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A method for calculating the electric field gain at the edge of the plate of a capacitor section with different dielectric systems has been developed. The dependence of the gain on the heterogeneity coefficient of the working dielectric and on the distance from the edge of the capacitor plate is constructed. The boundaries of the region of “high heterogeneity” in the working dielectric of the high-voltage pulse capacitor section are determined.

The high-voltage pulse modulator based on the modern semiconductor elements is described. The modulator is intended for use in the power supply system of LINAC helium ions injector and has the ability to smoothly adjust the amplitude (110…150 kV) and the pulse duration (0.5…1 ms). The use of a pulse-to-peak stabilization scheme, made on the basis of a parametric stabilizer with parallel switching of the load, made it possible to increase the accelerated current at the accelerator output by 2 times.

A pulse transformer has advantages of compactness and long lifetime achievability, and is considered an important candidate for the development of high voltage pulse generators. In this paper, a fast rise time high voltage pulse transformer with a compact structure is studied numerically and experimentally. Specifically, the structure of the pulse transformer was designed with paralleled winding groups. The response and insulation characteristics of the pulse transformer are investigated numerically. After that, a fast rise time high voltage pulse transformer was built, and scaling experiments were performed to analyze the influence of the feed structure of the pulse transformer. Importantly, the pulse transformer was successfully used in a low impedance generator, and high voltage pulses with a peak voltage of about 260 kV, a pulse duration of 170 ns, and a rise time of 65 ns were achieved on a resistive load of 32 Ω. The ratio of the transformer is approximately 1:3. Experiments show reasonable agreement with the numerical analysis.

This paper deals with a high-voltage pulse power supply for a 1.5 MW klystron. The precision pulse power supply can guarantee stable output power and safety of klystron. The proposed hardtube type high voltage pulse power supply can produced pulses flat-top voltage −90 [kV], pulse width 1.7 [ms], 120 [Hz]. And using auxiliary system called DRC (DRoop Compensator) can improved pulse flatness. The validity of the pulse power supply for klystron has been verified by PSIM simulation and experiment.

Nowadays, compact and reliable electronic devices including up-to-date ceramic micro-electro-mechanical systems require thick-film resistors with significantly reduced dimensions and stable and precise resistance values. For that reason, instead of standard laser trimming method, high voltage pulse trimming of thick-film resistors is being introduced. This method allows controlled and reliable resistance adjustment regardless of resistor position or dimensions and without the presence of cuts. However, it causes irreversible structural changes in the pseudorandom network formed during sintering causing the changes in conducting mechanisms. In this paper results of the experimental investigation of high voltage pulse trimming of thick-film resistors are presented. Obtained results are analyzed and correlations between resistance and low-frequency noise changes and changes in conducting mechanisms in resistors due to high voltage pulse trimming are observed. Sources of measured fluctuations are identified and it is shown that this type of trimming is a valid alternative trimming method to the dominant laser trimming. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III44003 and III45007]

Dynamic degradation becomes a critical issue for thin-film transistors (TFTs) used in emerging new displays driven by high frequency gate voltage ${V}_{\text {G}}$ pulses. In this study, ${V}_{\text {G}}$ pulse rising edge dependent dynamic hot carrier degradation of poly-Si TFTs is investigated. It is demonstrated that rising edge of ${V}_{\text {G}}$ pulses which swing within the OFF-state of TFTs causes the degradation, while that of normal ${V}_{\text {G}}$ pulses which switch between the ON and OFF states across the flat band voltage ${V}_{\text {FB}}$ of TFTs does not. Based on transient TCAD simulation, the underlying mechanism of rising edge dependent degradation is proposed, which is based on the non-equilibrium PN junction degradation model previously proposed to explain ${V}_{\text {G}}$ pulse falling edge dependent degradation of poly-Si TFTs. Hence, the dynamic degradation model of poly-Si TFTs related to both rising and falling edge of the ${V}_{\text {G}}$ pulses can be unified now, which is applicable to fast gate pulses with steep rising and/or falling edges in sub- $\mu \text{s}$ level.

