Breakdown Parameters Research Articles

Triboplasma assisted chemical conversion in granular systems: a semi-analytic model

Abstract We present a semi-analytic model for a novel plasma-assisted chemical conversion pathway using triboplasmas generated in granular flows. Triboelectric charge relaxation is a well known phenomena where the potential generated from contact charging of particles exceeds the breakdown voltage of the background gas. In this work, we extend the triboelectric charge relaxation theory to include non equilibrium plasma energy and particle balance equations to predict the formation of dissociated and excited species that act as precursors to chemical conversion, for example in plasma-assisted ammonia synthesis. 
Our example case study with nitrogen background gas and Teflon/aluminum tribomaterial system yielded high excited nitrogen species densities per collision that are comparable to current plasma-assisted conversion pathways. We also present a regime diagram for various gases where Paschen breakdown parameters are used to determine whether triboplasmas can be formed for a given effective work-function difference between two materials. Our sensitivity studies indicate particle velocity, particle radius, solids fraction and space charge effects play a critical role in overall plasma densities and excited species production.

The Characterization of Electric Field Pulses Observed in the Preliminary Breakdown Processes of Normal and Inverted Intracloud Flashes

We have studied the parameters of preliminary breakdown (PB) pulses in 395 normal and 319 inverted intracloud (IC) flashes observed in Gifu, Japan, and Ningxia, China, respectively, by using a low-frequency mapping system called fast antenna lightning mapping array (FALMA). These parameters are extracted from the first half of the PB pulses. It is found that compared to normal IC flashes, inverted IC flashes exhibited PB pulses with slower rise times (6.8 vs. 3.1 μs), wider half-peak widths (3.8 vs. 2.5 μs), longer zero-crossing times (26.2 vs. 14 μs), and extended fall times (4 vs. 3.2 μs). We further demonstrated that such discrepancies between normal and inverted IC flashes should not be caused by subjective factors, like noise threshold setting, or objective factors, like signal propagation distance. Based on this analysis, finally, we inferred that the discrepancies should be a reflection of the PB channel properties of normal and inverted IC flashes.

Model modification and influence of edge effect on effective area of giant electro-rheological polishing using plate electrodes

Abstract Giant electro-rheological polishing (GPRP) is recognized as an innovative ultra-precision machining technology with significant potential. However, the pronounced edge effect within the GPRP's polishing gap can introduce errors in calculating the effective area and designing the electrode structure. This, in turn, may lead to under-polishing and an increased risk of insulation breakdown. In this study, COMSOL was employed to investigate the electric field distribution characteristics within the polishing gap. This exploration aimed to refine the calculation model of the effective area, optimize the plate electrodes' structure and size, and diminish the likelihood of insulation breakdown. Through systematic finite element simulations, the impact of polishing voltage, inter-electrode gap, and plate length on the edge effect was thoroughly analyzed to ascertain its influence range. The simulation findings revealed that, while maintaining a constant inter-electrode gap for the tool electrode, variations in the polishing gap, polishing voltage, and plate length within specific ranges resulted in an edge effect influence range of approximately 1 mm. Moreover, when the machining gap, polishing voltage, and plate length remained unchanged, the edge effect influence range increased proportionally with the electrode gap within a specific range, approximately equivalent to the size of the electrode gap. Experimental validation of the giant electro-rheological effect confirmed the existence and influence range of the edge effect, aligning with the finite element simulation results. Ultimately, modifications to the calculation model of the effective area were proposed, along with a solution to optimize the electrode size and structure, with the objective of reducing the probability of insulation breakdown. In practical applications, this work can provide a valuable reference for electrode structure design, insulation breakdown improvement and parameter selection.

