 503.02 MPa $\cdot \mu \text{s}$ , comparing with the shock wave of HMX load (7.22 MPa and 371.28 MPa $\cdot \mu \text{s}$ ). Moreover, the RDX load also had greater ascent rate of pressure, which was nearly twofold of that of the HMX load. Finally, a simple multi-factor ignition mechanism for nitramine powder under microsecond exploding wire plasma was proposed and discussed.

Effect of current intensity on structural properties of cupper iodine nanoparticles produced by exploding Cu wire

Exploding wire Technique is a way for production metal and its compound nanoparticle that is capable of production of bulk amount at low cost semiconductor. In this work a copper iodine nanoparticles were fabricate by exploding copper wires with different currents in iodine solution. The produced samples were examined by XRD, FTIR, SEM and TEM to characterize their properties. The XRD proved the Nano-size for producer. The crystalline size increases with increasing current. FTIR measurements show a peaks located at 638.92 for Cu-I stretch bond indicate on formation of copper iodide compound and the peaks intensities increase with increasing current. The SEM and TEM measurements show that the thin films have nanostructures.

X-ray radiography of the overheating instability in underwater electrical explosions of wires

We present the measurements of the development of striation like instabilities during the electrical driven explosions of wires in a water bath. In vacuum based wire explosion experiments, such instabilities have long been known. However, in spite of intense research into the explosion of wires in liquids, the development of these instabilities has either not been observed or has been assumed to play a minor role in the parameters of the exploding wire due to the tamping of the wire's explosion. Using synchrotron based multiframe radiography, we have seen the development of platelike density structures along an exploding copper wire. Our measurements were compared to a 2D magnetohydrodynamics simulation, showing similar striation formation. These observed instabilities could affect the measurements of the conductivity of the wire material in the gas-plasma state—an important parameter in the warm dense matter community. The striations could also act as a seed for other instabilities later in time if the wire is in a dense flow of material or experiences a shock from an adjacent wire—as it would do in experiments with arrays of wires.

Optical emission spectroscopy for studying the exploding copper wire plasma parameters in distilled water

This work aims to study the exploding copper wire plasma parameters by optical emission spectroscopy. The emission spectra of the copper plasma have been recorded and analyzed The plasma electron temperature (Te), was calculated by Boltzmann plot, and the electron density (ne) calculated by using Stark broadening method for different copper wire diameter (0.18, 0.24 and 0.3 mm) and currentof 75A in distilled water. The hydrogen (Hα line) 656.279 nm was used to calculate the electron density for different wire diameters by Stark broadening. It was found that the electron density ne decrease from 22.4×1016 cm-3 to 17×1016 cm-3 with increasing wire diameter from 0.18 mm to 0.3 mm while the electron temperatures increase from 0.741 to 0.897 eV for the same wire diameters. The optical emission spectrum (OES) emitted from the plasma have Hα line, small peak at 590 nm corresponding to sodium and others peaks belong to Cu I. The relationship between the plasma electron temperature, emission line intensity and number density with the formed copper nanoparticles size and concentration were studied. It was found that the nanoparticles concentration increase with emission line intensity while its size decrease. It can be conclude the existence of a controlled relationship between the plasma parameters and the formed nanoparticles concentration and size.

Density evolution of a copper wire during nanosecond timescale underwater explosions

We present high-contrast X-ray images (∼30 μm space and ∼10 ns time resolution) of ns-timescale underwater electrical explosions of copper wires to the low density limit of ∼1 g/cm3, using a rod-ring electron diode as a source of X-rays. The radial density distribution, obtained by inverse Abel transform analysis of the X-ray images, is reproduced by one dimensional magneto-hydrodynamic (MHD) simulations using the SESAME equations of state and a modified Bakulin, Kuropatenko, and Luchinskii conductivity model for copper. These modifications are introduced by matching the experimental and simulated current and voltage waveforms and the radial wire expansion. For our ns-timescale copper wire underwater electrical explosions, the X-ray images display no MHD and thermal instabilities.

