JR

Junfeng Rao

Suzhou Institute of Biomedical Engineering and Technology

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Zi Li

Gannan Normal University

Song Jiang

University of Shanghai for Science and Technology

Yonggang Wang

First Hospital of Jilin University

Jie Zhuang

Chinese Academy of Sciences

M. Huang

South China Normal University

X.T. Ding

Chinese Academy of Medical Sciences & Peking Union Medical College

X.R. Duan

Southwestern Institute of Physics

Z.B. Shi

Southwestern Institute of Physics

J. Zhou

Southwestern Institute of Physics

Y. Zhou

Southwestern Institute of Physics

Cooperative Institutions

Southwestern Institute of Physics

Chinese Academy of Sciences

CEA Cadarache

University of Shanghai for Science and Technology

Southwest Jiaotong University

Huazhong University of Science and Technology

University of Science and Technology of China

Commissariat à l'Énergie Atomique et aux Énergies Alternatives

Zhejiang University

Institute of Plasma Physics

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Publisher’s Note: “Multi-stage voltage droop compensation based on resonant circuit for unipolar solid-state Marx Generators” [Rev. Sci. Instrum. 93, 114704 (2022)]

Review of Scientific Instruments (2022)

Junfeng Rao Yibo Huang Xiuzhi Wang Longyu Zhuang Jie Zhuang

First Page

Marx Generator

10.1063/5.0135928

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Citations (0)

Study on Overcurrent Protection of Magnetic Isolated Synchronized Driver for Marx Generators

IEEE Transactions on Plasma Science (2023)

Song Jiang Zhixin Wang Yonggang Wang Zi Li Junfeng Rao

Silicon carbide metal-oxide-semiconductor field-effect transistors (SiC MOSFETs) are widely used due to their high operating frequency and low switching losses in solid-state Marx generators (SSMGs). As a result, overcurrent protection of SiC MOSFETs in pulse power supplies has become increasingly important. This article proposes a passive overcurrent protection driver based on the gate charge self-sustaining effect. This driver circuit enables synchronized output of multiple drive signals and also provides overcurrent protection without affecting the normal operation of SSMGs. The negative bias voltage can ensure the reliable turn-off of switches after overcurrent protection. Two common overcurrent faults including hard switching fault (HSF) and a fault under load (FUL) were analyzed. Experimental results show that replacing Zener diodes with TL431 considerably improves the response speed of the protection from 2

$\mu$

s to 500 ns. The overcurrent protection threshold can be adjusted by TL431, increasing the flexibility of the protection circuit. Once the overcurrent protection is triggered, the gate–source voltage of the switch will remain negative to ensure it stay in the off-state.

Overcurrent

Zener diode

Insulated-gate bipolar transistor

10.1109/tps.2023.3335347

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A Multilevel Pulse Generator Based on Series Capacitor Structure for Cell Electroporation

IEEE Transactions on Plasma Science (2020)

Song Jiang Junjian Wang Yonggang Wang Zi Li Junfeng Rao

Research on the effect of pulsed electric field in cell electroporation attracts more attention, especially tumor ablation. This puts forward higher requirements for pulsed electric field parameters. The shape of the pulse waveform was also required in different electroporation applications. Based on this, a multilevel pulse generator with series capacitor structure was proposed in this article. Besides, it can also obtain the different shapes of the pulse waveforms by controlling the timing of semiconductor switches. The voltage amplitude, the number of pulses, and the pulsewidth are all adjustable. A ten-level test prototype with 11 switches was built. The structure was simple and was more compact. It can work stably under the simulated small resistance load. Finally, when the dc charging voltage was 1 kV, the system can achieve a maximum output voltage of ±500 V. The number of pulse in one pulse sequence was 1-500. The pulsewidth was adjustable from 1 to $10~\mu \text{s}$ . By controlling the switch's timing, it can also obtain the multilevel voltage output, exponential waveform voltage output, and composite waveform output combined narrow pulse with wide pulse.

