High-voltage Pulse Generator Research Articles

A high voltage pulse generator based on silicon-controlled rectifier for field-reversed configuration experiment.

A high voltage pulse generator based on a silicon-controlled rectifier has been designed and implemented for a field reversed configuration experiment. A critical damping circuit is used in the generator to produce the desired pulse waveform. Depending on the load, the rise time of the output trigger signal can be less than 1 μs, and the peak amplitudes of trigger voltage and current are up to 8 kV and 85 A in a single output. The output voltage can be easily adjusted by changing the voltage on a capacitor of the generator. In addition, the generator integrates an electrically floating heater circuit so it is capable of triggering either pseudosparks (TDI-type hydrogen thyratron) or ignitrons. Details of the circuits and their implementation are described in the paper. The trigger generator has successfully controlled the discharging sequence of the pulsed power supply for a field reversed configuration experiment.

Study of Pulsed Atmospheric Discharge Using Solid-State LTD

Pulsed atmospheric discharge has been studied by using a pulsed high-voltage generator based on linear transformer driver (LTD) scheme. Taking advantage of the output flexibility of the LTD, we have studied gas discharge behavior by applying two consecutive pulses to a coaxial discharge load consisting of a wire and a pipe. The experimental results have shown that the discharge current of the second pulse is always lower than that of the first pulse for the same voltage amplitude, when the two pulses are too close to each other ( $\mu {s}$ ). An explanation for this phenomenon has been explored by using a model that considers the effect of residual charge left by the first pulse. The findings obtained by this paper will help us understand the fundamental characteristics of pulsed atmospheric discharge.

A Unipolar/Bipolar High-Voltage Pulse Generator Based on Positive and Negative Buck–Boost DC–DC Converters Operating in Discontinuous Conduction Mode

This paper presents a new high-voltage pulse generator, which is based on positive and negative buck-boost (BB) converters fed from a relatively low voltage dc supply. The proposed generator is able to generate unipolar or bipolar high-voltage pulses via operating the BB converters with series or parallel connected outputs respectively using a common input dc source. The components of each converter are rated at half of the pulsed voltage magnitude in the unipolar mode. The converters in the proposed pulse generator operate in discontinuous conduction mode. This enhances system efficiency, as the circuit only operates when it is desired to generate a pulsed output voltage, otherwise the circuit is switched to idle mode with zero current. Detailed illustration of the proposed approach is presented along with a full design of the system components for given output pulse specifications. Finally, simulation and experimental results are presented to validate the proposed concept.

A Transformerless Bipolar/Unipolar High-Voltage Pulse Generator With Low-Voltage Components 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.

A High-Voltage Pulse Generator With Continuously Variable Pulsewidth Based on a Modified PFN

The amount of stored energy is an important issue in the low-droop and high-precision pulse generation. Pulse forming network (PFN) simulating an open-ended transmission line seems to be useful due to its minimum stored energy. The drawbacks of the PFN include low-output pulse quality and constant pulsewidth, which limit their applications. Another limitation of generating rectangular pulses using PFN is that half of the charged voltage appears in the output when delivering the entire stored energy to the matched load. This paper proposes a structure of PFN-based pulse generator that overcomes the above-mentioned limitations. For continuous pulsewidth adjustment, a lossless scheme is presented. By increasing the ratio of the load magnitude to the characteristic impedance, the amplitude of the output pulse voltage would be approximately equal to that of the charged voltage. Therefore, the semiconductor switches can be utilized in the PFN pulse generator easily. In addition, the pulse quality is enhanced and faster rising time is obtained in comparison with the conventional PFNs. In this proposal, the stored energy quantity is limited to three times the energy needed for the output pulse in the case of $R_{L}=10Z_{0}$ . To verify the proposed structure, a prototype is simulated using PSPICE software, and the experimental results are presented.

A generator of high-power nanosecond pulses based on a modular two-level summator

A modular approach to designing generators of high-power high-voltage nanosecond pulses on the basis of a two-level wave summator and transistor formers of partial pulses is considered. The design and parameters of the modules that are oriented at the development of generators of voltage pulses of up to 300 kV at a current of up to 4 kA are described. The capabilities of these modules are demonstrated based on the example of a pulse generator with a power of 10 MW, a varied pulse duration of 50–150 ns, and a pulse repetition rate of up to 2 kHz.

An accelerating voltage generator for compact pulsed neutron sources

A multistage generator of high-voltage pulses with a scroll geometry of spark switches, which is produced according to the Marx scheme, is presented. The device is designed for a small pulsed neutron source and makes it possible to obtain accelerating-voltage pulses with amplitudes of up to 450 kV at a stored energy of up to 50 J and a load current of up to 1.5 kA.

