Transient Discharge Research Articles

Novel Electro-Explosive Device Incorporating a Planar Transient Suppression Diode

In this letter, a novel, electrostatic discharge tolerant, semiconductor-based electro-explosive device was presented. The device which was called integrated semiconductor bridge (ISCB) chip consists of a monocrystalline silicon heating element, which was utilized to ignite pyrotechnic mix in weapon. Two planar transient suppression diode arrays were incorporated into the chip to protect against electrostatic discharge events. The characteristic of transient suppression diode array and electric discharge characteristic of the ISCB was tested by a capacitive discharge unit. Meanwhile, the behavior of the ISCB during electrostatic discharge events was also tested with a human body electrostatic discharge model. The results showed that the ISCB chip provided advantages including small size, fast ignition, electrostatic discharge insensitivity and low initiation energy applications.

Hand-generated piezoelectric mechanical-to-electrical energy conversion plasma

A transient spark discharge is an atmospheric pressure plasma that has applications in pollutant removal, medicine, water treatment, agriculture, bactericides, and nanomaterial synthesis. Conventional methods of generating transient sparks at atmospheric pressure usually require a high voltage input at nanosecond pulses. Piezoelectric crystals offer a path to creating plasma devices that do not require a high voltage power supply to generate high voltage outputs; they directly transform mechanical energy into electrical energy. This work examines a manually-operated piezoelectric mechanical-to-electrical energy conversion plasma device. Electrical characterization of the plasma discharge generated by this device shows that it behaves as a transient spark, discharging 0.96 mJ over approximately 30 ns, with consistent behavior across multiple consecutive discharges. Although this specific device had a low mechanical-to-plasma energy conversion efficiency of 1.54%, the piezoelectric crystal resets to an equilibrium condition after approximately 8 μs, which suggests that it could be operated with a mechanical input of up to nearly 125 kHz. This work shows the potential of generating plasma in off-the-grid situations using piezoelectric crystals. One particular application of a piezoelectric plasma device is for in situ pollution mitigation or plasma-enhanced combustion, embedding such a device on the high-frequency oscillating or rotating components of internal combustion engines and turbomachinery.

A modular brain-on-a-chip for modelling epileptic seizures with functionally connected human neuronal networks

Epilepsies are a group of neurological disorders characterised by recurrent epileptic seizures. Seizures, defined as abnormal transient discharges of neuronal activity, can affect the entire brain circuitry or remain more focal in the specific brain regions and neuronal networks. Human pluripotent stem cell (hPSC)-derived neurons are a promising option for modelling epilepsies, but as such, they do not model groups of connected neuronal networks or focal seizures. Our solution is a Modular Platform for Epilepsy Modelling In Vitro (MEMO), a lab-on-chip device, in which three hPSC-derived networks are separated by a novel microfluidic cell culture device that allows controlled network-to-network axonal connections through microtunnels. In this study, we show that the neuronal networks formed a functional circuitry that was successfully cultured in MEMO for up to 98 days. The spontaneous neuronal network activities were monitored with an integrated custom-made microelectrode array (MEA). The networks developed spontaneous burst activity that was synchronous both within and between the axonally connected networks, i.e. mimicking both local and circuitry functionality of the brain. A convulsant, kainic acid, increased bursts only in the specifically treated networks. The activity reduction by an anticonvulsant, phenytoin, was also localised to treated networks. Therefore, modelling focal seizures in human neuronal networks is now possible with the developed chip.

Resolving transient discharge cycle behaviour in modulated inductive plasmas

The further development of inductive plasma generators (IPGs) for space propulsion applications has driven the need for the development of non-intrusive experimental techniques that can resolve transient discharge cycle behaviour and accommodate a variety of propellant gases and gas-mixtures. In this work, a new approach is presented that simultaneously measures the antenna current, radially-resolved axial magnetic field strength and the radially-resolved emission in the visible range, at a sampling frequency sufficient to capture the driving and discharge cycle frequencies. Experiments were conducted using IPG7: a helical antenna IPG, driven nominally at 586 kHz, with 300 Hz discharge cycles. Nitrogen, argon-nitrogen, and argon-oxygen propellants were tested at capacitive and inductive conditions with input powers ranging from 4 kW to 36 kW. The propellants could be sourced from the space environment under in-situ resource utilisation. Analysis of the mean discharge cycle has made it possible to identify different coupling modes occurring within the cycle. These findings underscore the need to model such plasmas at the timescale of individual discharge cycles and demonstrate the value of the measured data for developing such models.

