Marx Circuit Research Articles

An avalanche transistor-based Marx circuit pulse generator with sub-nanosecond, high frequency and high-voltage for pathogenic Escherichia coli ablation

Pathogenic Escherichia coli, which will easily cause environmental pollution, is a potentially hazardous microorganism that enters the environment through various routes such as biological feces. The presence of this bacterium poses a serious health risk, especially in water sources. When consuming water containing excessive amounts of pathogenic Escherichia coli, both humans and animals may experience severe health issues, such as diarrhea and gastrointestinal infections. However, current treatment methods for this bacterium are not ideal, and traditional means sometimes struggle to completely eliminate these stubborn microorganisms. In recent years, the scientific community has been exploring new sterilization techniques to address this challenge without causing secondary environmental pollution. Among them, pulsed electric field (PEF) technology has garnered significant attention. By applying high-intensity electric field pulses, PEF technology can have a fatal impact on microbial cells in a very short period of time. Studies have shown that this technology can cause cell membrane perforation, destroying the integrity of the cell and leading to cell death. This method is not only capable of decomposing organic pollutants, but also has a significant bactericidal effect. Nevertheless, despite the theoretical potential of PEF technology, there is still relatively little research on its application, especially in terms of treating pathogenic Escherichia coli. Further studies and experimental verification are needed. This article investigates the bioelectromagnetic effects of electric pulses on pathogenic Escherichia coli in sewage through a self-developed pulse source device (capable of providing a voltage range from 1.7 kV to 2.2 kV, with a rise time of 190 ps and a maximum repetition rate of 20 kHz). The feasibility of using a pulsed electric field to purify water bodies is verified in this report.

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.

A Novel Boost Marx Pulse Generator Based on Single-Driver Series-Connected SiC MOSFETs

This paper presents a new type of all solid state boost Marx pulse generator (BMPG). On the basis of the classic pulse forming Marx circuit, without changing the voltage level of each voltage module, a new switch is added for the isolated inductor energy storage and recovery, so as to realize the output of high-voltage nanosecond pulses. At the same time, in order to improve the voltage level of the semiconductor switch and break the limitation of the voltage of the single-stage pulse forming circuit, a series-connected SiC MOSFETs with a single external driver is designed. The series switch has a simple structure with few components and is extremely easy to use in a modular high voltage pulse generator. Its theoretical feasibility is verified by mathematical model and circuit simulation, and the 10-stage prototype is built in this paper. Under the condition of input DC voltage of 500 V, it can output 18 kV high voltage pulses of 200 ns-1200 ns, and the gain multiple has reached 36 times.

Impact of Temperature on Turn-On Characteristics of Avalanche Transistors and Output Pulses of Their Marx Circuits

Impact of Temperature on Turn-On Characteristics of Avalanche Transistors and Output Pulses of Their Marx Circuits

An Energy-Saving Pulsed Magnetic Field Generator Based on Modular Marx Circuit

An Energy-Saving Pulsed Magnetic Field Generator Based on Modular Marx Circuit

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 Novel Variant of Marx Generator Circuit Using Hybrid Energy Storage

With the development of pulsed power technology and the expansion of its application areas, the requirements for pulsed high-voltage supplies are getting sophisticated. Many researchers are exploring new circuits or trying to improve the performance of the existing circuits. In this study, we introduce a variant circuit of the Marx generator based on hybrid energy storage (HES). This circuit topology, referred to as the LCL circuit in this article, allows two inductors and one capacitor to discharge simultaneously to obtain a higher output voltage. By observing the simulation results, we compared the performance of this proposed circuit with circuits based on other energy-storage methods, including capacitive energy storage (CES), inductive energy storage (IES), and the previously studied HES. After confirming the operation process of an LCL module, a two-stage experimental circuit has been built using power MOSFET switches for carrying out the verification experiments. With a charging voltage of 800 V, the output voltage of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim$</tex-math> </inline-formula> 8.4 kV with a rise time of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim$</tex-math> </inline-formula> 30 ns has been obtained on a 200- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega$</tex-math> </inline-formula> load. The voltage addition of two modules has indicated the potential of a Marx circuit for a much higher output voltage.

