High Voltage Potential Research Articles

Evidence of dark oxygen production at the abyssal seafloor

Deep-seafloor organisms consume oxygen, which can be measured by in situ benthic chamber experiments. Here we report such experiments at the polymetallic nodule-covered abyssal seafloor in the Pacific Ocean in which oxygen increased over two days to more than three times the background concentration, which from ex situ incubations we attribute to the polymetallic nodules. Given high voltage potentials (up to 0.95 V) on nodule surfaces, we hypothesize that seawater electrolysis may contribute to this dark oxygen production.

Identification of Critical Slowing of Conduction Using Unipolar Atrial Voltage and Fractionation Mapping

BackgroundAblation strategies targeting fractionated or low-voltage potentials have been widely used in patients with persistent types of atrial fibrillation (AF). However, recent studies have questioned their role in effectively representing sites of conduction slowing, and thus arrhythmogenic substrates. ObjectivesThe authors studied the relationship between local conduction velocity (CV) and the occurrence of fractionated and/or low-voltage potentials in order to identify areas with critically slowing of conduction. MethodsIntraoperative epicardial mapping was performed during sinus rhythm. Unipolar potentials with an amplitude <1.0 mV were initially classified as low-voltage and potentials with ≥3 deflections as fractionation. A range of thresholds were also explored. Local CV was computed using discrete velocity vectors. ResultsA total of 319 patients were included. Fractionated, low-voltage potentials were rare, accounting for only 0.36% (Q1-Q3: 0.15%-0.78%) of all atrial sites. Local CV at sites with fractionated, low-voltage potentials (46.0 cm/s [Q1-Q3: 22.6-72.7 cm/s]) was lowest compared with sites with either low-voltage, nonfractionated potentials (64.5 cm/s [Q1-Q3: 34.8-99.4 cm/s]) or fractionated, high-voltage potentials (65.9 cm/s [Q1-Q3: 41.7-92.8 cm/s]; P < 0.001). Slow conduction areas (CV <50 cm/s) could be most accurately identified by using a low voltage threshold (<1 mV) and a minimum of 3 deflections (positive predictive value: 54.2%-70.7%), although the overall sensitivity remained low (0.1%-1.9%). ConclusionsSites with fractionated, low-voltage potentials have substantially slower local CV compared with sites with either low-voltage, nonfractionated potentials or fractionated, high-voltage potentials. However, the strong inverse relationship between the positive predictive value and sensitivity of a combined voltage and fractionation threshold for slowed conduction is likely to complicate the use of these signal-based ablation approaches in AF patients.

Исследование влияния магнитного поля на характеристики частичных разрядов

The paper is devoted to the study of the dependences of the characteristics of partial discharges on magnetic induction. The design of the experimental setup has been developed. It allows applying both high voltage and current comparable to the operating one. The setup includes a high voltage source (dielectric tester), a current flow circuit, a high voltage current transformer and a sample of XLPE insulated cable. The operation of the electrical circuit of the experimental setup is simulated using software. The modeling has shown that if the operational electrical strength of the current transformer insulation is present, the high-voltage potential cannot contact the current flow circuit. After this, modeling of the magnetic field inside the insulating layer is carried out. Based on the developed design, an experimental setup is created. To record partial discharges, an artificial defect is created in a cable sample. The results of magnetic field modeling made it possible to estimate the magnetic induction in the field of an artificial cable defect. Next, experimental studies are carried out to assess the influence of the magnetic field of the cable core current on the characteristics of partial discharges. The measurement results have showed a decrease in the average apparent charge of partial discharges and partial discharge power with increasing current. In addition, waveforms are compared, but no significant differences are found. The magnetic field of the current may influence the PD performance in the long term due to its possible influence on the direction of growth of the electrical tree structure.

