Compact Pulse Generator Research Articles

Traveling-Wave Marx Circuit for Generating Repetitive Sub-Nanosecond Pulses

The traveling-wave Marx generator was first proposed by Carl Baum to analyze the switch-closure propagation process in fast pulsed-power systems. To improve the performance of the transistorized sub-nanosecond pulse generator, the traveling-wave Marx circuit with inter-stage transmission lines is studied. Simulations indicate that the delay time and the impedance of inter-stage transmission lines [microstrip lines on printed circuit board (PCB)] are main factors affecting the pulse waveform. Based on it, the series connection of modularized Marx circuits is proposed, which has the advantages of adjustable amplitude and bendable circuit layout. A compact high-amplitude pulse generator is developed with the amplitude of 8.2 kV, the rise time of 150 ps, and the PCB length of 35 cm. For higher pulse repetition rate, the heat dissipation design of PCB is necessary; however, due to the variations in the microstrip line structure, the commonly used metallic heat sink may cause a significant decrease in pulse amplitude. Thus, a novel heat dissipation design is proposed by optimizing the layout of metallic sinks and introducing heat-conducting ceramic sinks. A high-repetition-rate pulse generator is developed with the maximum pulse repetition rate of 600 kHz, the amplitude of 1.1 kV, and the rise time of 160 ps.

Electrostatic Characteristics of Two Conducting Spheres in a Grounded Cylinder

An understanding of the electrostatic interaction between charged electrical conductors embedded in a grounded cylinder is quite useful in the design of compact pulse generators. We get the complete solution for capacitance between the two spheres and the capacitance between the sphere and the grounded cylinder in series form. The dependence of these capacitances on various geometrical parameters is very useful in the design phase of Marx generators where the stray capacitances play crucial roles.

A Simple Design Erosional Plasma Gun Made of a Coaxial Cable with Polyethylene Insulation

A compact pulsed plasma generator of simple design made of a coaxial cable with polyethylene insulation has been described. A plasma gun generates a cloud of carbon-hydrogen plasma with an electron density of more than 1013 cm–3, including in a magnetic field produced of up to 500 G and also in the presence of the background plasma with a density of about 1012 cm–3, which is produced by an independent source. The high resource of the gun and stability of plasma parameters from one pulse to another allows using such a gun in laboratory experiments simulating dynamic processes in space.

Recent advances in compact repetitive high-power Marx generators

AbstractThis paper introduces recent activities on Marx-based compact repetitive pulsed power generators at the Institute of Applied Electronics (IAE), China Academy of Engineering Physics (CAEP), over the period 2010–2018. A characteristic feature of the generators described is the use of a simplified bipolar charged Marx circuit, in which the normal isolation resistors or inductors to ground are removed to make the circuit simpler. Several pulse-forming modules developed to generate a 100 ns square wave output are introduced, including thin-film dielectric lines of different structures, a pulse-forming line based on a Printed Circuit Board, and non-uniform pulse-forming networks. A compact repetitive three-electrode spark gap switch with low-jitter, high-voltage, and high-current was developed and is used in the generators. A positive and negative series resonant constant current power supply with high precision and high power is introduced. As an important part of the repetitive pulse power generator, a lower jitter pulse trigger source is introduced. Several typical high-power repetitive pulsed power generators developed at IAE are introduced including a 30 GW low-impedance Marx generator, a compact square-wave pulse generator based on Kapton-film dielectric Blumlein line, a 20 GW high pulse-energy repetitive PFN-Marx generator, and a coaxial Marx generator based on ceramic capacitors. The research of key technologies and their development status are discussed, which can provide a reference for the future development and application of miniaturization of compact and repetitive Marx generators.

Простейшая эрозионная плазменная пушка из коаксиального кабеля с полиэтиленовой изоляцией

Abstract—A compact pulsed plasma generator of simple design made of a coaxial cable with polyethylene insulation has been described. A plasma gun generates a cloud of carbon-hydrogen plasma with an electron density of more than 10^13 cm^–3, including in a magnetic field produced of up to 500 G and also in the presence of the background plasma with a density of about 10^12 cm^–3, which is produced by an independent source. The high resource of the gun and stability of plasma parameters from one pulse to another allows using such a gun in laboratory experiments simulating dynamic processes in space.

