Search

As part of the ongoing China Fusion Engineering Test Reactor (CFETR) studies, this work focused on the study of the electromagnetic (EM) loads distribution on inboard (IB) and outboard (OB) blanket vertical segments. In this paper, a major central disruption scenario with a 36-ms linear current quench was performed in the ANSYS finite element software. EM forces and moments, both on the single module and the complete blanket segment, were calculated for the updated helium-cooled ceramic breeder (HCCB) blanket. Furthermore, the effect of EM loads with respect to poloidal segmentations on the back plate (BP) was studied. Results show that the EM forces and moments in the IB blanket barely changed, but in the OB blanket, great changes occurred. With poloidal segmentations increasing, EM forces loads on the BP will be reduced. This paper may provide important data to support subsequent optimization of the BP of CFETR and could also be a technical reference for other fusion organizations. [ABSTRACT FROM AUTHOR]

High-voltage power supplies (HVPSs) are widely used to supply vacuum tubes. The amount of delivered energy from the HVPS to the tube is an important issue during the vacuum arc in the tube. The conventional protection mechanism consists of a shunt crowbar which diverts the fault current from the tube to itself as a parallel path. The crowbar circuit is usually built of the devices without the turn-off capability. It is a drawback since the output of the power supply is shortened for a long time. Thus, the restoration time of these power supplies is excessive. This demerit can have detrimental effects on mission-critical applications. In this paper, the insulated-gate bipolar transistor (IGBT)-based crowbar structure is studied to overcome this issue. In the proposed protection mechanism, the crowbar can be reopened intentionally after closing. A theoretical analysis is presented to compare power supply performance in the presence of the conventional crowbar with the IGBT-based crowbar. The experimental results are presented to demonstrate the practical considerations of the proposed crowbar structure and its appropriate performance. This paper shows that HVPS has more fault resiliency and less restoration time with the proposed IGBT-based crowbar. [ABSTRACT FROM AUTHOR]

This paper has introduced two important indexes, turn-off surge voltage (TSV) on power switch and peak positive pole potential (PPPP) of storage batteries, which can be used to evaluate switching transient process of high-voltage energy storage system. Research on them is of great significance to power switch choice and high-voltage isolation design in engineering applications. Power switch response process at the turning off moment and transient process in freewheel stage have been analyzed by the established small-signal model of single power switch; then, a power switch test platform for hybrid energy storage system was built to verify it. Taking pulsed-power supply charging device with a novel inductor of low resistance and high inductance as a research object, this paper has analyzed dynamic process of the TSV and the PPPP at the turning off moment through establishing state space model of the whole system. Comparison shows that the numerical curves match the simulated curves well. Finally, the exactness of the employed model has been further verified in two pulse capacitor charging experiments. [ABSTRACT FROM AUTHOR]

This paper embodies the results of experimental studies of a dielectric barrier discharge low-temperature nonequilibrium plasma reactor that runs in air and nitrogen at atmospheric-pressure conceived for surface treatment applications. A homemade reactor, of typical plane-to-plane geometry with the dielectric covering the upper electrode which is stressed by a high voltage (40 kV, 3–20 kHz) is used. Electrical signals (current and voltage), optical emission spectroscopy records, and total light emission measured by photomultiplier have been analyzed and used to distinguish different plasma regimes which are studied for the treatment of a lignocellulosic material (sugarcane bagasse). In the filamentary discharge regime, the gas temperature of few tens of degree Celsius above the ambient one was determined, the electronic temperature of some electronvolts and electron density in the range of 1012–1013 cm−3 were estimated. Plasma treated pellets of sugarcane bagasse were analyzed by diffuse reflectance infrared Fourier transform spectrometry and the relative results obtained under filamentary discharge regime have shown significant degradation of the lignin macromolecule. It has been shown important modifications on the lignocellulosic material, namely, the plasma attacks drastically the lignin bonds. Strong modification of lignin was observed near wavenumber of 3400 cm−1, due to stretching vibrations of OH, and for the band 1114 cm−1 which is related to C=C and C=O stretching. Severe decrease of the band intensity 1596 cm−1, which due to C=C stretching and C=O, is also a result of the treatments done in this paper. [ABSTRACT FROM AUTHOR]

In this paper, a new configuration of dielectric-barrier discharge (DBD) reactor with three electrodes was manufactured and used to produce ozone. Designed flatly, this reactor is capable of establishing three different discharge modes from type of the volume and surface discharges, without modifying its internal structure. The aim of presenting this paper is to experimentally analyze the three discharge modes and their combination using a second channel to produce ozone. The two reactor channels are identical in terms of dimensions, material, and manufacturing process. Two frequency-adjustable pulse generators of the same electrical characteristics and two high-voltage transformers were used in the course of the experiments. The applied sinusoidal voltage is from 0 to 12 kVp-p. The frequency range was determined and fixed for all three discharge modes for the highest ozone concentration at a fluctuation rate of 1 L/min. Effects of increasing the applied voltage on the obtained concentration from the three different discharge modes were experimentally analyzed. Using the provided inlets–outlets, the effect of flowing gas through the length and width of the discharge area on ozone concentration was investigated, and appropriate flow directions were determined for the flowing gas under either of the three discharge modes. Experimentally results have been done for this three discharge modes as well as hybrid modes. The maximum ozone production rate achieved up to 14.52 g/h in the series combination of two different volume discharge. At 96% oxygen purity, ozone production yield, in two modes volume discharge VaDBD and surface discharge SDBD, have been improved up to 529.87 g/kWh. However, the total input power of the entire system is 120.2 W. [ABSTRACT FROM AUTHOR]

Photoelectric characteristics are an important reference for high-voltage discharges and are closely related to the excited mode of the high-voltage source. In this paper, we built a large-scale volume dielectric barrier discharge (DBD) system, which is composed of multilayer parallel-plate DBD electrodes and is excited by a high-voltage source in the power density modulation (PDM) mode. Subsequently, we analyzed the applied energy equation and evaluated the DBD systems photoelectric characteristics. The results show that the energy values of different applied voltage cycles during a PDM period exhibit significant differences. However, the average energy in a PDM period is approximately constant. Moreover, the equivalent capacitance of the DBD cell is a function of both the applied voltage and energy density. For the DBD cell, with the increase in both the applied voltage and energy loaded on the DBD cell, the total equivalent capacitance ($C$) is approximately constant, the dielectric capacitance ($C_{\mathrm{ d}}$) increases exponentially and decreases linearly, while the discharge gap capacitance ($C_{\mathrm{ g}}$) decreases and increases in the same cases. In addition, the relative intensities of the discharge emission increase and the energy efficiency ratios of the relative photoquantum yield of active species decline with the increase in both the applied voltage and energy density loaded on the DBD cell. The experimental results have been analyzed by evaluating the influence of the electrical parameters, and the underlying physical principles have been discussed. This paper clearly demonstrates that the photoelectric characteristics of the DBD reactor are significantly influenced by both the applied voltage and energy density, thus providing helpful insights into the energy evaluation and application of high-voltage discharges. [ABSTRACT FROM AUTHOR]