Efficient Activation and High Mobility of Ion-Implanted Silicon for Next-Generation GaN Devices

Selective area doping via ion implantation is crucial to the implementation of most modern devices and the provision of reasonable device design latitude for optimization. Herein, we report highly effective silicon ion implant activation in GaN via Symmetrical Multicycle Rapid Thermal Annealing (SMRTA) at peak temperatures of 1450 to 1530 °C, producing a mobility of up to 137 cm2/Vs at 300K with a 57% activation efficiency for a 300 nm thick 1 × 1019 cm−3 box implant profile. Doping activation efficiency and mobility improved alongside peak annealing temperature, while the deleterious degradation of the as-grown material electrical properties was only evident at the highest temperatures. This demonstrates efficient dopant activation while simultaneously maintaining low levels of unintentional doping and thus a high blocking voltage potential of the drift layers for high-voltage, high-power devices. Furthermore, efficient activation with high mobility has been achieved with GaN on sapphire, which is known for having relatively high defect densities but also for offering significant commercial potential due to the availability of cheap, large-area, and robust substrates for devices.

Beamlet formation in negative ion sources for fusion applications: A computational grid system comparison

Divergence is a crucial parameter for neutral beam injection heating systems, since it affects the transmission of the beam through a duct. The divergence is determined by properties of the extracted ions, in combination with a grid system that extracts ions from the plasma and subsequently accelerates them to full energy. To disentangle different contributions to the divergence, eight different negative ion-based grid systems are studied with the IBSimu code, treating volume produced deuterium ions only. To ensure that the observed differences can be attributed to grid features, the grid systems are modeled without magnetic field. The ratio between acceleration and extraction potential that gives the lowest divergence shows good agreement with calculated and measured literature values. The divergence in various grid systems is studied at the ITER-heating neutral beams D− current density and extraction potential. At similar normalized emittance, there is a large range of divergences due to the variation in the axial velocity at different acceleration potentials. The normalized emittance is mostly determined by the starting emittance and emittance growth in the extraction stage. The starting emittance is due to the initial perpendicular temperature of the negative ions, which is assumed as 1 eV in simulations. The emittance growth is due to space charge in the extraction stage. Some of the investigated grid systems produce lower divergence beamlets at similar emittance by trading off beamlet size and divergence. The optimum divergence is limited by three parameters at fixed beamlet size: the D− perpendicular velocity distribution upstream of the grid system, the space charge in the extraction stage, and the available high-voltage potential to accelerate the beamlet.

Forced Triboelectrification of Fine Powders in Particle Wall Collisions

Triboelectric separation as an inexpensive and environmentally friendly technique could contribute to material-specific sorting. However, the application as a widespread method is limited due to the complexity of the process. In particle wall collisions, various parameters like collision energy and angle, work function of the contact partners, humidity, surface roughness, etc. influence the particle charging in a hardly predictable way. This study investigates the possibilities of forced triboelectric particle charging by applying an electrical potential to the metal contact partner (copper/steel pipe). The variations included different pipe lengths (0.5 m–3 m), particle materials, and particle sizes for limestone. A distinction is made between the net charge of the particles and the positive, negative, and neutral mass fractions. The work functions of the investigated materials vary from about 3.2 eV to &gt;8.5 eV for glass, limestone, artificial slag, and lithium aluminate particles. With the applied high-voltage potential, the particle net charge can be shifted linearly. For limestone, it is shown that the neutral fraction is highest at the Point of Zero Net Charge (PZNC). This observation may identify an approach for the material selective separation of one target component from a multi-material mixture.

Method for measuring the dielectrics charging potential under ion irradiation using shifting the bremsstrahlung edge

A method is proposed for measuring high-voltage charging potentials of dielectrics under ion irradiation by shifting the boundary of the bremsstrahlung X-ray spectrum. Since there is no bremsstrahlung output during Xe+ ion irradiation, it was proposed to use a probing electron beam to generate bremsstrahlung X-rays. To eliminate the effect of charge compensation on the surface, the value of the current of the probing probe of electrons was selected. The values of the equilibrium charging potentials of Al2O3 ceramics, Al2O3 sapphire, SiO2, and Teflon are obtained at different ion irradiation energies. The data obtained are compared with the results of spectrometric studies. Keywords: dielectric charging, ion irradiation, FIB-SEM, surface potential measurement.

Метод регистрации потенциала зарядки диэлектриков при ионном облучении по сдвигу границы тормозного рентгеновского спектра

A method is proposed for measuring high-voltage charging potentials of dielectrics under ion irradiation by shifting the boundary of the bremsstrahlung X-ray spectrum. Since there is no bremsstrahlung output during Xe+ ion irradiation, it was proposed to use a probing electron beam to generate bremsstrahlung X-rays. To eliminate the effect of charge compensation on the surface, the value of the current of the probing probe of electrons was selected. The values of the equilibrium charging potentials of Al2O3 ceramics, Al2O3 sapphire, SiO2, and Teflon are obtained at different ion irradiation energies. The data obtained are compared with the results of spectrometric studies.