This paper proposes a new high-voltage pulse generator (PG) fed from a low-voltage DC supply Vs , which charges one arm of N series-connected full-bridge (FB) modular multilevel converter (MMC) sub-module (SM) capacitors sequentially, through a resistive-inductive branch. By utilising FB-SMs, the proposed PG is able to generate bipolar rectangular pulses of peak NVs and unipolar rectangular pulses of either polarity, at high repetition rates. Asymmetrical pulses are also possible. The proposed topology is assessed via simulation and scaled-down experimentation, which establish the viability of the topology for water treatment applications.

Pulsed electric field is a commonly used and effective disinfection method in drinking water treatment applications. In this paper, a transformerless unipolar/bipolar high-voltage pulse generator is presented with well-regulated pulsed output voltage for drinking water treatment via underwater pulsed corona discharge. The proposed high-voltage pulse generator is fed from a relatively low-voltage dc supply. Then, capacitor-diode voltage multiplier centrally fed from a dc-dc boost converter is used to elevate the input voltage to a proper high-voltage level. Finally, a modular multilevel converter is employed to chop the elevated voltage into unipolar or bipolar pulsed output voltage (based on the user selection). The suggested arrangement provides a high-voltage gain with relatively low-voltage components, i.e., neither high-voltage nor series-connected components are needed in the proposed approach. A comparison between the proposed approach and the other Marx-Based pulse generators has been held to show the merits of the proposed approach. A detailed design of the generator passive components and semiconductor devices has been presented. Simulation and experimental results are presented for the unipolar as well as the bipolar pulsed output to validate the proposed concept. This work was supported by a National Priorities Research Program (NPRP) from the Qatar National Research Fund under Grant NPRP 7-203-2-097. Scopus

Repetitive Pulsed Electric Field (PEF) is a common technique for disinfecting liquids. By applying adequate PEF across germ cell membranes, an irreversible electroporation process, and cell destruction can be achieved. The PEF can be generated by applying a repetitive pulsed voltage using a high-voltage pulse generator across the cell membrane. Unipolar and bipolar high-voltage pulse generators are commonly used. Bipolar pulse generators can be implemented by employing a unipolar generator with an H-bridge output stage. The main disadvantage of this method is that the switches of the H-bridge are rated at the output high-voltage level, i.e. series-stacked semiconductor devices should be employed with static and dynamic voltage sharing to implement high-voltage switches. In this paper, a half-bridge submodule-based bipolar modular high-voltage pulse-generator fed from a relatively low-voltage dc supply is proposed. In the proposed approach, relatively low-voltage Insulated Gate Bipolar Transistors (IGBTs) are required to generate the high-voltage bipolar pulses. A detailed illustration of the proposed concept is presented. Simulation results are used to assure the viability of the proposed concept. Finally, experimental results have been obtained from a low-voltage model of the proposed generator. This publication was made possible by NPRP grant NPRP (7-203-2-097) from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. Scopus

In the paper, the applicability of decomposition products of internal insulation of high-voltage pulse capacitors is considered (aging is the reason for decomposition products of internal insulation). Decomposition products of internal insulation of high-voltage pulse capacitors can be used to evaluate their quality when in operation and in service. There have been three generations of markers of aging of insulation as in the case with power transformers. The area of applicability of markers of aging of insulation for power transformers has been studied and the area can be extended to high-voltage pulse capacitors. The research reveals that there is a correlation between the components and quantities of markers of aging of the first generation (gaseous decomposition products of insulation) dissolved in insulating liquid and the remaining life of high-voltage pulse capacitors. The application of markers of aging to evaluate the remaining service life of high-voltage pulse capacitor is a promising direction of research, because the design of high-voltage pulse capacitors keeps stability of markers of aging of insulation in high-voltage pulse capacitors. It is necessary to continue gathering statistical data concerning development of markers of aging of the first generation. One should also carry out research aimed at estimation of the remaining life of capacitors using markers of the second and the third generation.

The revival of thick-film technology can be attributed to the increasing demand for thick-film resistors that are being used both as sensing and as resistive elements in various contemporary applications such as various types of micro-electromechanical system (MEMS) sensors based on low temperature co-fired ceramic (LTCC) technology. New stricter requirements that, among others, include precise resistance values and increasing use of buried components brought to the focus the high-voltage pulse trimming process that can provide precise and reliable resistance tuning. In order to improve understanding of experimental findings related to resistors trimmed using energy of high-voltage pulses, this article focuses on statistical approach to high-voltage pulse trimming of RuO2 and Bi2Ru2O7-based thick resistive films. The bimodal conductance distribution model is used in the analysis of trimming effects on the resistive film and in evaluation of low-frequency noise induced by the high-voltage pulse trimming process where conduction fluctuations noise is caused by fluctuations of two local conductances. Expressions for the total conductance and the relative voltage noise spectrum of thick resistive film are given and analyzed using experimental investigations.