In inertial confinement fusion, the scientific issues include the generation and transport of driver energy, the pellet design, the uniform target implosion physics, and the realistic nuclear fusion reactor design. In this paper, we present a pellet injection into a power reactor in heavy-ion inertial fusion (HIF). We employ a magnetic correction method to reduce the pellet alignment error in HIF reactor chamber, including the gravity, the reactor gas drag force, and the injection errors. We found that the magnetic correction device proposed in this paper is effective to construct a robust pellet injection system with a sufficiently small pellet alignment error. [ABSTRACT FROM AUTHOR]

This paper discusses a novel methodology to increase the voltage droop compensation range in generalized solid-state bipolar high-voltage Marx modulators with one resonant stage. To maintain the modularity characteristic of bipolar Marx modulators, the imbedding of additional resonant stages is not straightforward. Nevertheless, this paper proposes to add a second resonant stage to the already existing resonant-type voltage droop compensation stage. This second stage increases the voltage droop compensation percentage of a generalized solid-state bipolar Marx generator. The compensation of the bipolar pulse voltage droop is now achieved by adding two auxiliary synchronous compensation resonant voltages, to the output capacitive decaying voltage. Simulation and experimental results are presented for six Marx plus two resonant stages, 16% voltage droop, with 3-kV pulse amplitude, 100- $\mu \text{s}$ pulsewidth, 40-ms relaxation time, and 10-Hz pulse repetition rate. [ABSTRACT FROM AUTHOR]

This paper presents the design and construction of a sample of Marx pulsed generator based on boost converter (BC) pulse-forming networks (BCPFNs). BCPFN is used instead of the conventional Marx floors for constructing this pulsed generator. BCPFN is carried out by connecting inductors and capacitors in series and parallel modes, respectively, by using solid-state switches, and during this procedure the pulsed generator converts to BC temporarily and increases the voltage of capacitors uniformly to a considerable value. This technique causes an increase in the discharging voltage level to the load that is many times more than its dc voltage source by charging the capacitors to a greater level. In order to take advantage of the benefits of Marx generator and PFN, this paper suggests a new circuit with the minimum number of switches. It means, to compose BCPFN and Marx, we have tried to design the circuit with fewer switches and instead of it we have achieved our desired performance with changing the operating mode in the states of BC, PFN, BCPFN, and BCPFN Marx. The results are simulated with MATLAB software. At the end, the experimental results of the construction of the above-mentioned system at low-power levels are presented, and the topology’s accuracy is proved by comparing them to the results of simulation. [ABSTRACT FROM AUTHOR]

This paper will describe the influence of mesh geometry on the homogeneity of discharges, power, and efficiency of ozone generation. Homogeneous discharges increase the efficiency of the generation of ozone. Geometry of mesh electrodes affects the power and type of discharges, concentration, and efficiency of the ozone generation. The analysis of selected results indicates the need for the use of mesh electrodes with a small cross section at least $0.1\times0.1$ mm2 mesh to obtain a homogeneous discharge. The mechanism by which the geometry of mesh electrodes on the homogeneity of discharge is illustrated in this paper. Homogeneous discharges increase the efficiency of the generation of ozone that reduces the cost of ozone production. The results of the experimental studies show an increase in the average efficiency of 60% of the ozone generation and a 20% reduction in the demand for power with the constant concentration of ozone, justifies the problem. [ABSTRACT FROM AUTHOR]

This paper presents a shutdown dose rate (SDR) calculation to estimate a newly developed preliminary concept of the equatorial port model for the Korean fusion demonstration reactor (K-DEMO). The equatorial port model was designed to provide effective radiation shielding abilities adopting the port shielding block and labyrinth structure, which was integrated into the modified K-DEMO neutronic analysis model by the Monte Carlo automatic modeling system. A rigorous two-step method was applied to couple transport (MCNP) and activation (FISPACT) codes according to three steps of calculation procedures. The results of neutron flux and decay gamma transport calculation for the equatorial port area have been indicated in this paper. The SDR calculation result near the equatorial port area reveals that a dose level in the equatorial port interspace was below $100~\mu $ Sv/h after 12 days of the shutdown. Shielding blocks and two labyrinth structures prove that they effectively attenuate neutrons on the current concept of the equatorial port model. [ABSTRACT FROM AUTHOR]

The halogen volatile organic compound (VOC) is a common industrial pollutant, mainly including trichloroethylene, dichloromethane, trichloroacetic acid, chloro-fluoro-carbons, carbon tetrachloride, trihalomethans, chlorodifuoromethanes, hydrofluorocarbons, and some other fluor alkaline, ether, and amine. The halogen VOCs have reproductive toxicity, immunotoxicity, and neurotoxicity. The traditional methods for treating them include masking method, dilution method, chemical oxidation method, incineration method, UV oxidation method, photocatalytic oxidation method, absorption method, and biological method. In this paper, advantages and disadvantages of traditional methods have been studied and analyzed. A new plasma technology has been put forward, which has the advantage of the rapid reaction to ambient temperature, wide applications, system compactness, simplicity of operation and short residual time, and the plasma technology is especially appropriate for the decomposition of VOCs. At present, as for the control of VOCs, the plasma technology has drawn much attention as an energy-saving technology. In this paper, the equipment for the decomposition of halogen VOCs has been analyzed, including the plasma rectors, power characteristics, operation conditions, and the decomposition mechanisms of C2HCl3, CH2Cl2, C2H3Cl3, CCl4, CHCl3, CF4, C2F6, and SF6 have been investigated and concluded. Finally, it is concluded that the combination of the plasma technology with traditional methods would be main direction of study in the future. [ABSTRACT FROM AUTHOR]

This paper is to experimentally investigate the effect of plasma-activated gas on the characteristics of a laminar lifted nonpremixed jet flame in a coflow stream. A coaxial dielectric-barrier discharge is employed to activate fuel (C3H8) and oxidizer, respectively. It is shown that an enhancement of 12% and 50% in the liftoff velocity is observed for oxidizer and fuel activation, respectively. With the addition of O3 (1650 ppm) by oxidizer activation, the flame liftoff height is continuously decreased and the blowout velocity is extended. In contrast, a larger liftoff height, accompanied with a smaller blowout velocity, exhibits for flames with fuel activation. The inconsistent effect of fuel activation on the flame liftoff is presumably a contribution of the gas expansion, the conversion rate, and the corresponding product selectivity. The gas expansion is due to the fuel activation that produces lighter hydrocarbons than propane. The conversion rate and the H2 and CH4 selectivities are found to be associated with the plasma energy density. The flame propagation can be greatly enhanced to produce a nozzle-attached flame when the plasma energy density is high enough to effectively decompose C3H8 into H2. Nevertheless, a decrease in plasma energy is more sufficient for the cleavage of C–C bonds, resulting in a significant decrease in H2 selectivity, but a nearly unaltered CH4 selectivity. The reduced conversion due to the lower plasma energy, along with the gas expansion, produces a lifted flame with a larger liftoff height than the nonactivated flame. [ABSTRACT FROM AUTHOR]