Analysis of the solid breakdown characteristics under high voltage pulse

As an efficient breakage technology, high voltage pulse breakage technology (HVP) has been an attractive topic due to its selective advantages. Typically, HVP is conducted in water and it is believed that the breakdown strength of water is higher than that of solids, and the discharge channel will be formed in solids under short voltage front rise time. The location of the discharge channel is important for understanding and optimizing of HVP. The study focuses on solid breakdown and the location of the discharge channel. The breakdown type during the HVP process is analyzed, the breakage characteristics of solid particles are investigated, the breakdown parameters are compared between water and solid, and the influence of solid composition on breakdown type is revealed. Under the settled conditions of this study, the results showed that: the discharge channel is easier to be formed inside the solid particle with the particle in contact with the electrode. And the discharge channel is formed in water with water gap between the solid and the electrode. The location of the discharge channel is affected by solid composition and the electrical breakdown probability can be improved with other compositions embedded in solid particles.

Effect of curdlan on improving dough rheological properties and performance of corresponding steamed bread

This study explored the effect of curdlan on dough rheological properties, and the performance of corresponding steamed bread. Curdlan addition significantly improved the rheological, dynamic rheological and fermentation properties of dough, and ultimately enhanced the textural and sensory properties of corresponding steamed bread. The microstructure confirmed that the dough with 0.5% curdlan had uniform size and dense gluten network. Addition of curdlan also increased the pasting temperature, the peak and final viscosities, but decreased the breakdown and setback parameters of starch. The steamed bread with 0.5% curdlan had minimum hardness (1266 g), maximum specific volume (2.50 mL/g) and highest sensory score (92.0). Storage experiments suggested that 0.5% curdlan decreased the crumb firming rate and alleviated the retrogradation of starch in steamed bread, indicating that curdlan was effective in retarding the steamed bread staling during storage. It was concluded that 0.5% curdlan had positive effect on rheological properties of wheat dough and quality of corresponding steamed bread.

Memory effect and statistical characterization of pulsed vacuum microdischarge breakdowns between palladium electrodes from 500 nm up to [formula omitted

The understanding of microgaps breakdown phenomena at controlled laboratory conditions represents an important prerequisite in the development of future micro-plasma technologies. The present work is focused on the observation of the electrical discharge parameters of the pulsed vacuum breakdown between palladium electrodes. The quasi-homogeneity of the generated fields was achieved using a plane-to-sphere geometry of the electrodes separated from 0.5 to 10μm. The first part of the study covers the conditioning process of the electrodes, including a comparison of the pair-virgin and single-virgin electrode configurations. A detailed statistical analysis of the discharge parameters, such as the breakdown voltage, the duration and the energy released during a pulse, and minimal power for maintaining the discharge is provided for different gap configurations for a voltage ramp speed of 107 kV/s. The analysis with respect to breakdown voltage yielded the observation of the memory effect between subsequent breakdowns.

Experimental Investigation of Laser Damage Limit for ZPG Infrared Single Crystal Using Deep Magnetorheological Polishing of Working Surfaces

Zinc germanium phosphide (ZGP) crystals have garnered significant attention for their nonlinear properties, making them good candidates for powerful mid-IR optical parametric oscillators and second-harmonic generators. A ZnGeP2 single crystal was treated by deep magnetorheological processing (MRP) until an Angstrom level of roughness. The studies presented in this article are devoted to the experimental evaluation of the influence of deep removal (up to 150 μm) from the surface of a ZnGeP2 single crystal by magnetorheological polishing on the parameters of optical breakdown. It was shown that the dependence of the ZnGeP2 laser-induced damage threshold on MRP depth is a smooth monotonically decreasing logarithmic function. The obtained logarithmic dependence indicates the thermal nature of optical breakdown and the dependence of the ZnGeP2 laser-induced damage threshold on the concentration of surface absorbing defects.