Influence of gas pressure and gas type on pseudospark electron beam

Pseudospark discharge is a discharge that occurs in the left band of the Paschen curve. According to previous studies, an electron beam will be generated in the initial stage of pseudospark discharge. This electron beam has the advantages of high energy, high current and self-confinement. It has a promising application in high-power microwave sources, surface treatment of metal materials, etc. To investigate the characteristics of this electron beam, a pseudospark discharge experimental platform is established in this paper. A pseudospark chamber is designed for pseudospark discharge. To trigger the discharge, a high voltage pulse trigger signal is generated by an avalanche transistor Marx circuit and a trigger unit is designed to generate trigger electrons. Faraday Cup is utilized to collect the electron beam and measure the electron waveform. In order to quantitatively characterize the electron beam, we define six electron beam characteristics, including trigger delay, peak current, electron beam charge, electron beam width, electron beam loop current ratio and electron beam loop charge ratio. To investigate the influence of gas pressure and gas type on electron beam characteristics, we experimentally obtained results of electron beam characteristics for different gas pressures and gas type. We mainly investigated the change rule of the electron beam characteristics when the gas pressure changes between 6 Pa and 20 Pa and the similarities and differences of the electron beams under the two gas environments, argon and nitrogen. We find that gas pressure can be used for the modulation of electron beam time delay. The width of the electron beam in the case of nitrogen has a very stable relationship with the gas pressure. Gas pressure and gas type are two important means of controlling the characteristics of pseudospark electron beams.

A Marx-Based Gaussian Monocycle Pulse Generator With Low Ringing Level for Ground Penetrating Radar Applications

The Gaussian pulse generator is the core component of the pulse ground penetrating radar (GPR) system, which requires high amplitude, narrow pulse width, and low ringing levels. Marx circuits are widely used to generate Gaussian pulses. However, due to the complex pulse-forming process, the high-amplitude pulses generated by conventional Marx circuits suffer from oscillation and severe ringing. In this study, a refined model of the Marx circuit based on lossy transmission line theory is proposed, which effectively reduces the oscillation and ringing level of the generated Gaussian pulses. Furthermore, a monocycle pulse-shaping network is proposed based on the short-circuit stub. The unipolar Gaussian pulse is converted into a Gaussian monocycle pulse for antenna radiation. Waveform experiment results show that the peak-to-peak value of the output pulse is 428 V, the pulse width is about 0.8 ns, and the ringing level is low at about 9%. The profile imaging result of the sand tank detection experiment further shows that the generated high-quality Gaussian monocycle pulse can provide good detection performance of underground buried targets for the pulse GPR system.

A Marx generator based on thyristors triggered in a shock ionization wave mode

Recently, a new trigger mode of thyristor which is called shock ionization wave mode is researched. Compared with the conventional trigger mode, this trigger mode can turn on the thyristor rather fast. In this mode, a trigger voltage with a high amplitude and fast rising speed is applied at both ends of the thyristor. Many single-tube conduction experiments are reported while the conduction threshold of shock ionization wave mode has not been investigated. Besides, the application of this trigger mode in some pulse power topology remains blank which is useful for this mode. In this paper, to explore the impact ionization wave mode conduction threshold of commercial thyristor, fast front high voltage nanosecond pulses are generated by avalanche tube Marx circuit. Pulse signals of different amplitudes are realized through the voltage division resistor. The impact ionization wave mode trigger threshold for commercial thyristors is about 2500 V in amplitude and 250 V/ns in voltage rising speed and the higher the rated parameter of the thyristor, the higher the threshold. To broaden the application of this mode, a novel Marx generator based on thyristors is proposed. A four-stage Marx generator is constructed and the amplitude of the output voltage can reach 1869 V.

High Repetition Frequency Subnanosecond Avalanche Marx Generator

Ultrawideband electromagnetic pulses have sub-nanosecond rise time and repetition frequency above 100 kHz. Ultrawideband characteristics make it increasingly used in biomedical, intentional electromagnetic interference, and other fields. Avalanche Marx circuits are an important way to generate high-voltage sub-nanosecond pulses with high repetition rates. However, traditional avalanche Marx circuits (TAMCs) are difficult to achieve a repetition rate of 100 kHz and often fail when they reach kilohertz. The second-stage transistor is extremely vulnerable to damage, which is the principal cause of circuit failure. In this article, through the analysis of its discharge mechanism, it is found that the damage to the second-stage transistor is related to the slow on-speed of the first-stage transistor. In fact, the first-stage transistor is the last to be avalanche broken down, causing the already-opened second-stage transistor to be subjected to enormous electrical stress for an instant. This electrical stress is the passive lift voltage of the second-stage transistor, which is the direct cause of easy damage to the second-stage transistor. Therefore, an improved avalanche Marx circuit (IAMC) is proposed. By connecting a protection resistor in series with the second-stage transistor, the passive lift voltage is suppressed. In order to verify the high refrequency capability of this circuit, a 20-stage pulse generator using an IAMC is developed. It achieves a rise time of 230 ps in a 50- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $</tex-math> </inline-formula> load, an amplitude of 1.65 kV, and a repetition rate of 100 kHz. After adding the necessary cooling device, it finally achieves a stable output of 230-ps rise time, 730-V amplitude, and 700-kHz repetition rate on a 50- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $</tex-math> </inline-formula> load.

