Application Of Pulsed Power Technology Research Articles

Development of Bipolar Pulse Power Supply Based on Peak Closed-Loop Control Method

With the wide application of pulsed power technology in tumor ablation, sewage treatment, and other related fields, researchers have found that bipolar electrical pulses are more effective than unipolar electrical pulses. In this article, a new bipolar pulse generator is proposed, which combines the features of boost circuit and Marx circuit to significantly improve the boost ratio of output pulse and the tunability of pulse peak. In order to improve the load regulation rate and peak stability of bipolar pulse power supply, a bipolar pulse power supply based on peak closed-loop control method is designed in this article. The high-voltage pulse is attenuated, and its peak is sampled by the pulse peak sampling circuit, and the pulse peak voltage is fed back to the DSP controller for comparison with the set peak value, and the proportional integral differential (PID) adjustment is performed according to the voltage deviation, and the boost ratio of the pulse generator is changed to realize the constant peak output of the bipolar pulse. In order to verify the feasibility of the proposed bipolar pulse generator with peak closed-loop control scheme, simulation and experimental studies of the bipolar pulse power supply with five-stage peak closed-loop control were conducted. The results show that the output repetition frequency of 5 kHz, pulsewidth of 5– <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10~\mu \text{s}$ </tex-math></inline-formula> , and peak pulse value within ±2.0 kV can be stabilized when the input voltage is 100 V.

A compact low impedance angular distribution Blumlein-type pulse forming network

A pulse forming network (PFN) has the advantages of compactness and long pulse achievability, which could meet the requirements of military and industrial applications of pulsed power technology well. In this paper, a compact low impedance Blumlein-type PFN based on ceramic capacitors is investigated numerically and experimentally. Generally, in order to increase the compactness of the PFN, an angular distribution and an axially parallel connected structure with a theoretical peak energy density of up to 5.8 J/L are employed. The dimensions of the PFN are Φ 560 × 345 mm2. A sharpening switch, which can efficiently reduce rise-time of the output pulses, is utilized to improve the performance of the PFN. The compact low impedance Blumlein-type PFN was assembled in our laboratory. The results of low voltage experiments show that the PFN could generate quasi-square pulses with an output power of 50 MW and a peak voltage of approximately 13.2 kV on a matched dummy load. Impedance and output pulse duration of the PFN are 3 Ω and 135 ns, respectively. The results of high voltage experiments show that pulses with a power of about 1 GW and an energy density of about 2.5 J/L were obtained. Experiments show reasonable agreement with numerical analysis.

Design of High-Voltage Square Pulse Generator Based on Cascade Switches and Time-Delay Driver

In the application of pulsed-power technology, capacitive loads require that high-voltage pulses have fast front and back edges. Using multiple semiconductor switches, insulated gate bipolar transistors (IGBTs) in series with discharge high-voltage capacitors can generate high-voltage pulses. By adding a group of truncation switches, square pulses with fast back edges can be obtained. A novel drive circuit using many transformers with their primary windings in series is proposed to generate two groups of reverse driving signals by changing the dotted terminals on the secondary sides. The dead time between these signals is realized by adding some time-delay circuits. In terms of drive control, both the discharging switches and the truncation switches are triggered synchronously since the primary windings of all transformers are connected in series, which ensures the synchronism of driving signals. Time-delay drive circuits are added to the secondary sides of transformers to ensure a proper dead time between the two groups of driving signals for both discharging and truncation switches. Moreover, all driving power is provided from the single driver on the primary side, greatly simplifying the drive circuit. The voltage balancing of cascade IGBTs is realized by using resistor–capacitor–diode (RCD) snubber circuits. Experiments were carried out over resistive and capacitive loads. Square pulses with a voltage amplitude of 10 kV, a pulsewidth of $8~\mu \text{s}$ , a rising time of 157 ns, and a falling time of 78 ns were obtained on a 20- $\text{k}\Omega $ resistive load. The voltage amplitude, pulsewidth, and frequency are continuously adjustable.