We study the oscillation regimes for the model of a gyrotron with a fixed Gaussian longitudinal field structure and three modes of an equidistant spectrum (an operation mode and two satellites symmetrically spaced by frequency) during autonomous operation and under the action of an external monochromatic signal. The two-parameter (dimensionless current and the cyclotronresonance mismatch for an operating mode) plane is partitioned into the regions corresponding to various regimes. It is shown that the presence of a maximum at the leading edge of the voltage pulse can lead to excitation of the parasitic modes in the process of the power-source switch-on and to quenching of oscillation of the operating mode. These undesirable effects can be suppressed by locking the operation-mode frequency by an external monochromatic signal, which provides oscillation at the operation mode.

Square wave pulses have been identified as more lethal compared to exponential decay pulses in PEF applications. This is because of the on-time which is longer causes a formidable impact on the microorganisms in the food media. To have a reliable high-voltage pulse generator, a technique of capacitor discharge was employed. Four units of capacitor rated 100 μF 1.2 kV were connected in series to produce 25 μF 4.8 kV which were used to store the energy of approximately 200 J. The energy stored was discharged via HTS 181-01-C to the load in the range of nano to microseconds of pulse duration. The maximum voltage applied was limited to 4 kV because it is a lab-scale project. The electrical circuit diagram and the development procedure, as well as experimental results, are presented.

The high-voltage pulse power supply system has been built as a part of the transverse deflecting system TDS BC1 designed for electron beam diagnostics in the linear accelerator of the X-Ray Free Electron Laser XFEL. The TDS BC1 includes deflecting structure, solid-state modulator, RF generator with THALES TV2002DOD klystron and pulse transformer, the waveguide system and other engineering subsystems. The results of building and testing of the system are considered. The system was successfully tested on a test stand at DESY with the klystron in diode mode as a load at full design parameters: U=260 kV, I=265 A, τ=6 μs.

Neutron sources like European Spallation Source consist of linear proton accelerator and beam target. The linear accelerator is supplied by inductive output tubes (IOTs) or klystrons that require high-voltage DC supply (40 kV). This study describes the design and experimental evaluation of high-voltage dry-isolation pulse transformer design evaluation prototype for interleaved IOT supply modules. In order to withstand high-voltage stress, a modular secondary winding module with multistage voltage field equalisation are designed. Inter-winding connections are realised in the air as the separate winding outputs are routed together through common high-voltage isolators. The novelties of the current manuscript are new pulse transformer design and the experimental work. Experiments with full-scale prototype verified the advantages and revealed, also, some drawbacks of this construction. Proposed transformer design could be used not only in IOT or klystron power supplies but also in high-voltage DC/DC or AC/AC converters and power electronic transformers, used in the medium-voltage distribution grids.

The effect of gamma radiation on the reliable measurement of single voltage pulses of electron beam injectors into plasma during fusion experiments is considered in the manuscript. For this purpose, a 10 GHz fast voltage divider was constructed. The high-voltage capacitor was a gas condenser, and the low-voltage capacitor was a parallel connection of 10 mica capacitors. It turned out that the received radiation dose corrects the transmission ratio since it aligns the frequency characteristic of the mica in the area of spatial charge. This phenomenon has been explained from both a positive and a negative aspect with an effect on the concrete application. The need for further research on this problem was also pointed out to establish a saturation dose and thus obtain a constant frequency characteristic of the mica. The interest in the fast-divider behavior in the neutron field is also highlighted. © 2020 Informa UK Limited, trading as Taylor & Francis Group.

This paper presents results of the comparative study of laser and high-voltage pulse trimming of thick-film resistors from the aspect of their low-frequency noise properties. For experimental purposes, a series of 10 k Ω/sq thick-film resistors was realized and exhibited to these two trimming methods. Preformed measurements showed that, from the structural point of view, these two trimming methods have opposing effects on thick resistive films. These effects can be correlated to resistor low-frequency noise performances. This is of the great importance from the aspect of both formation and exploitation of thick resistive films.