Development of a High-Power Burst Pulse Generator Based on the Sequential Operation of Magnetic Switches

Nanosecond and subnanosecond high-voltage pulses have used in new biological applications, such as cancer treatment using an ultrashort pulsed high electric field. For this treatment, the use of high-power pulsed electromagnetic wave has been proposed to obtain the required high electric field. This paper focuses on the design of a compact high-power pulsed electromagnetic wave generator using a nanosecond pulsed power generator for cancer treatment. We developed a pulsed power generator that continuously outputs multiple pulses via a nonlinear transmission line (NLTL) using magnetic switches. The NLTL comprises a ladder of capacitors and saturable inductors. The NLTL generates a pulse train by delaying the propagation of the pulse using the magnetic switch of each ladder. The frequency of repetition of the burst pulse is 13.8 MHz. The peak output voltage is 7 kV at the maximum input voltage of 28 kV. The number of pulses in the pulse train can be varied by the number of units of the magnetic switch.

Development of Compact Pulse Generator with Adjustable Pulse Width for Pulse Electric Field Treatment Technology

<span lang="EN-MY">The pulse generator which has been implemented in the pulse electric field (PEF) treatment system for food processing is worth to be highlighted and improved. It is parallel with the advancement in semiconductor technology, which offers robust and accurate devices. This research is an effort to produce a low cost, compact and reliable pulse generator as well as equipped with a pulse width modulation (PWM) method for wide selection of frequency and duty cycle. The result shows that the simulation process has proven the theoretical concept to be right and yields the desired outcome based on the designed values. Then, the actual printed circuit board (PCB) has been fabricated to obtain practical results which intended to be compared with the simulation outcomes. Concerning the frequency and its duty cycle, both parameters can be altered without affecting each other. It means by changing the frequency, duty cycle remains the same and vice versa. Thus, this proposed pulse generator achieves its objective and fits to be implemented in PEF treatment technology. It also can replace the conventional pulse forming network (PFN) which is bulky and costly</span><span>.</span>

A compact nanosecond pulse generator for DBD tube characterization.

High voltage pulses of very short duration and fast rise time are required for generating uniform and diffuse plasma under various operating conditions. Dielectric Barrier Discharge (DBD) has been generated by high voltage pulses of short duration and fast rise time to produce diffuse plasma in the discharge gap. The high voltage pulse power generators have been chosen according to the requirement for the DBD applications. In this paper, a compact solid-state unipolar pulse generator has been constructed for characterization of DBD plasma. This pulsar is designed to provide repetitive pulses of 315 ns pulse width, pulse amplitude up to 5 kV, and frequency variation up to 10 kHz. The amplitude of the output pulse depends on the dc input voltage. The output frequency has been varied by changing the trigger pulse frequency. The pulsar is capable of generating pulses of positive or negative polarity by changing the polarity of pulse transformer's secondary. Uniform and stable homogeneous dielectric barrier discharge plasma has been produced successfully in a xenon DBD tube at 400-mbar pressure using the developed high voltage pulse generator.

Note: Self-biased voltage to suppress secondary electrons by a ZnO varistor in a compact pulsed neutron generator.

A large amount of back streaming electrons will bring about a part of current drain on power supply, cause sparking or high-voltage breakdowns, and affect the neutron yield and waveform for a compact sealed-tube pulsed neutron generator. A novel idea which uses a ZnO varistor to provide a constant self-biased voltage to suppress the secondary electrons is introduced. The I-V curve for the ZnO varistor was measured in the experiment. The effects of suppressing the secondary electrons were investigated using a ZnO varistor, linear resistors, and an independent power supply, respectively. The results show that the secondary electrons are suppressed effectively by the compact ZnO varistor, while not increasing the size and the component of the device. It is a promising design for compact sealed-tube neutron generators.

