Discharge Voltage Research Articles

Electromagnetic-mechanical response mechanism and microstructure evolution during Al-Mg electromagnetic pulse welding

Electromagnetic pulse welding technology can achieve effective bonding of different metals without intermetallic compounds and heat-affected zones. Current research primarily focuses on bonding interface and strength, neglecting the fact that the strength of the joint is also related to the performance of the plate itself. This study investigates the macro-microscopic responses, and relevant mechanisms of plates under electromagnetic-mechanical coupling effects are revealed by the integration of microscopic characterization, a finite element model, and mechanical tests. The results show that diverse crystal structures have different mechanical response behavior. The elongation of aluminum after pure pulsed electromagnetic field (EMF) treatment is 27% higher than the untreated specimen while the tensile strength remains the same. But magnesium alloys show an increase of 16%, and 23% for tensile strength, and elongation, respectively. Under a pure EMF, the movement and recombination of dislocations are promoted in aluminum alloy, which is beneficial to reducing the dislocation density of aluminum alloy. As for magnesium alloy, twinning and recrystallization are induced to realize grain refinement. Under the coupling of electromagnetic-mechanical, there is an interaction between the electromagnetic effect and strain rate hardening on dislocations. The tensile strength of the Al specimen increases first and then decreases with the discharge voltage rising. This is determined by the dislocation entanglement behavior. This paper can provide a reference for an in-depth understanding of the mechanism and welding process of electromagnetic pulse welding.

Sensitive Determination of Alkali Metals by Liquid Anode Glow Discharge-Atomic Emission Spectrometry (LAGD-AES)

Liquid anode glow discharge-atomic emission spectrometry (LAGD-AES) was employed for the determination of alkali metals in brine and bottled drinking water samples. The results demonstrated that the optimum operating conditions are a discharge voltage of 630 V, a flow rate of 2.0 mL min−1, a supporting electrolyte solution of pH 1.7 HNO3, and a discharge gap of 0.5 mm. Alkaline-earth ions (e.g., Ca2+, Mg2+, and Sr2+) and Cr3+ interfere with the determination of alkali metals. The limits of detection (LODs) for the alkali metals, namely cesium (Cs), potassium (K), lithium (Li), sodium (Na), and rubidium (Rb) are 135, 6.21, 3.15, 7.57, and 31.1 µg L−1, respectively. The relative standard deviations are less than 5%, and the power consumption is approximately 13 W. The obtained results are in good agreement with the certified standard value for Li in the certified reference material and are consistent with the values obtained by ICP-OES and reference standards for K and Na in real samples. The concentrations of the Cs and Rb are considerably below the LAGD-AES detection limit. Consequently, they can be considered negligible. The results of the spiked water analysis are broadly consistent with the spiked values, with recoveries from 82% to 112%. LAGD-AES is an excellent technique for the sensitive determination of alkali metals due to its compact design, no requirement for inert gas, and low energy consumption.

Power-efficient 12-bit 800 MS/s voltage-time hybrid domain ADC with split TDC in 28 nm CMOS

In this paper, an 800 MS/s 12bit voltage-time hybrid domain ADC is presented. A four-channel split time-to-digital converter (TDC) is proposed in the first-stage sub-TDC, effectively reducing the impact of skew error. A configurable time amplifier (TA) is proposed to pre-configure the discharge voltage, optimizing the conversation rate and power consumption. The hybrid domain ADC verified in a 28-nm CMOS process with a core area of 0.033 mm2, which achieves 65.66 dB SNDR and 72.16 dB SFDR while consuming 7.93 mW from a single 0.9-V supply, resulting in Walden figure-of-merit (FoM) values of 6.34 fJ/conversion-step.

Thermorechargeable battery composed of mixed electrodes

A thermorechargeable battery (TB) can be charged by heating or cooling, and hence, converts thermal energy into electric energy. The manufacture of TB, however, requires adjustment of the cathode and anode potentials by pre-oxidation. Here, we demonstrated that application of mixed electrodes composed of reduced and oxidized compounds makes the adjustment process unnecessary. The TB made of mixed electrodes exhibited excellent thermal cycle stability of the thermal voltage VTB and discharge capacity QTB between 20 °C and 50 °C.