Valproic acid promotes differentiation of adipose tissue-derived stem cells to neuronal cells selectively expressing functional N-type voltage-gated Ca2+ channels

The differentiation of adipose tissue-derived stem cells (ASCs) to neuronal cells is greatly promoted by valproic acid (VPA), and is synergistically enhanced by the following treatment with neuronal induction medium (NIM) containing cAMP-elevating agents. In the present study, we investigated the synergism between VPA and NIM in neuronal differentiation of ASCs, assessed by the expression of neurofilament medium polypeptide (NeFM), with respect to Ca2+ entry. VPA (2 mM) treatment for 3 days followed by NIM for 2 h synergistically increased the incidence of neuronal cells differentiated from ASCs to an extent more than VPA alone treatment for 6 days, shortening the time required for the differentiation. VPA increased intracellular Ca2+ and the mRNAs of voltage-gated Ca2+ channels, Cacna1b (Cav2.2) and Cacna1h (Cav3.2), in ASCs. Inward currents through Ca2+ channels were evoked electrophysiologically at high voltage potential in ASCs treated with VPA. NIM reduced the mRNAs of NeFM and Cacna1b in VPA-promoted neuronal differentiation of ASCs. It was concluded that functional N-type voltage-gated Ca2+ channels (Cav2.2) are selectively expressed in VPA-promoted neuronal differentiation of ASCs. NIM seems to enhance the mRNA translation of molecules required for the differentiation. Neuronal cells obtained from ASCs by this protocol will be used as a cell source for regenerative therapy of neurological disorders associated with altered Cav2.2 activity.

Velocity-tunable beam of continuously decelerated polar molecules for cold ion-molecule reaction studies.

Producing high densities of molecules is a fundamental challenge for low-temperature, ion-molecule reaction studies. Traveling-wave Stark decelerators promise to deliver high density beams of cold, polar molecules but require non-trivial control of high-voltage potentials. We have overcome this experimental challenge and demonstrate continuous deceleration of ND3 from 385 to 10m/s, while driving the decelerator electrodes with a 10 kV amplitude sinewave. In addition, we test an alternative slowing scheme, which increases the time delay between decelerated packets of ND3 and non-decelerated molecules, allowing for better energy resolution of subsequent reaction studies. We characterize this source of neutral, polar molecules suitable for energy-resolved reaction studies with trapped ions at cold translational temperatures. We also propose a combined apparatus consisting of the traveling-wave decelerator and a linear ion trap with a time-of-flight mass spectrometer and discuss to what extent it may achieve cold, energy-resolved, ion-neutral reactions.

Stress Control Optimization using Particle Swarm Optimization Algorithm

Confined field upgrade, particularly in the zone near the high voltage potential and ground potential will quicken the corruption and in this way causing pre-developed disappointment of the protecting material. Other than electrical field upgrade, mechanical stresses and natural impacts additionally influence the presentation of the high voltage overhead separators. Therefore, multi-feature approaches are required to improve the HV separators execution and unwavering quality over their administration life. In the subsequent segment, the current pressure control techniques that incorporate crown ring, consolidated protection get together and end-fitting plan are checked on.

Charging Dielectrics when Bombarded with Ar+ Ions of Medium Energies

A complex facility for measuring the kinetics of high-voltage charging potentials of the surface of massive dielectrics when irradiated with medium-energy Ar+ ions has been created. Measurements of ion emission characteristics, accumulated charges and surface potential have shown effective charging to high positive potentials, close in value to the potential of an ion gun. It is assumed that sputtered ions dominate at the early stage of charging in the process of emission, while in the final stage of irradiation backreflected ions dominate.

