Showing papers on "Marx generator published in 2016"

A Novel Configuration of Modular Bipolar Pulse Generator Topology Based on Marx Generator With Double Power Charging

Abstract: A bipolar pulse has been proved to be more advanced in the treatment of tumor because of the elimination of muscle contractions and the effect for ablating nonuniform tissue. In this paper, a new type of modular bipolar pulsed-power generator based on Marx generator with double power charging is proposed. The concept of this generator is charging the two series of capacitors in parallel by two power sources, respectively, and then connecting the capacitors in series through solid-state switches with different control strategies. Utilizing a number of fast solid-state switches, the capacitors can be connected in series with different polarities, so that a positive or negative polarity pulse will be delivered to the load. The simulated models of this generator have been investigated in a PSPICE platform, and a laboratory prototype has been implemented in a laboratory. The simulation and test results verify the operation of the proposed topology in different switching modes. The development of this pulse generator can provide the hardware foundation for the research on biological effect without muscle contraction when the tumors are applied with bipolar pulse electric field.

A High-Performance Drive Circuit for All Solid-State Marx Generator

Abstract: In recent years, all solid-state Marx generators have been found more and more extensive applications in industrial, environmental, and biological fields. All solid-state Marx generators have many requirements for their drive circuits, such as good synchrony for driving signals at different stages, fine isolation between control signals and the main circuits, adjustable pulsewidths and frequencies, and good driving abilities. This paper proposes a high-performance drive circuit for a 24-stage Marx generator based on IGBTs. A half-bridge circuit using IR2110 outputs a high-current turning-on drive signal (positive) and a turning-off drive signal (negative) with adjustable dead time. The control drivers are input to the common primary side of 24 nanocrystalline magnetic transformers, which isolate the control circuit and the main circuit. Through gate circuits at the second sides of the magnetic cores, the turning-on drive signal charges 24 gate–emitter capacitors to required voltages and consequently all IGBTs move into on state until the turning-off signal arrives. Similarly, the negative turning-off drive signal charges all gate–emitter capacitors to a negative voltage which ensures all IGBTs stay in the off state. Therefore, the pulsewidth is determined by the phase difference between the turning-on and turning-off drive signals. Equipped with this drive circuit, the 24-stage Marx generator is able to produce stable high voltage pulse with a peak value of −9.6 kV, PRF $0.05\sim 5$ kHz, and different pulsewidths. In this paper, the design details and experimental confirmation of the proposed drive circuit are illustrated.

Repetitive High-Voltage All-solid-state Marx Generator for Excimer DBD UV Sources

Abstract: In order to develop an efficient and reliable pulsed power supply for excimer dielectric barrier discharge (DBD) ultraviolet (UV) sources, a pulse generator using Marx topology is adopted. MOSFETs are used as switches. The 12-stage pulse generator operates with a voltage amplitude in the range of 0–5.5 kV. The repetition rate and pulsewidth can be adjusted from 0.1 to 50 kHz and 2 to 20 $\mu \text{s}$ , respectively. It is used to excite KrCl* excilamp, a typical DBD UV source. In order to evaluate the performance of the pulse generator, a sinusoidal voltage power supply dedicated for DBD lamp is also used to excite the KrCl* excilamp. It shows that the lamp excited by the pulse generator has better performance with regard to radiant power and system efficiency. The influence of voltage amplitude, repetition rate, pulsewidth, and rise and fall times on radiant power and system efficiency is investigated using the pulse generator. An inductor is inserted between the pulse generator and the KrCl* excilamp to reduce electromagnetic interference and enhance system reliability. The experimental results show that it also helps to improve radiant power and system efficiency.

Development and Simulation of a Compact Picosecond Pulse Generator Based on Avalanche Transistorized Marx Circuit and Microstrip Transmission Theory

Abstract: The new biological effect of picosecond pulsed electric fields (psPEFs) has elicited the interest of researchers. A pulse generator based on an avalanche transistorized Marx circuit has been proposed. However, the problem of reflection in the transmission of the generated picosecond pulse based on this circuit has not received much attention and remains unresolved. In this paper, a compact picosecond pulse generator based on microstrip transmission theory was developed. A partial matching model based on microstrip transmission line theory was also proposed to eliminate reflection, and a series inductor was utilized to optimize pulse waveform. Through simulation studies and preliminary experimental tests, a pulse optimized with 1015 V amplitude, 620-ps width, and 10-kHz high stability repetition rate was generated. This pulse generator can be used with microelectrodes in cell experiments to explore the biological effect mechanism of psPEF.

