Pulse Forming Network Research Articles

Study on a rotational symmetry structure pulse forming network with low-impedance for compact pulse drivers.

A pulse forming network (PFN) is a significant component, contributing a lot to the overall dimension of pulse generators. In order to both reduce the size of PFN and improve the output waveform quality, this paper proposes a compact low-impedance PFN with a rotational symmetry structure. The PFN consists of four groups of Blumlein pulse forming units (PFUs) connected in parallel along the angular direction, and the spline curve structure is applied in each PFU, which achieves a higher space utilization rate. The theoretical maximum energy density of PFN is 6.6 J/L as the dimensions of PFN are φ500 × 138mm. Field-circuit co-simulation is carried out based on the spatial model of PFN and the double switch modulation circuit to analyze the effects of switch delay time (time between main switch and steep discharge switch), as well as the output port position affecting the output pulse waveform. The results show that the PFN is appropriate to achieve quasi-square wave pulse modulation as the switch delay time is 290ns with the output port positioned at the periphery. The verification experiments are also carried out. The results show that the PFN can generate a quasi-square wave pulse with an output voltage of 49.6kV, a pulse width of 83ns, and a peak power of 1 GW on a matched load. The output pulse exhibits a distinct flat top, with the fluctuation of the plateau being less than 3%.

Dynamic characteristics of a coaxial magnetic switch modulating pulse forming networks.

Pulsed power generators utilizing magnetic switch technology within the 100ns scale have become widespread for surface treatment, high power microwave generation, and food processing, in which the dynamic characteristics of the magnetic switch perform an important function. The saturation process, electric field between layers, and energy loss are closely associated with the applied time scale of the magnetic core, which affects the dynamic characteristics of the switch. However, compared with the study within the microsecond scale, the dynamic characteristics of magnetic switches within the 100ns scale have not been studied in depth. In this paper, the dynamic characteristics of a coaxial magnetic switch modulating pulse forming networks (PFNs) are studied via both field-loop co-simulation and scaled experimental test. It is found that increasing PFN section number (Ns) leads to an acceleration in the saturation process of the core, which helps understand the switch performance of the magnetic core more clearly. With respect to a specific magnetic switch based on a ferromagnetic core, it is quantitatively analyzed that increasing Ns from 1 to 10 leads to a 16.1% reduction in core saturation time (tsat), a 13.4% increase in eddy loss (EET), and a 5.7% rise in maximum interlamination field strength (Emax) under the 100ns scale; however, tsat is reduced by 19.3%, EET increases by 5.2%, and Emax rises by 2.3% under the microsecond scale. The results could provide a design reference for magnetic switches in pulsed power generators.

Design and Test of a Klystron Intra-Pulse Phase Feedback System for Electron Linear Accelerators

Beam stability and timing jitter in modern linear accelerators are becoming increasingly important. In particular, if a magnetic or radio-frequency (RF) compression regime is employed, the beam time of arrival jitter at the end of the linac can be strictly correlated with the phase noise of the accelerating fields of the RF structure working off-crest. For this reason, since 2008, an RF fast-feedback technique, which acts within each RF pulse, has been successfully employed at LNF-INFN (Laboratori Nazionali di Frascati dell’Istituto Nazionale di Fisica Nucleare) in the SPARC_LAB (Sources for Plasma Accelerators and Radiation Compton with Laser And Beam) facility on S-band (2856 MHz) klystrons powered by pulse-forming network (PFN) modulators, as reported in this paper. However, in order to meet the more stringent requirements of plasma wakefield acceleration schemes, some upgrades to this feedback system have been recently carried out. The first prototype has been experimentally tested on a C-band (5712 MHz) klystron, driven by a solid-state modulator, in order to investigate the possibility for additional improvement resulting from the inherently more stable power source. In this paper, the design, realization and the preliminary measurement results obtained at SPARC_LAB after such upgrades will be reviewed.