A parameterized bipolar high-voltage pulse generator without H-bridge based on cascade of positive and negative Marx generators is proposed. In the proposed circuit topology, the positive and negative Marx generators are connected directly without any auxiliary circuits. Each stage of the Marx generators consists of a diode, a storage capacitor, two MOSFETs switches. A 1 kV DC power supply is employed to charge the storage capacitors of the two kinds of Marx generators. The control signals of switches generated by FPGA circuit according to the setting parameters of high-voltage pulses and loads are sent to high-voltage pulse circuit via optical fiber. There are two remarkable features in the developed prototype: (1) the ability to adjust all of the parameters of the high-voltage pulse, especially the variable rising and falling time, (2) the better match properties to different loads. The key parameters of the developed bipolar high-voltage generator show as following: adjustable rising/falling time 50–500 ns, pulse width of top flat 0–1 ms, repetition rate 10 kHz (at ±15 kV and 200 pF), overshoot/undershoot less than 5%, and amplitude 0 to ±15 kV. The shape of waveform can be the rectangle and/or triangle. All the pulse parameters can be programmed arbitrarily.

Cold atmospheric plasmas (CAPs) driven by high voltage pulse power supply have various advantages in various applications, such as high reactivity, easy ignition and energy saving, etc. Design specific high voltage pulse power supply powered by renewable energy like photovoltaic cells (PV) could further enhance the application potential of CAPs. Here, a high voltage pulse power supply directly driven by PV was designed and the main parameters of 500Hz to 5kHz frequency, lμs to 10μs pulse width and over 10kV amplitude were obtained in this investigation. We analyzed the design process of the topological structure, which was mainly composed of boost circuit, Marx generator and transformer. The design of the overall topology, the Marx generator, the circuit parameters selection and the auxiliary circuit for IGBT were introduced and discussed in detail. The high voltage pulse power supply was developed and tested with three typical CAPs sources. This designed power supply exhibited excellent working performance with stable output of CAPs load. Further optimization of the power supply was also discussed in the end.

International audience; This work presents an analysis of the full-bridge voltage inverter widely used to supply dielectric barrier discharges. The main contribution of this work is the deduction of the analytical equations for the delivered power, peak voltage and duration of the discharge as a function of the DC input voltage and of the switching frequency, but also, as a function of the parasitic elements of the transformer and the parameters of the DBD load. To date, these equations are not found in the literature and are useful to design a power converter complying with specifications derived from plasma process requirements. The state plane is used to understand the different sub-intervals taking place in an entire switching period. The equations are verified using a simple example of design, which implementation accurately obeys the sizing equations, and provide the expected performances.

Testing of DC solid state circuit breakers (SSCB) over the full set of operating points requires a source capable of supplying short-circuit fault currents at the rated voltage. As the voltage and current levels of DC SSCBs increase, procurement of DC sources and loads capable of the required voltage and fault currents for development testing becomes impractical. This paper introduces a test circuit that enables fault interruption testing of an SSCB by dynamically switching between a low voltage, high current source and a pulse capacitor source. The circuit supplies rated current to a shorted SSCB at low voltage, allowing it to reach thermal equilibrium. Then a capacitor bank dynamically switches into the SSCB on top of the rated current, briefly providing a pulse at rated voltage that the SSCB can attempt to interrupt. The proposed pulse test circuit is designed using analytical models and simulations. The test circuit is then constructed and experimentally validated by testing a prototype 12 kV, 2kA, DC SSCB.

The non-thermal plasma as Dielectric-Barrier Discharges (DBD) plasma is a promising high voltage technology applied in many industrial fields. However, the high cost of the high voltage pulse source used in DBD generation is an issue for the application of DBD-based technologies, especially in the field of environmental treatment. This research presents a low-cost, high voltage pulse source used the characteristic of Silicon Diodes for Alternating Current (SIDAC) accompanied with a high voltage multiplier and the self-termination characteristic of the dielectric barrier discharge (DBD) without external control. The pulse source is designed with a simple modular structure, which requires no control, eliminates transformers requirement, results in reduced dimensions, weight, and high scalability at a low cost. Furthermore, the power supply can be powered directly by the output of the solar panel, which could be a solution for low-cost green DBD plasma generation in an area without power grid connection.