Nonequilibrium plasma is an effective and one of versatile advanced oxidation process due to the formation of reactive species such as hydroxyl radicals, oxygen atom, and hydroperoxyl radicals. In pulsed discharge, free electrons gain energy from an imposed electric field and lose this energy through collisions with neutral gas/liquid molecules. The transfer of energy to the molecules leads to the formation of a variety of new species including atoms, free radicals, and ions. These products are all active chemically, and in our case, we measure the amount of hydroxyl radicals generated in the reactor and also the amount of escaped ozone generated in the reactor and decolorized indigo reagent in a graduated cylinder (GC). In this paper, we used oxygen and argon gases in various flow rate and mixed ratios to feed a gaseous phase in a water spraying droplet reactor. The experimental results indicated that the oxygen and O2/Ar mixture flow rates in spraying reactor have an effect on both hydroxyl radical generation and decolorization of indigo reagent solution. Argon gas discharge has less effect on hydroxyl radical production compared to the oxygen gas discharge with the same flow rates and no effect on the decolorization of indigo reagent solution in GC. We obtained remarkable results on both hydroxyl radical generation rate and decolorization efficiency of indigo reagent solution when we discharged with the mixture of O2/Ar “especially when the ratio has more oxygen than argon gas.” Hence, the presence of oxygen in the water spray plasma discharge is very important as it influence the generation of reactive species such as O atoms and ozone in the gas and liquid phase, which can react directly with organic contaminants and also contribute to more production of hydroxyl radicals in the aqueous phase. [ABSTRACT FROM AUTHOR]

High power pseudospark switches (PSSs) can control pulsed high voltage, high peak current discharges. In this paper, a PSS in series with a saturable inductor at the anode is investigated. The commutation process is analyzed with a time-resolved method. And the effects of the number of magnetic cores and anode voltages on discharge characteristics are studied experimentally. At the beginning of commutation process, when the anode voltage is 10.4 kV with four magnetic cores, the inductor is unsaturated, and there is a flat plateau of the forward voltage drop after the anode voltage drops rapidly to about 200 V, at the same time the current rise rate is 2.8 kA/ $\mu \text{s}$. When the inductor is saturated, there is a voltage spike that occurs at the end of the flat plateau, and the current simultaneously rises rapidly at the rate of 6.4 kA/ $\mu \text{s}$. The current sharp rise lags behind the voltage drop of the pseudospark gap, and the electrode erosion and energy dissipation reduce significantly. When the anode voltage is 15.6 kV, the commutation losses reduce by about 30% with seven cores in series at the anode. As a result, it is evident that the discharge process will speed up if the anode voltage is higher. And the trigger delay decreases by up to 8% when the anode voltage varies from 5.2 to 15.6 kV. Finally, in order to obtain a reproducible pseudospark discharge by the use of a saturable inductor, the number of magnetic cores has to be optimized for different anode voltages. [ABSTRACT FROM AUTHOR]

This paper describes a study on the high-voltage compact solid-state pulsed-power modulator for parallel reactor operation. The current capacity of the pulsed modulator has been improved to drive multiple reactors in parallel. The pulse discharge switch uses the IXYK120N120C3 (1200 V/120 A) insulated-gate bipolar transistor for a high current output. The gate driver has been improved according to the characteristics of the replaced switch. The output specifications of the modified pulsed-power modulator are a maximum output voltage of 40 kV, a maximum output current of 300 A, a pulsewidth ranging from 1.5 to $5~\mu \text{s}$ , a maximum repetition rate of 3 kHz, and an average power of 13 kW. The modulator has the dimensions of $450 \times 475 \times 600$ mm3, a maximum peak power of 12 MW, and a maximum power density of 93 kW/L. A resistive load experiment and a plasma reactor parallel drive test were performed. Four parallel reactors were driven using one modulator. In addition, a 50% reduction in the concentration of toluene was obtained through the experiment of the toluene gas treatment using only parallel plasma reactors. [ABSTRACT FROM AUTHOR]

Because it possesses higher current turn-off capability, the inverse current commutation with semiconductor devices (ICCOS) is a better option for the opening switch of an inductive pulsed power supply than the integrated gate commutated thyristor. This paper investigates the counter-current capacitor, which is the key component that determines the turn-off result and the volume of the counter-current branch. The major contributions of this paper include the following: 1) deriving an analytical expression for the minimum precharged capacitor voltage that can reliably turn off the main switch; 2) verifying this expression through a series of experiments within a current range of 0 to 4000 A and an energy range of 0 to 50 kJ; 3) giving an approximate expression for the optimal capacitance that minimizes the precharged energy; and 4) investigating the variation trends of the optimal capacitance and the corresponding optimal precharged energy with varying inductor current. [ABSTRACT FROM PUBLISHER]

Based on the urgent needs for modularization and miniaturization of the inductive pulsed power supply system, this paper proposes the conceptual design and comparison of 100-kJ inductive storage power modules including four circuit topologies, three of which are proposed in our previous researches. The four circuit topologies are the STRETCH meat grinder, the XRAM with STRETCH meat grinder unit, the XRAM with strongly coupled inductors, and the XRAM with magnetic flux compression effect. The maximum load current of each constructed module is set to be 50 kA and its pulsewidth is at least 5 ms, which are the same as the main electrical properties of an existing 100-kJ capacitive module. A comparative study on energy density among the constructed inductive modules and the existing capacitive module is carried out in depth. Results show that the inductive modules, considering the volume of semiconductor switches and their control circuits, have higher energy density than that of the capacitive module. Among four constructed inductive modules, the XRAM with strongly coupled inductors module has the highest inductive energy density, and the XRAM with magnetic flux compression effect module has relatively better comprehensive performance. This paper offers the theoretical analysis foundation for investigating the inductive pulse power supply with higher energy. [ABSTRACT FROM PUBLISHER]

Superconducting pulsed-power supply (SPPS) provides an efficient method for both high-density inductive energy storage and high current pulse generation. An SPPS consisting of eight high-temperature superconducting pulsed-power transformer (HTSPPT) modules with XRAM methodology was designed and simulated in preliminary studies. It recycled the leakage flux energy and reduced the voltage across the opening switch with a capacitor in primary. However, the SPPS with XRAM methodology has two problems. The first one is that it can provide high pulse amplitude, but cannot provide enough width. The other one is that the ratio of the maximum capacitive energy over the total inductive energy is relatively large, which cuts down the overall system energy density. This paper proposes a modified topology of SPPS with capacitor reuse methodology. Multiple HTSPPT modules are divided into several groups. Each group shares the same capacitor. The procedure of the modified SPPS is presented in detail. A 270-kJ SPPS with capacitor reuse methodology is designed and simulated to illustrate the modified topology. With the load parameters of a small railgun, the peak value of the load current is 207.15 kA and the pulse half-height width is 5.56 ms, the ratio of the maximum capacitive energy over the total inductive energy is 11%. The characteristics of the modified topology are also described in detail in this paper. [ABSTRACT FROM PUBLISHER]