Electrical behavior of exploding copper wire in ambient air

This work experimentally investigates the electrical behavior of an exploding wire when the initial energy of the system varies from 28 to 709 J. This experiment uses 50-μm-diameter, 33-mm-long copper wires. The wire is surrounded by air at normal atmospheric pressure and temperature. The experiment monitored the current derivative, voltage between wire ends, total visible radiation emitted, and the shadow image of the wire to study how the electrical parameters vary as a function of initial energy. The results indicate a change in the initial discharge mechanism.

Underwater electrical wire explosion: Shock wave from melting being overtaken by shock wave from vaporization

The shock waves generated by an underwater electrical wire explosion were investigated. A microsecond time-scale pulsed current source was used to trigger the electrical explosion of copper wires with a length of 5 cm and a diameter of 200 μm. The energy-storage capacitor was charged to a relatively low energy so that the energy deposited onto the wire was not large enough to fully vaporize the whole wire. Two shock waves were recorded with a piezoelectric gauge that was located at a position of 100 mm from the exploding wire. The first and weak shock wave was confirmed to be the contribution from wire melting, while the second and stronger shock wave was the contribution from wire vaporization. The phenomenon whereby the first shock wave generated by melting being overtaken by the shock wave due to vaporization was observed.

Relationship between energy deposition and shock wave phenomenon in an underwater electrical wire explosion

An experimental study of pressure waves generated by an exploding copper wire in a water medium is performed. We examined the effects of energy deposited at different stages on the characteristics of the resulting shock waves. In the experiments, a microsecond time-scale pulsed current source was used to explode a 300-μm-diameter, 4-cm-long copper wire with initial stored energies ranging from 500 to 2700 J. Our experimental results indicated that the peak pressure (4.5–8.1 MPa) and energy (49–287 J) of the shock waves did not follow a simple relationship with any electrical parameters, such as peak voltage or deposited energy. Conversely, the impulse had a quasi-linear relationship with the parameter Π. We also found that the peak pressure was mainly influenced by the energy deposited before separation of the shock wave front and the discharge plasma channel (DPC). The decay time constant of the pressure waveform was affected by the energy injection after the separation. These phenomena clearly demonstrated that the deposited energy influenced the expansion of the DPC and affected the shock wave characteristics.

Generation of highly symmetric, cylindrically convergent shockwaves in water

We report on pulsed power driven, exploding copper wire array experiments conducted to generate cylindrical convergent shockwaves in water employing μs risetime currents >550 kA in amplitude and with stored energies of >15 kJ—a substantial increase over previous results. The experiments were carried out on the recently constructed Mega-Ampere-Compression-and-Hydrodynamics facility at Imperial College London in collaboration with colleagues of Technion, Israel. 10 mm diameter arrays consisting of 60 × 130 μm wires were utilized, and the current and voltage diagnostics of the load region suggested that ∼8 kJ of energy was deposited in the wires (and the load region close to the wires) during the experiments, resulting in the formation of dense, highly resistive plasmas that rapidly expanded driving the shockwaves in water. Laser-backlit framing images of the shockfront were obtained at radii <0.25 mm for the first time, and there was strong evidence that even at radii <0.1 mm this front remains stable, resulting in a convergence ratio of >50:1. Framing images and streak photographs showed that the velocity of the shockwave reached ∼7.5 km s−1 at 0.1 mm from the axis. 2D hydrodynamic simulations that match the experimentally obtained implosion trajectory suggest that pressures >1 Mbar are produced within 10 μm of the axis along with water densities of 3gcm−3 and temperatures of many 1000 s of Kelvin. Under these conditions, Quotidian Equation of State suggests that a strongly coupled plasma with an ionization fraction of ∼0.7 would be formed. The results represent a “stepping stone” in the application of the technique to drive different material samples into high pressure, warm dense matter regimes with compact, university scale generators, and provide support in scaling the technique to multi-mega ampere currents.

Numerical simulation of the initial plasma formation and current transfer in single-wire electrical explosion in vacuum**Project supported by the National Science Foundation of China (Grant Nos. 51322706, 51237006, and 51325705), the Program for New Century Excellent Talents in University, China (Grant No. NCET-11-0428), and the Fundamental Research Funds for the Central Universities, China.