This work focuses on the design, construction, and optimization of the configuration of a novel high voltage pulse power source for an efficient, large scale dielectric barrier discharge (DBD) generation. The pulses were generated by using the high speed switching characteristic of a very inexpensive device called Silicon Diodes for Alternating Current (SIDAC) and the self-terminated characteristic of DBD.

High voltage pulse transformers have an essential role in pulsed power systems and power conversion applications. Improving the electromagnetic behavior of such devices leads to better efficiency and low-level electromagnetic interference (EMI) noise propagation in systems. In this paper, a high voltage pulsed power system is considered and analyzed to improve the electromagnetic compatibility (EMC). The new generation of pulsed power systems that use SiC and GaN fast switches in capacitor charger power electronic circuit, face far more EMI challenges. Moreover, in this paper, the EMI propagation paths in the pulsed power system are realized and analyzed. The EMI noise level of the system is obtained and compared to the IEC61800-3 standard. To improve the EMC, the parasitic parameters of the transformer, as the main path of EMI circulation, are optimized to block the EMI propagation in the pulsed power system. For this aim, the parasitics are modeled and calculated with a novel and accurate energy distribution model. Then, by defining a cost function the geometry structure of the transformer is optimized to lower the parasitics in the system. Three pareto-optimal techniques are investigated for the cost function optimization. The models and results are verified by 3D-finite element method (FEM) and experimental results for several given scenarios. FEM and experimental verifications of this model, make the model suitable for any desirable design in any pulsed power systems. Finally, the EMI noise level of the system after optimization is shown and compared to the IEC61800-3 standard.

Pulse forming networks and Marx generators are the classical rectangular waveform pulse generators (PGs). They are inflexible and their capacitors must be fully charged to the required voltage from 0 V before delivering each high-voltage (HV) pulse. They are only able to generate unipolar pulses; if bipolar pulses are sought another generator fed from a negative supply voltage is added. Recently, several power electronics based PGs have been proposed. This study presents an HV power electronics based PG, which is based on half-bridge modular multilevel converter (MMC) sub-modules (SMs) charged sequentially in a voltage-boost mode. Each SM capacitor and main switch form a boost converter with the charging input supply and inductor. As a result, all SM capacitors are charged to a voltage greater than the input. During the discharging process, the SM capacitors are connected in series, producing a rectangular HV pulse across the load. The proposed charging method allows a reduction in the converter footprint in comparison with recently proposed MMC sequentially charged PG topologies. Although only rectangular pulse waveforms are sought in this study, an SM-capacitor voltage balance method allows multilevel pulse generation. The viability of the proposed converter is confirmed by MATLAB/Simulink simulation and scaled-down experimentation.

The electric circuit of a modulator at an output voltage up to 10 kV, allowing one to quickly, during a pause between pulses of about 2 ms, to change the pulse duration at a load of 10–30 μs is considered. For the possibility of increasing the pulse amplitude up to 60 kV using a pulsed transformer. At a pulse duration of more than 5 μs is most appropriate to use artificial forming lines based on discrete elements, capacitors and inductors, collected in the form of Γ-shaped LC chains. The pulse duration at the load is changed by changing the number of units of such chains forming a line, collected on a ladder diagram. “Soft” management switches, such as HiPakTM IGBT module switching thyristors, type 5SNA 0400J650100, voltage 6500 V, and a current 400 A, with the lowest possible internal resistance, are used. Computer simulation in the program allows one to optimize previously obtained results of calculation of the forming line assembled from l-shaped LC combinations for the specified load value of about 500 Ω. We performed model optimization of circuit elements and switches. The modeled parameters of components, from the point of view of obtaining a minimum cost and reliability while maintaining the specified electrical characteristics, are given. The EWB and Multisim software are best used.