10.1109/tps.2020.3032708

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Citations (4)

A new nanosecond switch triggered by array microhollow cathode discharge

Yaqing Teng Kefu Liu Jian Qiu Junfeng Rao

The structure and mechanism of array microhollow cathode are introduced in this paper. Triggered by such structure, nanosecond switches can realize multichannel discharge at atmosphere with low trigger voltage. The structure of microhollow cathode is two electrodes divided by 200μm thick dielectric and threaded by about 100μm hollow. Array microhollow cathode can produce multichannel atmospheric discharge with high-energy and high-density electrons. We focused on the influence of trigger current, the number of microhollow cathode holes, the diameter of the microhollow cathode hole and the ratio of switch working voltage on the trigger voltage and the delay time and jitter of the switch.

Nanosecond

10.1109/ppc.2011.6191501

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A New Driving Circuit With Delay Trigger for the Solid-State Marx Modulators

IEEE Transactions on Plasma Science (2021)

Zi Li Haotian Liu Song Jiang Junfeng Rao

The rising edge of the output pulses affects the discharged mechanism and efficiency of the nonthermal plasma generation. In the traditional Marx-type pulse generators, the magnetic isolation driving circuit could not adjust the rising edge of the output pulses and limits the application on a capacitive load. In this article, the factors affecting the rising edge of output pulses are analyzed. And a driving circuit based on magnetic isolation is proposed, which can control the rising edge of the output pulses. A synchronous driving signal is used to control multiple groups of switches using different sequences, and the magnetic core does not limit the driving signals. The experiments were carried out using a seven-stage solid-state Marx modulator. From the results, the rectangular pulses and stepped pulses are obtained at a capacitive load, and the 0.1- 2.3 μs adjustment rising edge can be obtained under 0-5 kV output voltage.

Signal edge

Marx Generator

SIGNAL (programming language)

Magnetic circuit

10.1109/tps.2021.3077601

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Citations (5)

Reverse avalanche breakdown characteristics of collector junctions in bipolar junction transistors

High Power Laser and Particle Beams (2016)

Junfeng Rao Wei Zhang Zi Li Song Jiang Pi Teer

Generating low-temperature plasma with high density requires fast pulses with high repetitive frequency, nanosecond rise time and nanosecond pulse width, which is very difficult for the widely used MOSFET and IGBT. Studies show that the bipolar junction transistors avalanche breakdown process has the characteristics of fast conduction, fast recovery and high stability, which is suitable for the self-breakdown switches in compact solid-state Marx generators. In this paper, it is found that the avalanche breakdown voltage can be adjusted by changing the resistance between BJTs gate and emitter. The experiments of avalanche breakdown and recovery show that BJT will turn off when the breakdown current attenuates below the maintain current, so the BJT avalanche breakdowns conduction time can be controlled by adjusting the parameters to change the attenuation of the discharging current in the circuit. Applying these conclusions to the actual circuit, fast pulses, with rise time of 5 ns, pulse width of 10 ns and amplitude of 2 kV and frequency of 100 kHz, are obtained.

Avalanche breakdown

Nanosecond

Insulated-gate bipolar transistor

Rise time

10.11884/hplpb201628.160158

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Research on the Bipolar Microsecond Pulse Generator Using the Multistage Resonant Charging

IEEE Transactions on Plasma Science (2021)

Zi Li Xiaoyue Wang Song Jiang Yonggang Wang Junfeng Rao

In this article, a bipolar pulse generator based on multistage resonant charging has been proposed, which can deliver microsecond-range pulses for medical and industrial applications. The main circuit consists of two sets of identical Marx generators connected back to back with the load between them. It can flexibly output bipolar pulses with adjustable amplitude, pulse width, and frequency. In this research, six eight-stage Marx generators have been employed to verify the performance of the proposed bipolar pulse generator. From the experimental results, the proposed generator can deliver pulses with the amplitude of ±10 kV to no-load and a resistive load of 50

$\text{k}\Omega $

. The repetitive frequency can be adjusted from 1 Hz to 1 kHz, and pulse width can be adjusted from 0.2 to

$400~\mu \text{s}$

with 50 ns rising and falling time. The relaxation time between the positive and negative pulses can be determined from 0.2 to 400

$\mu \text{s}$

. In the high-voltage field, the proposed Marx generator can deliver higher output voltage pulses and has smaller voltage differences between stages than the traditional solid-state Marx generator.

