Solid propellant pulsed plasma thruster driven by magnetic pulse compression circuit

A thorough theoretical analysis of a two-stage magnetic pulse compression (MPC) system is presented. The MPC system suffices to form 20kV, 70ns pulses across a 207Ω resistive load. Equivalent circuits for two consecutive operation stages of the compressor accounting for nonlinear processes in magnetic switches are analyzed. Both experiment and simulation results illustrated pre-pulse and reverse oscillation waveform on the resistive load. A thorough theoretical analysis of the cause of the pre-pulse and reverse oscillation waveform is presented. Equivalent circuits for final operation stage of the compressor accounting for pre-pulse and reverse oscillation waveform in Magnetic Switch (MS) are presented and analyzed. Simulation results illustrated how unsaturated inductance of MS and resistive load affected the amplitude of pre-pulse. To diminish the pre-pulse, unsaturated inductance of MS must be aggrandized which means a better ferrite core with higher differential permeability should be considered. Reverse oscillation waveform can be damped by increasing the inductance of freewheeling inductor which connected in parallel with the load. If a fast-recovering diode is applied as a substitute for the freewheeling inductor, current would mostly flow through the diode while charging, and almost no pre-pulse appears on the load, also the final operation stage matching improves, so that the pulse voltage reverse amplitude and damped oscillation duration are reduced drastically. The experimental results obtained with a resistive load are in fair agreement with the circuit calculation.

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.

In pulsed gas lasers, the excitation of the active medium is produced through the discharge of a storage capacitor. Performances of these lasers were essentially linked to the type of switch used and also to its mode of operation. Thyratrons are the most common switches. Nevertheless, their technological limitations do not allow a high repetition rate, necessary for optimization of the output power of this type of laser. These limitations can be surpassed by combining the thyratron to a one stage of a magnetic pulse compression circuit. The mpc driver can improve the laser excitation pulse rise time and increase the repetition rate, increasing the laser output power of pulsed gas laser such as; nitrogen, excimer and copper vapor lasers. We have proposed in this paper a new configuration of magnetic pulse compression, the magnetic switch is place in our case in the charge circuit, and while in the typical utilization of magnetic pulse compression, it is placed in the discharge circuit. In this paper, we are more particularly interested in the design and the modeling of a saturate inductance that represents the magnetic switch in the proposed configuration of a thyratron - mpc circuit combination.

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.

Recently industrial applications of ozone have increased in widely different areas including oxidation, sterilization, deodorization, bleaching and others. Especially, a demand of movable ozonizer for treatment of diesel exhaust gas has been growing up. Generally, a generation of ozone has been attained using ultra violet irradiation, electrolysis and electrical discharges such as a dielectric barrier discharge, a surface discharge, a pulsed streamer discharge and a superimposed silent and surface discharge. In the present situation, a ozonizer based on a dielectric barrier discharge has been commonly utilized in the world. However, a ozonizer based on a dielectric barrier discharge has disadvantages as a movable ozonizer since a discharge electrode, having a breakable dielectric layer and a sensitive gap separation, does not have enough resistance to vibration stress. In this study, the characteristics of ozonizer based on a pulsed streamer discharge were measured using a magnetic pulse compressor (MPC), which has a maximum output voltage of 60 kV, a maximum pulse repetition rate of 500 pulses per second and a pulse duration of about 130 ns, and discharge reactors with coaxial geometry. For the reactor of pulsed streamer discharges, an anode and a cathode electrodes are made by metallic material and a gap separation between electrodes has a little influence on a discharge condition. Therefore, this type of ozonizer has a merit to apply mobile situation. As the results, the ozonizer based on the pulsed streamer discharges has the better production yield of 150 g/kWh in the concentration range of 10 to 20 g/m

Energy consumption of pulsed arc discharge E in high pressure CO2 up to supercritical (SC) phase was investigated under positive pulsed voltage that was applied to needle-to-plane electrode by a magnetic pulse compression circuit. The gap distance of approximately several hundred μm was set inside a high pressure chamber. The peak current of pulsed arc discharge was in the range of 400-600 amperes at gas and supercritical phases. The E was calculated by the dumped oscillatory voltage and current under the post-breakdown. In the gas phase, the E increased with medium density up to sub-critical phase. Meanwhile, the E was almost stable irrespective of medium density in the supercritical phase. Spectroscopic measurement was also carried out to confirm the local thermal equilibrium of the arc plasma at SC phase. The spectral distribution was characterized by the black body (Planck) radiation and line spectra of atomic oxygen (777 and 845 nm).

