Solid-state Pulse Research Articles

Low cost pulsed electric field generator using DC-DC boost converter and capacitor diode voltage multiplier

Traditional high-voltage pulse generators, like Marx generators often face challenges related to efficiency and complexity. In this paper, a solid-state multi-module high-voltage pulse generator that integrates capacitor-diode voltage multipliers (CDVM) with DC-DC boost converters and closed-loop voltage control is proposed to overcome these challenges. The system achieves high output voltage by coupling the pulsed output voltages of individual low-voltage DC sources in series across each module. The proposed design was modeled using MATLAB, and experimental testing was conducted on a single stage. Comparative analyses between timedomain parameters, proportional-integral (PI), and fractional order proportional integral derivative (FOPID) controllers were performed. Both MATLAB simulations and experimental validations demonstrate the effectiveness of this approach. The rise time, peak time, settling time, and steady-state error are all improved using an FOPID controller, decreasing from 0.32 to 0.31 seconds, 0.42 to 0.35 seconds, and 3.15 to 2.20 seconds, respectively. These findings indicate that a closed-loop FOPID controller enhances time-domain performance parameters more effectively than a PI controller for a two-stage DC-DC voltage multiplier.

Nonlinear optical research on 2D NbSe2 nanosheets and their ultrafast photonics applications

Two-dimensional (2D) NbSe2 is a new material with a variety of excellent properties. In this article, 2D NbSe2 nanosheets are prepared using liquid phase exfoliation (LPE) and spin coating methods. At the same time, the properties of NbSe2 were calculated by using density functional theory (DFT), exploring the changes in the electronic band structure of NbSe2 with the number of layers, and studying the optical properties of NbSe2. The nonlinear optical properties caused by the Pauli blocking effect and the absorption spectra are studied through typical nonlinear testing techniques and an ultraviolet–visible-near-infrared (UV–VIS-IR) spectrophotometer. In addition, 2 µm solid-state pulse lasers have important applications in a variety of fields. For the first time, 2D NbSe2 nanosheets are prepared as saturable absorbers (SA) and applied them to solid-state lasers as nonlinear optical modulation devices, successfully achieving the generation of ultra-short pulse lasers with a pulse duration of 445.4 ps in 2 µm band. Our research results prove that 2D NbSe2 nanosheets is a promising nanomaterial, can be prepared into nonlinear optical modulation devices with excellent performance, and show great application potential as ultrafast photonic devices. It is beneficial to the miniaturization of solid-state pulse lasers in subsequent applications.

Re-examination of the intumescence mechanism of fire retarded PP with APP/pentaerythritol/zeolite-4A using advanced spectroscopic techniques

The mixture of ammonium polyphosphate (APP) and pentaerythritol (PER) is a very efficient flame retardant (FR) intumescent system suitable for polyolefins such as polypropylene (PP). The mechanisms of intumescence of this FR system in this polymer was investigated using different spectroscopic techniques including continuous wave (CW) electron paramagnetic resonance (EPR) spectroscopy and solid state nuclear magnetic resonance (NMR) technique. In this work, the intumescence mechanism of PP/APP/PER formulations with and without 4A is revisited. The intumescent system was in-depth investigated using NMR, CW EPR and pulsed EPR. The CW EPR technique confirmed that free radicals are mainly generated during the intumescence of the system between 250 and 350 °C. Thanks to the pulsed EPR and solid state NMR, it was evidenced that a key structural shift from a predominantly carbonaceous residue to a predominantly phosphorated residue. Besides, it was also evidenced that zeolite 4A totally collapses during extrusion of PP/APP/PER formulations reacting with APP to generate aluminophosphates. Then, silicophosphates are generated between 350 and 400 °C. Both alumino- and silicophosphates contribute to protect aromatic structures in the residue at high temperatures.

A compact solid-state high repetition rate trigger based on a spiral generator.