Improved Marx Pulse Generator With Auxiliary Trigger Topology (2022)

Marx multi-stage circuits based on avalanche transistors are widely used in high-power nanosecond pulse applications. In response to the low reliability of the conventional Marx circuit, this paper analyzed the corresponding failure mechanism and discovered that the conduction modes were the main cause of failure. Based on this, a new topology is designed, by changing the conduction mode from "overvoltage switching-on" to "triggering switching-on". The simulation and measurement results show that the new structure has the advantages of high efficiency, stable operation, low output delay and short output pulse front. Meanwhile, to further improve the output efficiency,= a multiplexed stacking solution is designed based on the new structure, and the simulation results show that the output efficiency is up to 95%. The research in this paper can provide solutions for accurate and reliable synchronous triggering of key units such as gas switches in pulsed power systems, and also provide references for the design of high-efficiency nanosecond pulse generators.

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.

Development of a High-Voltage Pulsed Electric Field Sterilization Power Supply Using a New Topology Circuit

Traditional thermal sterilization technology is easy to implement and safe, but it will destroy food nutrition and change food taste. Therefore, people began to turn their attention to non-thermal sterilization. High-voltage pulsed electric field sterilization technology is one of them; it has attracted much attention because of its high efficiency and little damage to food. Different types of loads will cause serious trailing of the pulse falling edge. In view of this situation, this paper proposes a new topology circuit that combines a solid-state switch with a half-bridge Marx generator. It can be used for high-voltage pulsed electric field sterilization. By improving the structure of the classical Marx circuit, the high-voltage pulse power supply of the new topology circuit has the characteristics of steep rising edge and short falling edge delay; does not require isolation inductance or isolation resistance, which solves the isolation problem between the DC charging power supply and the high-voltage terminal; and has a good voltage-clamping function and load adaptability. The working process of the topology circuit under resistive, capacitive and inductive loads and the voltage clamping effect when the solid-state switch does not work properly in the discharge process are analyzed in detail. The power supply is composed of an adjustable DC power supply, five-stage half-bridge Marx generator and control protection circuit. A field programmable gate array (FPGA) is used as the controller to generate control signals, and optical fiber isolation is used to provide control signals for the main loop. The power supply can output a high-voltage square wave pulse with a voltage amplitude of 10 kV, maximum pulse number of 1000 per second, maximum pulse width of 20 μs, pulse rise time of smaller than 300 ns and short pulse drop time, and the repeated voltage amplitude, frequency and pulse width are adjustable, which can meet the requirements of a high-voltage pulse sterilization experiment.

Development of Bipolar Pulse Power Supply Based on Peak Closed-Loop Control Method

With the wide application of pulsed power technology in tumor ablation, sewage treatment, and other related fields, researchers have found that bipolar electrical pulses are more effective than unipolar electrical pulses. In this article, a new bipolar pulse generator is proposed, which combines the features of boost circuit and Marx circuit to significantly improve the boost ratio of output pulse and the tunability of pulse peak. In order to improve the load regulation rate and peak stability of bipolar pulse power supply, a bipolar pulse power supply based on peak closed-loop control method is designed in this article. The high-voltage pulse is attenuated, and its peak is sampled by the pulse peak sampling circuit, and the pulse peak voltage is fed back to the DSP controller for comparison with the set peak value, and the proportional integral differential (PID) adjustment is performed according to the voltage deviation, and the boost ratio of the pulse generator is changed to realize the constant peak output of the bipolar pulse. In order to verify the feasibility of the proposed bipolar pulse generator with peak closed-loop control scheme, simulation and experimental studies of the bipolar pulse power supply with five-stage peak closed-loop control were conducted. The results show that the output repetition frequency of 5 kHz, pulsewidth of 5– <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10~\mu \text{s}$ </tex-math></inline-formula> , and peak pulse value within ±2.0 kV can be stabilized when the input voltage is 100 V.

Self-Powered Gate Drive Circuits With Optical Signal Isolation for In-Vehicle Marx Circuit of Ozonizer

Reducing the cost of a Marx circuit as a high-voltage power supply for nitrogen oxide (NOx) decomposition for diesel vehicles is required. The Marx circuit with MOSFETs has an advantage in size compared to the Marx circuit with gap switches. However, the Marx circuit with MOSFETs needs gate drive circuits on the gate of each MOSFET. The gate signal and drive power must be supplied to each gate with isolation in a low-cost way. However, the transformer for the isolation with high withstand voltage, such as 10 kV or more, is typically high cost because of the low demand. This article proposes the self-powered gate drive circuit using the charging path of the Marx circuit. The proposed gate drive circuit only requires a low withstand voltage because the power for the MOSFET on the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n$ </tex-math></inline-formula> th stage is supplied from the ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n -1$ </tex-math></inline-formula> )th stage via a low-voltage transformer. Besides, the gate signal is transmitted through pairs of LEDs and photodiodes instead of high-cost optical fibers. The proposed gate drive circuits are developed and implemented into a prototype of the Marx circuit with an output voltage of 4 kV. From the experiments, it is demonstrated that the proposed drive circuits provide both drive power and gate signal.

