High Voltage Pulse Research Articles

Hydrogen Peroxide Production of Individual Nanosecond Pulsed Discharges Submerged in Water of Elevated Conductivity.

The production of hydrogen peroxide (H2 O2 ) is a key parameter for the performance of pulsed discharges submerged in water utilized as advanced oxidation process. So far, any related assessment of the underlying mechanism was conducted for the application of several hundred discharges, which did not allow for a correlation with physical processes. Moreover, the production was rarely investigated depending on water conductivity as one of the most important parameters for the development of submerged discharges. Accordingly, hydrogen peroxide generation was investigated here for individual single discharge events instigated with 100 ns high-voltage pulses in water with three different conductivities and was associated with the discharge development, i. e. spatial expansion and dissipated electrical energy. The approach necessitated the improvement of an electrochemical flow injection analysis based on the reaction of Prussian blue with H2 O2 . Hydrogen peroxide concentrations were quadratically increasing with propagation time and stable for different water conductivities. H2 O2 production per unit volume of a discharge was constant over time with an estimated rate constant of 3.2 mol ⋅ m-1 s-1 , averaged over the crosssectional area of all discharge filaments. However, the individually dissipated energy increased with conductivity, hence, the production efficiency decreased from 6.1 g ⋅ kWh-1 to 1.4 g ⋅ kWh-1 , which was explained by increased resistive losses within the bulk liquid.

Preparation and electrochemical performance of FG/SnS2 composite as a cathode material for high power thermal batteries

SnS2 is a promising cathode material for its high specific capacity (1232 mAh/g), but it’s limited to the low decomposition temperature and conductivity as the thermal battery application. Herein, the flaky graphite(FG) coating SnS2 composite (denoted as FG/SnS2) with excellent thermal stability and conductivity was prepared. Then, as a thermal battery cathode material, it presented longer working time at current constant density of 100 mA/cm2, and higher pulse voltage at 2A/cm2 pulse current density than the pure SnS2. Application as the engineering unit thermal battery, its performance of higher working voltage, lower total resistance, and more stable output capacity indicated it can be used for high-power thermal batteries.

Research on High Voltage Protection of Arc Thruster Power Control Unit

The arc propulsion system needs a high-voltage (3800 V) pulse to break down the working medium in the thruster and form a stable arc. The arc thruster power control unit (ATPU) is prone to producing high voltage discharge when the high voltage pulse is output. According to the high voltage breakdown mechanism, this paper puts forward control measures to prevent the high voltage breakdown.

An Improved High Voltage Pulse Generator With Few Nanoseconds Based on the Synergy of DOS and LTD Topologies for Supra Electroporation

Supra electroporation, also known as nanoelectroporation, induced by nanosecond pulse could increase organelle membrane permeability with negligible effect on cell membrane, which has been used for tumor treatment through immunogenic cell death. In order to investigate the supra electroporation of organelle membrane, this study proposes a new topology to generate high voltage pulse with few nanoseconds. This circuit topology contains two main stages: firstly, the topology of diode opening switch (DOS) with LC resonance boosting is used to generate few nanoseconds pulse. Secondly, for improving the output/input voltage gain, four DOS modules are optimally connected (two modules in parallel and another two modules in series) using linear transformer driver (LTD) structure. Moreover, the turn-ON time of MOSFET switch and the inductance of LTD windings are optimized to further boost the voltage amplitude. Finally, experimental results validate the functionality of the proposed topology. The output/input voltage gain can reach 24. This generator can output the nanosecond pulses with full width half maximum (FWHM) of 5.1 ns, amplitude of 3.7 kV (input voltage is 0.15 kV), and repetition frequency up to MHz with unipolar and bipolar polarity in burst mode.

