Magnetic Pulse Compression Circuit Research Articles

Effects of tunable circuit parameters on pulsed discharge and input-output characteristics of a XeCl excimer laser

High-pressure, pulsed discharge-pumped XeCl excimer lasers are operating in the ultraviolet range at a wavelength of 308 nm. In this paper, a one-dimensional fluid model coupled to a magnetic pulse compression (MPC) excitation circuit and a laser gain model is established for describing the discharge and laser output characteristics of XeCl excimer lasers. The effects of the peaking capacitor (the terminal of the MPC circuit) on the discharge properties and input-output characteristics are explored. The results reveal that plays a key role in suppressing discharge pulse oscillation, which in turn influences the peak value and duration of the laser pulse. By optimizing the capacitance, a maximum excimer formation efficiency of 6.6% and a maximum laser output efficiency of 5% (output energy of 1.26 J) are obtained when , where is the storage capacitor in the MPC circuit.

Active and Passive Reset Circuits for Multistage Magnetic Pulse Compression (MPC) Circuits Used in Gas Laser Applications

Magnetic pulse compression (MPC) circuits are commonly used in pulsed power circuits for powering gas lasers to shorten the duration of the pulse. If the core of every magnetic switch in the MPC is biased to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-\Delta B_{r}$ </tex-math></inline-formula> by a reset circuit, then the voltage hold-off time is doubled, and the cross-sectional area required is halved. Reset circuits must be isolated from the high-voltage pulses appearing in the pulsed power circuit using filters. The required filter (inductor) size becomes too large if the reset circuit is connected directly in parallel to the magnetic switches, especially if the volt-sec product across the filter inductor is large. The most common, existing reset circuits available in the literature directly connect in parallel to the magnetic switch ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$s$ </tex-math></inline-formula> ) and, therefore, require larger filter sizes to protect the reset circuitry. In addition, reset circuits cannot always be wound on the magnetic core to create a step-down transformation of the pulsed power voltages (lack of physical space or the use of a single primary winding). This article proposes a new reset circuit topology which resolves these problems by enabling the use of the smallest possible filter size (inductance value). In addition, only a single reset circuit is needed to reset multiple magnetic switches in the MPC network. An active reset circuit is also proposed which is more suitable for resetting magnetic cores that are relatively harder, i.e., requiring higher H values to saturate (equivalent currents greater than a few amperes). The reset circuits discussed in this article can in general be applied to many pulsed power applications employing MPC networks.

Dynamics of magnetic pulse compression circuit of metal vapor laser

Solid-state pulse power supply uses magnetic pulse compression circuit (MPC) to reduce the rise time of the voltage pulse applied across the Metal vapor Laser (MVL). In MPC, the nonlinear characteristics of ferromagnetic material is leveraged, to obtain large change in its inductance. These inductors get saturated during application of desired voltages and offer low impedance, which acts like a closed switch. It is desirable to fix the operating point in the B-H curve for smooth functioning of the switch, hence a current is applied to the magnetic switch to reposition the operating point on B-H curve from positive saturation flux to negative before appearance of next pulse. In MVL proper reset becomes extremely important because of small tolerance in the timing, for obtaining low jitter requirement.At low repetition rate, resetting of magnetic switch is easy as the oscillation in L-C circuit in MPC dies out before the next pulse. However, as the repetition rate increases there is very little time for reset dynamics to take place before the next pulse. In this paper we are presenting detailed dynamics of 9 kHz pulse repetition rate MPC for MVL. B-H curve have been derived using voltage, current waveform and Jiles Atherton equation in simulation model. We have shown how MPC oscillation affects the B-H curve of the magnetic switch. An experimentally validated simulation model is developed for detailed analysis of dynamics of MPC and to observe other implications like effect of reset on jitter in output of MPC.