Challenges in Measurement of Low-Value ESL and ESR of High-Performance PFN Capacitors for Klystron Modulator

In the high voltage line type pulse modulators, Pulse Forming Network (PFN) capacitors are one of the important components. These capacitors operate at peak kilo ampere current range and at repetition rate in the range of a few hundred hertz. The performance of these capacitors is critical w.r.t. overall system performance, and they are required to operate at high power density and low losses with high reliability. The Equivalent Series Inductance (ESL) and Equivalent Series Resistance (ESR) are two critical parameters that affect the performance of these capacitors. PFN modulator demands a capacitor of very low ESL and ESR for reliable operation and generation of high-voltage pulses. Higher ESR value adversely affects the performance of the capacitor by raising its temperature and thus deteriorating its life. ESL value does not directly affect life, but it affects the quality of high voltage pulse. In RRCAT, the PFN capacitors purchased from Indian manufacturers were showing high-temperature rise and failures. Therefore, new capacitors were designed to have lower ESL and ESR values. Measurement of ESL and ESR is important to evaluate the performance of the capacitors. The low value of these parameters makes their measurement a challenging task and requires special techniques. For low values of ESL and ESR (less than 100 mΩ) measurement, a differential measurement technique was used in which modification and different layouts were explored to improve the repetitive accuracy of the measurements. The differential ESR and ESL measurement techniques with more emphasis on the low-value ESR measurement will be discussed in the paper.

Beam control system and output fine-tuning for safe and precise delivery of FLASH radiotherapy at a clinical linear accelerator.

We have previously adapted a clinical linear accelerator (Elekta Precise, Elekta AB) for ultra-high dose rate (UHDR) electron delivery. To enhance reliability in future clinical FLASH radiotherapy trials, the aim of this study was to introduce and evaluate an upgraded beam control system and beam tuning process for safe and precise UHDR delivery. The beam control system is designed to interrupt the beam based on 1) a preset number of monitor units (MUs) measured by a monitor detector, 2) a preset number of pulses measured by a pulse-counting diode, or 3) a preset delivery time. For UHDR delivery, an optocoupler facilitates external control of the accelerator's thyratron trigger pulses. A beam tuning process was established to maximize the output. We assessed the stability of the delivery, and the independent interruption capabilities of the three systems (monitor detector, pulse counter, and timer). Additionally, we explored a novel approach to enhance dosimetric precision in the delivery by synchronizing the trigger pulse with the charging cycle of the pulse forming network (PFN). Improved beam tuning of gun current and magnetron frequency resulted in average dose rates at the dose maximum at isocenter distance of >160 Gy/s or >200 Gy/s, with or without an external monitor chamber in the beam path, respectively. The delivery showed a good repeatability (standard deviation (SD) in total film dose of 2.2%) and reproducibility (SD in film dose of 2.6%). The estimated variation in DPP resulted in an SD of 1.7%. The output in the initial pulse depended on the PFN delay time. Over the course of 50 measurements employing PFN synchronization, the absolute percentage error between the delivered number of MUs calculated by the monitor detector and the preset MUs was 0.8 ± 0.6% (mean ± SD). We present an upgraded beam control system and beam tuning process for safe and stable UHDR electron delivery of hundreds of Gy/s at isocenter distance at a clinical linac. The system can interrupt the beam based on monitor units and utilize PFN synchronization for improved dosimetric precision in the dose delivery, representing an important advancement toward reliable clinical FLASH trials.

Research on the influence of gas ionization on pulse forming in linear transformer driver (LTD) electron beam generator

Currently, there is limited research on the influence of gas ionization on the pulse formation process in pulse power source-driven loads. This paper introduces a road-field-Particle-In-Cell (PIC)/Monte Carlo Collision (MCC) collaborative simulation method that can accurately simulate gas ionization in Linear Transformer Driver (LTD) electron beam generation (EBG). The method couples the electromagnetic field and charged particle simulated through PIC/MCC with the circuit modules, and the load's voltammetry characteristics can real-time feedback to the Blumlein Pulse Forming Network (BPFN) of the LTD. In contrast to prior simulations that used fitted ideal T-shaped pulse input waveforms to model the load, this method provides a clearer depiction of the influence of gas ionization on the pulse shape. Additionally, the paper conducts simulation studies on LTD electron beam generator operating at different argon gas pressures. The findings indicate that introducing gas can effectively increase current while reducing voltage amplitude, thereby lowering the diode impedance. A small amount of gas can slightly enhance peak power, but excessive gas diminishes peak power and significantly shortens voltage pulse width. This is attributed to the beneficial effect of a small amount of gas ionization-produced plasma on the device. However, an excessive amount of gas ionization-generated plasma can lead to impedance mismatch in the device, even resulting in a load short circuit. This phenomenon causes a decrease in pressure drop at the top, consequently shortening the pulse width.