Effect of low-frequency disturbance on the self-sustained discharge of hollow cathode

The existence of low-frequency disturbance can affect the discharge stability of a hollow cathode, and may even lead to the extinction of the discharge. In this paper, a semi-transient algorithm based on the classical 0-D theoretical model of an orificed hollow cathode was developed to study the discharge stability of a hollow cathode under a continuous low-frequency electric field disturbance. A laboratory experiment using an orificed BaO-W cathode was carried out to confirm the validity of transient analysis results and to determine an appropriate time step in the analysis. The theoretical evolution trend of the discharge current is largely in agreement with the experiment for a time step value of 12.5 μs although there is a 7% error in the discharge duration prediction. This study has identified the role of two emission enhancement mechanisms in the failure process of a self-sustained discharge, namely the Schottky effect and the sheath funneling effect. The presence of the sheath funneling effect induces larger amplitude oscillations and a sharp drop in discharge parameters when the effect ceases to exist, and this significantly weakens the discharge stability. The influence of operating conditions and disturbance parameters on transient discharge characteristics was examined for the NASA NSTAR cathode. Within the parameter range that was studied, findings show that higher xenon flow rates or lower discharge currents provide optimal duration as a result of higher electron temperatures and denser plasma at the initial state. For a fixed operation point, the discharge duration was found to decline exponentially with disturbance amplitude and quadratically with disturbance frequency.

Plasma-enhanced NOx remediation using nanosecond pulsed discharges in a water aerosol matrix

We report nitrogen oxides remediation using a transient pulsed plasma discharge in a water aerosol gas matrix using nanosecond high voltage pulses. While there have been many studies showing highly efficient conversion of NO to NO2 using plasma-driven processes, the total removal of NOx (i.e., NO plus NO2) is severely limited by the backreaction of NO2 to NO, which is also driven by the highly reactive radical species in the plasma. By injecting water aerosol into the gas matrix, we are able to selectively drive a plasma-based reaction which minimizes the backreaction of NO2 to NO. Here, the synergistic effect of the water aerosol and plasma discharge enables enhanced NOx removal by creating OH radicals which, in turn, drive NO2 to HNO3, which is highly soluble in water. In the presence of water aerosol, the plasma discharge results in a 100% reduction in NO and a 98% reduction in total NOx. Spectroscopic evidence of the short-lived, highly reactive OH radical is obtained through plasma emission spectroscopy and the vibrational signatures of the NO2− and NO3− intermediates are observed using SERS-enhanced Raman spectroscopy. We show that the NOx remediation increases with plasma power density demonstrating the scalability of this general approach.

Transient Spark Discharge Generated in Various N2/O2 Gas Mixtures: Reactive Species in the Gas and Water and Their Antibacterial Effects

Reactive species generated in the gas and in water by cold air plasma of the transient spark discharge in various N2/O2 gas mixtures (including pure N2 and pure O2) have been examined. The discharge was operated without/with circulated water driven down the inclined grounded electrode. Without water, NO and NO2 are typically produced with maximum concentrations at 50% O2. N2O was also present for low O2 contents (up to 20%), while O3 was generated only in pure O2. With water, gaseous NO and NO2 concentrations were lower, N2O was completely suppressed and HNO2 increased; and O3 was lowered in O2 gas. All species production decreased with the gas flow rate increasing from 0.5 to 2.2 L/min. Liquid phase species (H2O2, NO2‾, NO3‾, ·OH) were detected in plasma treated water. H2O2 reached the highest concentrations in pure N2 and O2. On the other hand, nitrites NO2‾ and nitrates NO3‾ peaked between 20 and 80% O2 and were associated with pH reduction. The concentrations of all species increased with the plasma treatment time. Aqueous ·OH radicals were analyzed by terephthalic acid fluorescence and their concentration correlated with H2O2. The antibacterial efficacy of the transient spark on bacteria in water increased with water treatment time and was found the strongest in the air-like mixture thanks to the peroxynitrite formation. Yet, significant antibacterial effects were found even in pure N2 and in pure O2 most likely due to high ·OH radical concentrations. Controlling the N2/O2 ratio in the gas mixture, gas flow rate, and water treatment time enables tuning the antibacterial efficacy.

