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The article offers information on an upcoming special issue of "IEEE Transactions on Plasma Science," which will contain papers presented at the joint conference of 4th Euro-Asian Pulsed Power Conference (EAPPC 2012) and 19th International Conference on High-Power Particle Beams (BEAMS 2012).

The article offers information on the Euro-Asian Pulsed Power Conference (EAPPC) which will be held in Kumamoto, Japan on September 8 to 12, 2014.

An introduction is presented in which the editor discusses various articles within the issue on topics including insulation, high energy density storage, and high power microwave devices.

The article discusses various reports published within the special issue for selected papers from the 17th International Conference on High-Power Particle Beams (BEAMS) Conference in Xi'an China on July 7-11, 2008, including high-power microwaves, other high-power particle beams applications, and pulsed power generation.

The article discusses on the 32nd International Conference on Plasma Science (ICOPS) held in Monterey, California. This Special Issue focuses on Plenary and Invited Papers from ICOPS. There are invited talks included in the issue which subjects ranged from the traditional interests in basic plasma processes, microwave generation and charged particle beams, and other plasma-related topics.

While the particle-in-cell (PIC) method is quite mature, verification and validation of both newly developed methods and individual codes have largely focused on an idiosyncratic choice of a few test cases. Many of these test cases involve either 1-D or 2-D simulations. This is either due to the availability of (quasi-) analytic solutions or historical reasons. In addition, tests often focus on the investigation of particular physics problems, such as particle emission or collisions, and do not necessarily study the combined impact of the suite of algorithms necessary for a full-featured PIC code. As 3-D codes become the norm, there is a lack of benchmark tests that can establish the validity of these codes; existing papers either do not delve into the details of the numerical experiment or provide other measurable numeric metrics (such as noise) that are outcomes of the simulation. This article seeks to provide several test cases that can be used for validation and bench-marking of PIC codes in 3-D. We focus on examples that are collisionless and can be run with reasonable computational resources. Three test cases are presented in significant detail; these include basic particle motion, beam expansion, and adiabatic expansion of plasma. All presented cases are compared either against existing analytical data or other codes. We anticipate that these cases should help fill the void of bench-marking and validation problems and help the development of new PIC codes. [ABSTRACT FROM AUTHOR]

A novel augmented railgun using multilayer magnets and sabots is proposed in this paper, in which the rails have dc constant currents. Using dc constant currents for the rails generates the constant acceleration for the projectile. The augmentation with multilayer permanent magnets increases the length of passing current, which improves the railgun efficiency. Furthermore, the proposed railgun does not require the high power supplies because each sabot carries only low current. In addition, the iron structure has been located at the top and bottom of the whole structure to produce a homogeneous magnetic field. Accurate analytical expressions have been derived for the Lorentz force and the velocity of the proposed structure in this paper. The railgun structure has been simulated in Maxwell software for various rail currents, and the analytical results have good agreement with simulation results. The amplitude of the Lorentz force in the z-direction has been calculated for various sabot materials to investigate the effect of the sabot materials on the performance of the railgun. Our results indicate that the velocity of the projectile can achieve to 300 m/s for the projectile mass of 2 kg in our proposed railgun. This makes the railgun a good candidate for the heavy projectiles in the launcher technology. [ABSTRACT FROM AUTHOR]

We study the Smith–Purcell (SP) radiation emission generated in terahertz (THz) frequency range by an electron beam passing close to the surface of a 3-D quasi-periodic array of metallic slots. When more than one electron beam is used in the SP-based periodic structures, the two or more colors can be generated. In this paper, two-color SP emission of radiation with variable frequency separations has been examined in a proposed quasi-periodic Fibonacci-class structure through 3-D-particle-in-cell (PIC) simulations. In spite of using an electron beam instead of implementing a double-electron beam streaming method, in this paper, a new method for successful two-color SP radiation generation in the THz frequency domain is reported in both quasi-spontaneous and quasi-super-radiant regimes. Finally, we show that quasi-superradiance simulations demonstrate the possibility of frequency separation controlling through repetition frequency of applied periodic bunches. [ABSTRACT FROM AUTHOR]

Firing accuracy is a critical quantity of interest in the performance analysis of electromagnetic railgun (EMRG) exterior ballistics. Since the simulation technique is always used to simulate the complex physical system at a low cost, it is employed to evaluate the firing accuracy of railgun projectile with uncertainty in this paper. An exterior ballistics simulation model of the railgun, including 3-DOF flight mechanical model, relative kinematic model, and guidance law model, is developed to simulate the ballistics behavior in the missile target intercept mission. The firing accuracy is studied in this paper to compare the capability of EMRG with different ranges and muzzle velocities. In order to explore the firing accuracy of the guided projectile, the guidance precision analysis and ballistics uncertainty quantification are studied. In the guidance precision analysis, the shot range and efficiency are used to make a comparison. In addition, the sensitivity analysis and firing accuracy analysis are also performed in terms of uncertainty quantification. The simulation results illustrate that the simulation of the guided projectile can give some practical guide to the projectile design of EMRG. [ABSTRACT FROM AUTHOR]