A 160 J, 100 Hz rep rate, compact Marx generator for driving and HPM source

Abstract: This paper presents the electrical and mechanical design considerations of a compact, 160 J modular pulse forming network (PFN) based Marx generator used to drive a high-power microwave (HPM) source with a time variant load at a PRF of 100 Hz. The modular Marx generator is designed to produce an open circuit output voltage of 600 kV from a 50 kV source using twelve stages. Each stage of the Marx was constructed from a PFN created with five, 2.1 nF, high voltage capacitors in parallel. Each Marx module was machined out of acetyl copolymer or Delrin to provide optimal strength, rigidity, and a dielectric constant that closely matches transformer oil. These Marx modules include air supply lines that are machined directly into each block of Delrin allowing airlines to connect to each module chamber rather than every spark gap. The spark gaps are comprised of two electrode inserts placed into the sealed pressure vessel contained within the Marx modules. The electrode inserts are of a sleeve-electrode design, which allows the user to insert the electrode into the sleeve, then the sleeve into the Marx module. The benefit of this design is the ability to adjust the electrode gap spacing without compromising the high pressure seal. Two continuous charging inductors run between each PFN and underneath the Marx modules. Due to high voltages generated by the Marx, outer field shaping rings are used to reduce the field stress across the induction coils, resulting in longer lifetime. The inductors are also of modular design allowing for individual coils to be replaced in the event of failure. Output voltage and current waveforms from a 60 Ohm water load are presented.

Experiment apparatus, based on Marx generator, for electric spark induced cavitation bubble

Abstract: The invention relates to an experiment apparatus, based on a Marx generator, for electric spark induced cavitation bubbles, and belongs to the cavitation and cavity dynamics field. A Marx generator is applied to the experiment apparatus for electric spark induced cavitation bubbles, and a step-up ratio of a transformer in a high-voltage pack is changed by the Marx generator to be 1/n of an original step-up ratio, n being the grade of the Marx generator. The experiment apparatus comprises a Marx generator ranging from 2 to 10 in grade, ball gaps in the air, and pin electrodes in water. The size of cavitation bubbles is controlled through the distance between the ball gaps and the distance between the pin electrodes. The experiment apparatus can be used for generating cavitation bubbles adjustable in diameter, observing burst form, burst time or the like of cavitation bubbles, and also studying mutual interacting relations among cavitation bubbles and solid boundaries, solid particles, liquid levels and the like.

Design of compact Marx module with square pulse output

Abstract: Compact pulsed power system based on compact Marx generator is widely used in terms of drive resistance and capacitive loads. This system usually adopts high performance components such as high energy density capacitors, compact switches, and integrated structure. Traditional compact Marx generator can only output double-exponential pulse profile. In this paper a compact, low-impedance Marx module which can output rectangular pulse profile is design and tested. This module has multiple circuits of different discharge frequencies in parallel to generate quasi-rectangular pulse. Discharge characteristic of an ideal module with infinite branches is calculated theoretically. A module with two branches has been designed and tested. Test results show that the impedance of the module is 1.2 Ω. When charging voltage is 100.6 kV and load resistance is 1 Ω, the peak output pulse is 45.2 kV voltage, the peak power is about 2 GW, the pulse width is about 130 ns, and the rise time is about 35 ns. The energy density and power density of the module are 15 kJ/m3 and 140 GW/m3, respectively.

Solid-state Marx generator for the compact linear collider breakdown studies

Abstract: A high repetition rate, semiconductor based, Marx generator has been designed and developed for a spark gap system: this system will allow the study of breakdown rate phenomena for different materials and surface finishes, for RF structures for the proposed Compact Linear Collider (CLIC). The Marx circuit is based on new SiC MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), with 15 compact stages, capable of running with capacitive type loads during normal operation and also short-circuit mode at reduced repletion rate. Experimental tests with 150 pF to 650 pF dummy capacitances and also the actual spark gap system are presented: these tests and measurements prove the performance of the Marx generator to generate pulses from 200 ns to 100 μs pulse width, up to 10kV, with frequencies up to 1 kHz and pulse voltage rise times less than 100 ns with a load capacitance of not more than 150 pF. In addition, first breakdown results validating the operation of the Marx generator during breakdown are presented.