Novel and de novo point and large microdeletion mutation in PRRT2-related epilepsy.

BackgroundPoint and copy number variant mutations in the PRRT2 gene have been identified in a variety of paroxysmal disorders and different types of epilepsy. In this study, we analyzed the phenotypes and PRRT2‐related mutations in Chinese epilepsy children.MethodsA total of 492 children with epilepsy were analyzed by whole exome sequencing (WES) and low‐coverage massively parallel CNV sequencing (CNV‐seq) to find the single nucleotide variants and copy number variations (CNVs). And quantitative polymerase chain reaction was utilized to verify the CNVs. Their clinical information was followed up.ResultsWe found PRRT2‐related mutations in 19 patients (10 males and nine females, six sporadic cases and 13 family cases). Twelve point mutations, four whole gene deletion, and three 16p11.2 deletions were detected. The clinical features of 39 patients in 19 families included one early childhood myoclonic epilepsy (ECME), one febrile seizure (FS), two infantile convulsions with paroxysmal choreoathetosis (ICCA), six paroxysmal kinesigenic dyskinesias (PKD), 12 benign infantile epilepsy (BIE), and 17 benign familial infantile epilepsy (BFIE). All patients had normal brain MRI. Interictal EEG showed only one patient had generalized polyspike wave and five patients had focal transient discharges. Focal seizures originating in the frontal region were recorded in one patient, two from the temporal region, and two from the occipital region. Most patients were treated effectively with VPA or OXC, and the child with myoclonic seizures was not sensitive to antiepileptic drugs.Conclusion PRRT2 mutations can be inherited or de novo, mainly inherited. The clinical spectrum of PRRT2 mutation includes BIE, BFIE, ICCA, PKD, FS, and ECME. The PRRT2‐related mutations contained point mutation, whole gene deletion and 16p11.2 deletions, and large microdeletion mutations mostly de novo. It is the first report of PRRT2 mutation found in ECME. Our report expands the mutation and clinical spectrum of PRRT2‐related epilepsy.

Seizures classification based on higher order statistics and deep neural network

The epileptic seizure is a transient and abnormal discharge of nerve cells in the brain that leads to a chronic disease of brain dysfunction. There are various features-based seizures classification algorithms listed in the literature. But, there is no standardized set of attributes that can perfectly capture the relevant information regarding the signal dynamics. In this paper, a computationally-fast seizure classification algorithm is presented. The obtained results through the proposed algorithm are consistent and repeatable. This paper describes an automated seizures classification technique using the nonlinear higher-order statistics and deep neural network algorithms. The sparse autoencoder based deep neural network is used to extract the essential structural details from the third-order cumulant coefficients matrix. The proposed algorithm achieves a reliable classification accuracy for both categories, i.e., binary classes and three-classes of electroencephalogram (EEG) signals with the softmax classifier. The proposed study is simulated on the publicly-available Bonn university EEG database. The achieved results show the effectiveness of the proposed algorithm for seizures classification.

Multi-source partial discharge detection and rapid localization of switchgear based on comprehensive diagnosis method

Partial discharge detection is an effective method to find potential insulation defects in switchgear. At present, the switchgear is mainly composed of busbars, circuit breakers, grounding knives, cables and other components, which leads to multiple faults and simultaneous discharges in the partial discharge detection process of the switchgear. In order to realize the partial discharge detection and rapid location of the switchgear, based on the introduction of the detection methods and location principles of ultrasonic, transient ground voltage and UHF partial discharge, this paper proposes to use ultrasonic, transient ground voltage and UHF detection technology to diagnose and analyse the multi-source partial discharge of the switchgear and realize the detection of partial discharge; the multi-source partial discharge of the switchgear is realized by the rapid localization method combining the UHF time difference method and the flat surface method. Through partial discharge detection and localization analysis of a 35kV switchgear, the feasibility of multi-source partial discharge diagnosis and rapid localization method is verified, which provides a basis for on-site inspection personnel to realize multi-source partial discharge detection and localization of switchgear.