Effects of pulse time offset between Cr and Zr dual cathodes in closed-magnetic-field unipolar high-power impulse magnetron sputtering

Two cathode (target) materials, Cr and Zr, were paired in a closed-field magnetron dual-cathode configuration and used in unipolar high-power impulse magnetron sputtering (HiPIMS). Two pulse widths (pulse-on durations) and various pulse-time offsets between the negative-voltage pulses of the Cr and Zr targets were investigated by setting the synchronization delay between the HiPIMS power supplies of the two targets at two different Ar pressures. Several trends were observed by analyzing the waveforms of the target discharge current, target discharge voltage, and substrate current. The closed-magnetic-field dual-cathode configuration significantly enhanced the HiPIMS discharge efficiency of the Zr target at all pressures; however, the enhancement for the Cr target was considerably lower. The ion fluxes toward the substrate were influenced by two competing mechanisms. The charged species generated from the previous pulse on one target could be attracted by the subsequent pulse of the adjacent target as a preionized medium to enhance the HiPIMS discharge. However, the fraction of the previously emitted ion flux toward the substrate could be reduced. When a shorter pulse width of 70 μs was applied, the ion flux that reached the substrate was mainly affected by the pulse power of the Zr target, and delaying the pulses of the Cr target with a relatively lower ion yield can achieve a higher ion flux toward the substrate. Increasing the pulse width significantly increased ion fluxes emitted from both the Cr and Zr targets, increasing the total ion flux toward the substrate. The study indicates that for the Cr and Zr dual cathode pair, a pulse time offset of one pulse width plus more than approximately 200 μs would be the most efficient way to obtain the highest ion fluxes toward the substrate and achieve a better film quality.

Effect of laser-assisted irradiation on plasma electrolytic oxidation of titanium alloys: Arc spot evolution characteristics and photoelectric synergistic mechanisms

Laser irradiation can be employed as an auxiliary energy field to optimize functional plasma electrolytic oxidation (PEO) coatings. Herein, the mechanism of the effect of laser-assisted irradiation on the morphology and composition of ceramic coatings prepared by PEO of titanium alloys in electrolytes with sodium tetraborate-based is discussed from the perspective of plasma arc spot evolution and photoelectric synergistic effect. X-ray diffraction (XRD), transmission electron microscopy (TEM), Mott-Schottky (M-S), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to analyze the coating characteristics. The results showed that laser-assisted irradiation promoted the oxidation of the coatings, accelerated the conversion of the anatase phase to the rutile phase, reduced the oxygen vacancy defects and formed the "ant nest" porous microstructure. Monitoring of the voltage, electric field, and plasma discharge arc spot indicated that laser-assisted irradiation restricted the electric field diffusion on the anode surface, reduced the termination voltage, and significantly increased the intensity (maximum discharge percentage increased from 14.238 % to 20.358 %) and uniformity of distribution of the plasma discharge. Instantaneous photoresponse curves and electrochemical impedance spectroscopy confirmed that the PEO coatings exhibited fast and sustained photoelectric response under simultaneous laser irradiation, progressively enhanced with increasing laser irradiation energy. The photogenerated electrons excited by the semiconductor TiO2 coating under the simultaneous irradiation of laser can be used as the initial carriers of the electron avalanche, which induces the generation of a plasma on the surface of the anode and thus enhances the plasma discharge behavior, which is the fundamental reason for the optimization of the coating characteristics.

Preparation of ZnNi/CNT composite structures and their catalytic application in Li/CFx battery

Li/CFx batteries play a crucial role in cutting-edge fields such as military and medical applications. However, they still need further research to enhance their low discharge voltage with improved discharge capacity. In this work, ZnNi/CNT composites were used as catalysts to promote performance of Li/CFx batteries. Results show that these composites could enhance the battery to exhibit high specific capacity with improved voltage platform. Further analysis finds that a higher ion diffusion coefficient at 0.1 C discharge was maintained with lower charge transfer impedance. Ex-situ test results further reveal the ZnNi/CNT could lead to the formation of smaller LiF structure after discharge process, which is crucial for promoting the electrochemical process of Li/CFx battery. This work could provide an important reference for the design of primary battery electrode structure.