The trigger generator made with a spiral generator (SG) has the advantages of light weight, compact structure, and low cost and has promising applications in the pulsed power field. This paper introduces a compact solid-state high-voltage pulse trigger system based on an improved SG, which has improved repetition rate and lowered the demands for semiconductor switches' maximum current and current rise rate when compared with previous studies. The improvement is achieved by winding outward an additional layer of the passive layer and low-voltage metal strip, which realizes a significant reduction of the peak current and current rise rate of the discharge switch. The final dimension of the trigger is 25 × 10 × 10cm3, excluding the power supply. An experiment carried out in single shot mode shows that the peak value of the output pulse can reach 50kV with a leading edge of 57ns. Repetitive experiments were carried out up to 1kHz, with the peak voltage of the output pulse being 30.5kV, the leading edge being 48ns, and the jitter being 0.84ns. Finally, the generator is used to trigger a gas switch, and it works stably and reliably.

Nanosecond pulse electric field treatment initiates mitochondrial apoptosis pathway by inducing mitochondrial morphological changes in myocardial cells.

As an emerging myocardial ablation technique, the mechanism of nanosecond pulse electric field (nsPEF) ablation is currently less studied. Mitochondria are one of the important membrane structure organelles in cells, participating in numerous life activities within the cell. This study aimed to explore the morphological changes of mitochondria in living cells following nsPEF treatment. Myocardial cells were treated with a self-made solid-state LTD high-voltage nanosecond pulse generator with a pulse width of 100ns for 80 times. The changes in mitochondrial membrane potential and cell apoptosis in rat myocardial cells after nsPEFs were investigated using JC-1 assay kit, apoptosis double staining assay kit, and mitochondrial fluorescence probe. The results showed that after nsPEF treatment, the mitochondrial membrane potential decreased, apoptosis increased, and the average mitochondrial area decreased from 0.48 µm2 in live myocardial cells to 0.16 µm2. The average circumference ranges from 3.17µm dropped to 1.60µm. The shape factor decreased from 1.92 to 1.41. The aspect ratio has decreased from 2.16 to 1.59. nsPEF treatment induces changes in the morphology of myocardial cell mitochondria. Based on the results of mitochondrial membrane potential and apoptosis, it can be inferred that under this equipment and parameter conditions, nsPEF treatment first causes changes in mitochondrial morphology, and then initiates the mitochondrial apoptosis pathway, which may provide experimental basis for investigating the potential mechanism of nsPEF ablation of myocardial cells.

Development of All Solid State Nanosecond Pulse Transformer Fault Detection Device Based on Marx Circuit

Abstract a nanosecond pulse generator with a fast leading edge for transformer fault diagnosis is developed. The device is composed of a full solid-state nanosecond pulse generator based on Marx circuit and with a tail cut switch and a field programmable logic gate array (FPGA) device. Among them, the nanosecond pulse source is mainly composed of DC power supply, control circuit and main circuit. The main circuit is a 9-level modular Marx circuit, using MOSFET as the main switch and tail cut switch; The control circuit generates a synchronous trigger pulse signal, which drives the MOSFET to work synchronously after being isolated through the optical fiber. The output nanosecond pulse voltage parameters are adjustable amplitude 0-8kv, pulse width 100˜1000ns, repetition frequency 1hz˜1000hz, rising edge 30ns and falling edge 40ns. The transformer fault diagnosis platform is built, and the transformer off-line and on-line fault diagnosis is carried out, which paves the way for further exploration of transformer fault diagnosis technology.

Comparison of methods for the NMR measurement of motionally averaged dipolar couplings

Motionally averaged dipolar couplings are an important tool for understanding the complex dynamics of catalysts, polymers, and biomolecules. While there is a plethora of solid-state NMR pulse sequences available for their measurement, in can be difficult to gauge the methods’ strengths and weaknesses. In particular, there has not been a comprehensive comparison of their performance in natural abundance samples, where 1H homonuclear dipolar couplings are important and the use of large MAS rotors may be required for sensitivity reasons. In this work, we directly compared some of the more common methods for measuring C–H dipolar couplings in natural abundance samples using L-alanine (L-Ala) and the N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLF) tripeptide as model systems. We evaluated their performance in terms of accuracy, resolution, sensitivity, and ease of implementation. We found that, despite the presence of 1H homonuclear dipolar interactions, all methods, with the exception of REDOR, were able to yield the reasonable dipolar coupling strengths for both mobile and static moieties. Of these methods, PDLF provides the most convenient workflow and precision at the expense of low sensitivity. In low-sensitivity cases, MAS-PISEMA and DIPSHIFT appear to be the better options.