Effects of Voltage and Current Waveforms on Pulse Discharge Energy Transfer to Underwater Shock Waves for Medical Applications

The effects of voltage and current pulse durations of underwater discharge on shock wave generation are reported. In this article, underwater discharges were generated by using a magnetic pulse compression (MPC) circuit. The compression number of the MPC circuit was varied from two compressions to one and no compression; also the capacitance of an output peaking capacitor connected in parallel to discharge electrodes (load) was varied from 10 to 6 and 2 nF. As a result, electric pulses with different rise time/duration and variable peak voltages and currents were obtained and applied to generate shock waves. The shock waves were quantitatively measured with optical principles using a fiber optic probe hydrophone (FOPH) pressure transducer. By reflecting the generated shock waves from a reflector, uniform shock waves were produced, which made it possible to accurately measure the shock waves. The maximum pressure of the generated shock wave after the reflection was in the range of 40 MPa. The energies of the output shock waves were calculated from the pressure histories and the electrical to shock wave energy conversion efficiency was calculated from the electrical energy used to generate the shock waves. The results indicated that the rise time of voltage and current significantly affects the electrical energy that can be delivered to generate the shock waves. For the range of the electric pulse durations of 100 to 500 ns of this article, the shock waves pressures were independent of the pulse duration for the same input energy consumed during the rise and full width at half maximum times of the current. The method presented here gives possibility to select the shock wave profile, which would be crucial for successful medial applications.

Elimination Effect of Airborne Fungi Using Dielectric Barrier Discharges Driven by a Pulsed Power Generator

Fungal spores causes various problems, from human to plants diseases. Because they are suspended in air, these fungi are difficult to control. Penicillium italicum is such an airborne fungus, mainly spreading itself through spores, and is responsible for the most problematic postharvest diseases affecting oranges and other fruits. Their elimination when passing through the discharge section of the dielectric barrier discharge was evaluated. Nonthermal equilibrium plasma was generated by applying the pulsed voltage generated with the magnetic pulse compression circuit to the reactor. The elimination and sterilization effects were evaluated via hemocytometer and colony counting method. When discharge was generated, the numbers of spores in the impinger decreased up to 2.5 Log10, but the numbers attached to the reactor increased by electrostatic precipitation. The spores that adhered to the reactors were not inactivated. These results indicate that most of the spores passing through the discharge space were collected in the reactor, and those were not sterilized by the discharge. However, they were not blown by the air flow with and without discharge either. Our results give evidence that an ethylene decomposition system using DBD should prevent postharvest disease caused by airborne fungi by the electric filter and eliminate them from the transportation container.

磁気パルス圧縮回路の小型化および自動制御に関する研究

磁気パルス圧縮回路の小型化および自動制御に関する研究

A repetitively pulsed xenon chloride excimer laser with all ferrite magnetic cores (AFMC) based all solid state exciter

Performance of repetitively pulsed xenon chloride excimer laser (λ~308nm) with solid state pulser consisting of magnetic pulse compression circuit (MPC) using all ferrite magnetic cores (AFMC) is reported. Laser system suitable for 100Hz operation with inbuilt pre-ionizer, compact gas circulation and cooling has been developed and presented. In this configuration, high voltage pulses of ~8µs duration are compressed to ~100ns by magnetic pulse compression circuit with overall compression factor of ~80. Pulse energy of ~18J stored in the primary capacitor is transferred to the laser head with an efficiency of ~85% compared to ~70% that is normally achieved in such configurations using annealed met-glass core. This is a significant improvement of about 21%. Maximum output laser pulse energy of ~100mJ was achieved at repetition rate of 100Hz with a typical pulse to pulse energy stability of ±5% and laser pulse energy of 150mJ was generated at low rep-rate of ~40Hz. This exciter uses a low current and low voltage solid state switch (SCR) that replaces high voltage and high current switch i. e, thyratron completely. The use of solid state exciter in turn reduces electromagnetic interference (EMI) effects particularly in excimer lasers where high EMI is present due to high di/dt. The laser is focused on a thin copper sheet for generation of micro-hole and the SEM image of the generated micro hole shows the energy stability of the laser at high repetition rate operation. Nearly homogeneous, regular and well developed xenon chloride (XeCl) laser beam spot was achieved using the laser.