A Boost-Inverter-Based Bipolar High-Voltage Pulse Generator

Bipolar repetitive high-voltage pulse generators are commonly used in modern pulsed power applications. Conventionally, bipolar high-voltage pulses can be generated by adding a high-voltage H-bridge at the output stage of a unipolar high-voltage pulse generator which increases complexity and cost of the bipolar high-voltage pulse generator. In this paper, a boost-inverter-based bipolar high-voltage pulse generator with high-voltage gain is proposed. The proposed generator can provide high-voltage bipolar output pulses with the desired specifications from a low input dc voltage. The proposed generator is based on employing two bidirectional boost dc-dc converters, where the load is connected differentially between the boost converters' output terminals. In the proposed approach, four controlled switches are required. Only two out of these four switches are rated at the high-voltage output level which affects positively the system cost. A detailed illustration of the proposed approach along with the design of its passive components is presented in this study. Simulation and experimental results are used to validate the proposed approach.

Gyromagnetic nonlinear transmission line generator of high voltage pulses modulated at 4 GHz frequency with 1000 Hz pulse repetition rate

Results of testing of a generator based on a solid-state drive and the parallel gyromagnetic nonlinear transmission lines with external bias are presented. Stable rf-modulated high-voltage nanosecond pulses were shaped in each of the four channels in 1 s packets with 1000 Hz repetition frequencies. Pulse amplitude reaches -175 kV, at a modulation depth of rf-oscillations to 50 % and the effective frequency ∼4 GHz.

Energy compression of nanosecond high-voltage pulses based on two-stage hybrid scheme.

Test results of high-voltage subnanosecond pulse generator with a hybrid, two-stage energy compression scheme are presented. After the first compression section with a gas discharger, a ferrite-filled gyromagnetic nonlinear transmitting line is used. The offered technical solution makes it possible to increase the voltage pulse amplitude from -185 kV to -325 kV, with a 2-ns pulse rise time minimized down to ∼180 ps. For the small output voltage amplitude of -240 kV, the shortest pulse front of ∼85 ps was obtained. The generator with maximum amplitude was utilized to form an ultra-short flow of runaway electrons in air-filled discharge gap with particles' energy approaching to 700 keV.

High-intensity pulsed beam source with tunable operation mode

The report presents the design of an electron and an ion pulsed accelerator. The powerful high-voltage pulse generator of the accelerator and the vacuum bushing insulator is able to change the polarity of the output voltage. The low-inductance matching transformer provides an increase in the DFL output impedance by 4 times. The generator based on a high voltage pulse transformer and a pseudo spark switch is applied for DFL charging. The high-impedance magnetically insulated focusing diode with Br magnetic field and the “passive” anode was used to realize the ion beam generation mode. The plasma is formed on the surface of the anode caused by an electrical breakdown at the voltage edge pulse; as a result, the carbon ion and proton beam is generated. This beam has the following parameters: the current density is about 400 A/cm2 (in focus): the applied voltage is up to 450 kV. The accelerator is designed for the research on the interaction of the charged particle pulsed beams with materials and for the development of technological processes of a material modification.

Design and testing of fluid resistor for repetitive high-voltage pulse generator

The paper presents a design and the results of testing of the liquid resistive load for a repetitive high-voltage generator (200 kV, 0.5 ms). The load uses a sealed dielectric case, which is to be placed into a vacuum volume (5×10-4 Torr) for electrical strength ensuring. Repetitive testing of the generator with the load (10 pps) caused the electrolyte heating, the load resistance decreasing, and the changing of a generator mode. An expansion tank is used to compensate thermal expansion of the electrolyte, which makes it possible to absorb up to 1 MJ of energy in the load without seals breaking. A generator load curve can be obtained for one experiment with a help of the fluid load without any additional depressurization of the vacuum volume.

Development of compact nanosecond pulsed X-ray source

AbstractA compact nanosecond pulsed X-ray source is described. The X-ray source consists of two important subassemblies: a high-voltage pulse generator and an X-ray diode. The high-voltage pulse generator is designed based on the principle of triple resonance circuit producing a high-voltage pulse across the X-ray diode with amplitude of up to 500 kV. The X-ray diode is a sealed transmission target X-ray tube. Its cathode is comb structure formed from thin tungsten sheets with thickness 50 µm, while its target is made of 100 µm titanium film. The X-ray dose at a distance of 20 cm from the diode is 20 mR per pulse, while the diode voltage is 512 kV. In the case, the full-width at half-maximum of the X-ray pulse is ~5 ns.

An all-solid-state microsecond-range quasi-square pulse generator based on fractional-turn ratio saturable pulse transformer and anti-resonance network.

High voltage pulse generators are widely applied in a number of fields. Defense and industrial applications stimulated intense interests in the area of pulsed power technology towards the system with high power, high repetition rate, solid state characteristics, and compact structure. An all-solid-state microsecond-range quasi-square pulse generator based on a fractional-turn ratio saturable pulse transformer and anti-resonance network is proposed in this paper. This generator consists of a charging system, a step-up system, and a modulating system. In this generator, the fractional-turn ratio saturable pulse transformer is the key component since it acts as a step-up transformer and a main switch during the working process. Demonstrative experiments show that if the primary storage capacitors are charged to 400 V, a quasi-square pulse with amplitude of about 29 kV can be achieved on a 3500 Ω resistive load, as well as the pulse duration (full width at half maximum) of about 1.3 μs. Preliminary repetition rate experiments are also carried out, which indicate that this pulse generator could work stably with the repetition rates of 30 Hz and 50 Hz. It can be concluded that this kind of all-solid-state microsecond-range quasi-square pulse generator can not only lower both the operating voltage of the primary windings and the saturable inductance of the secondary windings, thus ideally realizing the magnetic switch function of the fractional-turn ratio saturable pulse transformer, but also achieve a quasi-square pulse with high quality and fixed flat top after the modulation of a two-section anti-resonance network. This generator can be applied in areas of large power microwave sources, sterilization, disinfection, and wastewater treatment.