ASELSAN Inc. has been conducting experimental research on electromagnetic launch technologies since 2014. The first prototype, EMFY-1, has 25 $\text {mm} \times 25$ mm square bore and 3-m-length rails. In addition, two capacitor-based pulsed-power supplies (PPSs) with 1- and 4-MJ stored energy are built to supply launcher. During the design process of EMFY-1, a 3-D finite element (FE) model has been developed to simulate the electromagnetic and mechanical aspects of the railgun. This paper presents the simulation and experimental results of EMFY-1 with C-type aluminum armature. FE model, developed using COMSOL Multiphysics, includes both launcher and the PPS system. In addition to the velocity and position of the armature with respect to time, it is possible to observe the magnetic field, current density distributions and breech voltage using the FE model. In the experiments, pulse currents of the PPS modules, breech, and muzzle voltages are measured. The velocity of the projectile is measured using the B-dot probes. In this paper, two experiments of EMFY-1 will be presented. In the first experiment, the launch package with 42-g total mass is accelerated to 2778 m/s, and in the second experiment, the launch package with 130-g total mass is accelerated to 1560 m/s. The simulation results of the proposed FE model are compared with the experiments. It is observed that there is a good agreement between experimental and simulation results. [ABSTRACT FROM AUTHOR]

This paper consists of two parts. In the first part, the emission was generated in air, and the waveform recording the spectral line at 337 nm (= prominent N2 laser line) was noted. The pulse forming network (PFN) Marx generator having a large ($50~\Omega$) internal impedance was used. The pulses of the nitrogen emission at 337.1 nm of long ($< 3~\mu \text{s}$) duration and of short (≈10 ns) duration were obtained. The photodiode registered both the spontaneous emission and the stimulated (laser) emission in the 337 ± 5 nm spectral range. The data show that the laser emission predominates in the pulses of long duration. In the second part of this paper, it is suggested that the ultraviolet (UV) radiations emitted by the sun, together with the electric fields present at high altitudes, are capable of exciting the N2 molecules to the upper excited $\text{C}^{3}\Pi _{u} $ level to yield the laser emission of long duration. On the basis of the laser energy content dissipated into the plasma, the size of the transient luminous events (TLEs) known as the elves and the sprites was evaluated. The dynamics of initially small size, highly compressed, and very hot plasma formed inside the sprite was presented. It is proposed that the TLEs named “crepuscular twilight in the sky of New York” observed on December 28, 2018; “mysterious bright flash” occurred in Russia on January 9, 2018; and maybe the Tunguska event happened in Siberia on the morning of June 30, 1908 should be included in the list of the TLEs. [ABSTRACT FROM AUTHOR]

A novel brushless self-excited air-core compensated pulsed alternator (BSACPA) is presented in this paper. It consists of two submachines in cascade, among which one serves as an exciter and the other works as a generator. The rotor windings of the two submachines are connected by a reverse phase sequence to realize reversal of the magnetic field. The stator windings are connected by a rectifier to realize the brushless self-excited structure. As an air-core compensated pulsed alternator (CPA) of new topology, it is necessary to derive its mathematical model and carry out a comparative design. Thus, this paper focuses on the detailed design and analysis of a BSACPA prototype, which includes dimensional design and equivalent circuit establishment. In addition, the critical speed is also acquired. Accordingly, the numbers of winding coil turns are designed to increase the discharge current and power based on the theoretical analysis. Finally, the analysis and design are verified by finite-element analysis (FEA). [ABSTRACT FROM AUTHOR]

By triggering the switches in sequence and controlling the brick charging voltage independently, a pulsed power system can generate flexible current waveform in the load, which could allow high-accurate magnetic pressure in experimental materials in the study of EOS data and dynamic response of material characterization. Currently, a 1.5-MA driver with 20 independent bricks has been developed, and a programmable 256-brick parallel discharge driver which is able to generate shaped current greater than 6.5 MA is under construction in the China Academy of Engineering Physics. In this paper, for these two multibrick parallel discharge drivers, the method of optimizing the output current waveform of the driver is studied by using the genetic algorithm and the corresponding optimization results of different target current waveforms are obtained. An experimental platform is set up for studying the gas switch breakdown characteristics. The self-breakdown and triggering breakdown experiments of the switch are conducted, and its breakdown characteristics are researched. Meanwhile, the effect of breakdown delay and jitter on the output current waveform is studied by simulation. This paper is of great significance to the actual operation of the multibrick parallel discharge drivers. [ABSTRACT FROM AUTHOR]

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]