Protection of radio-electronic products from high-voltage pulses using a hot-swap controller

Formulation of the problem. The use of a protection unit in a radio-electronic device against short-term or long-term surges of high currents and voltages based on the controller makes it possible to eliminate the failure of power circuits, analog or digital component base and avoid local overheating. This circuit design significantly increases the reliability of the finished product. Target. Ensuring the protection of electronic devices from overvoltage or overcurrent. Development of a protection unit, calculation of nominal values of circuit elements. Results. Classical solutions of protection of power supply buses from overloads by electrical parameters are considered. The nominal values of the protective circuit elements were calculated using the RT1720 hot-swap controller. A submodule based on the RT1720 controller is designed. Practical significance. The circuit of the protective circuit based on the hot-swap controller can be used in secondary power supplies, as well as in various electronic products where a high level of reliability and a long service life are required.

Tailing phenomenon in high voltage solid-state pulse modulators: Analyzing and modeling

In many applications of high-voltage solid-state pulse modulators (SSPMs), the expected square pulsed shape is difficult to be generated and also there exists a long falling edge (also known as the “tailing”). In some fields that strictly need squared pulses, tailing will restrict the application of SSPMs. Although topological solutions have been proposed to eliminate the tail, its formation and regulatory factors are still not clear. Based on the classic switch–capacitor circuit, the tailing model is discussed and established for stacked and non-stacked SSPMs in this paper, which can help predict the pulsed tailing of SSPMs under various loads. The circuital factors (stage number, parasitic inductance, etc.) of the pulsed tail are studied. Meanwhile, the suggested tailing criteria for different load scenarios are proposed. The experiment verifies the accuracy of the tailing model. Finally, the applicable conditions of the tailing model are discussed. This model can not only help explain the mechanism of tailing but make predictions of tailing in SSPMs.

All-Solid-State Ultrashort Pulse Generator by Capacitive Chopping Circuit

High-voltage ultrashort pulse (HVUSP) is attaching more attention to advanced biomedicine. In this paper, a capacitive chopping circuit (CCC) topology with all-solid-state switches is proposed, which can generate adjustable HVUSP with high power efficiency. Dual capacitors of opposite polarity are connected in series with the load, thus cutting off the discharge loop of a single capacitor and chopping out a narrow pulse with adjustable width. The CCC can be stacked modularly for higher amplitude. The working principle is analyzed and the power efficiency under different working conditions is simulated, along with existing modularized HVUSP generation topologies. Finally, an 8-staged all-solid-state prototype based on the proposed CCC topology is developed. The adjustability of pulse parameters and staged performance are tested. The pulse width can be compressed to less than 10ns at 6.5kV. Output parameters can satisfy HVUSP electroporation in the biological scene.

Implementation of extreme ultraviolet spectroscopy on a sheared-flow-stabilized Z pinch

A diagnostic for extreme ultraviolet spectroscopy was fielded on the sheared-flow-stabilized (SFS) fusion Z-pinch experiment (FuZE-Q) for the first time. The spectrometer collected time-gated plasma emission spectra in the 5–40 nm wavelength (30–250 eV) range for impurity identification, radiative power studies, and for plasma temperature and density measurements. The unique implementation of the diagnostic included fast (10 ns risetime) pulsed high voltage electronics and a multi-stage differential pumping system that allowed the vacuum-coupled spectrometer to collect three independently timed spectra per FuZE-Q shot while also protecting sensitive internal components. Analysis of line emission identifies oxygen (N-, C-, B-, Be-, Li-, and He-like O), peaking in intensity shortly after maximum current (>500 kA). This work provides a foundation for future high energy spectroscopy experiments on SFS Z-pinch devices.

Autonomous Ultrasonic Thickness Measurement of Steel Bridge Members Using a Climbing Bicycle Robot