Influence of pulse width on decolorization efficiency of organic dye by discharge inside bubble in water

Decolorization of an organic dye by discharge in high conductive water using a pulsed power generator and a discharge reactor was investigated. The discharge reactor consisted of a glass tube and a tungsten wire inserted into the glass tube, which was immersed in the water. Room air was injected into the glass tube to generate bubbles in the water. High voltage pulses were generated by an inductive-energy storage system using semiconductor opening switch (SOS) and by a magnetic pulse compression circuit. Fast recovery diodes were used as SOS diode in the inductive-energy storage system. The pulse width was changed in range from 10 to 1200 ns. The high voltage was applied to the tungsten wire. Indigo carmine was employed as a specimen to evaluate decolorization efficiency. Potassium nitrate was used to adjust the solution conductivity. The dye solution was successfully decolorized at 7 mS/cm conductivity. Energy efficiency for decolorization increased from 0.680 to 55.6 mg/Wh with decreasing the pulse width from 1200 to 10 ns owing to the reduction of ohmic loss.

Effects of pulse frequency of input power on the physical and chemical properties of pulsed streamer discharge plasmas in water

A repetitive pulsed-power modulator, which employs a magnetic pulse compression circuit with a high-speed thyristor switch, was used to study the effects of the pulse repetition rate of input power on the physical and chemical properties of pulsed discharges in water. Positive high-voltage pulses of 20 kV with repetition rates of up to 1 kHz were used to generate a discharge in water using the point-to-plane electrode geometry. By varying the pulse repetition rate, two distinct modes of the discharge plasma were formed in water. The first mode was characterized by the formation of a corona-like discharge propagating through water in the form of streamer channels. The second mode was formed typically above 500 Hz, when the formation of streamer channels in water was suppressed and all plasmas occurred inside a spheroidal aggregate of very fine gas bubbles surrounding the tip of the high-voltage electrode. The production of hydrogen peroxide, degradation of organic dye Acid Orange 7 (AO7) and inactivation of bacteria Escherichia coli by the discharge in water were studied under different discharge plasma modes in dependence on the pulse repetition rate of input power. The efficiency of both chemical and biocidal processes induced by the plasma in water decreased significantly with pulse repetition rates above 500 Hz.

Single Nanosecond Pulsed Electric Field Effects on Embryonic Development of the Medaka Fish

The effects of nanosecond pulsed electric field (ns PEF) on the egg development of the medaka fish are investigated. A pulsed power modulator using a magnetic pulse compression circuit was employed to generate pulses of 0.5-20 kV pulses. Fertilized eggs of strain d-rR medaka were used. The ages of the experimental eggs were new laid, 24-h postfertilization, and 48-h postfertilization. Propidium iodide and fluorescein isothiocyanate (FITC)-dextran conjugate, and a fluorescence microscope were used to study the effects of ns PEF on the blastomeres and the extent of egg structure damage. The FITC was injected to experimental eggs by a microinjection system, which can deliver nanoliters of FITC without producing any damage to the egg structure. Each egg was set at the middle of a 2- or 4-mm cuvette, and a single pulse was applied. The control eggs were sham treated. After the pulse application, the eggs were observed under the fluorescence microscope until they hatched or died. By applying low electric field pulses (10 kV/cm), the effects were minimal and temporary. These eggs could recover and grow as fishes. By increasing the electric field (20 kV/cm), embryos showed abnormal growth with deformed body structure or missing organs. For higher electric fields (over 30 kV/cm), immediate extended damage were observed. The research was motivated by its application in regenerative medicine to control embryonic-stem-cell differentiation and proliferation.