Solid-state pulse modulator using Marx generator for a medical linac electron-gun

Abstract: A medical linac is used for the cancer treatment and consists of an accelerating column, waveguide components, a magnetron, an electron-gun, a pulse modulator, and an irradiation system. The pulse modulator based on hydrogen thyratron-switched pulse-forming network is commonly used in linac. As the improvement of the high power semiconductors in switching speed, voltage rating, and current rating, an insulated gate bipolar transistor has become the more popular device used for pulsed power systems. We propose a solid-state pulse modulator to generator high voltage by multi-stacked storage-switch stages based on the Marx generator. The advantage of our modulator comes from the use of two semiconductors to control charging and discharging of the storage capacitor at each stage and it allows to generate the pulse with various amplitudes, widths, and shapes. In addition, a gate driver for two semiconductors is designed to reduce the control channels and to protect the circuits. It is developed for providing the pulsed power to a medical linac electron-gun that requires 25 kV and 1 A as the first application. In order to improve the power efficiency and achieve the compactness modulator, a capacitor charging power supply, a Marx pulse generator, and an electron-gun heater isolated transformer are constructed and integrated. This technology is also being developed to extend the high power pulsed system with > 1 MW and also other applications such as a plasma immersed ion implantation and a micro pulse electrostatic precipitator which especially require variable pulse shape and high repetition rate > 1 kHz. The paper describes the design features and the construction of this solid-state pulse modulator. Also shown are the performance results into the linac electron-gun.

Prolongation of the lifetime of guided discharges triggered in atmospheric air by femtosecond laser filaments up to 130 μs

Abstract: The triggering and guiding of electric discharges produced in atmospheric air by a compact 100 kV Marx generator is realized in laboratory using an intense femtosecond laser pulse undergoing filamentation. We describe here an approach allowing extending the lifetime of the discharges by injecting a current with an additional circuit. Laser guiding discharges with a length of 8.5 cm and duration of 130 μs were obtained.

Plasma synthesis jet flow serial connection discharge device based on Marx generator

Abstract: The invention discloses a plasma synthesis jet flow serial connection discharge device based on a Marx generator. The negative pole of a direct current source is grounded, and the positive pole of the direct current source is connected with one end of a charge resistor; the other end of the charge resistor is connected with the positive poles of multiple charge diodes; the negative poles of the multiple charge diodes are connected with one ends of multiple charge capacitors; the other ends of the multiple charge capacitors are connected with the positive poles of multiple discharge diodes; multiple plasma synthesis jet flow exciters are connected to the negative poles of the charge diodes and the negative poles of the discharge diodes in parallel; a discharge resistor is arranged between two discharge diodes; the negative poles of the discharge diodes are grounded; ground electrodes of the plasma synthesis jet flow exciters are grounded; and two ends of a load are connected to the positive pole of the first discharge diode and the negative pole of the last discharge diode in parallel. The plasma synthesis jet flow serial connection discharge device has the following beneficial effects: when the multiple plasma synthesis jet flow exciters are serially connected to synchronously discharge, multi-way superposition pulses are formed at two ends of the load, so that the multi-angle and wide-range flow control can be realized in high-speed flowing field control field, and the high-voltage discharge experimental study can be performed.

Pulse generator with intermediate inductive storage as a lightning simulator

Abstract: Compact transportable generators are required for simulating a lightning current pulse for electrical apparatus testing. A bi-exponential current pulse has to be formed by such a generator (with a current rise time of about two orders of magnitude faster than the damping time). The objective of this study was to develop and investigate a compact pulse generator with intermediate inductive storage and a fuse opening switch as a simulator of lightning discharge. A Marx generator (six stages) with a capacitance of 1 μF and an output voltage of 240 kV was employed as primary storage. In each of the stages, two IK–50/3 (50 kV, 3 μF) capacitors are connected in parallel. The generator inductance is 2 μH. A test bed for the investigations was assembled with this generator. The generator operates without SF6 and without oil in atmospheric air, which is very important in practice. Straight copper wires with adjustable lengths and diameters were used for the electro-explosive opening switch. Tests were made with active-inductive loads (up to 0.1 Ω and up to 6.3 μH). The current rise time is lower than 1200 ns, and the damping time can be varied from 35 to 125 μs, following the definition of standard lightning current pulse in the IEC standard. Moreover, 1D MHD calculations of the fuse explosion were carried out self-consistently with the electric circuit equations, in order to calculate more accurately the load pulse parameters. The calculations agree fairly well with the tests. On the basis of the obtained results, the design of a transportable generator was developed for a lightning simulator with current of 50 kA and a pulse shape corresponding to the IEEE standard.