This paper presents the development of a steel-climbing bicycle robot integrated with an ultrasonic sensing device towards autonomous thickness measurement of steel bridge members. The bicycle-like robot has two magnetic wheels controlled by two independent steering actuators, which navigates on various steel surfaces (flat, curved, rough, concave, and convex). The compact ultrasonic sensing device is capable of high-voltage pulse excitation, filtering/amplification of the received ultrasonic signal, and high-speed analog-to-digital conversions (up to 80 MHz). Along with the ultrasonic sensing device, the robot carries a dual element transducer, an automatic gel couplant dispenser, a position tracking sensor, and a camera. A mounting/retrieving mechanism of the transducer is designed to ensure the reliable contact of the transducer on steel surfaces. The camera view assists an operator to safely navigate the robot to measurement locations, properly dispense gel couplant, and firmly press the transducer on a measurement surface. The automated robot localization provides accurate thickness measurement locations, which are mapped real-time in three-dimensional (3D) space together with the robot’s travel path. We validate the performance of the developed system in several indoor and outdoor tests. Weblink to a supplementary video demonstrating the robot’s maneuverability and ultrasonic thickness measurements is available in the Data Availability Statement of this article.

A Novel PWM Signal-Generation Strategy for Pockels Cell Drivers

A Pockels cell driver (PCD) can be viewed as a high-voltage pulse width generator for controlling the bi-refringence effect of electro-optical crystals. The main features of a PCD include a high repetition rate, fast on and off switching, variable pulse duration, and a true square pulse shape. The most commonly used PCD has a narrow pulse width tuning range, typically within a few microseconds. In this paper, we propose a PCD based on a novel pulse width modulation (PWM) signal-generation strategy that can continuously adjust its pulse width with a minimum step size of 10 ns and no restriction on the maximum width. Therefore, it is easily compatible with both “On-type” and “Off-type” applications of the electro-optic crystal quarter-wave voltage. The experimental results show that the rising and falling times of the proposed PCD are approximately 7.3 ns and 7.8 ns, respectively, with a maximum repetition rate of 1 MHz and a maximum voltage of approximately 2.0 kV. Finally, the functionality of the PCD is demonstrated in a home-built slab laser.

Enhanced Electrical Injury Using Triangular Interdigitated Electrodes for Catheter-Based Irreversible Electroporation

Irreversible electroporation (IRE) is a promising nonthermal ablation technique that uses high-voltage electrical pulses to create permanent pores in the cell membrane of target tissue. Recently, endoscopic IRE with catheter-based electrodes has attracted significant attention as a potential alternative tool for gastrointestinal tumors, but it has been challenged owing to the limited electric field distribution in an in-plane electrode configuration, in which rectangular interdigitated electrodes (IDEs) are commonly used. Herein, we report an enhanced electrical injury in tissue using triangular IDEs that cause strong electric fields to be induced at the tip of the electrode fingers. A set of 10 pulses with a duration of 100 μs and a frequency of 1 Hz were delivered to the tissue, and a finite element method was used to calculate the electrical injury in the gastrointestinal model. The probability of cell death by electrical injury at the triangular IDEs increases by approximately 10 times compared to that of conventional rectangular IDEs at the same electrode distance. These results could potentially pave the way toward designing electrodes in catheter-based IRE devices.

Piezoelectric Transformer-Based High-Voltage Pulse Generator Using Wide-Bandgap Semiconductors for Medical Electroporation Therapy.

In this paper, a new application of Piezoelectric Transformer (PT)-based power converters to generate high-voltage (HV) bipolar pulses for medical electroporation therapy is proposed. In particular, PT-based power conversion is investigated as an alternative to magnetics-based approaches of generating HV from a relatively low-voltage (LV)input source for application in electroporation therapy. The detailed PT-based system design and selection of wide bandgap semiconductor switches such as GaN FETs, high-voltage SiC diodes and SiC MOSFETs, as well as simulation results to demonstrate proof-of-concept using LTSpice are presented. Preliminary experimental results of the PT-based capacitor charger are shown, and work is ongoing to develop a complete hardware prototype of the proposed HV pulse generator.