Pulsed processing by cold plasma, applied to industrial emission control.

A promising pollution control technology is cold plasma driven chemical processing. The plasma is a pulsed electric gas discharge inside a near atmospheric-pressure-temperature reactor. The system is energized by a continuous stream of very short high-voltage pulses. The exhaust gas to be treated flows through the reactor. The methods applied involve the development of robust cold plasma systems, industrial applications and measuring technologies. Tests of the systems were performed at many industrial sites and involved control of airborne VOC (volatile organic compound) and odor. Electrical, chemical and odor measuring data were collected with state-of-the-art methods. To explain the test data an approximate solution of global reaction kinetics of pulsed plasma chemistry was developed. It involves the Lambert function and, for convenience, a simple approximation of it. The latter shows that the amount of removal, in good approximation, is a function of a single variable. This variable is electric plasma power divided by gas flow divided by input concentration. In the results sections we show that in some cases up to 99% of volatile pollution can be removed at an acceptable energy requirement. In the final sections we look into future efficiency enhancements by implementation of (sub)nanosecond pulsed plasma and solid state high-voltage technology and by integration with catalyst technology.

A solid-state pulse power sub-nanosecond SiC DSRD-based generator with high-voltage and high repetition frequency for pulse discharge water treatment

Water treatment is one of the most important issues for all walks of life around the world. The unique advantages of the solid-state power electronic pulses in water treatment make it attractive and promising in practical applications. The output voltage, rising time, repetition rate, and peak power of output pulses have a significant impact on the effectiveness of water treatment. Especially in pulse electric field treatment and pulse discharge treatment, the pulse with fast rising time achieves the advantage of generating plasma without corona, which can avoid water heating effect and greatly improve the efficiency of the pulse generator. High repetition rate can significantly reduce the peak power requirement of the pulse in water treatment application, making the equipment smaller and improving the power density. Therefore, the study developed a high-voltage high frequency sub-nanosecond pulse power generator (PPG) system for wastewater treatment. It adopts SiC DSRD (Drift Step Recovery Diode) solid-state switches and realize modular design, which can achieve high performance and can be flexible expanded according to the requirements of water treatment capacity. Finally, an expandable high-voltage PPG for water treatment is built. The output parameters of the PPG include output pulse voltage range from 1 to 5.28 kV, rise time <600 ps (20%–90%), repetition up to 1 MHz. The experiment results of PPG application for pulse discharge water treatment is presented. The results indicate that the proposed generator achieves high-efficiency degradation of 4-Chlorophenol (4-CP), which is one of the most common chlorophenol compounds in wastewater. From experiment, the homemade system can degrade 450 mL waste water containing 500 mg/L 4-CP in 35 min, with a degradation rate of 98%. Thereby, the requirement for electric field intensity decreased. Through the further quantitative analysis, the impact of frequency, voltage, and electrode spacing on the degradation effect of 4-CP is confirmed.

Review of High Voltage Pulsed Power Supplies and Power Electronics in Pulse Power Generation

Recently, pulse-shaped power supplies have become more popular. Pulsed power is versatile and useful as a supply method since it can take several shapes and has many pulse characteristics. The release of electrons, protons, and neutrons from an atom and the synthesis of molecules to generate ions or other molecules require a lot of immediate energy. Pulsed power is needed for decomposition, molecular fusion and material joining, radiation generation (e.g., electrons, lasers, radar), explosive processes for concrete recycling, wastewater and exhaust gas treatment, and material surface treatments. Industrial and environmental applications require pulsed power, which requires efficient and adaptive pulse modulators. Higher-quality repeating pulses are needed for plasma fusion and laser weapons. Marx Generators, Magnetic Pulse Compressors, Pulse Forming Networks, and Multistage Blumlein Lines have several uses. Pulse modulators use spark gap and hydrogen thyratron gas/magnetic switching technologies for their high voltage tolerance and low-rise times. These creatures are inefficient, unreliable, repetitious, and short-lived. These devices are heavy, bulky, and expensive. Solid-state switching technology can replace conventional devices, improving pulse supply. High-frequency switching repeats the pulsed power supply. These items are compact, efficient, affordable, reliable, and durable. Solid-state transistor applications may not meet switch voltage ratings and rise time constraints. Various power electronics configurations can produce solid-state high-voltage pulses.