Purpose. Experimentally determine the rational modes and energy efficiency of decontamination treatment of flowing food products using high-voltage impulse actions in comparison with traditional pasteurization. Methodology. We used pulse generation method with the help of a step-up transformer, high-voltage pulse capacitors and spark gaps with a system of peaking of pulse front to obtain high-voltage pulses in working chambers - the generator load. The pulses on the load were measured by a low-resistance resistive voltage divider, were transmitted over a broadband coaxial cable and recorded using an analog C8-12 oscilloscope or a Rigol DS1102E digital oscilloscope with a bandwidth of 100 MHz for each. The working chambers were filled with water, milk or milk whey and consisted of an annular hull made of PTFE and metal electrodes forming the bottom and the chamber cover having flat linings of food grade stainless steel for contact with the food product inside the chamber. Results. We obtained high-voltage pulses on the generator load with a base duration of 300 to 1200 ns at pulse repetition rates up to 500 pulses per second. We obtained experimentally the amplitude of the voltage pulses on the generator load up to 75 kV, and the electric field strength up to 35 kV/cm in working chambers with a gap of 22 mm and up to 50 kV/cm in working chambers with a gap of 15 mm. These characteristics of the pulses allowed complete and irreversible inactivation of microorganisms in food liquids in working chambers. Originality . We showed that there are modes of treatment food products with the help of high-voltage pulse actions, which allow better to preserve the biological and nutritional value of the products in comparison with heat treatment with their complete disinfection and at a significantly lower specific energy consumption. Practical value. The experimental regimes for treating milk, whey and water with reduced specific energy consumption open the prospect of industrial application of a complex of high-voltage pulse actions for the disinfecting treatment of water-containing food products.

One of the main problems faced by developers of modulators for spatial-harmonic magnetrons with cold secondary emission cathode is the selection of the correct shape of an anode voltage pulse that will ensure the stable operation of the magnetron. In this paper, the effect of the shape of the anode voltage pulse on the operation of transmitters based on magnetrons with cold secondary emission cathodes is investigated. The influence of different parts of the pulse on such parameters of the magnetron as the required current of the starting cathode necessary for stable excitation of secondary emission from the cold cathode, the stability of operation on the selected mode of oscillation, and the generation of the maximum power is experimentally studied. It is shown that the magnitude of the starting cathode current is determined, first of all, by the steepness of the pulse front. Its optimum value is usually about 150 kV/ms. In this case, starting cathode should provide a current of only a few tens of milliamperes, which can significantly increase the lifetime of the device. The article also shows that the presence of a pulse spike at the beginning of a voltage pulse facilitates a premature transition to a non-working mode of oscillation. As a result, this leads to a decrease in the output power of the magnetron. The duration of the decay determines the ability of the magnetron to operate at small pulse duration. For very short pulses, the energy expended on the microwave generation can be equal to the energy expended on the formation of the pulse decay. As a result, it was concluded that the usage of spatial-harmonic magnetrons with cold cathode requires a careful refinement of the characteristics of a pulse modulator. The steepness of the front of its output pulse should be about 150 kV/ms, and the pulse spike at the beginning of the voltage pulse should be as small as possible. When working on very short pulses it is necessary to provide a longer rate of pulse decay.

The current monitoring objectives in the discharge circuit of the pulse-current generator for the pulse-discharge technologies were analyzed. The designed control and current protection system of the 4-channel pulse-current generator performs the real time reaction on the appearance of the idle discharges and the short-circuit mode, stores the numbers of the nominal and idle discharges, and, during the short-circuit mode, blocks and turns off the generator. The system simulation and testing of the experimental prototype were successfully performed.

This work is devoted to describing of constructions and main characteristics of some types compact pulse generators with amplitude of voltage pulses up to 200 kV, rise-times about 10 ns and pulse energy per pulse up to 20 J. For reduction of rise-time of high-voltage pulses were used spark-discharge two electrodes commutators (sharpeners) at working pressures up to 100 atm.

A new design of high-voltage pulse generator which working at pulse repetition rates in diapason $1\div 10\ \text{kHz}$ is proposed. Pulse generator ensure maximal values of pulses $150\div 200\ \text{kV}$ with rise time about $20\div 40$ nanoseconds and storage energy per pulse up to $5\div 8\ \mathrm{J}$ . Such parameters were achieved by combination of two cascade Marx generator with low inductance pulse transformer. Application this pulse generator to excitation of super-atmospheric pressure CO2 laser demonstrated its reliability at the pulse repetition rates up to 5 kHz at total pressures of CO2:N2:He mixtures $1\div 5\ \text{atm}$ .