Metal-coated plastics recycling by pulsed electric discharge

Recycling of useful materials such as metals and plastics are evaluated important from the viewpoint of resource conservation and environmental protection. In this respect, the application of pulsed power technology to the recycling field has attracted considerable attention. We used a compact disc-read only memory (CD-ROM) as a separation processing target in this study. A magnetic pulse compression pulsed power generator (MPC-PPG) was designed and constructed to provide a positive pulse voltage. By applying an electric discharge, the protective layer containing the metal layer was separated from the plastic substrate in the atmospheric air. Here, to clarify the mechanism of the metal separation, shock waves and their induced fluid flow generation and propagation were observed by schlieren and shadowgraph visualization methods. Initially, the Mach number of the shock wave was 5.6, soon afterward the shock wave velocity decreased gradually. The fragments of the metal and the protective layers were removed from the plastic substrate with the shock wave propagation. The proposed method and process is applicable to the recycling of electronic wastes on an industrial scale for efficient recovery of valuable materials.

Mechanism of metal removal from metal-coated plastics using pulsed power

Recycling of electronic waste (E-waste) is an important subject from the viewpoint of resource conservation and environmental protection. Recently, application of pulsed power technology in the recycling field has attracted considerable attention. We have been investigating metal separation from CD-R as an example of metal-coated plastic, by applying pulsed power with concentric ring electrodes. We visualized discharges with an ultra-high-speed framing camera to clarify the mechanism of metal removal. During the first shot a fan-shape discharge was observed after the breakdown of a protective layer. It expanded until the current reached its peak value, and then gradually disappeared. The protective layer containing a metal layer was separated from the plastic substrate around the fan-shape discharge. Similar discharge pattern continued until the metal layer around the high voltage electrode was completely removed. Afterward, a surface discharge bridged between the high voltage electrode and the remaining metal layer, then continued with a fan shape. A similar discharge pattern lasted until complete removal of the metal layer. Precise observations revealed the characteristics of the fan-shape discharge, which was accompanied by the vaporization of the metal layer. Furthermore, the length and velocity of the discharge propagation were analyzed using an image processing software.

An Application of Pulsed Power Technology and Subcritical Water to the Recycling of Asphalt Concrete

In order to resolve the issues related to the recycling of asphalt concrete, this study focuses on the application of pulsed power technology and subcritical water to the recovery of asphalt from asphalt concrete lumps. At the result, the recycled aggregate over 5 mm with asphalt content of approximately 0.99% was produced using pulsed power technology. Furthermore, the application of subcritical water to recover asphalt from the residues of pulsed power discharge inside of asphalt concrete lumps resulted in an about 91% pure asphalt recovery rate and recycled fine aggregate with pure asphalt content of less than 0.5%.

An Adjustable Magnetic Switch

In this paper, an adjustable magnetic switch (AMS) based on splice winding is investigated numerically and experimentally. The proposed AMS has advantage of high power level, high repetitive rate capability, long lifetime achievability, and electrical parameters tunability, which meets the growing requirements of the military and industrial application of pulsed power technology. Adjustment of the electrical parameters of magnetic switch is achieved by altering the number of windings via the modification of the joint points between the AMS and the main circuit. Specifically, basic principle of the AMS is analyzed based on characteristics of the magnetic switch. Detailed design considerations are described for achieving modification of the winding’s number ranging from 1 to $M$ (positive integer larger than 1), which is limited by the insulation density, easily and reliably. In order to verify the design, two typical electrical parameters of an AMS are numerically calculated and simulated by the circuit simulation software. Accordingly, a test experiment platform was setup in our laboratory and the primary experimental study demonstrates that the AMS can successfully alter the electrical parameters with results similar to the calculation. A typical ( $1-\cos \omega t)$ pulse with rise times of 4 and 5 $\mu \text{s}$ , a peak voltage of approximately 20 kV, and a peak current of over 1.0 kA was achieved on the capacitor load. The experimental results show reasonable agreement with the theoretical and numerical analyses.

A Comparative Study of Water Electrodes Versus Metal Electrodes for Excitation of Nanosecond-Pulse Homogeneous Dielectric Barrier Discharge in Open Air

Atmospheric pressure low-temperature plasmas produced by dielectric barrier discharge (DBD) provide a promising approach for civilian application of pulsed power technology. In this paper, repetitive nanosecond pulses were generated using a magnetic compression solid-state pulsed power generator, and the rise time and pulse duration of the nanosecond pulse are ~30 and 70 ns, respectively. The DBD in open air is created using two kinds of electrodes, i.e., water and metal electrodes. The electrical, luminous, and optical characteristics of the DBDs under these two electrodes are studied and compared. The experimental results show that no filaments are observed and the discharge is homogeneous when water electrodes are used. The DBD still behaves in a filamentary mode when the discharge gap is extended to 4 cm in the case of metal electrodes. The results are validated by fast images taken by an intensified charge-coupled device camera. In addition, some discussion about the experimental results is presented. Improvement of discharge uniformity is due to the effect of resistive stabilization using water electrodes.