Confining Stress Response to Hydraulic Fracturing Volumetric Opening on the Representative Volume Element (RVE) Scale

Confining stress response is considered an accompanying behavior of hydraulic fracturing. Along these lines, an evaluation model of confining stress response was presented in this work. It was established on a rock representative volume element (RVE) and based on the hydraulic volumetric opening model, which stems from the theories of poroelasticity, breakdown damage, and hydraulic fracture mechanics. From the extracted outcomes, it was demonstrated that the confinement of the stress response depends on the matching among the characteristic parameters (εb,εs,m) of the rock breakdown, the volumetric opening, and channel flow regimes of the fracturing fluid. Examples in four limiting fracturing regimes show that (1) the confinement of the stress response is strongly determined by the existence of various fracturing regimes and takes place in a different manner during fracture initiation and opening. More specifically, during fracturing initiation, the ratio of the confining stress response to the far-field stress (Pcmax/σh) is 2.0500 in the M regime, 1.9600 in the M˜ regime, 2.7126 in the K regime, and 1.7448 in the K˜ regime, while when the fracture is opened, these values (PC/σh) are 1.8994, 1.8314, 1.6378, and 1.2846, respectively. (2) The impact of the confined stress response to the fluid pressure is also affected by the fracturing regimes; e.g., in both M and M˜ regimes, the peak confinement stress responses lag behind peak pore pressures, but in the K and K˜ regimes, lag off disappears. (3) The pore volumetric opening (Vpe) leads to an increase in the confining stress response, while the fracture opening (Vpd) leads to a reduction in the confining stress response.

Influence of gas pressure on the magnetized plasma parameters of laser-induced breakdown

Influence of gas pressure on the magnetized plasma parameters of laser-induced breakdown

Omics Signatures of Tissue Injury and Hemorrhagic Shock in Swine.

Advanced mass spectrometry methods were leveraged to analyze both proteomics and metabolomics signatures in plasma upon controlled tissue injury (TI) and hemorrhagic shock (HS)-isolated or combined-in a swine model, followed by correlation to viscoelastic measurements of coagulopathy via thrombelastography. TI and HS cause distinct molecular changes in plasma in both animal models and trauma patients. However, the contribution to coagulopathy of trauma, the leading cause of preventable mortality in this patient population remains unclear. The recent development of a swine model for isolated or combined TI+HS facilitated the current study. Male swine (n=17) were randomized to either isolated or combined TI and HS. Coagulation status was analyzed by thrombelastography during the monitored time course. The plasma fractions of the blood draws (at baseline; end of shock; and at 30 minutes, 1, 2, and 4 hours after shock) were analyzed by mass spectrometry-based proteomics and metabolomics workflows. HS-isolated or combined with TI-caused the most severe omic alterations during the monitored time course. While isolated TI delayed the activation of coagulation cascades. Correlation to thrombelastography parameters of clot strength (maximum amplitude) and breakdown (LY30) revealed signatures of coagulopathy which were supported by analysis of gene ontology-enriched biological pathways. The current study provides a comprehensive characterization of proteomic and metabolomic alterations to combined or isolated TI and HS in a swine model and identifies early and late omics correlates to viscoelastic measurements in this system.

Flour nutritional profile, and soxhlet-extracted oilphysicochemicalbreakdown-storage performance ofwhitemelon (Cucumeropsis mannii Naudin) seed varieties from Southeast Nigeria.

White melon (Cucumeropsis mannii Naudin), is among common and yet underutilized oil seed crop within the West African region, does not have sufficient information specific to its nutrient composition for foreign consumers. To supplement existing information, therefore, we investigated the nutritional profile of defatted and full-fat flour, alongside physicochemical breakdown and storage performance of soxhlet-extracted oil from two white melon (C. mannii) seed varieties found in Southeast Nigeria. Nutritional profile involved the determinations of proximate composition, minerals, vitamins, functional properties as well as amino acid profile. Physicochemical breakdown involved the determinations of fatty acid profile, lipid breakdown parameters, as well as associated physical attributes. Results showed defatting of flours increased the protein (69.04%), carbohydrates (16.26%), crude fiber (2.68%), ash (11.9%), mineral (Na ranging from 223.92-246.99 mg/100g), and vitamin contents (Vit B1 ranging from 0.453-0.712 mg/100g). Total amino acid differed slightly when comparing miniature (30.36 g/100g) and large (22.36 g/100g) seeds. Soxhlet-extracted oil possessed low thiobarbituric acid, acid, and peroxide values (0.030 and 0.038 mg MDA/kg, 1.08 and 1.27 mg KOH/g, and 2.95 and 3,94 mEqO2/kg, for large and miniature seeds respectively), and peak linoleic acid (5 and 6.45 mg/ml, for miniature and large seeds respectively). During storage, the thiobarbituric acid and peroxide values of soxhlet-extracted oil increased yet within acceptable limits.