In this paper, a computational model is constructed to investigate the phenomenon of the initial plasma formation and current transfer in the single-wire electrical explosion in a vacuum. The process of the single-wire electrical explosion is divided into four stages. Stage I: the wire is in solid state. Stage II: the melting stage. Stage III: the wire melts completely and the initial plasma forms. Stage IV: the core and corona expand separately. The thermodynamic calculation is applied before the wire melts completely in stages I and II. In stage III, a one-dimensional magnetohydrodynamics model comes into play until the instant when the voltage collapse occurs. The temperature, density, and velocity, which are derived from the magnetohydrodynamics calculation, are averaged over the distribution area. The averaged parameters are taken as the initial conditions for stage IV in which a simplified magnetohydrodynamics model is applied. A wide-range semi-empirical equation of state, which is established based on the Thomas–Fermi–Kirzhnits model, is constructed to describe the phase transition from solid state to plasma state. The initial plasma formation and the phenomenon of current transfer in the electrical explosion of aluminum wire are investigated using the computational model. Experiments of electrical explosion of aluminum wires are carried out to verify this model. Simulation results are also compared with experimental results of the electrical explosion of copper wire.

Numerical model for electrical explosion of copper wires in water

This paper presents a simple but quite accurate numerical model for analyzing electrical explosion of copper wires in water. The numerical model solves a circuit equation coupled with one-dimensional magneto-hydrodynamic (MHD) equations with the help of appropriate wide-range equation of state (EOS) and electrical conductivity for copper. The MHD equations are formulated in a Lagrangian form to identify the interface between the wire and surrounding water clearly. A quotidian EOS (QEOS) that is known as the simplest form of EOS is utilized to build wide-range EOS for copper. In the QEOS, we consider the liquid-vapor phase transition, which is critical in analyzing the wire explosion system. For the electrical conductivity of copper, a semi-empirical set of equations covering from solid state to partially ionized plasma state are employed. Experimental validation has been performed with copper wires of various diameters, which are exploded by a microsecond timescale pulsed capacitive discharge. The simulation results show excellent agreements with the experimental results in terms of temporal motions of a plasma channel boundary and a shock front as well as current and voltage waveforms. It is found that the wire explodes (vaporizes) along the liquid branch of a binodal curve irrespective of wire dimension and operating voltage. After the explosion, the wire becomes a plasma state right away or after the current pause (dwell), depending on the operating conditions. It is worth noting that such a peculiar characteristic of wire explosion, i.e., current pause and restrike, is well simulated with the present numerical model. In particular, it is shown that the wire cools down along the vapor branch of the binodal curve during the current dwell, due to a significant difference of thermodynamic characteristics across the binodal curve. The influence of radiation for studying nonideal plasmas with a wire explosion technique and a physical process for shock wave formation by an exploding wire is discussed as well.

Technique for determining the channel expansion rate at the stage of electrical breakdown using a grounded intercepting ring

A method is described that allows one to study the conductivity dynamics of a channel produced by explosion of a wire at the stage of electrical breakdown. Experimental data have been presented for the expansion rate of the conductivity channel in extended (up to 1.9 m long) arbitrarily shaped gapes that were produced by an exploding copper wire 90 µm in diameter. The initial stored energy and applied voltage were, respectively, 2.7–3.7 kJ and 8–10 kV. It has been shown that the expansion rate of the conductivity channel coincides with the propagation rate of a shock wave and is inversely proportional to the square root of its radius and propagation time. The radius of the shock wave is a linear function of the square root of its propagation rate. Experimental data are in satisfactory agreement with the calculated results obtained by Lin [18] in terms of the model of an intense shock wave. It has been shown that the diameter of the conductivity channel depends on the position of the trailing edge of the shock wave.

Temporal shock wave analysis produced by copper exploding wires in air at atmospheric pressure

In this work, experimental results concerning the temporal evolution of the shock wave radii generated by an exploding copper wire of fixed length are presented. The variables of the experience were the diameter dimension—from 50 to 500 μm—and the initial capacitor voltage—from 5 to 25 kV. The diagnostic device was a streak shadow image system synchronized with the experiment. The result is a parametric collection of data showing the shock wave position across the time depicting the different stages of the experience.