Methods for calculating the moisture discharge characteristics of insulators

This paper presents a detailed analysis and comparison of methods for calculating the moisture discharge voltage of insulators. The initial section provides a brief overview of the principles underlying air discharge along the surface of insulators, which is crucial for understanding moisture discharge processes. Two primary calculation methods for moisture discharge voltage are considered. The first method is based on Tepler's formula, which requires specific input data that can only be obtained experimentally. Although this approach is classical, it complicates practical application due to the difficulty of acquiring the necessary parameters under real-world conditions. The second method, described in the literature, relies on readily available data, significantly simplifying the calculation process. Based on this method, an automated tool for calculating the moisture discharge characteristics of insulators has been developed. The use of this tool reduces dependency on experimental data, providing accurate results with minimal time and resource expenditure. To demonstrate the effectiveness of the proposed tool, a moisture discharge characteristic calculation was performed for the insulator type LK 70-110. According to the analysis results, the moisture discharge voltage for this insulator is 549 kV, with a stress of 2.1 kV per centimeter of leakage current path length. These figures align with the average values obtained using the first method, confirming the reliability and accuracy of the new approach. The conclusions indicate that the second calculation method is fully satisfactory for standard insulator calculations. It can also be applied in specific conditions, such as under-chemo-substations, where precision and efficiency are critically important. Thus, the proposed calculation method can become an effective tool for engineers and researchers involved in the design and analysis of insulation systems. This work significantly contributes to the development and improvement of methods for assessing the moisture discharge characteristics of insulators, representing an essential step towards enhancing the reliability and safety of electrical networks and their operation.

Enhancing Rare Earth Element Recovery from Coal Ash Using High-Voltage Electrical Pulses and Citric Acid Leaching

The study investigates the application of high-voltage electrical pulses (HVEP) as a pretreatment to enhance the leaching efficiency of rare earth elements (REE) from coal ash (CA) produced from the combustion of Ekibastuz Basin coal in Almaty, Kazakhstan. HVEP treatment was applied to the finest (<40 µm) non-magnetic fraction of CA under controlled conditions, optimizing discharge current, voltage, and treatment duration. Leaching experiments with 1 M citric acid at various solid-to-liquid ratios, temperatures, and durations were conducted on both treated and untreated samples. Results indicated that HVEP-treated CA significantly improved REE recovery rates compared to untreated samples, with optimal conditions achieving 74% cerium, 79% yttrium, and 77% lanthanum recovery. The leaching of untreated CA under the specified conditions allowed no more than 28% REE to be extracted into the solution. The leaching process was found to follow first-order kinetics, with the chemical reaction of metal dissolution being the rate-limiting step.

Performance of an inertial electrostatic confinement fusion device having a multi-grid configuration

The aim of this work is to enhance the performance of an inertial electrostatic confinement fusion (IECF) device, addressing the issues with glow discharge voltage, current, and gas pressure while achieving significant fusion reactions at reduced pressure. Previous success involved a fusion rate of 106 n/s in a single-grid IECF system, but broader applications require higher neutron production by improving ion density, ion energy, and plasma confinement. Electrostatic focusing ion beams are proposed for better ion confinement. Comparing a single-grid IECF device with a triple-grid one, computational modeling using a 2D-3 V XOOPIC code suggests significant improvements in ion confinement with tailored potentials in the triple-grid device. The simulation demonstrates that modifying electrostatic fields in the triple-grid setup creates a potential well with humps, guiding ion beams to the central region and enhancing ion density.

High-Performance Aqueous Zinc-Organic Battery with a Photo-Responsive Covalent Organic Framework Cathode.