The role of irreversible electroporation using pulsed electric field is to generate high-voltage (HV) pulses with a predefined magnitude and duration. These HV pulses are applied to the treatment chamber until decontamination of the sample is completed. In this paper, a new topology for HV rectangular pulse generation for water disinfection applications is introduced. The proposed topology has four arms comprised of series-connected half bridge modular multilevel converter cells. The rectangular pulse characteristics can be controlled via the software controller without any physical changes in power topology. The converter is capable of generating both bipolar and monopolar HV pulses with microsecond pulse durations at high a frequency rate with different characteristics. Hence, the proposed topology provides flexibility by software control, along with hardware modularity, scalability, and redundancy. Moreover, a cell’s capacitance is relatively small, which drastically reduces the converter footprint. The adopted charging and discharging process of the cell capacitors in this topology eliminate the need of any voltage measurements or complex control for cell-capacitors voltage balance. Consequently, continuity of converter operation is assured under cell malfunction. In this paper, analysis and cell-capacitor sizing of the proposed topology are detailed. Converter operation is verified using MATLAB/Simulink simulation and scaled experimentation. [ABSTRACT FROM AUTHOR]

A pulsed discharge plasma (PDP) system with a multineedle-to-plate geometry electrode was applied in this paper to investigate the regeneration of granular activated carbon (GAC) spent with phenol in the PDP system. Regeneration percentage of the GAC under different conditions of initial solution conductivity and pH values was studied to clarify the regeneration of the GAC by the PDP. Formation of hydrogen peroxide (H2O2) with the same solution conditions was also investigated in this paper. The obtained results show that there was the same changing trend of GAC regeneration and H2O2 formation under different solution conditions, which clarify the critical effect of •OH on the GAC regeneration in the PDP system. The methods of scanning electron microscope (SEM), Brunauer–Emmett–Teller, Boehm titration, and Fourier transform infrared spectroscopy (FTIR) were used in this paper to demonstrate the medication of the GAC by the PDP treatment. The obtained results show that the regenerated GAC could recover a partial pore structure compared with the original GAC by the SEM analysis. The surface area, micropore volume, and total pore volume of the regenerated GAC increased, while the mesopore volume and the macropore volume decreased on the regenerated GAC; comparing with the original GAC, there was higher amount of acidic functional groups and lower amount of basic functional groups on the surface of the regenerated GAC; the intensities of O–H, C=C, C=O, and C–O enhanced significantly by the FTIR analysis. [ABSTRACT FROM AUTHOR]

Triple dc plasma torch system was used for the synthesis of nanoparticles. Three thermal plasma jets are ejected from each plasma torch and they are merged into a strong single plasma plume. Since the feedstock is injected into the jet merging area, this system is suitable for refractory nanoparticle synthesis and enable to high production yield caused by the complete evaporation is possible. In this paper, numerical simulation was carried out to analyze thermal plasma characteristic inside a reactor according to the plasma-forming gas and carrier gas compositions: Ar, Ar–H2, and Ar–N2 plasma; Ar, He, and N2 carrier gas. Then, it was comparatively interpreted with the actually synthesized nanoparticle in order to understand the condensation process of nanoparticles. It was revealed that the thermal environment is able to control readily in the triple torch system by the operating condition depending on the target materials. [ABSTRACT FROM AUTHOR]

In this paper, we discuss and demonstrate the potential of normally-on GaN high-electron-mobility transistors (HEMTs) as opening switches in miniaturized pulsed-power circuits. The high-breakdown electric field of GaN (~3 MV/cm) makes it possible to fabricate high-voltage devices in small dimensions, resulting in smaller parasitics and faster switching times. GaN HEMTs as opening switches are compatible with inductive topologies, which offer more than one order of magnitude higher energy density than capacitive topologies, allowing further miniaturization of pulsed-power systems. In this work, we demonstrate the application of fabricated 1.5-kV normally-on GaN HEMTs on an inductive switching topology, resulting in 300-fold voltage step-up, which makes it possible to generate high-voltage pulses with a low-voltage dc source in miniaturized circuits. [ABSTRACT FROM AUTHOR]

In this paper, we present the results of experimental investigation of the properties of dusty plasma formed in a pulsed plasma accelerator (IPU-30) through the interaction of pulsed plasma beams with a carbon-based target. In the experiments, the interaction of beams of the pulsed plasma with the surface of the carbon plates affords instantaneous heating of the target substrate and subsequent ejection of dust particles from the surface of the plates into the plasma bulk. These dust particles are dragged by the plasma beam creating a moving plasma-dust cloud. A high-speed camera (Phantom VEO710S) is used to obtain the velocity of the dust particles in a beam of the pulsed plasma. Ejection of dust particles is investigated at two different values of the discharge voltage (7 and 12 kV). [ABSTRACT FROM AUTHOR]

Theoretically, the energy conversion efficiency of the synchronous induction coil launcher (SICL) can reach 100%, but at present, the test data show that the highest current is only a little higher than 20%, which shows that the efficiency of the coil launcher has a lot of room for improvement. In this paper, three improved schemes are proposed for the topology of the traditional crowbar circuit based on the pulse capacitor to improve the electromechanical energy conversion efficiency of the electromagnetic coil launcher. They are main circuit breaking, crowbar break-off circuit, and crowbar circuit with inductor, respectively. In order to verify the feasibility of the above three methods, a five-stage coil launcher was simulated and analyzed. Then, based on the model, three improved circuits were calculated and analyzed by the finite-element simulation software. The results show that all of the three methods can improve the efficiency of energy conversion to a certain extent. Both the first and second methods have limited effect on increasing efficiency. In addition, they need to add some expensive equipment such as circuit breaker. So, they are not recommended. The third way of increasing an inductor in the crowbar circuit could increase the muzzle velocity and efficiency obviously. The muzzle velocity increased from 30.6 to 35 m/s. The effect of armature capture is reduced which is worthy of recommendation. [ABSTRACT FROM AUTHOR]

This paper proposed the use of a ringer, a self-switched inductive storage system, for applications involving reluctance accelerators, a kind of electromagnetic launcher, and compatible with applications where portability is a requirement. There will be shown three different useful approximations for the analysis of the ringer, employed as a power source for a reluctance accelerator. First, it described the equations governing the que behavior of an ideal unloaded ringer, and then the equations for the ringer with an uncoupled inductive load, and ultimately a Lagrangian model for the ringer as an inductive power source for a reluctance accelerator, capable to make predictions about the currents through the circuits and the exit speed of the projectile for a given firing. The accuracy of the predictions made with the third approximation, the Lagrangian model, was tested experimentally. [ABSTRACT FROM AUTHOR]