Effects of Pseudo-spark Discharge Pulsed Electron Beam Irradiation on the Microstructure and Properties of 6061 Aluminum Alloy

The evolutions of the microstructure and properties of 6061 aluminum alloy irradiated by the pulsed electron beam generated by pseudo-spark discharge is the main focus of this paper. The pseudo-spark discharge is a low-pressure, transient discharge which has been recognized as a high efficient electron beam source with the rapid current growth of ~1012A/s, high power density of ~109W/cm2, short-duration pulse of 102~103ns and self-focusing beam diameter of 0.5~6mm. These characteristics enable the material treated by the pseudo-spark pulsed electron beam to melt and cool rapidly, and form the fine grain structure. In this work, the evolutions of the micromorphology and surface properties of 6061 aluminum alloy and the influences of the beam parameters are investigated and analysed. The corrosion resistance of the surface is investigated by the electrochemical corrosion experiments. The mechanism of the “crater” in the surface microstructure formed by the pseudo-spark pulsed electron beam under varying beam accelerating voltages is also analysed and discussed. The experimental results in this paper demonstrate that the re-melting layer of the material surface appears after the given pseudo-spark pulsed electron beam irradiations, and "large crater" morphology forms under higher voltage. The homogenization of the element distributions on the surface and reduction of the impurity on the re-melting layer after given pulsed electron beam treatments are capable of improving the mechanical properties of the alloy workpiece surface, and the corrosion resistance of the surface is also increased after given pulsed electron beam treatments.

Experimental investigations of nanosecond-pulse electron beam profile for metal surface treatments

In this paper, a transient hollow cathode discharge (THCD) generated pulsed electron beam is applied for the metal surface treatment. And the profile of this pulsed beam current density distribution is experimentally investigated via a high accuracy variable beam entrance Faraday Cup (VBEFC) system. The influences of the varying beam pulses on the post-treated surface microstructure and properties of 306 stainless steel and 6061 aluminum alloy are investigated in this paper. The experimental results demonstrate that the THCD generated pulsed electron beam profile has a characteristic pattern of concentrated energy flux within a 2 mm circular region where the high energy electrons are the most concentrated. And such a concentrated energy flux pattern can be further promoted by the increased accelerating voltage and the self-focusing space charge effect. The pulsed e-beam surface treatment results on 306 stainless steel show that the surface morphology variations are identical with the evolutions of the beam current profiles under varying accelerating voltages. Additionally, the surface treatment results on 6061 aluminum alloy show that the micro-hardness of the alloy can be improved from the initial 63.1 HV to 85.1 HV by increasing the beam accelerating voltage up to 25 kV, promoting the concentrated energy flux of the generated beam pulse.

Measurement approach for custom designed cold plasma generator

More recently corona discharges have started to be used as cold atmospheric plasma sources for biomedical applications. This is due to the simple way of its generation. Nevertheless, there are still difficulties of gas discharge stabilization. For this reason, determination of corona discharge electrical characteristics is very important. At the same time, it should be remembered that common measurement approaches and tools may not always be used. Particularly the corona discharge generation in small air gaps was crucial in this study, which immediately restricted an application of commercial current and voltage probes. As a result, special method for the voltage measurement across the air gap was proposed. In addition, corona discharge current pulses of nanosecond duration were measured in high resolution. All this made it possible to obtain complete information about the transient discharge current and voltages. Presented methods might be useful for gas discharge investigation of conditions like that discussed in the paper.

Novel and de novo mutation of PCDH19 in Girls Clustering Epilepsy.

Background PCDH19 has become the second most relevant gene in epilepsy after SCN1A. Seizures often provoked by fever.MethodsWe screened 152 children with fever‐sensitive epilepsy for gene detection. Their clinical information was followed up.ResultsWe found eight PCDH19 point mutations (four novel and four reported) and one whole gene deletion in 10 female probands (seven sporadic cases and three family cases) who also had cluster seizures. The common clinical features of 16 patients in 10 families included fever‐sensitive and cluster seizures, mainly focal or tonic‐clonic seizures, and absence of status epilepticus, normal intelligence, or mild‐to‐moderate cognitive impairment, the onset age ranges from 5 months to 20 years. Only four patients had multiple or focal transient discharges in interictal EEG. Focal seizures originating in the frontal region were recorded in four patients, two from the parietal region, and one from the occipital region.Conclusion PCDH19 mutation can be inherited or de novo. The clinical spectrum of PCDH19 mutation includes PCDH19 Girls Clustering Epilepsy with or without mental retardation, psychosis, and asymptomatic male. The onset age of PCDH19 Girls Clustering Epilepsy can range from infancy to adulthood. Sisters in the same family may be sensitive to the same antiepileptic drugs. And our report expands the mutation spectrum of PCDH19 Girls Clustering Epilepsy.