Design and Experimental Realization of a New Pulsed Power Supply Based on the Energy Transfer Between Two Capacitors and an HTS Air-Core Pulsed Transformer

The application of pulsed power technology in the industrial and military fields requires a pulsed power supply as the large current generator. Based on theoretical analysis, it can be found that the traditional capacitor-based pulsed power supply may generate a large residual current during the discharging phase, which results in an adverse influence on the output current and energy transfer efficiency. To obtain higher energy transfer efficiency by eliminating the residual current, a new pulsed power supply based on the energy transfer between two capacitors and a high temperature superconducting (HTS) air-core pulsed transformer is proposed and a small-scale experiment is carried out under the different initial conditions. The experimental results show that a large pulsed current of 3.79 kA within 5 ms can be realized with the initial voltage 1.3 kV, whose energy transfer efficiency exceeds 65%. Finally, the feasibility of this new pulsed power supply is verified and it provides some guidance for future work.

Pulsed Power Applied to Process Industry

This paper is devoted to the application of pulsed power technology to biotechnology, which includes processing of fruit juices, beverages, and dairy products. Pulsed power refers to the technology where a steady accumulation of energy followed by its rapid release results in the delivery of a large amount of instantaneous power over a very short period of time. By releasing the stored energy over a very short interval, a huge amount of peak power can be delivered to a load.

Industrial Applications of Pulsed Power Technology

Recent progress of the industrial applications of pulsed power is reviewed in this paper. Repetitively operated pulsed power generators with a moderate peak power have been developed for industrial applications. These generators are reliable and low maintenance. Development of the pulsed power generators helps promote industrial applications of pulsed power for such things as food processing, medical treatment, water treatment, exhaust gas treatment, ozone generation, engine ignition, ion implantation and others. Here, industrial applications of pulsed power are classified by application for biological effects, for pulsed streamer discharges in gases, for pulsed discharges in liquid or liquid-mixture, and for bright radiation sources.

Agricultural and Food Processing Applications of Pulsed Power Technology

Recent progress of agricultural and food processing applications of pulsed power is described in this paper. Repetitively operated compact pulsed power generators with a moderate peak power have been developed for the agricultural and the food processing applications. These applications are mainly based on biological effects and can be categorized as decontamination of air and liquid, germination promotion, inhabitation of saprophytes growth, extraction of juice from fruits and vegetables, and fertilization of liquid medium, etc. Types of pulsed power that have biological effects are caused with gas discharges, water discharges, and electromagnetic fields. The discharges yield free radicals, UV radiation, intense electric field, and shock waves. Biologically based applications of pulsed power are performed by selecting the type that gives the target objects the adequate result from among these agents or byproducts. For instance, intense electric fields form pores on the cell membrane, which is called electroporation, or influence the nuclei.

Industrial Applications of Pulsed Power Technology

A review of mainly the past two years is undertaken of the industrial applications of pulsed power. Repetitively operated pulsed power generators with a moderate peak power have been developed for industrial applications. These generators are reliable and have low maintenance. Development of the pulsed power generators helps promote industrial applications of pulsed power for such things as food processing, medical treatment, water treatment, exhaust gas treatment, ozone generation, engine ignition, ion implantation and others. Here, industrial applications of pulsed power are classified by application for biological effects, for pulsed streamer discharges in gases, for pulsed discharges in liquid or liquid- mixture, and for material processing.

Development of Pulsed Power Technology and Its Wide Applications

For the wide applications of pulsed power technology, highly repetitive pulsed power generators have been recently developed by use of semiconductor switches. Two examples of recent topics will be introduced. One is a combination of an inductive energy storage and semiconductor opening switch. It produces a sharp voltage spike, which is followed by capacitor discharge with long pulse width. It will be used for excimer laser excitation. Another is stacked MOS-FETs, which can be used in the power supply for the accelerators. Various applications of pulsed electromagnetic energy will be expected using highly rep-rated pulsed power generators.