A repetitive frequency square wave generator based on Blumlein pulse forming network and pseudospark switch.

The Blumlein pulse forming network (PFN) has widely beenused in pulsed power technology to generate square waves with short pulse widths. In this paper, we developed a repetitive frequency square wave generator based on Blumlein PFN and pseudospark switch (PSS). A Blumlein PFN with unequal capacitances has been proposed, and the PFN parameters have been optimized for better output waveforms. A single-gap PSS with a withstand voltage of 40kV and a repetitive frequency of 100Hz has been designed to switch the Blumlein PFN. The experiment results show that the square wave generator can output pulses with a voltage of 26kV, a rise time of 25ns, and a pulse width of 90ns on a matched load of 11Ω. It has operated steadily for 10h with a repetitive frequency of 100Hz, and the jitter remains at around 1ns after 1.05 × 106 shots.

New SiC Kicker Power Supply for J-PARC

A new kicker power supply using silicon carbide metal–oxide semiconductor field-effect transistors (SiC-MOSFETs) is under development at the Japan Proton Accelerator Research Complex (J-PARC). SiC-MOSFETs fabricate compact high-speed pulse power supplies to replace the thyratron switch power supply. The base circuit of the new power supply uses the linear transformer driver (LTD) system, and the semi-conductor module circuit comprises a radial symmetry type that achieves low noise. The three main components of the current kicker power supply, i.e., the thyratron, pulse-forming network (PFN) circuit, and end clipper, can be assembled on a single board as the new module circuit board. The new power supply contains a 1.25 kV/2 kA main board that forms a trapezoidal pulse and a 0.1 kV/2 kA correction board, compensating for the flat section droop. The 32 main boards and 20 correction boards are hierarchically connected in series to achieve the waveform specifications required for the J-PARC rapid cycling synchrotron (RCS) kicker power supply: output voltage of 40 kV, output current of 2 kA, and pulse width of 1.2 μs. Furthermore, a 25 % power saving has been confirmed and an insulating cylinder for the conductor has been developed to suppress corona discharge and withstand continuous operation for a long time.

A Novel Strategy for Enhancing Performance of Rectangular Pulse Generators: Simulation and Optimization of Blumlein Pulse Forming Networks

A Novel Strategy for Enhancing Performance of Rectangular Pulse Generators: Simulation and Optimization of Blumlein Pulse Forming Networks

Analysis and Design of a Pulsed Power Generator for a Low-Energy Magnetic Pulse Welding System

Magnetic pulse welding (MPW) is a joining method that uses Lorentz force generated from an electromagnetic field. This method not only has the advantage of not causing thermal deformation of the material and no by-products compared to the method of joining by melting by heat but also enables the joining of dissimilar metals rather than the joining of the same metal. Joining dissimilar metals can reduce the weight of mechanical devices and apply them to various fields. Recent research on MPW has focused on the characteristics of bonding according to the material or structure of metal rather than on pulse power research that generates the main factor of operation. However, in the operation of MPW, a Lorentz force is generated by the induced current caused by the electromotive force created in the flyer tube and the external magnetic field in the actuator. Therefore, it is necessary to analyze and optimize the pulse power to improve reliability and to miniaturize the system to expand the MPW utilization range. In this paper, we analyzed MPW operation according to a section of the pulse power output waveform. A condition for obtaining the maximum current in the flyer tube was proposed, and a plateau-shaped waveform was derived as an ideal output waveform capable of maintaining the Lorentz force. Through analysis, the proposed pulse power device is designed as a pulse-forming network (PFN) that generates a plateau output waveform. The design specification is that the circuit of PFN (type E) is designed so that the output waveform is pulse width 10 (μs) and the maximum output current is 100 (kA), and it is verified by simulation.