Electric field determination from intensity ratio of and N2 bands: nonequilibrium transient discharges in pure nitrogen

We developed an extension of the spectrometric method to estimate a reduced electric field (E/N), which is applicable in nitrogen-containing plasmas. The method is based on the intensity ratio of the emission bands of the first negative system (FNS) of and the second positive system (SPS) of N2. It uses the emission occurring in the wavelength interval 375–410 nm, which includes six SPS and two FNS bands. The choice of the spectral window is guided by much simpler acquisition and processing of experimental data than the SPS(0, 0) and FNS(0, 0) pair that is typically used. Following this idea, we construct a kinetic model for pure molecular nitrogen, which determines the population of the upper states responsible for the FNS and SPS emission. Moreover, we perform sensitivity analysis of the kinetic model, which allows us to reveal the most significant processes for the investigated intensity ratios. For these processes, we provide an in-depth review of the kinetic data that are available in the literature. We use the fact that the spectral window investigated contains bands to obtain three independent intensity ratios with sufficient signal-to-noise ratio ((FNS(0, 0)/SPS(0, 2), FNS(0, 0)/SPS(1, 4), FNS(0, 0)/SPS(2, 5)), which are usable for more accurate electric field determination. We also provide analytical formulas representing intensity ratio dependencies on E/N. Furthermore, we focus on different spectrometric representations of FNS and SPS bands, which also affect the precision of E/N determination. We examine the FNS/SPS band profiles in terms of different rotational temperatures and instrumental functions. Finally, we propose a simple procedure that enables the use of bandhead intensities in the intensity ratio dependencies, thus avoiding the need to evaluate integral band intensities from the recorded spectra.

Divergent paths to seizure-like events.

Much debate exists about how the brain transitions into an epileptic seizure. One source of confusion is that there are likely to be critical differences between experimental seizure models. To address this, we have compared the evolving activity patterns in two widely used in vitro models of epileptic discharges. Brain slices from young adult mice were prepared in the same way and bathed either in 0 Mg2+ or 100 µmol/L 4AP artificial cerebrospinal fluid. We have found that while local field potential recordings of epileptiform discharges in the two models appear broadly similar, patch‐clamp analysis reveals an important difference in the relative degree of glutamatergic involvement. 4AP affects parvalbumin‐expressing interneurons more than other cortical populations, destabilizing their resting state and inducing spontaneous bursting behavior. Consequently, the most prominent pattern of transient discharge (“interictal event”) in this model is almost purely GABAergic, although the transition to seizure‐like events (SLEs) involves pyramidal recruitment. In contrast, interictal discharges in 0 Mg2+ are only maintained by a very large glutamatergic component that also involves transient discharges of the interneurons. Seizure‐like events in 0 Mg2+ have significantly higher power in the high gamma frequency band (60–120Hz) than these events do in 4AP, and are greatly delayed in onset by diazepam, unlike 4AP events. We, therefore, conclude that the 0 Mg2+ and 4AP models display fundamentally different levels of glutamatergic drive, demonstrating how ostensibly similar pathological discharges can arise from different sources. We contend that similar interpretative issues will also be relevant to clinical practice.