Solid-State Marx Generator Using Hybrid Energy Storage

For pulsed power generation, the energy storage unit is one of the most fundamental components. The common energy storage methods in the current pulse power systems are capacitive energy storage (CES) and inductive energy storage (IES), each with its own advantages and disadvantages. In this study, we have tested a circuit using both CES and IES, which we refer to as a hybrid energy storage (HES) approach. Compared with a CES or IES system, the output characteristics of an HES system show potential flexibility given by two free parameters <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\rho $ </tex-math></inline-formula> , which corresponds to the impedance relation between the source and the load, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sigma $ </tex-math></inline-formula> , which corresponds to the initial relation between CES and IES. By using a five-module solid-state Marx circuit, an HES-based pulsed power generator has been demonstrated. In each module, power MOSFETs are used as switches for controlling the initial energy ratio between the capacitor and the inductor, before allowing both of them to release their energy to the load simultaneously. The results have characterized HES as the third choice for energy storage of pulsed power systems, after CES and IES.

Contactless Terahertz Sensing of Ultrafast Switching in Marx Generator Based on Avalanche Transistors

In this letter, we have studied the temporal evolution of switching for each stage of the Marx generator with picosecond temporal and millimeter spatial resolutions employing terahertz measurements. The Marx circuit utilizes collapsing-field-domain (CFD)-based avalanche switches, which are formed in a bipolar GaAs structure and result in the picosecond speed of powerful carrier generation and electrical switching. The application of the CFD-based avalanche switches emitting mm-wave pulsed radiation in the Marx generator provides a unique opportunity to accurately track the switching instants for each of the circuit stages with a picosecond time precision. The collapsing domains cause the sub-THz pulses radiated by each of the avalanche switches, and the same domains generate the electron-hole plasma thus causing simultaneously the electrical switching. In this work, we report the direct measurements of the switching instants for each of the four stages Marx generator and suggest an interpretation of non-trivial experimental results.

A modularized high-power ultra-wideband radiation system based on the space-synthesis method.

In this paper, a high-power ultra-wideband radiation system, composed of multiply radiation modules, is developed based on the space-synthesis method. The radiation module mainly consists of a transistorized pulser, a 2 × 2 combined antenna array, and a power divider. To improve the out parameters [the amplitude, the pulse repetition frequency (PRF), and the rise time] of the transistorized pulser based on the Marx circuit, the influence of the traveling wave process on the output pulse must be concerned. Based on the theoretical analysis, the printed circuit board circuit parameters and the circuit structure of the pulser are optimized. To improve the power synthesis efficiency, the pulse jitter characteristic of the pulser is improved by replacing the conventional base triggering mode with the collector voltage ramp triggering mode for the first-stage avalanche transistor in the pulser. The previous optimized antenna array is utilized in this radiation system, which has a better radiation performance in the prescribed aperture area. In addition, based on the gradient microstrip structure, the power divider integrated with the pulser is designed, which has the advantages of wide bandwidth, low loss, and light weight. Experimental results show that the peak effective potential rEp of the radiation system of 20 radiation modules is 221.8 kV, the maximum PRF could reach 10 kHz, and the half-power radiation angles of its radiation field are about 5° in both the E plane and the H plane. More radiation modules could be integrated into the system to achieve a higher electric field in the future.

Valued waste/wasted value: Waste, value and the labour process in electronic waste recycling in Singapore and Malaysia

AbstractThis paper focuses on value creation in electronic waste, and supports the argument (c.f. Herod et al., 2014) that ‘waste’ embodies congealed labour – the product of the labour process. This analysis of itinerant rag‐and‐bone collectors demonstrates that value creation by informal labour accrues as congealed labour in recycled e‐waste through the agentic acts of collecting, salvaging and extracting. This paper highlights the central role of informal labour in this labour process and pushes further the conceptualisation of ‘wasted labour’ (McGrath‐Champ et al., 2015) by calling for greater attention to the agentic nature of labour in value creation, rather than simply being a passive means of production. Drawing on Marx's circuit of capital, this paper articulates the central role played by informal labour – an oft overlooked economic actor – in enabling the subsequent recycling processes and conceptualises them as pivotal to the recycling industry.