Covalent organic framework (COF) materials, known for their robust porous character, sustainability, and abundance, have great potential as cathodes for aqueous Zn-ion batteries (ZIBs). However, their application is hindered by low reversible capacity and discharge voltage. Herein, a donor-acceptor configuration COF (NT-COF) is utilized as the cathode for ZIBs. The cell exhibits a high discharge voltage plateau of ≈1.4V and a discharge capacity of 214 mAh g-1 at 0.2 A g-1 when utilizing the Mn2+ electrolyte additive in the ZnSO4 electrolyte. A synergistic combination mechanism is proposed, involving the deposition/dissolution reactions of Zn4SO4(OH)6·4H2O and the co-(de)insertion reactions of H+ and SO4 2- in NT-COF. Meanwhile, the NT-COF with a donor-acceptor configuration facilitates efficient generation and separation of electron-hole pairs upon light exposure, thereby enhancing electrochemical reactions within the battery. This leads to a reduction in charging voltage and internal overvoltage, ultimately minimizing electricity consumption. Under ambient weather conditions, the cell exhibits an average discharge capacity of 430 mAh g-1 on sunny days and maintains consistent cycling stability for a duration of 200 cycles (≈19 days) at 0.2 A g-1. This research inspires the advancement of Zn-organic batteries for high-energy-density aqueous electrochemical energy storage systems or photo-electrochemical batteries.

New strategy for Mg-air battery voltage-efficiency synergy by engineering protective film with cation vacancies on Mg anode surface

Although the Mg-air battery with high theoretical energy density is desirable for the energy supply of marine engineering equipment, its applications remain limited due to the low actual discharge voltage and inferior Mg anode utilization rate. In addition to the microstructure of Mg alloy anodes, the properties of discharge product films are of great importance to the discharge performance. Herein, the discharge behaviors of Mg-Y-Zn alloys are first studied mainly from the perspective of film properties. Through contrastive analysis, it is found that the sufficient Y3+ produced during the discharge process can substitute Mg2+ in Mg(OH)2 to introduce effective cation vacancies. The Mg-Y-Zn anode with profuse cation vacancies in the product film shows a synergy of potential and efficiency, and this can be attributed to an increase in the migration pathway for Mg2+, reducing the diffusion over-potential caused by the protective product film. This study is expected to provide a new strategy from the perspective of cation vacancy design of discharge film for developing high-performance Mg-air batteries.

Analysis of gap distance of ultra high voltage AC transmission lines in areas with altitude above 2000m

Abstract Research on long-wave front discharge characteristics of lines and long gaps of substation equipment in high-altitude areas needs to be conducted in a systematic manner immediately in order to guarantee the safety and economy of high-altitude UHV lines with respect to external insulation. However, at present, the gap discharge test of transmission lines is mainly carried out in areas below 2000m above sea level. The actual test is challenging to conduct in the high altitude region, and the test data is incomplete. To further confirm the validity of extrapolation of existing altitude test data to high altitude areas, this paper conducts theoretical analysis based on the real test data under standard meteorological conditions provided by GB/T 24842 standard. The altitude correction methods in IEC 60071-2: 2018 and IEC 60060-1: 2010, the m-coefficient method and g-parameter method, are used to correct the lightning impulse, power frequency, and standard switching impulse of AC transmission line gaps. The discharge voltage in areas below 5000m above 2000m is obtained, and several significant discharge characteristic parameters are obtained. Based on the 50% discharge voltage requirements of various voltage types of 1000kV transmission lines, combined with the discharge voltage curves at multiple altitudes, the minimum air gap distance of transmission lines at the altitude of 2000m-5000m is obtained. The comparative analysis of the correction results of the two methods provides a way of thinking for the next step to carry out the true test of UHV AC transmission line gap discharge in higher elevation regions.

Exploring efficiency in next generation high temperature superconducting-enhanced applied field magnetoplasmadynamic thrusters: A combined numerical and experimental study