Voltage droop compensation based on resonant circuit for generalized high voltage solid-state Marx modulator

Abstract: The purpose of this paper is to present and discuss the voltage droop compensation associated with long pulses generated by solid-state bipolar or unipolar high-voltage Marx modulators. In particular a novel design scheme for voltage droop compensation based on resonant circuit in solid-state bipolar (positive and/or negative pulses) high-voltage Marx generator, using off-the-shelf components, design and control, is described. The compensation consists in adding one auxiliary resonant stage to the existing Marx stages, without changing the modularity and topology of the circuit. The auxiliary compensation voltage is added to the output voltage to compensate the pulse voltage droop. Experimental results are presented for five stages Marx circuit, 10% voltage droop, using 1 kV pulse amplitude, 100 µs pulse width, 9.5 ms relaxation time and with 50 Hz pulse repetition rate.

Development of a Marx-coupled trigger generator with high voltages and low time delay

Abstract: Coupled by the Marx of the "JianGuang-I" facility, a high voltage, low time-delay trigger generator was developed. Working principles of this trigger generator and its key issues were described in detail. Structures of this generator were also carefully designed and optimized. Based on the "JianGuang-I" Marx generator, a test stand was established. And a series of experiment tests were carried out to the study performance of this trigger generator. Experiment results show that the output voltage of this trigger generator can be continuously adjusted from 58 kV to 384 kV. The time delay (from the beginning of the Marx-discharging pulse to the time that the output pulse of the trigger generator arises) of this trigger pulse is about 200 ns and its peak time (0%∼100%) is less than 50 ns. Experiment results also indicate that the time-delay jitter of trigger voltages decreases rapidly with the increase in the peak voltage of trigger pulses. When the trigger voltage is higher than 250 kV, the time-delay jitters (the standard deviation) are less than 7.7 ns.

Design and development of a Marx generator based 40kV pulsed power supply for non-lethal electric fence

Abstract: A non-lethal electric fence is an effective tool for security. Non-lethal electric fence employs high voltage (several tens of kV) pulses of short (micro-seconds) duration at rate of few pulses per second. Moreover the electric current and energy transferred to the load is controlled below certain limits to ensure non-lethal and non-injurious features. Fence energizer, which is essentially a high voltage pulsed power supply (HVPPS), is the pivotal part of the fence system. Among different HVPPS schemes, Marx generator is superior being reliable and energy efficient. However, it was never used for low power applications such as electric fencing. This work investigates potential of Marx generator in low power applications in general and as energizer for a non-lethal electric fence in particular. Specifically, a Marx generator is designed and implemented for a 40kV electric fence. Other design parameters include 220V ac input, output pulse duration of 1μs–15μs, repetition rate of up to 100 pulses per second, stored energy of 80J and release of energy less than 20mJ per pulse. A complete design is presented here for these specifications with validation in simulation. The design is then implemented using semiconductor switches and electrolytic capacitors for 100 stages of Marx voltage multiplier. The implemented system is tested through air-breakdown test and output pulse is measured through a capacitive voltage divider.

A compact, low cost Marx bank for generating capillary discharge plasmas

Abstract: We describe in detail a low power Compact Marx Bank (CMB) circuit that can provide 20 kV, 500 A pulses of approximately 100–200 ns duration. One application is the generation of capillary discharge plasmas of density ≈1018 cm−3 used in laser plasma accelerators. The CMB is triggered with a high speed solid state switch and gives a high voltage output pulse with a ns scale rise time into a 50 Ω load (coaxial cable) with 45 kV are demonstrated in air discharges.