The partial electrical breakdown mechanism by high voltage electric pulses in multi-fractured granite

High-voltage electric pulse (HVEP) technology has currently become a new efficient rock breaking method. In order to reveal the influence of internal fracture characteristics of heterogeneous granite on electric pulse rock breaking, the two-dimensional numerical model of multi-physical field coupling electrical breakdown of fractured rock is established, which the high-voltage electric pulse plasma generation in multi-fractured heterogeneous granite is realized from the coupling of circuit field, current field, breakdown field, heat transfer field and solid mechanics. This paper analyzes the influence of fracture porosity, fracture types and granite heterogeneity on the electrical breakdown of rock (i.e. the formation of plasma channel inside the rock). At the same time, the two-dimensional numerical model of electrical breakdown parameters, which considers the circuit structure parameters of the pulsed tool, the initiation and development of the electrical breakdown, the dependence between electrical breakdown intensity and time, and rock heterogeneity, are analyzed. The simulation results indicate that with the heterogeneity H of granite changing, the plasma channel inside the rock samples are different, while the time required for breakdown t and rock breaking volume Vrock of rock samples with different heterogeneous H will show obvious fluctuations; among the rock samples with different heterogeneity H, existing a single crack requires a longer breakdown time and the extreme value of the internal conductivity is also significantly larger. And then, the formation of plasma channel is directional selective, extending towards fractures and the weak electrical breakdown intensity. With the dip angle of the fracture increasing, the required breakdown time increases accordingly, and conversely, the broken volume decreases accordingly. The larger porosity of fracture is, the larger broken volume and the shorter required break down time of the rock sample. Furthermore, with the continuous action of electric pulses, multi-fractured rock form interpenetrating plasma channels to improve the rock breaking efficiency. The research results can provide help and theoretical support for optimization of electric pulse rock breaking parameters and the development of electric pulse drilling technology.

Electrical Characterization of Plasma-Assisted Electron Beam Source With Sub-mm Sheet Aperture

In this article, the electrical characterization of a plasma-assisted electron beam source with a sub-mm sheet aperture has been performed. The developed sheet electron beam source comprises a hollow cathode cavity, two floating anodes, and one ground potential anode with a sheet aperture of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.5\times0.3$ </tex-math></inline-formula> mm. The source has been characterized under varying applied gap potential range, i.e., 10–30 kV in self-breakdown operating mode. The breakdown parameters and resultant beam parameters, such as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V} - {I}$ </tex-math></inline-formula> characteristics, electron beam current density, duration to reach the conductive phase, and the energy transformation efficiency of the developed source, have been analyzed. The successive breakdown phenomenon has also been presented in the profile of the developed electron beam source.

“TEG” talks: technology worth spreading?

“TEG” talks: technology worth spreading?