The unique biological effects stimulated by short pulsed electric field have many applications in tumor treatment, such as irreversible electroporation, electrochemotherapy, gene transfection and immune therapy. These biological effects require high voltage pulses with different pulse width in the range from nanoseconds to hundreds of microseconds. To fulfill this requirement, a compact high voltage pulse generator has been designed based on a switchable capacitor array and a SiC MOSFET switching array. The proposed pulse generator has one output channel with an adjustable pulse width from 100 ns to 100 &micro, s, an amplitude range from 0 kV to 2 kV, a repetition rate less than 1.2 kHz and a voltage drop less than 5%. The mechanism of the stacked switches circuit was investigated, in connection with a switchable capacitor array. The introduction of a switchable capacitor array extends the pulse width from nanosecond scale and microsecond scale compared with other similar design methods. The pulse generator has been designed in simulation and implemented in experiment. The developed pulse generator provides a convenient and economical tool for the further studies of the unique biological effects stimulated by different pulsed electric fields for tumor treatment.

High Voltage Pulse (HVP) comminution has the potential to be used in ore pre-concentration. Mineralisation after HVP breakage is concentrated into the finer sizes and size separation can then be used to produce high and low grade ore streams. Previous work on this technique has been performed using a single particle (SP) testing method where HVP energy is applied to every single particle. This paper presents an improved method where HVP is applied to multiple particles (MP). The MP method gives HVP the “freedom” to differentiate between particles and selectively only break those containing mineralisation. The MP method is shown to result in better mineralisation deportment into the finer sizes, at a lower specific energy, than the SP method of HVP application. This enables higher metal recovery and waste rejection rates during ore pre-concentration. HVP MP breakage consumes more energy but generates a better ore pre-concentration result than mechanical breakage. The ways to further enhance HVP selective breakage using the MP method are discussed.

This paper puts forward a repetitive high-voltage pulse modulator, consisting of a step-up pulse transformer to decrease the number of needed semiconductor switches, and a bipolar Marx generator to reduce the turns ratio of PT, leakage inductance, and distributed capacitance, and also to improve the pulse shape. An equivalent circuit of the proposed modulator considering parasitic elements is established. Based on the equivalent circuit, circuit operation is analyzed in detail. In order to verify the theory analysis and circuit operation, simulations are conducted. In addition, a laboratory prototype is implemented. The simulations and experimental results of resistive load and dielectric-barrier discharges load turn out matched quite well with the theory analysis, demonstrating that the prototype can operate with a voltage amplitude in the range of 0–25 kV, a repetition rate of 0.1–5-kHz stably.

With increasing restrictions of environmental regulations and safety concerns on the traditional poisonous coatings, it is highly desirable to develop a new green anti-biofouling method in marine environment. In this paper, graphene composite coating and carbon fiber (CF) composite coating connected with high voltage pulse electric field (HPEF) were developed to inhibit the attachment of diatoms. The polarizing microscopy showed that the attachment rates of Thalassiosira and Navicula reached the lowest levels which were 0.23 cells mm(-2) and 6.06 cells mm(-2) on the graphene composite coating, 0.38 cells mm(-2) and 4.17 cells mm(-2) on the CF composite coating, under the HPEF with 1 h duration, 23.15 kHz frequency, 0.5 duty cycle and 19 kV pulse amplitude. While the attachment rates of Thalassiosira and Navicula were 21.21 cells mm(-2) and 61.89 cells mm(-2) on the graphene composite coating, 22.75 cells mm(-2) and 62 cells mm(-2) on the CF composite coating, without HPEF. Scanning electron microscopy(SEM) revealed that HPEF disintegrated the diatom cells, which could underlie the considerable inhibition of the diatom attachment by the HPEF. Additionally, the hardness, flexibility and shock resistance tests indicated that graphene and CF could considerably increase the mechanical properties of epoxy resin coating. HPEF stimulation had no obvious effect on the mechanical properties of the composite coatings.

The self-assembly behavior of quaterrylene (QR) molecules on Ag(111) surfaces has been investigated by scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. It is found that the QR molecules are highly mobile on the Ag(111) surface at 78 K. No ordered assembled structure is formed on the surface with a sub-monolayer coverage up to 0.8 monolayer due to the intermolecular repulsive interactions, whereas ordered molecular structures are observed at one monolayer coverage. According to our DFT calculations, charge transfer occurs between the substrate and the adsorbed QR molecule. As a result, out-of-plane dipoles appear at the interface, which are ascribed to the repulsive dipole-dipole interactions between the QR molecules. Furthermore, due to the planar geometry, the QR molecules exhibit relatively low diffusion barriers on Ag(111). By applying a voltage pulse between the tunneling gap, immobilization and aggregation of QR molecules take place, resulting in the formation of a triangle-shaped trimer. Our work demonstrates the ability of manipulating intermolecular repulsive and attractive interactions at the single molecular level.