A nanosecond pulse generator based on avalanche transistor

Abstract: Ultra-wideband (UWB) pulse generators based on an avalanche transistor are widely used in time domain ground penetrating radar(GPR). For shallow subsurface detection, it is essential to increase the pulse amplitude while maintaining the pulse width in order to improve the spatial resolution of GPR. Eliminating pulse trailing is also necessary to improve GPR performance. In this paper, a simple nanosecond generator was designed based on an avalanche transistor. The generator consists of a trigger circuit and a two-stage MARX circuit. The trigger signal is produced by the avalanche transistor in the trigger circuit. Resistors between the base and emitter of the transistor (Rbe) in the MARX circuit are optimized to improve the performance of the output pulse. The output characteristics of the generator are studied for different Rbe and charging capacitor. The results prove that optimizing resistors and charging capacitors decreases the width of the pulse and eliminates the pulse trail. A pulse with width of 900 ps and an amplitude of 25.2V was achieved. The RMS time jitter value of the pulse generator was found to be less than 400 ps.

Pulse current injection source for HEMP conduction immunity test

Abstract: The invention discloses a pulse current injection source for an HEMP conduction immunity test, and relates to a pulse current generating apparatus technology. The injection source comprises a high-voltage charging power source, a Marx generator, an impedance match module and a controller, wherein the output end of the high-voltage charging power source is connected with the input end of the Marx generator, the high-voltage charging power source is used for providing high-voltage charging power supply for the Marx generator, the output end of the Marx generator is connected with the input end of the impedance match module, and the Marx generator outputs dual-index waves and outputs dual-index pulse current waveforms conforming to requirements of standards after shaping and impedance matching of the impedance match module. The pulse current injection source can conveniently change the output current waveforms, peak currents and source internal resistance of the pulse current injection source, facilitates realization of high-altitude nuclear power magnetic pulse conduction immunity tests with different standards by use of one pulse current injection source, and is high in versatility and convenient to use.

High-altitude nuclear explosion electromagnetic pulse standard signal analog device

Abstract: The present invention relates to a high-altitude nuclear explosion electromagnetic pulse standard signal analog device, especially to a pulse source with standard high-altitude nuclear explosion electric field wave shape generated in a TEM chamber which is used for performing electric field probe scaling and mini key components anti-nucleus electromagnetic reinforcing experiment. The high-altitude nuclear explosion electromagnetic pulse standard signal analog device is small in size and low in output voltage with no need for complex pulse voltage-multiplying devices such as Marx generator; the high-altitude nuclear explosion electromagnetic pulse standard signal analog device employs a discharge loop with coaxial design and components with small sizes and compact structure and steadily control the fixed inductance of the loop to the nH magnitude so as to easily regulate the total inductance of the loop; through regulation of the size of the discharging loop capacitance and the loop inductance, the high-altitude nuclear explosion electromagnetic pulse standard signal analog device is able to output pulse waves with different rising edges and falling edges so as to satisfy the requirement of different standards; and the similarity of the output signal wave and the standard wave is larger than 95%, and the high-altitude nuclear explosion electromagnetic pulse standard signal analog device is stable in signal, simple in method, high in reliability and low in cost.

Design of bipolar pulse generator topology based on Marx supplied by double power

Abstract: Pulsed power technology has been used for the ablation tumor. Considerable research shows that a high-strength unipolar pulse electric field can induce irreversible electroporation (IRE) on the cell membrane, which can effectively kill cells. But some scholars and doctors have found that muscle contractions occur during treatment, which are associated with the delivery of electric pulses. Confirmed by further studies that bipolar pulses have been proven more advanced in the treatment of tumor because of the elimination of muscle contractions and the effect for ablating non-uniform tissue. So the bipolar pulse generator is needed for the research on the tumor ablation with bipolar pulses. In this paper, a new type of modular bipolar pulsed-power generator base on Marx generator with double power is proposed. The concept of this generator is charging two series of capacitors in parallel by two power sources respectively, and then connecting the capacitors in series through solid-state switches with different control strategy. Utilizing a number of fast solid-state switches, the capacitors can be connected in series with different polarities, so that a positive or negative polarity pulse will be delivered to the load. A laboratory prototype has been implemented in laboratory. The development of this pulse generator can provide the hardware foundation for the research on biological effect without muscle contraction when the tumors are applied with bipolar pulse electric field.

An Electric Fence Energizer Based on Marx Generator

Abstract: Non-lethal electric fence technologies gained considerable recognition in various application areas ranging from security to live-stock management and farm automation. Fence energizer, which is essentially a High Voltage Pulsed Power Supply (HVPPS), is a pivotal part of a non-lethal fence system with several design options. Marx generator, which is a well-recognized HVPPS, has never been tried as a fence energizer. This paper investigates potential of Marx generator as a fence energizer and identifies specific requirements and challenges that need to be addressed. Finally, a design of Marx generator is presented for a non-lethal electric fence having voltage rating of 40 kV, output pulse duration of 15 μs, pulse rate of up to 100 Hz and maximum output energy to be lower than 20 mJ per pulse to ensure its non-lethal nature. To meet the design requirements, a novel gate driver design is presented which is compact, cost effective and meets specific requirements of non-lethal nature of the fence.