Interface instability of the thermal plasma jet

This work is first focused to experimentally study the interface instability and expansion mechanism of thermal plasma jet and provide a better understanding of the complex fluid-dynamic interactions occurring on the surface of the plasma bubble due to the Kelvin–Helmholtz effect. The experimental techniques used include a plasma generator, a pulse-forming network based on the capacitive energy storage, pressure measurement system along the capillary tube, and high-speed camera system to trace the development processes of the plasma interface. Results indicate that the plasmas jet has a better advantage of radial expansion with a high light at the beginning. However, the axial expansion velocity is larger than the radial one with time going on; thus, a torch-shaped jet body occurs under the Rayleigh–Taylor effect and can be divided into two parts including a plasma head and tail. With a dissipation of the initial energy and turbulent mixing between the plasmas and the gas, the jet boundary is broken and even the local rupture phenomena occur on the plasma jet surface. The turbulent dissipation is also very violent when the discharge voltage increases to 3000 V; thus, the turbulent mixing layer between the plasma jet and the gas is quite thicker and the plasma jet boundary is also fuzzy resulting in that the fold surfaces with much larger degree exist earlier. These experimental phenomena are also explained further from the mechanism by deriving the momentum equations of the interface of the plasma jet into the gas. Finally, a fitting formula of the surface area as an important factor in the expansion process of the plasma is obtained to analyze the interface characteristic of the plasma jet.

A Compact Gigawatt Pulsed Power Generator for High-Power Microwave Application

Nanosecond square voltage pulse is of wide interest because of its potential military and industrial applications, such as high-power microwave (HPM). In this article, a gigawatt pulsed power generator (PPG) for HPM based on the multistage pulse forming networks (PFNs) with a voltage superposition using the Marx scheme, i.e., PFN-Marx generator, is proposed through the theory analysis, numerical simulation, processing manufacturing, and performance experiment. The PPG consists of the main subsystems of the primary power and pulse modulation subsystems. The primary power subsystem is a modular bipolar dc high-voltage generator based on the ac–dc–ac, high-frequency transformer, and voltage multipliers by using the power electronics switches. It can generate bipolar dc high voltage of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm$</tex-math> </inline-formula> 42 kV to charge the PFN-Marx generator. As for the pulse modulation subsystem, the PFN-Marx technique is preferred, which consists of 24-stage and six <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{L}$</tex-math> </inline-formula> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{C}$</tex-math> </inline-formula> sections. To verify the PPG, an experimental prototype is fabricated and tested. It has a characteristic impedance of about 40 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol\Omega$</tex-math> </inline-formula> and can deliver square voltage wave with an output voltage pulse of about 500 kV, full-width at half-maximum (FWHM) of 94 ns, and 10%–90% rise time of fewer than 35 ns, indicating its ability to deliver peak power beyond 6.25 GW. In addition, a transit-time oscillator was connected and can radiate microwave power of 0.8 GW at 12.89 GHz for the cathode voltage of 372 kV and the beam current of 9.3 kA.

Study on discharge characteristics of pulsed power module under the condition of discharge short circuit fault

Efficiency and safety are key factors that must be emphasized in pulsed power applications. The discharge characteristics of pulsed power supply directly determine the performance of the railgun. This paper conducts a research on short-circuit faults in transmission coaxial cables of pulsed power supply. In order to study the effect of short-circuit fault on the discharge characteristics of pulsed power supply and system efficiency,a pulse-forming network with cable short-circuit failure and dynamic railgun model are established in the paper. The effect of short-circuit fault on peak current is discussed by simulation. The results show that the short-circuit fault currents are all higher than the currents under normal conditions, and the closer the short-circuit location is to the power supply side, the higher the peak value of current is. In some extreme case, the peak fault current exceeds 1.5 times the normal, which requires consideration of short-circuit fault protection measures, such as the addition of a DC circuit breakers.