Marx Generator

Microsecond

10.1109/tps.2021.3133504

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Citations (6)

An all solid-state repetitive high-voltage rectangular pulse generator based on magnetic switch

IEEE Transactions on Dielectrics and Electrical Insulation (2015)

Junfeng Rao Zi Li Kun Xia Shang-zhi Xin

An all solid-state high-voltage rectangular pulse generator is proposed in this paper. This generator broadly consists of a Marx generator, a pulse forming line (PFL) and a magnetic switch (MS). As the power supply, the Marx generator discharges to the PFL through an inductor. The inductor should cooperate with MS since it influences the discharging process directly and determines the volt-second product of the MS and the pre-pulse over the load. The MS saturates at exactly the moment the discharging process ends. Then PFL discharges to the matched resistor load through the saturated MS and a high voltage rectangular pulse is obtained over the load. The design of Marx generator and MS are introduced in this paper. Experiments under a single shot and repetitive frequency of 5 kHz were carried out. PSPICE simulations with a simplified model of MS were carried out to verify the experimental results. The experimental result matches well with the results of the simulation. A rectangular pulse with 12.5 kV voltage amplitude, 46-ns rise-time, 220 ns pulse-width was obtained over the 50 Ω resistor load.

Marx Generator

Pulsed Power

10.1109/tdei.2015.004956

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Citations (13)

MicroRNA-16 Modulates Melatonin-Induced Cell Growth in the Mouse-Derived Spermatogonia Cell Line GC-1 spg Cells by Targeting Ccnd1

Biology of Reproduction (2016)

C. Li Shaohua Chen Hui Li L. Chen Yang Zhao

Melatonin exerts a range of physiological effects. However, the functional significance of melatonin in spermatogenesis and the underlying mechanisms remain unclear. MicroRNAs (miRNAs) are essential in the initiation and progression of testicular development, including spermatogenesis. Thus far, limited information is known about the role of miRNAs in melatonin-mediated spermatogenesis. In this study, the expression levels of testicular miRNA machinery genes, namely, Dgcr8and Xpo5,were significantly increased by melatonin. The miRNA expression profile was identified in the testes of melatonin-treated mice. Ten miRNAs were significantly up-regulated, and 15 miRNAs were down-regulated. Melatonin (25 μM) enhanced cell growth and reduced apoptosis in GC-1 spg cells. Among the down-regulated miRNAs, miR-16 expression was influenced by melatonin in GC-1 spg cells. The miR-16 mimics in GC-1 spg cells significantly suppressed cell growth and promoted cell apoptosis. Conversely, transfection of the miR-16 inhibitor significantly increased cell growth and decreased cell apoptosis. The protein expression level of CCND1 (Cyclin D1) in GC-1 spg cells was decreased by the miR-16 mimics and increased by knockdown of miR-16. Moreover, bioinformatics and reporter activity analyses showed that Ccnd1was a potential target of miR-16. These results suggested that miR-16 may function as a novel regulator of testicular functions during melatonin stimulation by targeting Ccnd1.

10.1095/biolreprod.115.138313

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Citations (19)

A Novel Drive Circuit for Solid-State Rectangular Pulse Generator

Haotian Liu Junfeng Rao Song Jiang Zi Li

Rectangular high-voltage narrow pulses are preferred in most Dielectric barrier discharge (DBD) loads and corona discharges in water. Usually at least two groups of switches are required to generate rectangular pulses over capacitive loads. One group discharge the energy-storage capacitors to the load and the other group discharges the energy stored in the parasitic capacitor of the capacitive load so as to chop off the slow tailing of pulses. Therefore, two independent drive circuits are required for these pulse generators. In this paper, a novel drive circuit combined with time-delay circuits, which can drive many different groups of switches with only one drive circuit, is propos ed. Using magnetic transformers with common primary winding, many synchronized driving signals can be generated. With some special time-delay circuits, these synchronized driving signals are modulated into many groups of different driving signals. Experiments prove that rectangular and stepped pulses can be generated using this single drive circuit.

Rise time

10.1109/ipmhvc.2018.8936813

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Citations (1)