The integration of superconductors into space propulsion has emerged as a promising avenue. Superconductors have demonstrated significant effectiveness in space propulsion devices in terms of performance. This study introduces a low-power High-Temperature superconducting Applied Field MPD thruster, utilizing High-Temperature superconductors to propel plasma out of the thruster to generate thrust. Replacing traditional copper magnets with High-Temperature superconducting magnets has not only led to substantial improvements but has also addressed challenges such as the increased weight of traditional copper coils, the energy-intensive nature of copper magnets consuming high power, and the extremely low temperatures required by conventional superconductors, necessitating the use of helium cooling tanks, which can add to the overall weight of the thruster.The research combines numerical simulations with detailed experimental validation to evaluate performance. As predicted by the simulation model, experimental results demonstrate a thrust of 220 mN at 15 mg/s and 15.2 kW, and 180 mN at 5 mg/s and 14.8 kW, with a specific impulse of 2760s, while maintaining a discharge current of 200 A. Additionally, the discharge voltage in the experimental setup increases with magnetic field strength but decreases with mass flow rate. Plasma fall voltage also increases with both the applied magnet field strength set by the High-Temperature superconducting magnet and the mass flow rate. Meanwhile, the fractional electrode fall voltage decreases with the applied field. Discharge voltage, plasma fall voltage, and electrode fall voltage are analyzed as factors influencing the increase or decrease in thrust, specific impulse, and efficiency of the High-Temperature superconducting-enhanced Applied Field Magnetoplasmadynamic thruster.Furthermore, the study concludes with a comprehensive examination of the High-Temperature superconducting-enhanced Applied Field Magnetoplasmadynamic thruster, offering valuable insights for researchers. Notably, the achieved efficiencies for Applied field Magnetoplasmadynamic thruster at low input power surpass those of the same configuration with traditional copper magnet, highlighting the potential benefits of utilizing High Temperature superconducting magnets for enhanced performance.

Hysteresis between gas breakdown and plasma discharge

In direct-current (DC) discharge, it is well known that hysteresis is observed between the Townsend (gas breakdown) and glow regimes. Forward and backward voltage sweep is performed using a one-dimensional particle-in-cell Monte Carlo collision (PIC-MCC) model considering a ballast resistor. When increasing the applied voltage after reaching the breakdown voltage (Vb), transition from Townsend to glow discharges is observed. When decreasing the applied voltage from the glow regime, the discharge voltage (Vd) between the anode–cathode gap can be smaller than the breakdown voltage, resulting in a hysteresis, which is consistent with experimental observations. Next, the PIC-MCC model is used to investigate the self-sustaining voltage (Vs) in the presence of finite initial plasma densities between the anode and cathode gap. It is observed that the self-sustaining voltage coincides with the discharge voltage obtained from the backward voltage sweep. In addition, the self-sustaining voltage decreases with increased initial plasma density and saturates above a certain initial plasma density, which indicates a change in plasma resistivity. The decrease in self-sustaining voltage is associated with the electron heat loss at the anode for the low pd (rarefied) regime. In the high pd (collisional) regime, the ion energy loss toward the cathode due to the cathode fall and the inelastic collision loss of electrons in the bulk discharge balance out. Finally, it is demonstrated that the self-sustaining voltage collapses to a singular value, despite the presence of a initial plasma, for microgaps when field emission is dominant, which is also consistent with experimental observations.

Design, construction, and testing of an exploding wire pulsed plasma system for generating shock waves in industrial applications

Exploding Wire Pulsed Plasma System (EWPPS) used in oil recovery operations has been construct and developed with an initial energy release of 1.5 kJ in a fusion laboratory. Recently, the final experiments have been carried out on the purpose device operating in microsecond time scale in air and fluid medium successfully. In this setup, a single wire feeder is used for tests. Also, to study and develop the shock waves caused by wire explosions in the industry, the diagnostic tools of voltage probe, current coil, pressure probe and photodiode have been used. Choosing the optimal material of wire is one of the basic factors in creating a suitable shock wave. In addition, the impact of wire inductance on discharge current, voltage, pressure and shock wave strength has been investigated by applying two sets of wires, refractory (Cu, Cu-Ni, and Steel) and non-refractory (W, W-Al, Mo). The results show that the strongest shock wave is produced while the transition from warm wire to dense plasma happens. The soft X-ray intensity of both wire series has been measured using a photodiode BPX-65 (<10 keV). The comparison shows higher X-ray intensity for non-refractory wires than that for refractory wires. In good agreement, the maximum value of the shock wave was 8.7 and 6.6 MPa for non-refractory metals with high inductance and refractory metals with low inductance, respectively.

