Chengxiang Li

Pulsed power systems require compact high-voltage pulse generators with high current capability, where series–parallel configurations of semiconductor switches are inevitable. However, voltage imbalance in series devices and current mismatch in parallel branches significantly degrade system reliability under high-current pulsed conditions. In this work, a high-current solid-state Marx pulse generator based on a series–parallel IGBT configuration is proposed with a coordinated voltage balancing and current sharing strategy. A passive RC snubber is employed to suppress dynamic voltage imbalance, while a coupled inductor is introduced to mitigate transient and steady-state current mismatch. Simulation and experimental results demonstrate that the prototype achieves a peak output of 5 kV and 1000 A with adjustable pulse widths of 2–10 μs. The current imbalance degree is reduced from 45.8% to 3.1%, indicating significantly improved current sharing performance. The proposed method provides an effective and scalable solution for high-current pulsed power applications.

The rapid expansion of the nuclear power industry has intensified the demands for composite components including zircaloy and stainless steel. Driver-assisted electromagnetic pulse welding (EMPW) is a promising welding method for the fabrication of these composite components, where the driver thickness is one of the key parameters. However, current studies have not yet provided a sufficient insight of the thickness modification on the energy transfer process and welding effect. In this study, the basic principles and energy transfer process of copper-ring-driver-assisted EMPW are systematically explored. An index is proposed to quantify and predict the effect of driver thickness on the dynamic performance, where the local maximum is obtained when the thickness is equal to the skin depth of driver material. To reveal the spatial–temporal distribution of electromagnetic parameters, a multifield coupled finite-element simulation model is set. Based on the model, the energy transfer efficiency is calculated, where the optimized effect is found with driver thickness of 0.7mm. Experiments of copper-driver-assisted EMPW are conducted subsequently with different discharge voltages and driver thicknesses for welding zircaloy tube and stainless steel rod. Mechanical properties and microstructural characterization show that, within the selected parameters, welding effect of the zircaloy–stainless steel joint are optimal with 0.7-mm driver thickness, supporting the numerical analysis. This work provides a reference for the optimization of the EMPW technology in the field of nuclear power.

High-voltage ultrashort pulses with fast-rising edges have great prospects in the fields of biomedical, food sterilization, military weapons, and so on. It is hard to balance high-voltage and fast-rising edge requirements in the development of ultrashort pulse generators. This article proposed a novel high-voltage ultrashort pulse generator with a subnanosecond rising edge based on the diode opening switch (DOS) and the avalanche transistor module (ATM). By analyzing the output characteristics of DOS through the 1-D Poisson equation, the factors affecting the rising edge and amplitude in the circuit were determined, thereby determining the parameters of the DOS circuit. A pulse rising edge sharpening circuit has been designed based on the characteristics of avalanche transistor collector–emitter fast voltage rise rate conduction. The microstrip transmission line is designed as a sharpening capacitor to increase the voltage rise rate of energy. Furthermore, a PSPICE circuit simulation model was built to study the sharpening effect of ATM and the influence factors. Compared to existing DOS circuits with a rising edge of 3.1 ns, the prototype pulse generator developed in this article generates ATM-based ultrashort pulses with a rising edge of 0.6 ns and an amplitude of 4.2 kV and realizes an increase in output amplitude and a shortening of the rising edge at the same time.

Electromagnetic pulse welding (EMPW) represents a critical application of pulsed power technology in advanced manufacturing. However, conventional EMPW techniques exhibit relatively low efficiency in converting electromagnetic energy into the kinetic energy of the flyer, often requiring high voltage and large current to achieve reliable metallurgical bonding. To address this limitation, an enhanced EMPW method based on loading loop pulse current is introduced. By injecting an additional pulsed current into the flyer, the current density and resulting Lorentz force density are significantly increased, leading to a higher collision velocity and improved joint quality. A multiphysics finite-element model was established in COMSOL to investigate the distributions of current, magnetic field, Lorentz force, and collision velocity under the influence of the loaded pulse current. Experimental validation was conducted to support the numerical findings. Simulation and experimental results demonstrate that, at a discharge voltage of 7 kV, the proposed method achieves a Lorentz force density of $2.09\times 10^{11}$ N/m² and a flyer collision velocity of 224.5 m/s. These values are comparable to those obtained in conventional EMPW at 10 kV, which produces a Lorentz force density of2.03 × 10¹¹ N/m² and a velocity of 226.7 m/s. Despite comparable welding performance, energy consumption is reduced by approximately 51%, indicating a substantial improvement in the utilization of electromagnetic energy. The proposed approach offers a promising solution for improving energy efficiency in EMPW and supports broader industrial applications of this technology.

Cu is widely used to fabricate highly efficient conductive coatings in the power electronics industry due to its exceptional electrical and ductility. To achieve higher spraying speed and better Cu coating quality, this article deeply studied the method of accelerated plasma spraying (APS) based on electromagnetic pulse welding (EMPW). A multiphysical field simulation model was constructed to study the plasma and Cu powder motion processes. The electromagnetic parameters, temperature, and Cu powder velocity were obtained. The relationship between electrode parameters and the Lorentz force was obtained by combining the plasma equation of motion with numerical analysis. The velocity of the Cu powder motion was obtained through the capture of the spraying process. The findings revealed that the electrode spacing exerted an influence on the plasma motion. The simultaneous impact of the compression shock wave and the Lorentz force propelled the Cu powder, which remained in the solid state, toward the ceramic. The Cu powder speed reached 1024 m/s and the maximum Cu coating thickness of 140 $\mu$m was obtained when the discharge voltage was 5 kV. This study elucidated the mechanism of APS based on EMPW, thereby providing a theoretical foundation for APS in mechanism analysis and future applications.

High-voltage nanosecond pulse generators with compactness and repetition frequency have become a vital demand in some fields. In this article, the principle of inductive energy storage (IES) is applied to twisted pair wire (TPW), which serves as an energy storage unit for generating nanosecond pulse. As a kind of transmission line, the electromagnetic field constraint of TPW is realized by twisting, so it has greater bent flexibility than a coaxial transmission line, which makes it possess higher 3-D space utilization. Furthermore, an isolated superposition device (ISD) based on TPW is proposed for modular stacking. The inductive isolation effect between adjacent modules produced by ISD can ensure a more efficient power superimposition. Their parameter selection methods are studied and the components are developed accordingly. The application of TPW and ISD with small volumes makes it easy to achieve a compact pulse generator. Experiments of single-module circuits and multimodule superposition are carried out to verify the feasibility. Finally, a compact ten-stage high-voltage nanosecond pulse generator prototype is built, with a voltage amplitude of 10 kV and pulsewidth of 10.6 ns. It can operate at a repetition frequency of 200 kHz.