A New Modular Bipolar High-Voltage Pulse Generator

Adapting power-electronic converters that are used in pulsed-power application attracted considerable attention during recent years. In this paper, a modular bipolar high-voltage pulse generator is proposed based on the voltage multipliers and half-bridge converters concept by using power electronics switches. This circuit is capable to generate repetitive high voltage bipolar pulses with a flexible output pattern, by using low voltage power supply and elements. The proposed topology was simulated in MATLAB/Simulink. To verify the circuit operation a four-stage laboratory prototype has been assembled and tested. The results confirm the theoretical analysis and show the validity of the converter scheme.

Resistance of Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 under high voltage microsecond pulse induced breakdown

Ferroelectric ceramics have been widely used in lots of fields, such as mechanical-electric transducer, ferroelectric memory, and energy storage devices. The dielectric breakdown process of ferroelectric ceramic has received much attention for years, due to the fact that this issue is critical in many electrical applications. Though great efforts have been made, the mechanism of dielectric breakdown is still under debate. The reason is that the electrical breakdown is a complex process related to electrical, thermal, and light effects. In the present work, we investigate the breakdown process of Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3(PZT95/5) ceramic, which is a kind of typical ferroelectric ceramic working in the high voltage environments. The high voltage pulse generator is used in the breakdown experiments to apply a square pulsed voltage with an amplitude of 10 kV and a width of 7 s. The resistivity change in the breakdown process is recorded by the high-frequency oscillograph in nano-second. The results show that there are two different breakdown types for our sample, i.e. body-breakdown and flashover. To better understand the breakdown mechanism of the PZT95/5 ceramic, the formation of the conductive channel in ceramic in the process is investigated by comparing the resistivity development in body-breakdown and flashover processes. The development of the conductive channel formation can be divided into three steps in body-breakdown. In the first step that lasts for the first 40 ns of breakdown, the conductive channel starts forming, with the equivalent resistance sharply decreasing to about 105 in the mean time. Then, i.e. in the second step, conductive path grows into a stable one with the equivalent resistance decreasing to the magneitude of about 102 . The resistance decreases slowly to about 130 in the third step, which means that the conductive channel is completely formed. The channel formation of flashover can also be divided into three steps. The first step is similar to that of body-breakdown, with the equivalent resistance decreasing to about 105 in about 40 ns. In the second step of flashover, the conductive path keeps growing into a stable one with the equivalent resistance decreasing to 102 , but with a different resistance changing rate from that in body-breakdown, and the resistance decreases slowly to about 20 in the end. Different behavior between the body-breakdown and the surface flashover can be explained by different carrier densities on the conductive paths in the two breakdown processes. In the body-breakdown, the carrier density in the conductive channel is higher than that in the surface flashover, which improves the electron transfer and reduces the resistance. This may explain the reason why the channel formation in body-breakdown is faster than in flashover. This study is helpful for further materials design and applications.

A Full-Bridge Submodule-Based Modular Unipolar/Bipolar High-Voltage Pulse Generator With Sequential Charging of Capacitors

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.

高電圧刺激による原木栽培ナメコの収量増加におけるパルス幅の影響と投与エネルギー依存性

Effect of electrical stimulation on yield of Pholiota microspora in log cultivation was investigated experimentally. The pulsed voltage was generated by two types of high-voltage pulsed power generator, based on Cockcroft-Walton circuit and Marx generator in order to evaluate an influence of the applied voltage pulse width. The input energy was controlled by number of the pulsed voltage applying. The pulsed voltage was applied to the cultivation log before harvest of first flush. The fruit body yield was evaluated by total weight harvested during two harvest seasons. The experimental results showed that the fruit body yield increased to be 1.5-3.0 times higher by applying pulse voltage. The fruit body yield in the second season also increased by pulse voltage applying at former harvest season. This result indicates that the pulse high-voltage stimulation affect the yield at not only same harvest season but also next harvest season. The yield increment is mainly determined by input energy into cultivation log.

Output voltage adjustment of a pulsed high-voltage nanosecond generator with inductive energy storage and a solid-state switching system

The possibility of adjusting the output voltage of a high-voltage nanosecond pulse generator with inductive energy storage and a solid-state switching system was investigated. All components of the adjustment system are installed in the low-voltage input circuit of the generator, whose voltage was less than 1000 V. The smooth adjustment of the output voltage in the range of 70–115 kV was achieved. The experimental setup and the obtained results are described.

Conceptual study of a Bipolar modular high voltage Pulse generator with sequential charging

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.