Design and Performance of a Compact Marx Generator for Two-Electrode Gas Switch Used in ICF Power Conditioning System

Abstract: As the high-current, high-coulomb transfer two-electrode graphite gas switch had no trigger electrode and must be triggered by a nanosecond pulse, a compact Marx generator was developed to produce a nanosecond rise-time, voltage level around 100 kV negative pulse to trigger the gas switch. This paper presented the structure of the compact Marx generator and the performance used in ICF power conditioning system. The effect of the ultraviolet radiation was utilized to decrease the amplitude of the breakdown voltage of the spark gaps. Coaxial structure of the metal shell was employed to reduce the inductance of the Marx generator. Additional isolation circuits were improved to prevent the electromagnetic disturbance which was significant for the application of the two-electrode graphite gas switch. The results showed that the designed compact Marx generator was suitable and have been successfully used as the trigger generator in ICF power conditioning system.

Transformer-less Grid-Connected High-Voltage Marx Pulse Generator with Unity Power Factor for Domestic Drinking Water Disinfection

Abstract: Qatar has no rivers, thus the main natural water resource in Qatar is the groundwater table. The average groundwater recharge from rainfall is approximately 55.9 million m3/year, in addition to 2.2 million m3/year inflow of groundwater from Saudi Arabia, i.e. the total average renewable groundwater resource is 58.1 million m3/year for the period 1972-2005. Desalinated sea water and treated sewage are non-conventional water sources in Qatar. The quantities of produced and treated wastewater in the country were 55 and 53 million m3 in 2005 respectively. In 2005, a total water withdrawal of 444 million m3 was estimated, which are divided unequally into agricultural, municipal and industrial purposes. The Permanent Water Resources Committee (PWRC) was established in April 2004 to secure water resources for various uses for the benefit of Qatar. Qatar has carried out a number of studies, and established committees for the unification of integrated water resources management as follows: Increasing natural recharge by drilling wells with a special design. Development of water monitoring and irrigation scheduling. Artificial recharge of groundwater. Development of deep aquifers. Increasing treatment and reuse of waste-water: The amount of treated sewage increased from 46 million m3 in 2004 to 58 million m3 in 2006. All of the above mentioned facts clarify the importance of securing water (quality and quantity) for the state of Qatar. Many disease-causing germs may be present in water supplies. Sixty percent of all persons living in developing countries live without an adequate supply of drinking water where unsafe water is a major cause of infant mortality in these countries. Table 1 lists some of the germs that inhabit water and which can be harmful to humans. Table 1: Water inhabiting germs Germs Minimum dose for infection Survival time in water, days Escherichia coli 1,000,000 4-16 Vibrio cholera 3 7-32 Campylobacter jejuni 500 16-49 Salmonella typhi 3 4-35 Hapatitis Type A 1 Unavailable Entamoeba coli 10 10-16 Giardia lamblia 10 16-77 Water disinfection processes kill micro-organisms in the drinking water. Disinfection can be achieved by means of chemical disinfectants such as chlorine, which is the most commonly used chemical for disinfection because of its low price. It also remains in water, which inhibits reproduction and growth of the germs. However, this process may produce toxic disinfection byproducts which are very harmful to human health. Other disinfection processes such as ozonization or ultraviolet light are expensive for drinking water disinfection. The objective of this work is to implement an electrical disinfection process for controlling germs in water, since the germ cells are destroyed when the electric field strength and pulse duration are above critical values, i.e. dielectric breakdown of the cell membrane. In electrical disinfection water treatment techniques, the high voltage sources used can be classified into: high voltage DC generators, high voltage AC generators, and high voltage pulse generators. The main disadvantage in case of continuous DC sources is the degradation effect on electrodes (electrolysis of electrodes). Although the electrolysis is less in case of AC sources, the AC field application has a dead band region. Since the application time is of the order of a few milliseconds, some bacteria may pass through the electrodes when the electric field has a low strength. On the other hand, pulsed electric field is an effective solution to guarantee killing all harmful germs and avoid electrolysis of electrodes. In PEF processing, water is passed through a small treatment chamber where it is subjected to a short pulse of very high voltage. The high voltage field created across the liquid kills microorganisms by disrupting cell membranes. By applying a high PEF with of sufficient pulse width, an electrical discharge in water will occur. The electric discharges in water can effectively create a variety of simultaneous aspects such as shock waves, ultraviolet radiation, and the formation of chemically active radicals acting on biological cells and chemical compounds dissolved in water. Generally, there are two main types of PEF treatments, namely, underwater pulsed corona discharge and pulsed arc discharge. In corona discharge, the streamer filaments do not propagate across electrodes gap, while in case of arc discharge, the streamers bridge the electrodes. As a result, the pulsed corona has lower power requirements compared to the pulsed arc discharge. In this work, underwater pulsed corona discharge will be considered. In this work, a new grid-connected high-voltage pulsed power generator is proposed to generate pulsed streamers and plasma inside water, which will react with germs and destroy them. The proposed generator consists of: (i) Uncontrolled full-bridge rectifier to rectify the grid voltage, (ii) DC-DC Boost Converter (BC) in conjunction with Capacitor-diode voltage multipliers (CDVMs) to assure operating with unity input power factor (PFC feature) and elevate the rectified voltage to a proper voltage level, (iii) Conventional solid-state Marx generator, as the generated voltage from BC and CDVMs stage is used to charge the Marx generator capacitors (which are connected in parallel during the charging process), then when it is needed to generate a pulse, these capacitors are connected in series to discharge in the load during the pulse duration. The charging and discharging cycles are repeated sequentially to generate train of repetitive pulses. The load here is the water to be purified, which electrically can be represented as a resistive load. The value of this resistance depends on the conductivity of water, i.e. depends on the amount of dissolved salts in the water. The generated high voltage pulse is applied across high voltage electrodes, and the water sample to be treated should exist between these two electrodes. The generated pulsed electric field has the ability to kill germs in the water, since by applying the pulsed electric field, an ultraviolet radiation will be produced and will destroy the structure of the germs. The main advantages of the proposed approach can be summarized as follows: (i) The proposed generator has no step-up low frequency transformer which reduces the generator weight and volume and enhances the generator efficiency. (ii) The proposed generator can draw a sinusoidal input current at unity power factor thanks to the existence of PFC feature provided by the BC. (iii) Relatively low voltage semiconductor devices and capacitors will be employed which affects positively on the cost, i.e. it can be considered as a cost effective high-voltage pulse generator for domestic applications.