Compact solid-state Marx-bank sub-nanosecond pulse generator based on gradient transmission line theory

For non-invasive treatments in the biomedical field, sub-nanosecond pulse electric field matching ultra-wideband antennas have aroused great interest for their excellent directivity and targeted treatment. Sub-nanosecond pulse generators have proved difficult to control in pulsed power technologies despite many studies of pulse generators based on avalanche transistor theory and the Marx circuit. However, no solution exists to the problems of non-ideal waveform of the output sub-nanosecond pulse and the relatively low effectiveness of the Marx circuit. To resolve these problems, the paper describes a sub-nanosecond pulse generator simulation model based on gradient transmission line theory in PSPICE simulation software and the development of a compact solid-state sub-nanosecond pulse generator (18 cm×18 cm×4 cm). From experimental tests, trigger signals of 5-V amplitude, 5-ns rise and fall times (pulse-width 10 ns-50 ns) were generated by Field-Programmable Gate Array (FPGA). A pulse with 1600-V voltage amplitude, 300-ps full width at half maximum, 150-ps rise time, and 10-kHz high-stability repetition rate was generated in an attenuator load with high-bandwidth (8 GHz, 50 Ω). The effectiveness (Output pulse voltage amplitude / Charge voltage × Stages) of this Marx circuit reached to 41.7%, improving considerably on previous efforts.

Development and Simulation of a Compact Picosecond Pulse Generator Based on Avalanche Transistorized Marx Circuit and Microstrip Transmission Theory

The new biological effect of picosecond pulsed electric fields (psPEFs) has elicited the interest of researchers. A pulse generator based on an avalanche transistorized Marx circuit has been proposed. However, the problem of reflection in the transmission of the generated picosecond pulse based on this circuit has not received much attention and remains unresolved. In this paper, a compact picosecond pulse generator based on microstrip transmission theory was developed. A partial matching model based on microstrip transmission line theory was also proposed to eliminate reflection, and a series inductor was utilized to optimize pulse waveform. Through simulation studies and preliminary experimental tests, a pulse optimized with 1015 V amplitude, 620-ps width, and 10-kHz high stability repetition rate was generated. This pulse generator can be used with microelectrodes in cell experiments to explore the biological effect mechanism of psPEF.

Pulse generator with intermediate inductive storage as a lightning simulator.

Compact transportable generators are required for simulating a lightning current pulse for electrical apparatus testing. A bi-exponential current pulse has to be formed by such a generator (with a current rise time of about two orders of magnitude faster than the damping time). The objective of this study was to develop and investigate a compact pulse generator with intermediate inductive storage and a fuse opening switch as a simulator of lightning discharge. A Marx generator (six stages) with a capacitance of 1 μF and an output voltage of 240 kV was employed as primary storage. In each of the stages, two IK-50/3 (50 kV, 3 μF) capacitors are connected in parallel. The generator inductance is 2 μH. A test bed for the investigations was assembled with this generator. The generator operates without SF6 and without oil in atmospheric air, which is very important in practice. Straight copper wires with adjustable lengths and diameters were used for the electro-explosive opening switch. Tests were made with active-inductive loads (up to 0.1 Ω and up to 6.3 μH). The current rise time is lower than 1200 ns, and the damping time can be varied from 35 to 125 μs, following the definition of standard lightning current pulse in the IEC standard. Moreover, 1D MHD calculations of the fuse explosion were carried out self-consistently with the electric circuit equations, in order to calculate more accurately the load pulse parameters. The calculations agree fairly well with the tests. On the basis of the obtained results, the design of a transportable generator was developed for a lightning simulator with current of 50 kA and a pulse shape corresponding to the IEEE standard.