Simulation and Experimental Study on the Responses of Subcellular Structures in Tumor Cells Induced by 5 ns Pulsed Electric Fields

In order to explore the bioelectric effect of 5 ns pulsed electric fields on tumor cells, a spherical single-cell multiphysics model was first established based on the finite element simulation platform. In consideration of the dielectric relaxation of the biological plasma membrane under the high-frequency electric fields, the electroporation and Maxwell stress tensors on the cell membrane and nuclear envelope were analyzed; secondly, taking MDA-MB-231 cells as the research object, combined with fluorescent probe technology, the state change and fluorescence dissipation of its subcellular structure exposed to pulse fields were studied. The results showed that 5 ns pulsed electric fields directly acted inside the cell, causing an electroporation effect and tensile stress on the nuclear envelope, destroying the integrity and order of the cytoskeleton, and damaging the functions of subcellular structures including endoplasmic reticulum, mitochondria, etc. This study provides theoretical and experimental evidence for the research and application of a high-voltage short pulse in the field of biomedical engineering.

Protein-Mediated Electroporation in a Cardiac Voltage-Sensing Domain Due to an nsPEF Stimulus.

This study takes a step in understanding the physiological implications of the nanosecond pulsed electric field (nsPEF) by integrating molecular dynamics simulations and machine learning techniques. nsPEF, a state-of-the-art technology, uses high-voltage electric field pulses with a nanosecond duration to modulate cellular activity. This investigation reveals a relatively new and underexplored phenomenon: protein-mediated electroporation. Our research focused on the voltage-sensing domain (VSD) of the NaV1.5 sodium cardiac channel in response to nsPEF stimulation. We scrutinized the VSD structures that form pores and thereby contribute to the physical chemistry that governs the defibrillation effect of nsPEF. To do so, we conducted a comprehensive analysis involving the clustering of 142 replicas simulated for 50 ns under nsPEF stimuli. We subsequently pinpointed the representative structures of each cluster and computed the free energy between them. We find that the selected VSD of NaV1.5 forms pores under nsPEF stimulation, but in a way that significant differs from the traditional VSD opening. This study not only extends our understanding of nsPEF and its interaction with protein channels but also adds a new effect to further study.

Experimental study of stability and pollutant emissions of turbulent biogas flames under microsecond pulsed plasma

Biogas is a mixture of methane (50–80%.vol), carbon dioxide (20–45%.vol), and in smaller proportions of N2, O2, H2S, and NH3. For a high rate of CO2 in the biogas, the combustion can generate strong instabilities and the flame can be very lifted from the burner and even blown. To overcome these problems of instabilities and flame extinction, the use of a microsecond pulsed plasma is considered for this study. This study aims to characterize the effects of microsecond pulsed discharges on the stabilization and emission characteristics of non-premixed swirling biogas/air flames at different operating conditions of combustion (CO2 rate, power, and equivalence ratio) and plasma (pulse repetition frequency and input electrical voltage). The plasma is performed above a coaxial burner with a swirler of the oxidizer. It is generated by a DC-pulsed power generator with a high voltage (HV) pulse duration of a few microseconds. The burner consists of two concentric tubes and a central metal rod used as a cathode for the plasma. The outer tube contains a swirler and supplies the oxidant flow, and the inner tube delivers the fuel (methane, biogas) around the central metal rod. High voltage pulses are applied on two anode tungsten wires that are symmetrically arranged from either side of the cathode to obtain two plasma zones in the stabilization region of the flame. The burner is placed in a parallelepiped combustion chamber with a volume of 100x48x48 cm3. Mass flow rates of air and fuel are regulated by thermal mass flow controllers (Brooks SLA5851S). OH* chemiluminescence measurements are done to describe the structure and the flame stability throughout the lift-off heights (Hf) variation. Results showed that plasma generated by microsecond HV pulses can improve flame stability by decreasing its Hf especially at low fuel velocities. In this regard, the optical emission spectra (OES) were visualized. The results reveal that the pulsed plasma generates chemically active species such as excited N2*, CH*, OH* molecules, and H* atoms, leading to improved flame stability. Their intensities' dependence on the pulse repetition frequency, the sight position of the OES, the concentration of CO2 in the fuel, and the fuel velocities were investigated in detail. Furthermore, the NOx and CO emissions in the burned gas are investigated over a wide range of repetition pulse frequencies. It is seen that the microsecond pulsed plasma slightly increases the NOx emission and reduces CO concentration in the flue gases.

