Wenbo Xu

While the LC-Marx generator represents an effective topology for compact high-voltage pulse generation, its inherent oscillatory decaying waveform severely constrains its deployment in critical systems mandating flat-topped square waves, such as dielectric barrier discharges (DBDs) and flash X-ray systems. To address this limitation, this paper proposes a novel high-voltage square-wave generator based on an asynchronous timing synthesis strategy. This is achieved through three synergistic innovations. First, the adoption of the LC-Marx topology halves the required number of switches through alternating capacitor polarity charging and enhances energy efficiency by allowing the main discharge current to bypass the switches. Second, a high-voltage solid-state switch, based on a series-stacked common-source common-gate JFET structure, is designed. This design eliminates the necessity for complex isolated drivers and floating power supplies, thereby resolving the scalability challenges inherent in conventional Marx generators. Third, an innovative asynchronous timing synthesis strategy is employed to transform the oscillatory pulses into a high-quality flat-top square wave by precisely time-delaying and superimposing the outputs of multiple LC-Marx modules. This paper elucidates the design principles of the switch and the methodology for square-wave synthesis. A prototype was developed and successfully generated 10 kV, 1 μs pulses with a top flatness of under 3%, thus corroborating the viability and demonstrating the distinct advantages of the proposed architecture for developing next-generation high-performance solid-state pulsed power sources.

Progress of wide-bandgap semiconductor devices has promoted the development of pulsed power switches to miniaturization, high power and high repetitive frequency. The miniaturization and high power of switches means that the chip and its surroundings face the challenge of high voltage tolerance in a small space inevitably. Therefore, the potential insulation problem is particularly prominent. For insulation design, the quantitative characterization of the electric field strength at electrical weak points is fundamental. Current characterization methods mainly focus on simulation, but accuracy and reliability of the results are constrained by the degree of modeling integrity and the inherent uncertainties of simulation. In addition, the existing measurement methods are generally not suitable for pulsed electric field. Therefore, for high-voltage pulsed conditions, based on the vector synthesis principle of electric field strength, two kinds of sensors suitable for measuring normal and tangential electric fields are designed in this paper. Then, a composite electric field probe has been developed through board-level integration, capable of simultaneously detecting normal electric fields from 5 kHz to 2 GHz and tangential electric fields from 5 kHz to 500 MHz. The probe enables non-contact measurement inside switch modules for quantitative analysis of the pulsed electric field. The probe is tested with a grounded coplanar waveguide (GCPW) transmission line, and the near-field scanning of a series MOSFETs module is performed. Results show that the probe is capable of full bandwidth measurement for pulsed spatial electric field of switch modules, compared with existing probes of the same type, which is of great significance for insulation margin assessment and compact package design of modules. Finally, this probe is less expensive and offers excellent performance in terms of isotropy, suppression of unwanted field coupling, and spatial resolution.

Nanosecond pulse electric field (ns-PFE) can target the organelles in cells, which can induce tumor cell apoptosis. This interesting electrophysiological effect implies that it is possible to inhibit tumor recurrence and metastasis. Due to the anisotropy of biological tissue, higher requirements are put forward for the output impedance regulation ability and waveform of pulse generator, such as shorter and adjustable pulse width, voltage amplitude over 10 kV. Pulse forming line (PFL) is one of the effective ways to generate nanosecond pulse. The electrical parameters and geometric dimensions of the dielectric in the PFL are fixed, which causes its output impedance and pulse width to be constant. Therefore, a new type multiswitch inductive PFL (MS-IPFL) topology is proposed in this article to solve the problems. Double switches are used to control the transmission process of electromagnetic wave in transmission line, which can realize the flexible regulation of pulse width and output impedance. In addition, an interesting fact is that it can achieve modular pulse superposition through transmission line time isolation method to generate high voltage output. Finally, 10-stage-modules stacker with voltage amplitude of 10 kV was successfully developed. The pulse width can be flexible adjusted in 10–20 ns and repetition frequency can reach 200 kHz in burst mode.