System protection for lithium-ion batteries management system: a review

&lt;span&gt;Robustness of a battery management system (BMS) is a crucial issue especially in critical application such as medical or military. Failure of BMS will lead to more serious safety issues such as overheating, overcharging, over discharging, cell unbalance or even fire and explosion. BMS consists of plenty sensitive electronic components and connected directly to battery cell terminal. Consequently, BMS exposed to high voltage potential across the BMS terminal if a faulty cell occurs in a pack of Li-ion battery. Thus, many protection techniques have been proposed since last three decades to protect the BMS from fault such as open cell voltage fault, faulty cell, internal short circuit etc. This paper presents a review of a BMS focuses on the protection technique proposed by previous researcher. The comparison has been carried out based on circuit topology and fault detection technique&lt;/span&gt;

Effect of a magnetic cusp configuration on the ion species ratio in a NBI ion source

In arc discharge plasma, ion species ratio depends on plasma density and ion confinement time. To increase an atomic ion species ratio in an NBI (neutral beam injector) ion source, various ion sources have been designed with a higher ratio of plasma volume to effective ion loss area for increasing ion confinement time. In such designs, most NBI ion sources have a large arc chamber with strong cusp magnetic field. KSTAR NBI ion source also has a large arc chamber with a strong azimuthal line cusp configuration but its atomic ion (H+) beam fraction is small because its normal operation power levels of the arc discharges are comparatively lower than those of other NBI ion sources. In particular, the H2+ ion beam fraction is relatively large at about 40%. This means that there are many primary electrons in the beam extraction region. Through several Ele-orbit code simulations, it was found that some magnetic cusp configurations are effective in preventing primary electrons from nearing the plasma grid facing a plasma and having a high voltage potential. To reduce the molecular ion fraction in KSTAR NBI ion source and consequently increase its atomic ion fraction, experiments regarding the application of several new magnetic cusp configurations to the arc chamber were performed. Experimental results show that the new magnetic cusp configuration can increase the atomic ion fraction to approximately 80%, despite the low arc operation power at KSTAR NBI ion source.

Development and qualification of ITER current lead electrical insulation

The ITER high temperature superconducting current lead is a critical component for the magnet system, which has the benefit of reduction in the heat load of the cryogenic system compare with the conventional lead. The current lead is located in the coil terminal box and dry box at the end of the ITER feeder system. As a warm to cold transition section, the current leads feed the huge current from the power supply system into the coils. At the outer surface of the current lead, one layer of a composite insulation is applied to isolate the high voltage potential of the current lead to the ground potential of the environment. The main body of the current lead is that of a long cylinder, but at the cold termination and the cooling inlet, the local geometry is much more irregular. So the insulation wrapping and curing technology of the current lead had to be developed to acquire its uniform mechanical and electrical performance. Now, the multi-stage autoclave curing technology has been qualified in ASIPP and the series ITER current leads are being manufactured based on the qualified procedure. In this paper, the latest insulation progresses for the ITER current lead are introduced, the high voltage testing results as part of the formal qualification are presented and discussed.

Зарядка диэлектриков при бомбардировке ионами Ar-=SUP=-+-=/SUP=- средних энергий

A complex setup for measuring the kinetics of high-voltage potentials of bulk dielectrics charging under irradiated of ions Ar+ with medium energies has been created. Complex measurements of ion-emission characteristics, accumulated charges and surface charging potential showed effective charging to high positive potentials. The measured surface potentials is close in value to the potential of the ion gun. It is assumed that at the early stage of charging in the process of emission, sputtered ions dominate, and in the final stage of irradiation – backscattered. The reported study was funded by RFBR according to the research project № 18-02-00813A

Measurement of the charge distribution deposited by an annular plasma synthetic jet actuator over a target surface

Annular plasma synthetic jet actuators demonstrated their ability to produce a tubular flow normal to the surface where the dielectric barrier discharge (DBD) is ignited. These fluid-dynamic actuators enhance the delivery of reactive species towards the target to be treated. In these actuators, long life charged particles are generated within the plasma region and then carried on by the induced flow. In this work, the potential distribution induced by charges deposited over an insulating target has been measured. Surface DBD actuators, made with different dielectric materials, have been supplied by different sinusoidal voltages at a constant average power supplying the discharge. Actuators with the exposed electrode connected to both the high voltage potential and grounded have been tested. The charge distribution accumulated on a target surface perpendicular to the flow has been measured at different time intervals with the plasma on. Charges advected by the flow are always positive. The potential distribution on the target surface generated by the charges has been measured. For both configurations, firstly an M-shaped distribution develops and, later on, it becomes bell-shaped. A charge build-up mechanism has been found to be faster when the exposed electrode is connected to the high voltage terminal. The target has been placed at a variable distance from 1 to 5 cm from the actuator surface. At a distance of 5 cm, induced potentials are two times smaller than those with the target at 1 cm. Measurements allow us to estimate a charge flux toward the target on the order of 1011 particles (cm2 s)−1. The results presented in this work show that the presence of charged particles in the jet flow outside the plasma could be an important factor to be accounted for when these plasma actuators are used for treatment purposes (indirect plasma treatment).