WaveGate: a versatile tool for temporal shaping of synchrotron beams.

We present a full performance characterization of a solid state pulse picker for hard x-ray pulses at synchrotrons. The device is called WaveGate. Specifically, we quantify its efficiency (>30 %), timing capabilities (switching times between 100 ns and ms), on-off contrast (>104) and influence on the coherence properties of the incident x-ray beam. In addition, we discuss the implementation of the WaveGate in an optical pump - x-ray probe setup. Even if single pulse selection is performed by external detector gating, the WaveGate drastically increases the efficiency of a measurement. Finally, we introduce advanced timing schemes that can be realized by modulating the time structure of the synchrotron beam.

A Solid-State Marx Generator with Prevention of through Current for Rectangular Pulses

In solid-state high-voltage pulse generators, switches may be triggered on by fault due to electromagnetic interference, resulting in high through current and breakdown of switches. To generate rectangular high-voltage pulses, this paper proposes a solid-state Marx generator (SSMG) with fast recovery diodes to prevent through current. Only charging currents with the same direction flow through these fast recovery diodes breaks the short-circuit loops in and between stages. A 52-stage SSMG prototype based on the proposed circuit was developed. PSpice simulations and experiments were performed for comparison. It was found that the through current can rise to 250 A without any protection. With 10-μH protection inductors in each state, the through current amplitude drops to 50 A. Under the same condition, there is no continuous through current with the proposed fast recovery diodes. Furthermore, 22-kV repetitive rectangular pulses were also obtained in experiments. This proved that the proposed Marx generator can prevent the through current in power cells.

Influence of avalanche transistor switching mode on waveform characteristics of solid-state pulse source.

The design of the Marx circuit based on avalanche transistors (ATs) is one of the effective techniques for developing solid-state pulse sources to generate nanosecond pulses. However, the influence of the avalanche transistor as a switching device on the output pulse characteristics is still unclear. In this study, investigating the switching mechanism of the AT with a mixed-mode simulation of the semiconductor device has been accomplished. An experiment has checked the simulation model's transient switching characteristics. The switching mechanisms of ATs in the Marx circuit were divided into base triggering mode (BTM) and voltage ramp mode (VRM). This paper proposes a modified circuit for adjusting the output pulse parameters of solid-state pulse sources. The results show that to satisfy the simulation accuracy, the width parameter of the AT model in the BTM must be 100μm, much less than the actual physical size. Because of the higher electric field when the initial impact ionization occurs, the AT operates at a higher switching speed in the VRM than in the BTM. In addition, since the carriers of initial impact ionization locate at the p-n0 interface or the n0-n+ interface, the AT switching process will oscillate in the VRM. All ATs in the modified Marx circuit switch to operate in the BTM. The leading edge of the output pulse increases from 275 to 1125ps, and the pulse trailing oscillation has disappeared. The research results provide an important technical means for optimizing the output waveform of solid-state pulse sources.

A Flexible Solid-State Marx Modulator Module Based on Discrete Magnetic Coupling Drivers

With the increasing and deepening application of high-voltage nanosecond solid-state pulse generators in biological, industrial, and environmental fields, the development of existing pulse generators faces many challenges, such as fixed pulse shapes, the usage of isolated driver power supplies, lower power density, and limited output electrical performance. Hence, a novel high-frequency multilevel nanosecond modular solid-state Marx modulator (SSMM) based on discrete magnetic coupling gate drivers is proposed. The gate voltage of the two MOSFETs can be rapidly synchronized at a high repetition frequency to achieve an amplitude-controlled gate voltage within 100 ns. The feasibility of the driver was verified by PSpice simulation and prototype testing. Moreover, a stackable SSMM module (S2M3) structure is proposed to solve the problem of common-mode interference conducted through the driver, which improves the reusability, scalability, and redundancy of modulators. The characteristic parameters of the developed 14-stage S2M3 are as follows: an output voltage amplitude of 5.45 kV with a 100 ns–50 ms width, a minimum rise time of approximately 18 ns, and a continuous repetition frequency of 100 kHz. S2M3 has the ability to change the pulse shape, and the pulse frequency can reach 2.8 MHz within the burst.