This paper focuses the tunability of a reflex triode virtual cathode oscillator (vircator). The vircator cathode is a bimodal carbon fiber (CF) material, while the anode is polished pyrolytic graphite. These materials have ideal operating characteristics for use within a vircator. These materials have high operating temperatures greater than 1000 K which support large current densities of ~200 A/cm2. A 12-stage, 158-J pulse-forming network (PFN)-based modular Marx generator is used to drive the vircator at 350 kV, 4 kA with ~100-ns pulsewidth at a pulse repetition frequency up to 100 Hz. The 12 stages of the Marx are constructed from a PFN using five, 2.1 nF, high-voltage ceramic capacitors in parallel. The Marx is broken into six modules each containing two stages. The Marx modules are machined from acetyl copolymer commonly called Delrin to provide rigidity and strength. Each Marx module includes air supply lines machined directly into each block, allowing external airlines to connect to each module chamber, rather than every spark gap. After the Marx erects, the energy is used to drive the virtual cathode oscillator (vircator) where subsequent frequency generation is manipulated through a new rectangular waveguide used as the resonant cavity. The new design has three parts of the cavity that can be changed; the bottom plate, back wall, and anode–cathode gap (A–K) distance. Each of these parts moves via linear actuators, two on the bottom plate, one on the A–K gap, and linear bellows for the back wall. The square waveguide cavity is welded into a circular stainless steel sleeve and is housed within a 10-in circular vacuum chamber. The anode is stationary in the vacuum chamber and connects to the Marx generator through a nickel shaft that feeds through the back wall, circular sleeve, and the rectangular waveguide. The anode is pyrolytic graphite, while the cathode is CF. The waveguide bottom plate, back wall, and cathode move around the stationary anode. This allows the height of the resonant cavity and the back wall distance from A–K gap to be independently changed of each other. [ABSTRACT FROM AUTHOR]

The superconducting inductive pulsed-power supply (IPPS) is considered to have broad application prospects in the field of electromagnetic launch because of its low electrical loss. In order to obtain a higher efficiency in continuous electromagnetic launch, a repetitive IPPS circuit topology based on a high-temperature superconducting pulse power transformer (HTSPPT) has been proposed in our previous studies. It can recover most of the remaining energy for generating continuous current pulses by using a bridge-type capacitive switching circuit. As a follow-up work, this paper presents a multimodule repetitive superconducting IPPS model for a railgun system. This multimodule model consists of 24 HTSPPT modules connected to an XRAM-like circuit topology. In order to verify the feasibility of the repetitive superconducting IPPS and study its driving characteristics, the dynamic launching process of a simple 4-m-long railgun system was simulated. The influence of the capacitance in the bridge-type capacitive switching circuit on the main performance of the system, such as the maximum output current, the maximum primary voltage, the launch efficiency, the maximum capacitive energy ratio, and the remaining energy recovery ratio, was analyzed. The simulation results show that the repetitive superconducting IPPS is suitable for driving the simple railgun. In addition, it also concluded that the system performances conflict with each other and the optimal capacitance value for each HTSPPT module should be determined by the tradeoff of system performances. [ABSTRACT FROM AUTHOR]

The influence of the electric parameters, applied voltage, and pulse repetition rate on the energy efficiency for hydroxyl radical production from pulsed discharge inside of a bubble is investigated in this paper, as a possible application for waste water treatment. To evaluate the energy efficiency, indigo carmine, a common dye, is used as a chemical probe of hydroxyl radicals. Argon is injected into water through a vertically positioned glass tube, into which high-voltage wire electrode is placed to generate plasmas at low applied voltage. The energy efficiency increases with the decreasing pulse repetition rate and output voltage with the same indigo carmine concentration. The results show that the energy efficiency for the hydroxyl radical production increases with the decreasing amount of energy input into the solution per unit time because of the decrease in the recombination reaction of the hydroxyl radicals in the solution. The impedance between the electrodes decreases with the increasing output voltage, which increases the ohmic losses in the solution but does not contribute to the production of hydroxyl radicals. [ABSTRACT FROM AUTHOR]

One of the conceptual designs of the breeder blanket for a European demonstration fusion power station (DEMO) is the water-cooled lithium lead (WCLL) concept. The design development of the WCLL blanket in recent years has undergone the evolution of the neutronics model employing the MCNP code, with key changes in radial lengths and thickness as well as dimensional differences in inner structures such as breeding zone, shielding zones, and manifold. Furthermore, there has also been a significant increase in projected fusion power. Such changes were made with respect to its nuclear, thermohydraulic, and thermomechanical performances. In this paper, neutronic characteristics of WCLL modules were analyzed in terms of fusion power increase and dimensional changes of the blanket geometry presented in DEMO 2014 and 2015 models. For comparison, outboard and inboard blanket modules of the equatorial region were selected. Investigated neutronic characteristics include activity, decay heat, and contact dose rates. The numerical experiment was carried out with MCNP particle transport code and FISPACT/FISPACT-II activation calculation codes with EAF-2010/TENDL-2015 nuclear data libraries. [ABSTRACT FROM AUTHOR]

This paper is aimed at finding the effect of varying inductive energy storage systems’ (IESSs) inductance on resistance of an electrically exploded conductor-based opening switch and profile of current transferred into load, which has not yet been fully understood. Based on experimental results obtained, it is observed that when the inductance of IESS is varied, the magnitude of load current changes so as to conform to the magnetic flux conservation law but its rise time remains unchanged. Resistance of the opening switch and energy deposited in it has been estimated using recorded voltage and current waveforms. It has been found that with increasing inductance of IESS, the resistance of switch increases, whereas energy deposited in it decreases. Using these estimated values of energy, a possible explanation of observed behavior in resistance is presented. Effect of a mismatch between the inductance of IESS and load is seen to only affect the energy transfer efficiency or magnitude of load current but not its rise time emphasizing the novel finding that for a given load, the rise time of load current is independent of the inductance of IESS. [ABSTRACT FROM AUTHOR]

Chlorobenzene (CB) is a toxic compound and is broadly used as a raw material for phenol, solvents, and agrochemical products, among other substances. CB being a very lightly soluble compound in water (~0.450 mL/L) is highly volatile, and it can be found in both liquid and gas phases. In this paper, the treatment of CB was carried out in an aqueous solution assisted by nonthermal plasma (NTP) generated by a dielectric barrier discharge. NTP was utilized as a generator, producing active species for the treatment of CB in both liquid and gas phases, attaining high degradation efficiencies >95% and using a low electric power consumption <20 W. Energy efficiencies of CB removal in kg/kWh were estimated, and relatively high values ~0.5 kg/kWh were obtained with a low-energy consumption. Attained degradation efficiencies were determined using gas chromatography and mass spectrometry. Optical emission spectroscopy study was conducted to determine the gas temperature during experimentations. Thus, the estimated magnitude was lower than 110 °C in overall cases. Meanwhile, the resulting excitation temperature was near to 0.2 eV. This magnitude is in the range of typical temperatures for similar NTP devices. [ABSTRACT FROM AUTHOR]