Gap distance of UHV substation in areas with an altitude of 5000 m and below

Abstract In view of the increasing energy consumption and power demand, the construction of UHV AC is growing rapidly, and the construction of the project is gradually advancing to higher altitudes. It is urgent to conduct research on typical gap discharge in substations at high altitudes. Combined with the engineering requirements, this paper corrects the test data at an altitude of 0 m according to GB/T 24842 standard through altitude correction and combines the discharge voltage requirements of various typical gaps in substations to obtain the minimum air gap distance in UHV substations at an altitude of 5000 m and below. The calculation results of the two altitude correction methods are compared and analyzed, and the applicability of the two methods is analyzed.

Rational design of copper phosphate based polyanionic framework for high performance supercapacitor

The key to high-performing supercapacitors is their abundance, low cost, and ability to deliver high capacitance in a wide electrochemical window. A new class of phosphate-based polyanion material has been developed to deliver high capacitance via the effective utilization of their oxidation states. Cu3(PO4)2 was synthesized by the facile hydrothermal technique and delivers an ultra high specific capacitance of about 814 F/g with multiple discharge plateaus at a current density of 1 A/g within a voltage window ranging from 0.4 v to -1.2 V. This intriguing behavior is mainly due to the multi functional Cu while interacts with the electrolytic ions and also the inductive effect of a phosphate group (PO4)2− contributes to a high discharge voltage of -1.2 V during charging and discharging process. It shows exceptional cyclic stability of 100 % over 10,000 cycles without sacrificing its coulombic efficiency and it is pertinent the structural stability of the system. The symmetric device was fabricated and delivered power density and energy density of 4.5 kW/kg and 31.5 Wh/kg, and also maintained excellent cyclic stability at 92 % with high reversibility of charged ions. This offers new insights into the high potential of using polyanion-type compounds as high-capacity materials for advanced energy storage systems.

Transition Metal Selenide-Based Anodes for Advanced Sodium-Ion Batteries: Electronic Structure Manipulation and Heterojunction Construction Aspect.

In recent years, sodium-ion batteries (SIBs) have gained a foothold in specific applications related to lithium-ion batteries, thanks to continuous breakthroughs and innovations in materials by researchers. Commercial graphite anodes suffer from small interlayer spacing (0.334 nm), limited specific capacity (200 mAh g-1), and low discharge voltage (<0.1 V), making them inefficient for high-performance operation in SIBs. Hence, the current research focus is on seeking negative electrode materials that are compatible with the operation of SIBs. Many studies have been reported on the modification of transition metal selenides as anodes in SIBs, mainly targeting the issue of poor cycling life attributed to the volume expansion of the material during sodium-ion extraction and insertion processes. However, the intrinsic electronic structure of transition metal selenides also influences electron transport and sodium-ion diffusion. Therefore, modulating their electronic structure can fundamentally improve the electron affinity of transition metal selenides, thereby enhancing their rate performance in SIBs. This work provides a comprehensive review of recent strategies focusing on the modulation of electronic structures and the construction of heterogeneous structures for transition metal selenides. These strategies effectively enhance their performance metrics as electrodes in SIBs, including fast charging, stability, and first-cycle coulombic efficiency, thereby facilitating the development of high-performance SIBs.

Enhanced Oxygen Accumulation for a Hydrophobic Cathode in Lean-Oxygen Seawater Batteries.

The unsatisfactory oxygen reduction reaction (ORR) kinetics caused by the inherent lean-oxygen marine environment brings low power density for metal-dissolved oxygen seawater batteries (SWBs). In this study, we propose a seawater/electrode interfacial engineering strategy by constructing a hydrophobic coating to realize enhanced mass transfer of dissolved oxygen for the fully immersed cathode of SWBs. Accumulation of dissolved oxygen from seawater to the catalyst is particularly beneficial for improving the ORR performance under lean-oxygen conditions. As a result, SWB assembled with a hydrophobic cathode achieved a power density of up to 2.32 mW cm-2 and sustained discharge at 1.3 V for 250 h. Remarkably, even in environments with an oxygen concentration of 4 mg L-1, it can operate at a voltage approximately 100 mV higher than that of an unmodified SWB. The introduction of a hydrophobic interface enhances the discharge voltage and power of SWBs by improving interfacial oxygen mass transfer, providing new insights into improving the underwater ORR performance for practical SWBs.