Investigation on structural failure of filament reinforced barrel containment

During the launching process of a composite railgun, some working conditions may lead to the structure failure of its filament reinforced barrel. For instance, the instantaneous electric power impact caused by the unexpected large pulse current and surge from the pulse-forming network, which inspires the electrodynamic response beyond the safety limit of the barrel. More importantly, the alternating load after a long-term working causes damage accumulation and failure in the composite structure. For the railgun, considering that the radial deformation of the barrel has special effect on the contact state of the rail and armature in bore, it is necessary to focus on whether the radial stiffness of the barrel is affected even if the strength of the barrel does not decrease significantly by hidden injuries in the fiber wraps. In this study, based on the common used method of progressive failure theory, the radial stiffness attenuation process of the barrel is analyzed. The fiber fracture and composite delamination failure modes are found to be the main factors for radial stiffness attenuation of railgun barrel containment as persistent deformation will generate after these damage propagation. In addition, the loss of prestress in the fiber containment is evaluated based on structural analysis for the barrel in service and in manufacturing time. The research has found that optimized preloading seems important for improving the strength performance of the barrel.

A Multiphase Rail Launcher With Circular Geometry and Modular Design: Development, Construction, and First Experiments

Electromagnetic railguns allow to accelerate payloads to extremely high muzzle speeds ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt;$</tex-math> </inline-formula> 2 km/s). Conventionally, the launcher design is based on two rails. The power supply consists of a capacitor bank and a pulse-forming network allowing unipolar operation. In this work, a different system setup is presented. The idea is to use multiphase alternating current instead of direct current to drive a rail launcher. The basic idea had been brought up in the past in connection with the use of compulsators as power supply. Here, it is suggested to connect the launcher to a (noncompensated) multiphase generator. An interesting but not obvious feature of such an approach is that a stationary acceleration force profile can be realized. However, the launcher becomes more complex as more than two rails are required and an appropriate power supply has to be developed. When considering this approach, an important finding is that if one aims at high speeds, several stages are required. It means that a modular or segmented setup is required. As the passage of the armature between the segments is expected to be a critical point, the idea came up to build a three-phase circular geometry, meaning that the armature leaves at the “muzzle” and re-enters at the “breech” of the launcher. This also allows using an electric motor for a preacceleration in order to minimize sliding contact problems during start. As power supply served a redesigned 100-kW high-current transformer, which can be connected directly to the local power grid. Experimental data including electrical parameters (e.g., an armature current of 20 kA) are presented and discussed. For the first time, it can be experimentally shown that stationary acceleration profiles can be realized, in principle.

Design of an Oil-Immersed Pulse Modulator for X-Band 50-MW Klystron

This article presents a compact high-voltage pulse modulator used for a 50-MW <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$X$</tex-math> </inline-formula> -band pulsed klystron (11.4 GHz) at Shanghai Advanced Research Institute, Chinese Academy of Sciences (SARI, CAS). The pulse modulator includes a ten-section pulse-forming network (PFN), protection circuits, a thyratron module, and a pulse transformer. To reduce the volume of the pulse modulator and maintain the system stability, an oil-immersed tank is proposed to insulate the main electronic components, which leads to a volume reduction of 65%. The modulator is designed with a peak pulse voltage of 427 kV, a peak pulse current of 304 A, a repetition rate of 50 Hz, and a flat-top pulsewidth of 1.3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $</tex-math> </inline-formula> s. The circuit schematic is provided, while the design criteria of the main components and mechanical structure are discussed. The experimental results and measurements show the design and hardware to be capable of fulfilling the requirements.

Lifetime Analysis of Mica Paper Capacitors Under Microsecond Pulse

In recent years, the development of mica paper capacitor (MPC) technology has dramatically improved the withstand voltage and energy storage density of capacitors, which is suitable for pulse power systems. The lifetime of capacitors is a key factor that ensures the reliability of a system. In this article, the investigation of the lifetime characteristics of MPCs under microsecond pulse is presented. The structure of an MPC is analysed, and two numerical simulations are performed to study its characteristics. A lifetime test platform is established to test MPCs, which has stable operation performance. Essential electrical degradation parameters of MPCs are obtained and analyzed. The operational factors that influence the lifetime of MPCs are analysed, and a lifetime empirical model under given operational factors is proposed based on the lifetime test results. The results suggest that the lifetime empirical model could match well with lifetime test results. Furthermore, the structure of a pulse forming network (PFN)-Marx is analyzed by the lifetime model, and constructive suggestions are proposed. This article is devoted to studying the characteristics of MPCs and analyzing the lifetime under various operational factors, which finally helps the device to specify operating conditions and ensure reliability.