Nanosecond Pulse Generator Based on an Unbalanced Blumlein-Type Multilayered Microstrip Transmission Line and Solid-State Switches

This paper combines an unbalanced Blumlein-type multilayered microstrip transmission line with solid-state switches to develop a high-voltage nanosecond pulse generator. This study was performed to emphasize the importance of a compact nanosecond pulse generator for biomedical applications. The unbalanced Blumlein-type transmission line reduces current flow through the solid-state switches. A multilayered microstrip transmission line is stacked onto the four-layered printed circuit board to minimize the system volume. Voltage wave propagation analysis is used to explain the principle of the system, which produced a rectangular pulse. The strategy to produce different pulse widths and the controlled timing of the related solid-state switches is interpreted according to this analysis, highlighting the approach needed to achieve a 50–100 ns pulsewidth. Also, the relevant principle of the variable load impedance of the unbalanced Blumlein-type multilayered microstrip transmission line system is also analyzed. To demonstrate the performance of the generator, a miniaturized system is established. Eventually, the nanosecond pulse generator produces a rectangular pulse on a resistor load of 50 $\Omega $ , with amplitude of 0–2 kV, pulsewidth of 50–100 ns, rise time of approximately 20 ns, and repetition frequency of 0 to several kilohertz. Also, when a 500 $\Omega $ resistor is used instead of a 50 $\Omega $ resistor, the output of the nanosecond pulse voltage is approximately two times that of the applied charging voltage.

Design and Development of a Compact Trip Pulse Generator

Design and Development of a Compact Trip Pulse Generator

A Frequency-Selective CMOS IC-Based Pulse Generator for Recording and Imaging in the Auditory Cortex In Vivo

A Frequency-Selective CMOS IC-Based Pulse Generator for Recording and Imaging in the Auditory Cortex In Vivo

Compact pulse generators with soft ferromagnetic cores driven by gunpowder and explosive.

Compact pulse generators which utilized soft ferromagnets as an initial energy carrier inside multi-turn coil and hard ferromagnets to provide the initial magnetic field outside the coil have been studied. Two methods of reducing the magnetic flux in the generators have been studied: (1) by igniting gunpowder to launch the core out of the generator, and (2) by detonating explosives that demagnetize the core. Several types of compact generators were explored to verify the feasibility. The generators with an 80-turn coil that utilize gunpowder were capable of producing pulses with amplitude 78.6 V and the full width at half maximum was 0.41 ms. The generators with a 37-turn coil that utilize explosive were capable of producing pulses with amplitude 1.41 kV and the full width at half maximum was 11.68 μs. These two methods were both successful, but produce voltage waveforms with significantly different characteristics.

A compact 300 kV solid-state high-voltage nanosecond generator for dielectric wall accelerator.

Compact solid-state system is the main development trend in pulsed power technologies. A compact solid-state high-voltage nanosecond pulse generator with output voltage of 300 kV amplitude, 10 ns duration (FWHM), and 3 ns rise-time was designed for a dielectric wall accelerator. The generator is stacked by 15 planar-plate Blumlein pulse forming lines (PFL). Each Blumlein PFL consists of two solid-state planar transmission lines, a GaAs photoconductive semiconductor switch, and a laser diode trigger. The key components of the generator and the experimental results are reported in this paper.

小型高輝度短波長光源に向けたパルス発生器の設計と超音速Heガス流による液体金属流の制御法の検討

To demonstrate repetitive-intense X-ray source by using pulsed-power discharge, we proposed an innovative X-pinch method using compact pulse generator and liquid metal injection. The compact pulse generator using small pulse-forming-network modules (PFNMs) has been developed. The current rising rate of the PFNMs with X-pinch system is over 0.1 kA/ns at low operation voltage. To suppress the expansion of liquid metal in a vacuum chamber, we have demonstrated liquid metal injection with coaxial supersonic flow generated by an aerospike nozzle. The results indicate that the expansion of liquid metal is suppressed with the coaxial supersonic flow.

Ignition System Based on the Nanosecond Pulsed Discharge

A new design of the compact nanosecond pulse generator based of the drift step recovery diodes as an ignition system for internal combustion engines (ICEs) has been presented. Experimental results of the comparative analysis of the standard ignition system and an ignition system on the basis of the nanosecond pulsed discharge for the four-cylinder ICE have been presented. It was shown that a nonequilibrium plasma formed by the discharge was an effective way to reduce the specific fuel consumption as well as the concentration of nitrogen oxides in the engine exhaust gases. A numerical analysis of possible mechanisms of the nonequilibrium plasma influence on the suppression of the nitrogen oxides formation has been carried out.