The increased usage of diesel fuel of late has led the researchers to pay more attention toward abatement of increased emission of oxides of nitrogen (NOx) in the engine exhaust. The focus is, therefore, lies in providing a technique that is economical, feasible, and long lasting. The combination of electric discharge plasma with adsorbent/catalyst derived out of solid waste can be one such possible technique. In this paper, waste foundry sand from foundry industry and red mud or bauxite residue from aluminum industry have been used. Diesel engine exhaust under dry condition was exposed to an oxidizing discharge plasma environment. The plasma-treated exhaust was subjected to either adsorption over waste foundry sand or catalysis over red mud. Studies were carried out in the laboratory environment with 20% loading of diesel generator. The oxidizing plasma environment was either with direct plasma or with indirect plasma in which case ozone injection into the exhaust was accomplished. The ozone-adsorbent cascading system has resulted in about 87% NOx reduction in the dry exhaust case. The effect of O3:NO ratio was discussed from the point of NO/NO2. [ABSTRACT FROM AUTHOR]

This paper presents the results of investigation of the possibilities to produce high volume and concentration of nitrogen oxides in inductively coupled plasma/radio frequency plasma for industrial applications. Calculations of the equilibrium composition of air and air–oxygen plasma at different temperatures and pressures have been conducted. The data obtained can be used to design and develop efficient systems for the nitrogen oxides synthesis. [ABSTRACT FROM AUTHOR]

In this paper, a high-voltage unipolar pulse power generator is introduced for electroporation applications. Operating principle of the proposed structure is based on the buck–boost (BB) converter. The generator is comprised of parallel modules connected to the converter through an SCR and is supplied by a low-voltage dc source. Each module consists of an insulated gate bipolar transistor (IGBT), two diodes, and a capacitor. In fact, the proposed topology is a combination of the Marx generator and BB (MG-BB) converter. In comparison with other modular MG-BB structures, the proposed topology achieves interesting advantages including simpler structure, reduction of IGBTs voltage rating, and reducing number of components (inductors and switches). In order to clarify the features of the proposed structure, it has been compared with other unipolar MGs considering different aspects including the number of circuit components, number of required input supplies, amplitude of the output pulse, and the maximum voltage across switches and diodes. To validate the effectiveness of the structure, simulation and experimental results are presented. The results confirm that the proposed topology is capable of generating unipolar pulses with desirable amplitude and repetition frequency using a low-voltage dc supply. [ABSTRACT FROM AUTHOR]

Nonlinear transmission lines (NLTLs) have been studied over the past several years to generate high-power radio frequency signals. Their operation consists of a lumped line based on the nonlinear behavior of the LC section components, capacitors or inductors, as a function of the applied voltage or current, respectively. However, considering high-power signals, the application of these devices using nonlinear ceramic capacitors as the capacitive lumped lines are restricted to frequencies around 100 MHz since at high voltages, parasitic impedances in the line structure limit the maximum operating frequency. On the other hand, the use of variable capacitance diodes has enabled the operation of NLTLs at higher frequencies. This paper provides the results of a study of NLTLs for RF generation based on silicon carbide Schottky diodes. The principle of operation and its simplified theory are presented. Initially, the voltage dependence of the diode capacitance is modeled. Experimental and simulation results are compared. Frequency oscillations around 200 MHz were generated. The extraction of the radio frequency energy is realized, and the radiation of the electromagnetic wave is performed using double-ridged horn antennas. Finally, some parameters are analyzed, and all results discussed. [ABSTRACT FROM AUTHOR]

According to the Chinese fusion engineering testing reactor (CFETR) central solenoid model coil (CSMC) properties test requirements, a large cryogenic test platform will be built. The feeder, as one of the important components of the platform, should be studied to afford the much valued help for the basic test facilities. This paper focuses on the feeder structural design and the stress analysis in conditions of different loads. All of the work could not only provide necessary help for building CFETR CSMC test platform but also provide the important service experience of the large cryogenic test platform in the future. [ABSTRACT FROM AUTHOR]

Surface-dielectric-barrier discharges (SDBDs) can be applied for a wide range of applications, such as ozone generation, surface treatments, and air-pollutants removal. An important advantage of the SDBD plasma is that relatively low high-voltage (HV) pulses (<10 kV) are needed to generate the plasma. They are effective in removing a wide range of pollutants. Despite their high energy efficiency, plasma decomposition generally results in the reaction by-products and the formation of ozone and nitrogen oxides. This drawback can be overcome by combining the SDBD plasma with catalysis. In this paper, a novel plasma-catalytic topology is proposed for the purpose of on-demand air purification. The main idea of the plasma-catalytic reactor is that both the plasma and the catalytic function are configured as planar structures which are positioned in parallel to each other. The plasma is generated along a planar dielectric structure. We use an SDBD for this purpose. Plates coated with the catalytic material are positioned in parallel to the SDBD plates. The air to be treated is flushed along the plates. There are no restrictions to the type or combination of catalysts used; the catalysts and their specifications can be chosen freely. We have developed a modular plasma-catalytic SDBD reactor to handle large flows, which can be scaled up and scaled down easily. To energize the plasma, an SDBD power modulator was developed. The modulator is able to generate a HV output pulse over an SDBD plasma load with a magnitude adjustable from 4.78 to 6.95 kV. The pulse rise time is about $1~\mu \text{s}$ and its ramp is about 6 kV/ $\mu \text{s}$. The energy per pulse then ranges from 1.1 to 17.4 mJ. The output power can be adjusted up to 48 W at a repetition rate of 5.5 kHz. The maximum possible pulse repetition rate is 22 kHz, but it is limited to 5.5 kHz due to the limited current rating of the available dc power supply. The total energy efficiency of the power modulator is 68%. A single modulator unit can power up to two SDBD reactor plates of $100\times 150$ mm size, having plasma at both sides of the plate. The operational efficiency of the developed SDBD catalytic reactor has been investigated by studying the removal of NOx and ethylene. The removal efficiency of NOx and ethylene is determined as a function of energy density and operational parameters, such as their initial concentrations and the gas flow rate. [ABSTRACT FROM AUTHOR]

Recently, inductive energy storage systems have attracted interests due to high energy densities. The high-temperature superconducting pulsed-power supply (HTSPPS) is one inductive PS topology for electromagnetic launching system. The topology can achieve a high amplitude load current and cut down the electrical losses due to the zero resistance characteristic of superconducting inductors. However, in this topology, the integrated gated commuted thyristor is used as a switch and cannot withstand high current, which limits the expansion of the system. Besides, it has significant current amplification ability as a single unit, but one module cannot provide sufficient amplitude and appropriate pulsewidth for the load current of the electromagnetic launching. In this paper, by applying the principle of inverse current commutation with semiconductor devices (ICCOS) in the HTSPPS, a novel circuit topology called HTSPPS with ICCOS is presented. This topology is analyzed and the multiple modules system is established. Simulation results show that the HTSPPS with ICCOS exceeds the current limitations of the original one and ensures the reliable cutting off of the main switch. It has potential applications in the future of high-energy systems while reducing the cost greatly. By asynchronous cooperative triggered discharge of the multiple HTSPPS with ICCOS modules in parallel, the appropriate amplitude and flat shape current of the load can be achieved through the careful design of the trigger time. [ABSTRACT FROM AUTHOR]