Evaluation of a novel electrode design for high voltage pulse ore pre-concentration

High Voltage Pulse (HVP) enabled ore preconcentration has the potential to provide large energy savings and upgrade Run-of-Mine ores. The concept is well established in laboratory settings but is yet to be demonstrated at the throughputs needed for industrial uptake of the technology. To scale up this concept from laboratory batch tests to a continuous operation, a novel grizzly-electrode design that integrates pulse discharges for particle breakage and size-based separation into a single step has been patented. In the initial evaluation of the system, two cylindrical electrode bars were adopted with an experiment design to simulate continuous feeding operation. Synthetic particles and a low-grade gold-copper ore were used for the initial evaluation. The evaluation showed pre-concentration can be achieved. Factors affecting the system performance were identified and limitations of the grizzly electrodes are discussed.

Influence of electric field, blood velocity, and pharmacokinetics on electrochemotherapy efficiency

The convective delivery of chemotherapeutic drugs in cancerous tissues is directly proportional to the blood perfusion rate, which in turns can be transiently reduced by the application of high-voltage and short-duration electric pulses due to vessel vasoconstriction. However, electric pulses can also increase vessel wall and cell membrane permeabilities, boosting the extravasation and cell internalization of drug. These opposite effects, as well as possible adverse impacts on the viability of tissues and endothelial cells, suggest the importance of conducting in silico studies about the influence of physical parameters involved in electric-mediated drug transport. In the present work, the global method of approximate particular solutions for axisymmetric domains, together with two solution schemes (Gauss-Seidel iterative and linearization+successive over-relaxation), is applied for the simulation of drug transport in electroporated cancer tissues, using a continuum tumor cord approach and considering both the electropermeabilization and vasoconstriction phenomena. The developed global method of approximate particular solutions algorithm is validated with numerical and experimental results previously published, obtaining a satisfactory accuracy and convergence. Then, a parametric study about the influence of electric field magnitude and inlet blood velocity on the internalization efficacy, drug distribution uniformity, and cell-kill capacity of the treatment, as expressed by the number of internalized moles into viable cells, homogeneity of exposure to bound intracellular drug, and cell survival fraction, respectively, is analyzed for three pharmacokinetic profiles, namely one-short tri-exponential, mono-exponential, and uniform. According to numerical results, the trade-off between vasoconstriction and electropermeabilization effects and, consequently, the influence of electric field magnitude and inlet blood velocity on the assessment parameters considered here (efficacy, uniformity, and cell-kill capacity) is different for each pharmacokinetic profile deemed.

Simulation of High-voltage Pulse Generator for Environment-friendly, Non-thermal Pasteurization Applications

Nowadays, the demand for high-voltage pulse generators has begun to proliferate in many industries. Particularly in the food processing industries, the conventional method of pasteurization involves the use of heat treatment processes, which are not environment-friendly; hence, researchers are working towards environment-friendly, non-thermal food processing techniques by which the microorganisms present in the liquid food can be eliminated. High-voltage pulsed electric field technology is one of the popular non-thermal food processing techniques. Recent advancements in power electronic switching technology have facilitated the development of solid-state pulse generators for these applications. In this paper, the simulation of a high-voltage pulse generator for eco-friendly pasteurization applications has been attempted using a cascaded boost converter topology. The entire simulation is carried out using MATLAB/Simulink software. The designed two-stage cascaded boost converter is tested for varying duty cycles and loads. The results with resistive and inductive loads have been analyzed.