Комплексная цифровизация, реализуемая при освоении запасов Гремячинского месторождения калийно-магниевых солей

The paper reviews the main trends in digitalization of the production processes implemented during the development of the Gremyachinskoe potassium-magnesium salt deposit. The main objective of the digital projects is to maintain competitiveness in the current market conditions. When implementing the integrated digital transformation project, the EuroChem-VolgaKaliy created a clear system of criteria to control the efficiency of the business processes and intriduced instrumental control over the actual duration of the technological cycle. Comparing more complete information on personnel with production metrics data creates objective ratings of face teams and foremen, which makes it possible to reduce production cycle time and increase average daily production volumes by 26%. An important area for further implementation of the project will be upgrading the IT-infrastructure, robotization of the office tasks, e.g. automatic generation of production requests, transfer of messages between the related divisions with no manual entry of information. After the information array is formed, it is planned to introduce the dependency analysis of production indicators with definition of equipment breakdown parameters. This will help to reduce the total number of downtime cases and increase the productivity of the mine as a whole, and will ensure a significant reduction in duration of unscheduled emergency repairs. A promising trend in activities of the Gremyachinskoe mining-and-processing integrated works is application of artificial intelligence in planning of mining operations. In order to solve these tasks it is envisaged to create 3D models, to simulate various methods and technologies of mining salt formations, to determine the design parameters of the mining method with account of the actual morphology and thixotropy of the formations.

Overview of Aging Mechanisms in Sige Hbts

SiGe HBTs offer significant performance advantage over Si BJTs with improved base resistance and base transit time. However, each faster technology iteration usually comes at the cost of reduced breakdown parameters. As a result, devices are often restricted to smaller operation biases, and rely on fully utilizing these imposed limits to attain maximum circuit performance. Both high voltage and high current operation have been shown to take a toll on a device’s aging behavior. One unintended consequence of technology scaling is that it forces designers to consider alternate circuit architectures and operate these devices under non-traditional modes such as reverse active, off-state, and saturation. Although not as optimal for device performance as forward active operation, these modes enable improved radiation hardening, power savings and even simpler circuit design.A bipolar transistor’s operation can be categorized into four main modes as shown in the figure below based on the applied voltage to the base-emitter (VBE) and base-collector (VCB) junctions. Due to the asymmetrical junction engineering for vertical HBTs, the forward-active mode is usually the most optimized for device performance. Because it is the most utilized mode, it is also the most characterized for device reliability. In this paper, in addition to the mixed mode stress used to characterize SiGe bipolars, we will discuss some of the recent learning in SiGe HBT reliability in the other less-understood modes of operation. We begin with a brief overview of SiGe HBT reliability physics including hot carrier generation (Auger vs. Impact-Ionization), the temperature dependence of competing mechanisms and the physical damage responsible for electrical degradation. Using measurements and simulations, we discuss in detail the device degradation under off-state and saturation modes. We demonstrate how the hot carrier generation physics responsible for degradation in the forward-active mode is still applicable in the other regions of operation. Figure 1

Avalanche-like breakdown behavior of copolymer organic semiconductor-based Schottky junction structure

Organic field-effect transistors have demonstrated their outstanding off-state breakdown performance. Yet, the physical nature of their electric breakdown remains unexplored. In this paper, by employing a lateral back-to-back Schottky junction composed of diketopyrrolopyrrole-based conjugated copolymer (DPPT-TT) and Au metal, the breakdown performance of copolymer organic semiconductor (OSC) is experimentally demonstrated. The nondestructive/repeatable breakdown behavior and positive coefficient between temperature and breakdown voltage indicate that the avalanche-like breakdown mechanism plays a dominant role in determining the breakdown characteristic of OSC-based power devices. Based on the lateral back-to-back Schottky junction, a characterization method of key breakdown parameters is proposed. The extracted critical electric field (EC) of DPPT-TT is up to 5.0 MV/cm, which is more than one order of magnitude higher than that of single-crystal silicon. Despite the fact that copolymer OSCs are narrow bandgap semiconductors, they still deliver excellent breakdown performance, making them a promising building block for future power electronics.