Volume-Averaged Electrochemical Performance Modeling of 3D Interpenetrating Battery Electrode Architectures

Recent advancements in micro-scale additive manufacturing techniques have created opportunities for design of novel electrode geometries that improve battery performance by deviating from the traditional layered battery design. These 3D batteries typically exhibit interpenetrating anode and cathode materials throughout the design space, but the existing well-established porous electrode theory models assume only one type of electrode is present in each battery layer. We therefore develop and demonstrate a multi-electrode volume-averaged electrochemical transport model to simulate transient discharge performance of these new interpenetrating electrode architectures. We implement the new reduced-order model in the PETSc framework and asses its accuracy by comparing predictions to corresponding mesoscale-resolved simulations that are orders of magnitude more computationally-intensive. For simple electrode designs such as alternating plates or cylinders, the volume-averaged model predicts performance within ∼2% for electrode feature sizes comparable to traditional particle sizes (5-10μm) at discharge rates up to 3C. When considering more complex geometries such as minimal surface designs (i.e. gyroid, Schwarz P), we show that using calibrated characteristic diffusion lengths for each design results in errors below 3% for discharge rates up to 3C. These comparisons verify that this novel model has made reliable cell-scale simulations of interpenetrating electrode designs possible.

Grounding the DC Microgrid

A comprehensive knowledge of the available grounding strategies and their effects is essential for design, operation, and protection of the dc microgrid. This paper investigates and compares different dc microgrid grounding strategies that involve the choice of grounding configurations and grounding devices. The impacts of different grounding strategies on line-to-ground (LG) fault detection and protection, transient LG fault current magnitude, leakage current level, common mode voltage, personnel/equipment safety, system reliability, service continuity, and insulation requirements are thoroughly investigated. LG fault response of a low-voltage dc microgrid with different grounding devices is studied by detailed simulation of a realistic study system modeled in the PSCAD software. The study results indicate that: 1) the ungrounded, bipolar solidly grounded, unipolar parallel resistance grounded, and bipolar resistance grounded dc microgrids enable LG fault ride through, due to the low fault current; 2) the unipolar solidly grounded, bipolar solidly grounded, diode-grounded, and thyristor-grounded dc microgrids experience significantly large transient discharge currents under LG faults; and 3) the unipolar solidly grounded, diode-grounded, thyristor-grounded, and unipolar low-resistance-grounded dc microgrids provide considerable steady-state LG fault current which necessitates fast detection and clearance of faults.

Pump-off identification with time series analysis of transient water discharge rate

To advance the prognosis of progressing cavity Pumps (PCPs) used for artificial lifting, the pump-off need to be identified to forestall failure. This study developed a new technique for determining the Pump-off events Activation Times (PATs) of the PCPs using the transient Water Discharge Rates (WDRs) from coal seam gas producing wells. The Gaussian distribution function parameters of the rolling standard deviations of the water discharge rate (RSWR) and the transition probability of the rolling standard deviations of the water discharge rate (TP_RSWR) were used to build the model. By determining the anomalies in the RSWR signals with the bottom-up segmentation technique and computing the statistical characteristics at the changepoint locations, the steady-state of the WDR signals was established. This steady-state signal, which represents the Operation Transition Level (OTL) between the Normal Operation (NOP) and the Pump-off Event (POE) was used for monitoring the transition of the PCPs' operating status. An algorithm was developed in Python and tested it on field data from 36 coal seam gas wells. The performance of my technique was determined with precision, recall and F1 score, which gave an average value of 94.94%, 92.63%, and 93.56% respectively. It is expected that the implementation of this technique in the real-time estimation of PATs will be vital for reducing PCPs faults seeing that poor PATs detection results in PCPs running dry and consequently failures due to the extreme temperatures and abrasions.

Direct Simulation of the Full-Wave Partial Element Equivalent Circuit Using Standard SPICE [Application Notes

The partial element equivalent circuit (PEEC) [1] is a computational electromagnetic (EM) method featuring circuit-oriented solutions for full-wave (FW) EM problems. An arbitrary threedimensional structure consisting of conductors and dielectric/magnetic materials can, after proper discretization, be transformed into an equivalent circuit composed of inductors, capacitors, and controlled sources that may be solved using a Simulation Program With Integrated Circuit Emphasis (SPICE)-like simulator or can be combined with external lumped circuits in a straightforward manner. Classical and recent applications of PEEC include interconnect modeling [2], [3], power integrity analysis [4], transient lightning modeling [5], transient electrostatic discharge simulation [6], power electronics [7], antenna analysis [8], [9], and modeling of magnetic materials [10]. Three very good and in-depth treatments of the subject can be found in [11]–[13].