Recently, all solid-state pulsed power modulators, which are operated with high repetition rate, long lifetime and high reliability, have been developed to be used for industrial applications of plasmas, such as high repetition rate pulsed gas lasers, high energy density plasma (EUV sources) and pulse ozonizer. We have studied and developed high repetition rate compact pulsed power modulator for discharge plasma in water. This modulator is consisted of thyristor switch and magnetic pulse compression (MPC) circuits. This modulator is able to generate an output voltage of about 25 kV with voltage rise time of less than 200 ns. A repetition rate is 500 pulses per second (pps). We conducted the operation test and generated the streamer kind discharges in the water. We observed that plasma behavior is changed at high repetition rate of 500 pps.

This paper presents a novel type of solid state ballast and ignitor for HID (high intensity discharge) lamps. This ballast is composed of a single-ended resonant-type inverter, which can supply high frequency (100 kHz) power to a 70 W metal-halide lamp, one of the HID lamps, without an acoustic resonance. The proposed ignitor is composed of a magnetic pulse compression (MPC) circuit, which can generate sufficiently high voltage pulses for the instantaneous restarting of the HID lamp. The characteristics of this proposed inverter and ignitor circuits for HID lamps are described in this paper. Based on the results obtained from experiments, the proposed circuits are more useful than the conventional one.

Magnetic pulse compression (MPC) system has been widely used over a few decades as a technique for producing short duration, high peak power pulses reliably. Novel MPC system which do not contain external demagnetization circuits, have broadened the appliance of MPC systems, in which circuit in each level of storage energy capacitors is composed of two capacitors in series, and the two-capacitance combination is connected to the output of previous stage, so that not only the pulse is compressed but also the voltage is doubled as well. In this paper, a 20-kHz high repetition-rate pulse generator with adjustable output amplitude based on Novel MPC system is presented. The pulse generator makes use of commercially available insulated gate bipolar transistor (IGBT), switching a capacitor bank into a ferrite transformer together with a voltage doubling circuit. The capacitor bank is charged to 530 V by a three-phase rectifier, also switched by a commercial diode. The amplitude of the output voltage of the pulse generator is controlled by the amplitude of the gate voltage of the IGBTs. Pulses with a width of 70 ns can be generated with repetition rates up to 20 kHz in burst. The amplitude can be controlled from 5 to 40 kV into a $500~\Omega $ resistive load.

The pulsed corona discharge process shows the encouraging results for the removal of NO/sub x/ and SO/sub x/ gases based on small-scale experiments. The lifetime and the reliability of the system are major difficulties to realize this newly developed technology because the downtime for maintenance affects the plant availability. The combination of a high power solid-state switch with a magnetic pulse compressor (MPC) is a suitable scheme to meet these requirements. An average 120-kW MPC modulator has been constructed and tested with a plasma reactor for an industrial incinerator plant. The plasma reactor has wire-plate electrodes and can treat the gas of 50000 Nm/sup 3//Hr. This modulator can generate 150 kV pulses with 500 nsec (FWHM) pulse width, and 300 Hz repetition rate. This paper presents design details and the operational characteristics of the MPC modulator.

In 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.

To provide a spatially homogeneous and sufficiently high-voltage discharge, the laser described here used LC inversion and two-stage magnetic pulse compression in the excitation circuit and used UV radiation for pre-ionization. It also employed one commercial thyratron as a high-voltage switch. Evaluation of the dynamic magnetic characteristics of four magnetic materials in a magnetic pulse compression circuit showed that the Fe-based nanocrystalline soft magnetic alloy was the best core material for a compact switch with low core loss. At a 10 Hz repetition rate the maximum output energy obtained in a 80/spl times/60 nm discharge cross section and in 70 ns pulses (FWHM) was 6.2 J.

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

An efficient nitrogen laser has been developed. The exciter of the nitrogen laser employs a magnetic pulse compression circuit. A laser pulsed energy of 20 mJ is achieved under a single-pulsed mode, with an efficiency of 1.3% to the output energy of the exciter, and 0.43% to the charging energy. Several types of electrodes were tested. A maximum efficiency and laser light pulse energy are obtained with triangular-rectangular electrodes and at a laser gas pressure of about 100 Torr. >

This paper reports on experimental studies of chemical activities of pulse discharge plasmas generated in contact with water surface. The pulse discharge propagated in the form of streamer channels along the water surface. Hydrogen peroxide was used as a chemical probe for the evaluation. Point-to-plane electrode geometry and pulse high voltage of positive polarity was used for the experiments. A magnetic pulse compression pulsed power modulator was employed. Effects on discharge characteristics of the air gap distance between the high voltage electrode tip and water surface as well as solution conductivity were determined. The discharge characteristics were identical for different gap distances and solution conductivities; meanwhile, the streamer channels' length and their light emissions on water surface were changed with conductivity. No significant effect of gap distance between the needle tip and water surface on the formation of H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> by the pulsed water surface discharge was determined. However, the formation rates of H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> decreased with increasing medium conductivity.