Yolk-shell structured Sb@C anodes for high energy Na-ion batteries

Despite great advances in sodium-ion battery developments, the search for high energy and stable anode materials remains a challenge. Alloy or conversion-typed anode materials are attractive candidates of high specific capacity and low voltage potential, yet their applications are hampered by the large volume expansion and hence poor electrochemical reversibility and fast capacity fade. Here, we use antimony (Sb) as an example to demonstrate the use of yolk-shell structured anodes for high energy Na-ion batteries. The Sb@C yolk-shell structure prepared by controlled reduction and selective removal of Sb2O3 from carbon coated Sb2O3 nanoparticles can accommodate the Sb swelling upon sodiation and improve the structural/electrical integrity against pulverization. It delivers a high specific capacity of ~ 554mAhg−1, good rate capability (315mhAg−1 at 10C rate) and long cyclability (92% capacity retention over 200 cycles). Full-cells of O3-Na0.9[Cu0.22Fe0.30Mn0.48]O2 cathodes and Sb@C-hard carbon composite anodes demonstrate a high specific energy of ~ 130Whkg−1 (based on the total mass of cathode and anode) in the voltage range of 2.0–4.0V, ~ 1.5 times energy of full-cells with similar design using hard carbon anodes.

A Timing Synchronizer System for Beam Test Setups Requiring Galvanic Isolation

In beam test setups detector elements together with a readout composed of frontend electronics (FEE) and usually a layer of field-programmable gate arrays (FPGAs) are being analyzed. The FEE is in this scenario often directly connected to both the detector and the FPGA layer what in many cases requires sharing the ground potentials of these layers. This setup can become problematic if parts of the detector need to be operated at different high-voltage potentials, since all of the FPGA boards need to receive a common clock and timing reference for getting the readout synchronized. Thus, for the context of the compressed baryonic matter experiment a versatile timing synchronizer (TS) system was designed providing galvanically isolated timing distribution links over twisted-pair cables. As an electrical interface the so-called timing data processing board FPGA mezzanine card was created for being mounted onto FPGA-based advanced mezzanine cards for mTCA.4 crates. The FPGA logic of the TS system connects to this card and can be monitored and controlled through IPBus slow-control links. Evaluations show that the system is capable of stably synchronizing the FPGA boards of a beam test setup being integrated into a hierarchical TS network.

Influence of void defects on partial discharge behavior of superconducting busbar insulation

For a magnetic confinement fusion device, the superconducting magnets and busbars need to be insulated with one layer of solid insulation to isolate the high voltage potential from the ground. The insulation layer commonly consists of several interleaved layers of epoxy resin-impregnated glass fiber tapes and polyimide films. The traditional electrical inspection methods for such solidified insulation on the magnet and busbar are a DC voltage test or a Paschen test. These tests measure the quality of the insulation based on the value of leakage currents. However, even if there is a larger quantity of high dielectric strength material implemented, if there are some microcavities or delaminations in the insulation system, the leakage current may be limited to microampere levels under testing levels over dozens of kilovolts. Therefore, it is difficult to judge the insulation quality just by the magnitudes of leakage current. Under long-term operation, such imperceptible defects will worsen and finally completely break down the insulation because of partial discharge (PD) incidents. Therefore, a PD detection test is an important complement to the DC voltage and Paschen tests for magnet and busbar insulations in the field of fusion.It is known that the PD detection test is a mature technique in the electric power industry. In this paper, the PD characteristics of samples containing glass fiber-reinforced composite insulations for use with the superconducting busbar were presented and discussed. Various samples with different void contents were prepared and the PD behaviors were tested.