Optimal design and selection of arm inductances have been as a challenging subject in the field of modular multilevel converter (MMC). The average steady-state model is generally used as the analytical circuit model that neglects the switching frequency and harmonic values. Also, most of the researchers neglect the saturation effect of inductor core to simplify the analytical model. Contrary to the transformers, choosing the maximum flux density of inductance core is a sensitive issue, in order to design and minimize the inductors. Increasing the flux density reduces the inductor size, but getting close to the saturation region might alter the performance of the converter. This paper presents a systematic optimization approach to minimize high-power MMCs with saturable arm inductance considering technical, thermal, and manufacturing constraints. An accurate steady-state analytical model of MMC converter has been proposed and verified. A combination of converter circuit model and inductance electromagnetic model is employed to find the optimal arm inductances and capacitor values. The effect of nonideal inductance core on converter outputs has been investigated. A dimensioning model of inductor consisting of electromagnetic and thermal models is presented. To compute the optimal inductor size, a novel hybrid optimization loop is proposed including the analytical model of the converter and the inductor in which circuit, electromagnetic, and thermal properties are taken into consideration. In order to increase the accuracy of the dimensioning model, an internal verification loop is employed to verify and correct the analytical model using finite-element analysis. The proposed optimization loop aims to find the minimum inductor size considering technical and manufacturing constraints. Finally, the converter mass sensitivity of MMC converter versus some important constraints, such as temperature rise and capacitor ripple, has been investigated. [ABSTRACT FROM AUTHOR]

In this paper, the spatially resolved spectrum of the nitrogen second positive system ($\text{C}^{3}\Pi _{\mathrm {u}} \to \text {B}^{3}\Pi _{\mathrm {g}}$) has been measured in a nanosecond pulsed streamer corona N2 discharge with a wire-plate electrode structure. The spatial distributions of emission intensity of N2 ($\text{C}^{3}\Pi _{\mathrm {u}} \to \text {B}^{3}\Pi _{\mathrm {g}}$ , 0–0) at different pulse peak voltages, pulse repetition rates, and gas components are used to explore the distribution and variation of the high electron density (higher than 11.03 eV) with the reaction radiation rate analysis. It is found that the high electron density increases with increasing both the peak voltage and pulsed repetition rate but decreases with increasing the oxygen contents. The spatial distribution of the emission intensity of N2 ($\text{C}^{3}\Pi _{\mathrm {u}} \to \text {B}^{3}\Pi _{\mathrm {g}}$ , 0–0) is normalized to the value of the emission intensity at the wire electrode at different experimental conditions. The results show that the normalized distribution of the spatially resolved spectral intensity of N2 ($\text{C}^{3}\Pi _{\mathrm {u}} \to \text {B}^{3}\Pi _{\mathrm {g}}$ , 0–0) is independent of pulsed peak voltage, pulsed repetition rate, and gas component, which indicate that the normalized distributions of the high-energy electron density in the gap space at different experimental conditions are similar. These experimental results are significant to understand the discharge characters of pulsed streamer corona discharge and establish the molecule reaction dynamics model of pulsed streamer corona discharge. [ABSTRACT FROM AUTHOR]

In the framework of prospective activities for a demonstration power plant, DEMO will be the next step for fusion energy following ITER tokamak. Some of the key design top-level questions can be addressed using macroscopic system-level codes. Those system codes aim to model the whole fusion plant with all its subsystems and identify the impact of their interactions on the design choices. The code SYstem COde for MOdelling REactors (SYCOMORE) is a modular system code developed to address key questions relevant to the tokamak fusion reactor design by giving a global view of technology and physic domains. Among all components, SYCOMORE provides a representation of the magnet system, which is of importance regarding some factor of merits, e.g., fusion power or cost. SYCOMORE is ultimately coupled with an optimizer, scanning a high number of operation configurations and ranking them along selected merits. This scanning requires fast computation for each scanned point, so the magnets modeling must meet a tradeoff between simplicity and accuracy. In this paper, we describe that the way toroidal field (TF), central solenoid (CS), and poloidal field (PF) systems modeling in SYCOMORE was chosen taking into consideration the driving design criteria used in usual magnet design method (temperature margin, copper maximum temperature during quench, mechanical resilience in stainless steel structural parts, etc). The specificities of the reduced magnet representation chosen approach will be exposed, and the benchmarking of the simplified model of the two main systems (TF and CS) applied on DEMO reactor configuration will be compared with the output of a more sophisticated design method using an elaborated tool (CEA design tool) that is used to establish the CEA design of DEMO magnets. Together with this benchmark, a discussion on the limits of this approach will be conducted. PF system implementation being in an early stage, the winding pack design module will be exposed (with its associated benchmarking part with CEA design tool), but not the part of PF current reconstruction with respect to system features. Parametric explorations of DEMO configurations will be reported along different conceptual choices related to the magnets (e.g., superconductor material and performances, and structure resilience limits), and the impact on the magnet system main design features will be exposed. Main lines of the future development work will also be presented. [ABSTRACT FROM AUTHOR]

Inductive pulsed power supply (IPPS), especially superconducting pulsed power supply (PS), has been the focus of research in recent years due to its high energy density and low power requirement for the input PS. Quite a lot of fantastic work regarding two or multiple IPPS modules has been presented. But they disregard the mutual inductance between modules. This paper establishes a double-module IPPS based on two high-temperature superconducting pulsed power transformers and takes the mutual inductance between modules into consideration. The influence of the mutual inductance between two modules on three discharge modes of the system is researched. Simulations and experiments on synchronous discharge, time-delay discharge, and asynchronous discharge are carried out, respectively. The results demonstrate that taking the mutual inductance into consideration, the amplitude and the pulsewidth of the output currents are both improved a lot, especially the obtainable energy of load is improved by nearly half. For time-delay discharge, the mutual inductance makes the delay time slightly increase. However, for asynchronous discharge, the mutual inductance increases the positive maximum value of the primary current of the second module. It may exceed the critical current and lead to quench. Consequently, the mutual inductance between modules has positive impacts on synchronous discharge and time-delay discharge of the IPPS system while it brings both advantages and disadvantages to asynchronous discharge. [ABSTRACT FROM AUTHOR]

Dielectric barrier discharge (DBD) is a promising technology for ozone generation. In this paper, each electrode consists of tungsten rod and quartz glass. To improve the discharging efficiency, the air of the used quartz tube was evacuated. Moreover, to evaluate the performance of ozone formation, the electrical characteristics of volume DBD (VDBD) (two electrodes) and coupled VDBD (three electrodes and seven electrodes) are investigated. Under the condition of the same electric field using the COMSOL Software, the density of the current pulses is shifted to the right in the current waveforms. The results of ozone production show that a dynamic balance between ozone formation and ozone decomposes is complex at high frequency and high flow rate. The highest energy yield is 1650 g/kWh at a specific input energy of 0.6545 J/L. [ABSTRACT FROM AUTHOR]