Pulsed field ablation as a precise approach for cardiac arrhythmia treatment via cardiac microenvironment remodeling

PFA uses short-duration, high-voltage electrical pulses to induce transient or irreversible electroporation on cell membranes, causing cell death. Selective inhibition of chaotic electrical signals in morbid cardiomyocytes significantly aids the treatment of atrial fibrillation, ventricular tachycardia, and other heart arrhythmias. Recent preclinical and clinical studies have only investigated physical changes, such as lesion size and myocardial scar. Compared to radiofrequency ablation and cryoballoon ablation, PFA causes less postoperative myocardial cell fibrosis and inflammatory reaction and does not result in myocardial necrosis or tissue scar formation. However, the regulatory mechanism of cellular stress following PFA treatment remains unknown. This study aimed to analyze the transcriptome of the mouse ventricle after PFA treatment. The animals were subjected to a 225-V electric pulse with a 1.5-mm gap between the positive and negative electrodes. Hearts were harvested at 3, 6, 12, 24 h, and 2, 5 days for myocardial zymogram testing. PFA-treated ventricular regions were selected for single-nucleus sequencing. We discovered that PFA remodeled the cardiac microenvironment as a whole. Further, we discussed the possible stress response and wound-healing mechanism in non-targeted cells. In conclusion, PFA allowed effective and selective ventricular myocardium ablation with controllable inflammation.

Efficacy and safety of high-voltage pulsed radiofrequency combined with pregabalin on severe thoracic postherpetic neuralgia

Objective: To investigate the efficacy and safety of high-voltage pulse radiofrequency combined with pregabalin on severe thoracic postherpetic neuralgia (PHN). Methods: A total of 103 patients with PHN who were admitted to the Department of Pain Medicine of Henan Provincial People's Hospital from May 2020 to May 2022 were retrospectively selected, including 50 males and 53 females, and aged 40 to 79 (65.4±9.2) years. The patients were divided into two groups according to the treatment methods they received: the control group (n=51) and the study group (n=52). The patients in the control group were treated with oral pregabalin, and the patients in the study group received pregabalin plus high-voltage pulse radiofrequency therapy. The pain intensity and efficacy of the two groups were evaluated before treatment and 4 weeks after treatment. The pain intensity, the sleep quality and the efficacy of treatment was evaluated by visual analogue scale (VAS) score, Pittsburgh Sleep Quality Index (PSQI) score and nimodipine method, respectively. The levels of pain factors including serum neuropeptide Y (NPY), prostaglandin E2 (PGE2), substance P (SP) and β-Endorphin were measured. The differences of the above indicators and the incidence of adverse reactions were compared between the two groups. Results: The VAS scores and PSQI scores of the study group and the control group before treatment were (7.94±0.76), (8.20±0.81), (16.84±3.90) and (16.29±3.84), respectively, with no statistically significant difference (both P>0.05). After 4 weeks of treatment, the VAS scores and PSQI scores of the two groups were (2.84±0.80), (3.35±0.87), (6.78±1.90) and (7.98±2.40), respectively, and the VAS score and PSQI score in the study group were lower than those in the control group (both P<0.05). Serum levels of NPY, PGE2, SP and β-Endorphin were (298.5±31.0) ng/L, (92.3±11.0) μg/L, (156.8±21.4) ng/L, and (8.6±1.6) ng/L in the study group and (304.2±28.6) ng/L, (94.4±12.9) μg/L, (152.7±23.8) ng/L and (8.2±1.8) ng/L in the control group, with no significant differences (all P>0.05). After 4 weeks of treatment, levels of NPY, PGE2, SP and β-Endorphin were (240.7±26.8) ng/L, (74.4±8.6) μg/L, (108.9±15.7) ng/L and (4.4±0.9) ng/L, which were lower than those in the control group [(268.1±29.4) ng/L, (79.7±8.3) μg/L, (115.2±16.2) ng/L, (5.2±1.3) ng/L, respectively], with statistically significant differences (all P<0.05). After treatment, 29 cases were cured, 16 cases were markedly effective and 6 cases were effective in the study group, while 16 cases, 24 cases and 8 cases were cured, markedly effective and effective in the control group. The overall efficacy of patients in the study group was better than that in the control group (Z=-2.32, P=0.018). The incidence of adverse reactions in the study group and control group was 11.5% (6/52) and 7.8% (4/51), respectively, with no statistically significant difference (χ2=0.40, P=0.527). Conclusion: High-voltage pulse radiofrequency combined with pregabalin can significantly improve the pain and sleep quality of patients with severe thoracic PHN and reduce the level of pain factors, with a high safety profile.