Pulses for feelings

Spinal cord stimulator implants could use less power and be made much smaller as work from Taiwan and Israel eliminates off-chip high-voltage devices from the implant's pulse generator. This will reduce implant-related discomfort for patients using such implants to control chronic pain, and the work could also be applied to other medical devices, including muscle micro-stimulators. A prototype ultrasonic wirelessly powered SCS that incorporates the 16-channel pulse generator presented in this work (mounted in the internal module) For a growing number of people, spinal cord stimulators (SCSs) provide a low-cost alternative to pharmaceutical pain relief with fewer side effects. An SCS delivers electrical impulses to the patient's spinal cord, which help to control the pain they experience. A typical SCS consists of an external controller unit and an internal module, wirelessly connected to each other. The internal module, implanted in the patient, will include three main components. The first is the electrode array, attached to the outermost part of the spinal canal, to deliver the electrical pulses to the spinal cord. The second is the pulse generator that produces the required pulses and is implanted away from the spine in a location with more space, such as the lower abdomen. The final component is the lead that connects the generator to the electrode array. A key issue with current SCS designs is the need for off-chip power devices, because the stimulating pulses that have to be generated are relatively high voltage. The off-chip devices add bulk to the pulse generator, which has to be implanted in the body. This limits the choice of implantation location for the pulse generator module and increases the discomfort for the patient associated with the implant. In this issue of Electronics Letters, a team from National Sun Yat-Sen University, Taiwan, and Tel Aviv University, Israel, presents a compact pulse generator with no off-chip power devices, created using a high voltage (HV) CMOS process. Their 16-channel high-voltage stimulation generator uses a charge pump composed of five cascaded voltage doublers to boost the core voltage (2.5 V) to over 10 V, meeting the requirements of an SCS. The generator is capable of producing different pulse waveforms to meet a range of different application requirements. “A total of 16 stimulation waveform generators are included to drive 16 corresponding sets of electrodes, where each generator is composed of a high-voltage operational amplifier and high-voltage analogue switch. They are meant to be programmable and digitally controllable,” explained team member Prof. Chua-Chin Wang. Although HV CMOS is a known technology, moving the design to it from a standard CMOS process was not straightforward, imposing many design restrictions. For example, although the HV CMOS can sustain a voltage drop between drain and source of over 60 V, the voltage drop between gate and source is limited to 5 V, which required the development of a corresponding protection mechanism. However, now that the pulse generator has been realised, it should be relatively simple to use it as a direct replacement for much bulkier units with off-chip power components, giving the design great potential for rapid uptake in clinical devices. The HV CMOS design produced by the team already requires less power to operate than previous designs, but the team is now working to further reduce the power consumption. This is always a very important consideration for implanted devices, which have to be either wirelessly powered externally (or charged), or require repeated surgical procedures to replace batteries. Left: The layout of an SCS implanted in a patient. Right: The 16-channel pulse generator, developed with all on-chip power devices for compactness The team are also working more widely on the development of complete SCS systems with wireless power transmission and wireless communication between the controller and the implanted components. This includes the use of ultrasonic transmitters and receivers as well as more conventional EM methods, since ultrasound has a long history in medical use to prove its safety. The team have already produced an ultrasound-based prototype SCS that uses the pulse generator presented in this issue of Electronics Letters. Early results suggest that the efficiency of the power transfer will be an issue that needs to be addressed and Wang commented that this also drives the need to further reduce the power consumption of the implanted components, including the pulse generator, “In the future, the life time extension of the battery in the SCS internal module will become a major problem. Since the conversion efficiency of the wireless charger remains a task to beat, power saving in the internal module will be increasingly important to reduce the number of charging times and the heat dissipation.”