Paralleled pulse-forming units (PFUs) with different triggering delays might be a paramagnetic way for generating flat-topped current wave for electromagnetic launch. Many researchers have reported that multiple capacitive storage PFUs were implemented such current waves in laboratories. However, due to its low energy density, the applications of the capacitive pulsed-power supplies are limited. Since the inductor has advantages in energy density, the inductor pulsed-power supply becomes one of the hottest topics recently. The slow transfer of energy through capacitive hybrid meat grinder with inverse current commutation with semiconductor devices proposed by Tsinghua University has demonstrated its advantage and applicability recently. Using this kind of topology, this paper proposes the design of an inductive storage PFU with a stored energy of 100-kJ. The maximum load current reaches to 50 kA and its pulsewidth is at least 5 ms. The optimized inductive storage PFU shows superiority in contrast to the capacitive storage PFU with the same energy. This paper offers the theoretical analysis and the testing foundation for investigating the inductor pulsed-power supply with higher energy. [ABSTRACT FROM PUBLISHER]

The STRETCH meat grinder is one typical inductive pulsed-power supply topology for electromagnetic launch system. It has remarkable current amplification ability as a single unit, but one module cannot provide enough amplitude and width for the load current of the railgun launching. This paper discusses the effects of different triggering delays on the load current with two STRETCH meat grinder modules. To reduce the magnetic field coupling between the two modules, the two main switches are opened simultaneously. To make the load current waveform with no notch, the thyristor of the first module is triggered when its pulse-forming capacitor is fully reversely charged. For the thyristor of the second module, we consider several time points of triggering delay. Because of the practical constraint for the maximum rail current that ensures no rail erosion, the rectangular waveform is the most appropriate load current waveform. Therefore, the comparing criterion can be defined as the ratio of the load current waveform area and its maximum rectangle area at different current levels. Higher ratio means that the current is more like a rectangular wave and is better accordingly. Based on the above criterion and extensive simulation research, we found that the best delay time is the moment when the capacitor is reversely charging the inductor completely. This paper and the result are of great theoretical significance for the further study on the collaborative triggering of multiple STRETCH meat grinder modules. [ABSTRACT FROM PUBLISHER]

Matching a pulse source to a plasma load is one of the main challenges to overcome to maximize the full potential of pulsed discharges for air purification applications. In this paper, we propose experiments that investigate the matching of a nanosecond pulse source to a corona plasma reactor that is aided by a high voltage on a tertiary electrode. The corona plasma reactor is a wire-cylinder reactor, as is commonly used in pulsed power plasmas. A tertiary electrode is situated on a dielectric layer against the cylinder of the reactor. On this tertiary electrode, we can apply a pulsed RF or dc voltage to provide an additional plasma and bias voltage in the corona plasma reactor. The pulse source that energizes the main corona plasma is the nanosecond pulse source of Kumamoto University, Japan. In this paper, we show the results of experiments with a dc voltage on the tertiary electrode. We varied the amplitude of the pulsed voltage as well as the dc voltage and investigated their effect on the corona plasma with energy and ozone measurements. The results show that the matching to the reactor increases with increasing dc voltages. However, the matching effect decreases with higher repetition rates. Furthermore, ozone measurements confirmed that a better matching also results in a higher ozone production, but in a lower ozone production energy yield. [ABSTRACT FROM PUBLISHER]

In this paper, we present the final implementation of our 0–50-kV picosecond rise time 0.5–10-ns pulse generator. The pulse generator will be used in future work to generate a (sub)-nanosecond streamer plasma for air purification research. The pulse generator is a single-line pulse generator with an oil spark-gap (SG), which generates 0.5–10-ns pulses with a 200-ps rise time and can operate at repetition rates of over 1 kHz into a 50- \Omega load. It is an improvement over the first implementation of our nanosecond pulse generator that we designed and verified experimentally in previous work. In this paper, we evaluate the performance of the final design. Furthermore, we present 3-D electromagnetic simulations of the nanosecond pulse generator and show that the simulations are in good agreement with the measurements. A variation in pulse duration from 0.5 to 10 ns is possible and the output pulses are square shaped without the large plateau behind the main pulse that was present in the pulses from the first implementation of the nanosecond pulse generator. At high voltages, the pulse top becomes less flat due to a time-dependent mismatch in the spark-gap. Furthermore, investigation of electrode erosion of the oil spark-gap shows that the erosion rate of the electrodes is in the range of 200–600 \mu \mathrmcm^3 \cdot \mathrmC^-1 for the electrode that is mainly the cathode and 100–300 \mu \mathrm{cm}^{3} \cdot \mathrm{C}^{-1}$ for the electrode that is mainly the anode, respectively. This is almost an order of magnitude higher than most gas spark-gap studies show for brass electrodes. Therefore, electrode erosion in the oil spark-gap will be a limiting factor on the lifetime of the system. We designed a new electrode with a stainless steel head to increase this lifetime. [ABSTRACT FROM PUBLISHER]

Air-borne micrometer and submicrometer particles produced by anthropogenic sources contaminate atmospheric air, especially in large cities where both population and industrial activities are higher leading to a reduced air quality. Recent research has pointed out particles less than 2.5 \mum in diameter (PM2.5) as a potential health hazard. To address this issue, stricter legislation has been put into force to reduce PM2.5 emissions. This paper is focused on the development of an impulsive microelectrostatic precipitation technology for charging and removal of fine air-borne particles in an economically feasible way. In this paper, a compact coaxial precipitator has been developed for possible indoor air cleaning applications. High-voltage impulses together with dc voltage have been used for energization of the reactor as it has been shown to enhance the precipitation efficiency. This precipitation system has been used for removal of fumes and fine air-borne particles from ambient air. In addition to the experimental part, analytical work has been conducted to optimize the electrostatic precipitation process and to reduce its power consumption. [ABSTRACT FROM PUBLISHER]

A nonlinear lumped element transmission line (NLETL) that comprises an $LC$ -ladder network where either the capacitors or inductors are nonlinear is used to convert an input rectangular pulse to a series of RF pulses at the output. This paper describes the implementation and demonstration of a high-voltage nonlinear hybrid line (NLHL) where both the line components (inductors and capacitors) are nonlinear. Lines with only one nonlinear component have been described in numerous publications in simulation and experiment whereas an NLHL has been described in only a few papers in simulation. There is no report about NLHL being tested to-date according to the best of our knowledge. We have built and tested an NLHL using commercial-off-the-shelf components. Instead of using complex pulse forming networks or pulse forming lines, a storage capacitor and a fast semiconductor switch are used to provide an input pulse with good approximation of a rectangular pulse shape. The experimental results are compared with simulations predicted by the in-house developed nonlinear lumped element transmission line (NLETL) circuit model. Analyses on the voltage modulation and frequency content of the output pulses are carried out. The conditions for producing RF pulses in NLHL and its performance are discussed. [ABSTRACT FROM PUBLISHER]