Time-Resolved High-Speed Visualization and Analysis of Underwater Shock Wave Focusing Generated by a Magnetic Pulse Compression Unit

Paper reports on visualization and analysis of underwater shock waves generation, focusing, and propagation. Recently, shock waves have been attractive with rising attention in medical field. Extracorporeal shock wave lithotripter has been one of its very successful applications. However, the effects of shock waves on living tissue are not sufficiently understood, due to unknown parameters involving the shock wave interaction. For better understanding of affecting points, a precise and controllable shock wave source is required. In this paper, in order to study shock wave effects, pulsed electric discharges produced by magnetic pulse compression circuit were used to generate underwater shock waves. A half-ellipsoidal reflector was used for shock wave focusing. The whole sequences of the shock wave generation, propagation, focusing, and cavitation bubbles, which appeared after shock wave passage, were visualized by time-resolved high-speed shadowgraph method. The peak pressure of shock wave focusing at second focal point reached 180 MPa. A cylindrical test section was used to observe phenomena around the electrode from the pulse discharge to bubble collapse. The first cavitation bubble's collapse occurred at about 750 μs. In the experiment, the two shock waves, one generated by expansion of plasma and another generated by collapse of the cavitation bubble were studied. Using high-speed visualization and image analysis, the velocity and pressure of the two shock waves were evaluated. The peak pressure of shock wave generated by bubble collapse reached 157 MPa.

Analysis of temporal jitter in a copper vapor laser system

Temporal jitter in a magnetic pulse compression based copper vapor laser (CVL) system is analyzed by considering ripple present in the input dc power supply and ripple present in the magnetic core resetting power supply. It is shown that the jitter is a function of the ratio of operating voltage to the designed voltage, percentage ripple, and the total propagation delay of the magnetic pulse compression circuit. Experimental results from a CVL system operating at a repetition rate of 9 kHz are presented.

Water Remediation Using Pulsed Power Discharge under Water with an Advanced Oxidation Process

AbstractIn the present study, the degradation of organic contaminants by streamer discharge using a pulsed power generator under water is investigated. The experiments are conducted based on the decolorization of two dyes, Acid Red 1 and Acid Blue 74, and the decomposition of 1,4-dioxane. A gas-liquid separated reactor is developed and employed to achieve degradation with high energy efficiency. A tungsten wire electrode is placed in the gas phase, and a grounded 316 stainless steel wire is immersed in the water. The pulsed high voltage is generated by a magnetic pulse compression circuit and is applied to the wire electrode to generate streamer discharges in the gas region, which propagate into the bubble injected into the water. Oxygen and argon gases are injected to identify the dominant reactions of the degradation of organic contaminants. Acid Red 1 and Acid Blue 74 solutions are successfully decolorized by the discharges. The ozone produced by discharges in the gas region primarily decolorizes the dye solutions. The total organic carbon (TOC) of the 1,4-dioxane solution decreases due to discharge when argon is injected. The decrement rate of TOC does not increase through gaseous ozone injection or by discharges in the case of oxygen injection. These results show that the chemical species produced by discharges and by chemical reactions in the solution, such as hydroxyl and hydroperoxyl radicals, primarily decompose 1,4-dioxane. Iron ions dissolved by electrolysis enhanced the TOC decrement rate according to the Fenton reaction in acidic conditions.

Characteristics of Micro Underwater Shock Waves Produced by Pulsed Electric Discharges for Medical Applications

The paper reports on the production and focusing of micro underwater shock waves for medical applications. Shock wave focusing has various scientific, industrial and medical applications. For precise shock wave therapies near sensitive organs, such as cranioplasty in the close vicinity of the brain, a micro-shock wave source is required. A half-ellipsoidal cavity with a 20.0 mm minor diameter and with a ratio of the major to the minor diameters of 1.41 was designed and constructed as an extracorporeal shock wave (ESW) source. Underwater shock waves were generated by using the electric discharge produced by a magnetic pulse compression circuit (MPC) and an electrode. The input voltage and the input current were measured by using an oscilloscope and a current monitor. The whole sequence of shock wave generation, propagation, and focusing was observed by using time-resolved high-speed shadowgraph visualization method. Pressure histories were measured at different stand-off distances by using PVDF needle and fiber-optic probe hydrophones. A wide range of peak overpressures from 10 to 200 MPa at the focus was obtained, and a small focal zone and focal energy flux density were measured. We conclude that the present compact extracorporeal shock wave generator has appropriate characteristics for application in precise and sensitive medical procedures.