Analysis of high voltage shunt capacitor bank over-voltage breakdown detection

The traditional over-voltage breakdown detection method ignores the suppression of the inrush current of over-voltage breakdown, resulting in low over-voltage signal detection accuracy and a large detection deviation. As a result, a method is proposed for detecting and analyzing the ageing over-voltage breakdown of high voltage shunt capacitor banks. The breakdown model of aged components of the container group is built to determine the breakdown time of the container's overvoltage. Based on this, the annual load of the capacitor bank's aged component material is evaluated, and data on over-voltage breakdown strength is collected. The Mallet algorithm is used to decompose and convert strength data into electrical signals. The high voltage shunt capacitor's over-voltage breakdown inrush current suppressor is built by combining the second-order under damping circuit and the voltage divider. Based on this, the parameters of HV shunt capacitor overvoltage breakdown are obtained, and the detection of HV shunt capacitor overvoltage breakdown of aged HV shunt capacitor banks is completed. The simulation results show that the proposed detection method's over-voltage breakdown output is in perfect agreement with the monitoring device's actual output and has ideal application performance.

Platinum-group elements in Late Quaternary high-Mg basalts of eastern Kamchatka: Evidence for minor cryptic sulfide fractionation in primitive arc magmas

The geochemical variations of magmas across and along supra-subduction zones (SSZ) have been commonly attributed to profound changes in the phase and chemical compositions of the mantle source and subduction-derived melt and fluid fluxes, as well as the physical parameters (e.g. depth, temperature, oxygen fugacity etc) of slab dehydration, mineral breakdown and melting. Here we test the variability of the Late Quaternary primitive magmas in the southern and northern parts of the meridionally oriented Eastern Volcanic Belt (EVB) of Kamchatka, with a slab depth varying from 60 to 160 km. Eight high-Mg (Mg# > 60 mol%) basalts were characterized for major, trace and platinum-group element (PGE) abundances, as well as the compositions of olivine phenocrysts and olivine-hosted spinel inclusions. The basalts in our study are geochemically typical of SSZ magmas and contain similar liquidus assemblages of forsteritic olivine (Mg# 78–92 mol%), low-Ti Cr-spinel and clinopyroxene. Although the absolute abundances of major and trace elements, and their ratios, in the basalts fluctuate to some extent, the observed variability cannot be correlated with any of considered parameters in the geometry of the Kamchatka SSZ and conditions of melting. This unexpected result led to the evaluation of the platinum-group element (PGE) systematics against the lithophile and chalcophile trace element geochemistry and the compositions of phenocrysts. Total whole-rock PGE content varies from 2.3 to 11.7 ppb, whereas the normalized PGE concentration patterns are typical for supra-subduction zones magmas and broadly similar in all studied samples. They are enriched in Rh, Pd and Pt relative to mid-ocean ridge basalts (MORB) and have nearly identical concentrations of Ir-group PGE. The only parameter that correlates well with PGE contents is the average Mg# of olivine phenocrysts from 84 to 90.3 mol%. This is interpreted to result from minor cryptic fractionation of sulfide melt, together with primitive olivine, in low-to-mid crustal conditions. Negative Ru anomalies on chondrite-normalized diagrams correspond to the Fe2+/Fe3+ ratios in spinel (a proxy for magma redox conditions), which reflects a replacement of monosulfide solid solution by laurite in the mantle wedge during oxidation.

Effect of an Electric Field on an Optical Breakdown in the Air Stream

Experimental data on the effect of an electric field on the plasma of an optical discharge in an air flow have been obtained. Two configurations of an external electric field under the action of an optical discharge on the plasma are considered. To create an electric field, flat (the field along the beam and across the flow) and ring electrodes (the field across the laser beam and along the flow) were used. It was found that there are two modes of combined discharge (optical and electrical). When the field was created symmetrically with respect to the flow axis, an electrical breakdown was observed from the nozzle exit (positively charged electrode) to the focusing point of the laser beam, while no streamers were observed in the optical discharge wake. In another case, an electric discharge is realized between flat electrodes simultaneously with optical breakdown. In a field of constant strength above 3 kV/cm, the presence of an optical discharge plasma promoted electrical breakdown of the medium. In this case, the parameters of the electrical breakdown depended on the shape of the electrodes, the polarity of the applied voltage, and the air flow rate.