Development of a high-power pulse-forming network Marx generator with a long pulse duration.

To meet the application needs for producing long-pulse electron beams and high-power microwaves, a pulse-forming network Marx generator with a pulse duration of 260ns is presented in this paper. This generator is composed of 20 stages of pulse-forming network modules. Each module is formed with nine capacitors connected in parallel. The generator functions at 44kV, which is lower than the rated voltage of the mica paper capacitor, to improve the lifetime. The impedance of the generator is designed to reach 45Ω. To avoid the strong coupling between the adjacent stages, the physical layout of the generator adopts a zigzag design. The generator is housed in a gas pressurized vessel of 600mm in diameter and 580mm in length. Across a 50Ω load, it can deliver quasi-rectangular pulses with a pulse duration of 260ns and an amplitude of 500kV for a single shot. The output pulse features a plateau duration of 160ns and a leading edge of 45ns. In burst mode, it can steadily output ten pulses of 450kV at a repetition rate of 10Hz on either a resistive load or a diode.

Design, simulation, and development of bipolar pulse forming network based Marx generator for S band backward wave oscillator.

Pulse power systems have a wide range of applications, one of which is microwave generation. Microwave emission is associated with a certain time delay between the application of a high voltage pulse and the generation of the microwave signal. This time delay is known as microwave delay time, and it depends on the time period of the microwave signal being generated. As the time period of the microwave signal increases, the required input electrical pulse duration also goes up. To achieve this, a pulse forming network (PFN) based Marx generator is proposed. The Bipolar Marx generator is preferred over the uni-polar Marx generator to obtain the high voltage high current pulse. This also helps in maintaining the impedance requirement for Backward Wave Oscillator (BWO) devices that generate the microwave pulse. To the best of our knowledge, PFN based Marx generators have been developed up to 400kV. Here, a bipolar Marx generator has been designed with ratings of 800kV peak voltage, 10kA peak current, and 150ns flattop pulse duration. The design includes analytical calculations and numerical analysis by electromagnetic simulation. The triggering method to get a wide triggering range has also been discussed. The design values have also been experimentally verified, and the resulting parameters were applied to a BWO to simulate the microwave power that it can produce. A peak microwave power of ∼1 GW has been observed in the particle-in-cell simulation.

The design of a high-voltage, long-pulse width, flat-top compensation pulse generator based on metal oxide varistors.

In recent years, the pulse forming technology based on metal oxide varistors (MOVs) has been verified to be an effective way to generate high-voltage quasi-square pulses. Due to the limited varistor voltage of a single MOV brick, multiple MOV bricks connected in series are required to stabilize a pulse with high amplitude (larger than hundreds of kV), which leads to the rise of the series inductance of the MOV branch and the flat-top droop in the output waveform. This paper provides two solutions to reduce the influence of the MOV branch inductance on output waveforms. One is that a coaxial evolute structure of the MOV bricks connected in series is designed, which can not only improve the insulation capacity but also reduce the branch inductance. Another is that a flat-top compensation scheme named "PFN-MOV" (Pulse Forming Network) is proposed, which adds an LC filtering branch to shape the signal into a flat-top rising wave with ripple and then offsets the flat-top droop caused by the inductance of the MOV branch. Based on the above ideas, a high-voltage, long-pulse width, flat-top compensation pulse generator is designed and tested, and a quasi-square pulse with voltage amplitude of more than 500kV, pulse width greater than 800ns, rise time of less than 50ns, and flat top of about 600ns is obtained experimentally. This MOV based generator has the advantage of simple design, compact construction, and better flat top, which is promising to be used as a compact long-pulse driver in many fields, such as high-current accelerator, industrial dedusting, medical sterilization, and cancer treatment.