Research into feasibility of designing high-voltage pulse capacitors based on composite film dielectric systems is presented.

Repetitive high pulsed electric field (PEF) is an effective method to kill microorganisms and bacteria in water treatment applications. The PEF can be generated by applying high-power electromagnetic pulse across the sample to be treated. There are two main types of high-voltage pulse generators, namely, unipolar and bipolar. In this paper, a full-bridge submodule-based modular high-voltage pulse generator, having the ability to generate unipolar and bipolar high-voltage pulses with different shapes from a relatively low-voltage input dc supply, is proposed. In the proposed configuration, relatively low-voltage insulated gate bipolar transistors (IGBTs) are required to generate the high-voltage bipolar pulses. A thyristor rated at the level of the pulsed output voltage is required in the proposed configuration to bypass the load during the charging process of capacitors. In the proposed approach, a thyristor is used instead of the self-commutated high-voltage switch (e.g., series-connected IGBTs), as thyristors are available with high-voltage ratings and possess inherent reverse voltage blocking capability. A detailed illustration of the proposed configuration and its operational concept are introduced in this paper. Simulation and experimental results are presented to validate the proposed approach.

This paper presents a generic hybrid optimization methodology based on space mapping techniques for the design of various high voltage pulse transformer structures used in klystron modulators. It is using two dimensioning models with different levels of complexity: a coarse model based on 2D FEA less accurate but cheaper to evaluate and a fine 3D FEA model more accurate but time consuming. A specific correction mechanism is applied to align the 2D FEA dimensioning model with the more accurate 3D FEA dimensioning model. With a suitable selection of the correction factors, the convergence of this hybrid optimal design methodology is obtained with a limited number of time consuming 3D FEA simulations. The method is applied to the optimal design of a monolithic high voltage pulse transformer for the CLIC klystron modulator. The influence of the klystron operating voltage on the size of the optimal pulse transformer is evaluated with the proposed design methodology.

In order to generate bipolar high-voltage (HV) pulses across certain load from HV dc (HVdc) power supply, a voltage source inverter (VSI) stage should be inserted between the load and the supply. In order to meet the required HV level, series connection of semiconductor devices should be employed with dynamic voltage sharing between the involved devices. Modular multilevel converter (MMC) can be used instead of the conventional two-level VSI to alleviate the complexity introduced by the deployment of series-connected devices. The voltage level of the HVdc power supply and the voltage rating of the available semiconductor devices determine the suitable number of MMC voltage levels ( N ). Capacitor voltage balancing is a vital issue for proper operation of the MMC. In general, conventional sensor-based balancing techniques require a significant amount of measurements, which increases the complexity of the system. In addition, the high dv/dt during switching times causes electromagnetic interference, which may adversely affect the accuracy of the measurements. In this paper, a sensorless voltage balancing technique is proposed for the MMC-based bipolar HV pulse generator that reduces the system sensitivity, cost, and complexity. A detailed illustration of the proposed approach is presented in this paper. The simulation and experimental results are used to validate the proposed concept. 1973-2012 IEEE. Scopus

High-voltage pulse-generators can be used effectively for bacterial decontamination in water treatment applications. Applying a pulsed electric field to the infected water sample guarantees killing of harmful germs and bacteria. In this paper, a modular high-voltage pulse-generator with sequential charging is proposed for water treatment via underwater pulsed streamer corona discharge. The proposed generator consists of series-connected modules similar to an arm of a modular multilevel converter. The modules' capacitors are charged sequentially from a relatively low-voltage dc supply, then they are connected in series and discharged into the load. Two configurations are proposed in this paper, one for low repetitive pulse rate applications, and the other for high repetitive pulse rates. In the first topology, the equivalent resistance of the infected water sample is used as a charging resistance for the generator's capacitors during the charging process. While in the second topology, the water resistance is bypassed during the charging process, and an external charging resistance with proper value is used instead. In this paper, detailed designs for the proposed pulse-generators are presented and validated by simulation results using MATLAB. A scaled down experimental setup has been built to show the viability of the proposed concept. Scopus