High-Performance Pulsed-Power Generator Controlled by FPGA

The high reliability, high repetition rate, high performance, and compactness of pulsed-power generators are required for industrial applications. Also, the control of a pulsed-power generator becomes more complicated with increasing functions. An all-solid-state pulsed-power generator can be controlled by using a field-programmable gate array (FPGA). The pulsed-power generator consists of a charger, a magnetic pulse compression circuit, and a controller using the FPGA. The performance characteristics of the pulsed-power generator, such as the variable firing interval from shot to shot and the diagnosis of incorrect operation, are easily achieved by rewriting the programming of the Verilog hardware description language on the FPGA.

水中ストリーマ状放電プラズマ生成のための高繰り返し小型磁気パルス圧縮回路開発

水中ストリーマ状放電プラズマ生成のための高繰り返し小型磁気パルス圧縮回路開発

Characteristics of Magnetic Core in Magnetic Pulse Compression System

In order to obtain the characteristics of magnetic core under … 0:5{5 „s saturation time, a one-stage magnetic pulse compression circuit without external demagnetization circuits which are commonly used in magnetic compressors is designed. The current through the core is calculated by voltage across the resistive load, and the loop voltage is picked up with a single wire loop and integrated by software. B{H curves are derived from the measured voltage and current wave forms. B{H curves show that the core loss is in inverse proportion to the time to saturation, whereas the percentile core loss decreases as the charging energy increases. While the eddy current loss and dissipated energy are in direct proportion to dB/dt. The low inductance of magnetic switch indicates that the core is saturated and behaves as an air core. By applying custom characteristics to each stage in Pspice simulation, more practical energy transfer in magnetic pulse compression and the efiects of leakage current are presented.

A method of water-bloom prevention using underwater pulsed streamer discharge

Water-bloom (also named as cyanobacterial bloom) is becoming a very serious pollution problem all over the world. In this paper, a new method for the prevention of water blooms using underwater streamer discharges is reported. Blumlein pulse forming network (B-PFN) and magnetic pulse compression circuit (MPC) were employed to apply high voltage pulses to water with cyanobacterial cells. The experimental results confirmed that the cyanobacterial cells sank to the bottom of the water bodies after applying underwater streamer discharges. Transmission electron microscope (TEM) observations showed that the discharge collapsed the gas vesicles (GVs)—the intercellular structure of water-bloom forming cyanobaterial cells—and did not affect the other part of contents of the cells. Cynabacterial cells lost buoyancy and sank to the bottom of the water bodies. Because of lower temperature and without enough sunlight at the bottom of the water bodies, the cells can be prevented from proliferation too quickly.

A design approach for systems based on magnetic pulse compression

A design approach giving the optimum number of stages in a magnetic pulse compression circuit and gain per stage is given. The limitation on the maximum gain per stage is discussed. The total system volume minimization is done by considering the energy storage capacitor volume and magnetic core volume at each stage. At the end of this paper, the design of a magnetic pulse compression based linear induction accelerator of 200 kV, 5 kA, and 100 ns with a repetition rate of 100 Hz is discussed with its experimental results.

Effect of a magnetic pulse compression circuit on the operation of a halide laser

A magnetic pulse compression (MPC) circuit is used to investigate the operation of a thyratron and the output parameters of a copper chloride laser as a kind of halide copper vapor laser. The inverse voltage on the thyratron anode, maximum and rise time rate of the current, and losses of the thyratron are determined and compared in circuits with MPC and without MPC. Experimental data shows that, in the circuit with MPC, the lifetime of the thyratron is increased, and the output power of the laser is also increased by about 60%, while the width of the optical output is decreased by up to 53%.