Cancer Treatment: An Overview of Pulsed Electric Field Utilization and Generation

Patients diagnosed with cancer receive different types of treatments based on the type and the level of the tumour. An emerging treatment that differs from well-developed systematic therapies (i.e., Chemotherapy, Radiotherapy, and Immunotherapy) is Tumour Treating Field (TTF) treatment. Tumour behaviour under TTF treatment varies based on the electric field intensity; the process of exposing the tumour cells to an electric field is called electroporation. From the electrical perspective, the most efficient method for electroporation is to use a voltage pulse generator. Several pulse generator topologies have been introduced to overcome existing limitations, mitigate the drawbacks of classical generators, and provide more controllable, flexible, and portable solid-state voltage pulse generators. This paper provides a review of cancer treatment using TTF and highlights the key specifications required for efficient treatment. Additionally, potential voltage pulse generators are reviewed and compared in terms of their treatment efficacy and efficient use of electrical power.

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.

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.

Wavelength Effects on the Reflectivity of Niobium by Solid-State Laser Pulses

This study utilized solid-state lasers with a 50 ns pulse duration in a Q-switched mode of operation at wavelengths of 1.06 µm and 0.69 µm to investigate the hemispherical reflectivity of niobium. Our experimental results show that the reflectivity of niobium decreases notably as the laser fluence increases towards the plasma formation threshold for ablation at both studied wavelengths, which we attribute to changes in the absorptivity of the surface resulting from plasma formation. We also observed a significant effect of laser wavelength on the reflectivity values of the sample at low laser fluence. By determining the threshold fluence values for each wavelength, we estimated the surface temperature associated with the threshold fluence for plasma formation. Our calculations revealed discrepancies between published values for optically polished and mechanically polished niobium, which we suggest may be due to the presence of nano/micro defects, oxide films, and contaminants that amplify the wavelength-dependent effects on reflectivity. These findings have important implications for the design of optical components and laser processing techniques that use niobium, as well as for the development of accurate models of laser-material interactions. Further research is needed to fully understand the underlying mechanisms driving the observed effects and to explore potential applications of niobium in laser-based technologies.

The Development of Solid-state Pulse Generator based on Marx Circuit with Chopping Switch

A solid-state pulse source is mainly formed by replacing the spark switch in a traditional pulse source with semiconductor switch device. Compared with conventional gas switch devices such as spark switches, semiconductor switch devices have the advantages of high work repetition frequency, long service life, small size, high efficiency, high reliability, easy control, and active shutdown. However, there are still problems, such as the solid-state switch being easily broken down by high voltage, the rising and falling edges of the pulse being slow, and the loss is enormous. In this paper, a solid-state pulse generator based on Marx with a chopping switch circuit is developed, which effectively solves the above problems. The pulse generator comprises DC power, a switching power circuit, a Marx circuit with a chopping switch, a serial port touch screen, and an optical fiber transmission circuit.

An Inductive Isolation-Based 10 kV Modular Solid Boost-Marx Pulse Generator

The solid-state Marx pulse generator is widely used in various fields such as biomedical electroporation, food processing, and plasma material modification. In this paper, an inductor is chosen as an isolation device and by adding a switch to the circuit, a solid-state boost-Marx pulse generator (BMPG) is formed. On the one hand, the inductor forms a boost circuit to multiply the output voltage gain, and on the other hand, it solves the shortcomings of conventional Marx pulse generators where the charging speed and total efficiency during high-frequency pulse generation are drastically affected by the isolation resistor. The selection criteria for inductors is well derived. Based on the PSpice simulation verification, a 12-module prototype of BMPG is built. The test results show that the circuit can achieve 10 kV high-voltage pulse output with a pulse width of 200–1000 ns and an adjustable repetition frequency of 0–10 kHz. While the input DC voltage requirement is only 235 V, the pulse voltage boost multiple is up to 42.5 times. Additionally, with the different switching sequences, the proposed BMPG can realize the adjustable change of pulse rising time and falling time.