Design and hardware implementation of two stage solid state bipolar Marx generator

Abstract: Impulse generators were used to generate high voltage pulses. Marx generator is a multistage impulse generator. Conventional Marx generator used spark gap switches. In recent years these switches are replaced with semiconductor switches. The bipolar Marx generator is able to produce positive, negative and bipolar pulses. This paper deals with design and implementation of 2 stage solid state Bipolar Marx Generator. The specifications of Marx Generator are 200 V output voltage, 200 Hz repetitive frequency and a pulse width of 300 μs. The circuit is simulated using MATLAB software and the output obtained is 194 V. Hardware is tested with 50 V input voltage. The output obtained is 92 V.

Gas spark switches with increased operating life for Marx generator of lightning test complex

Abstract: A new design of gas spark switches with an increased operating life and stable dynamic characteristics for the Marx generator of the lightning test complex has been developed. The switches are characterized by the following parameters in the mode of operation: voltage up to 80 kV, discharge current up to 50 kA, flowing charge up to 3.5 C/pulse. An increased operating life is achieved by using torus-shaped electrodes with increased working surface area and a trigger electrode in the form of a thick disk with a hole located between them. Low breakdown delay time and high stability of breakdown voltage under dynamic conditions are provided by gas preionization in the spark gap using UV radiation of an additional corona discharge in the axial region.

Design of a 500 kV pulse generator with the rise time of nanosecond level

Abstract: An electromagnetic pulse (EMP) generator with output voltage of 500 kV is designed. It mainly consists of three parts, a low inductance Marx generator, a gas-sealed peaking circuit and a trigger source. PSPICE simulation of the generator is shown in this paper. The Marx generator uses a series circuit and charged by a ±50 kV high voltage DC source. A peaking part is utilized to steep the rise time of the output of Marx generator.