Inductively coupled plasma sources driven by RF power at low-pressure regimes are well adopted for high-volume manufacturing of semiconductor devices. One vexing challenge to the utility of these plasma processing reactors is the existence of the E–H-mode transition. Industry notably avoids the process region associated with this transition, where plasma instabilities and bimodal power coupling prohibit reliable RF power delivery. One plasma instability detailed in this paper is associated with a hysteresis in coupled RF power (current) varying for the E-mode, or weakly capacitive coupling to the plasma, in comparison to the stronger current coupling in the H-mode, where inductive coupling is preferentially dominant. As a result, approximately two orders of magnitude of electron density is relinquished in this transition region from serving industrial manufacturing processes. We characterize the plasma parameter variation through the E-mode to H-mode with a time-resolved measurement of the electron density. Electronegative chemistries are incorporated into our experimental setup. The experimental scheme serves to evaluate RF power delivery and ameliorate its coupling through the transition region. We seek to extend this paper to adopt more efficient power coupling for toroidal plasma sources. [ABSTRACT FROM AUTHOR]

This paper proposes a novel single-stage double-layer saddle multipole field electromagnetic launcher (SSDFEL), which combines the characteristics of reconnection gun to achieve simultaneous linear acceleration and gyroscopic stabilization of the projectile. Since the saddle driving coils are divided into two layers, the magnetic field density inside the launcher is enhanced. The eddy current induced on the inner and outer surfaces of the projectile is greatly changed by the hollow cylindrical projectile with six symmetrical vertical slots twisted at a certain angle, and the projectile is simultaneously propelled to perform rotation motion and linear motion. In this paper, the electromagnetic field finite-element software is used to simulate and calculate this model. The simulation results indicated that the double-layer driving coil distribution has larger axial acceleration force and bigger circumferential torque than that of the single-layer driving coil distribution, the energy conversion efficiency has also been obviously increased, and there is an optimal initial twisted angle, which accelerates the projectile to the peak of rotation. To verify the results, an SSDFEL was established and tested. The experiment results confirm that the rotation performance can be affected by the initial twisted angle and a better launching effect is achieved than a single-layer distribution. In general, the experimental results are in agreement with the simulation results. [ABSTRACT FROM AUTHOR]

More and more oil and gas reservoirs are used for commercial carbon-dioxide-enhanced oil recovery (CO2-EOR), resulting in associated CO2 storage that occurs as part of the process. CO2/brine corrosion of oil tube steel that can occur anywhere along the wellbore is a challenging issue faced by the oil and gas industry. In this paper, to enhance their corrosion resistance in CO2/brine, J55 and N80 oil tube steels were coated with trimethylsilane (TMS) with the plasma chemical vapor deposition (PCVD) method. Both atmosphere and vacuum direct-current (DC) discharges were utilized for TMS plasma coatings (TMS-PCs) deposition. X-ray photoelectron spectroscopy (XPS) was used to characterize the coating surface chemistry. It was found that TMS-PCs deposited with vacuum direct current (DC) coatings (VDCPCs) had higher Si- and C-rich composition than atmospheric DC plasma coatings (ADCPCs). The corrosion resistance of samples with or without TMS-PC was evaluated through the weight loss method (WLM) and the 3-D pitting corrosion quantitative evaluation method (3D-PCQEM), which was conducted in CO2/brine with the self-built corrosion-resistant performance evaluation system (CRPES) and a 3-D scanning optical microscope. The results demonstrated that the TMS-PCs can significantly decrease not only the uniform corrosion rate but also the pitting corrosion rate of N80 and J55 oil tube steels. TMS-PCs deposited with VDCPC showed a lower corrosion rate than that of ADCPC. The scanning electron microscopy (SEM) was used to characterize the surface morphology of the samples before and after WLM, and the results indicated less corrosion and pitting corrosion on coated samples than that of uncoated controls. The energy dispersive spectrometer (EDS) was used to characterize the coating surface chemistry before and after WLM, which also indicated that the ferric content of coated samples was higher than that of uncoated controls after WLM. The results obtained in this paper indicate that TMS-PCs may serve as a very promising barrier against the corrosion and pitting corrosion of tube steel in CO2/brine. [ABSTRACT FROM AUTHOR]

The design, construction, and operational characteristics of a low-impedance and low pulse drop transmission line transformer (TLT) are described in this paper. The multicore coaxial transmission line used for this transformer is different from traditional coaxial transmission line since its inner conductor consists of several high-voltage cables that are connected in parallel by using two metal disks placed at both ends of them. Simultaneously, the impedance of the coaxial transmission lines with ten cables designed in this paper is perfectly reduced from 60 to $13.5~\Omega $. Moreover, the transmission lines can withstand a high voltage of several tens of kilovolts with 13.9 mm in diameter. The transmission lines were then used to construct TLTs. The transformers are wound inductively in separated cylinders made of polypropylene to enhance the isolation from the input to the output of the transformers. Consequently, the pulse drop is substantially reduced, minimizing pulse distortion in the transformer. A three-stage TLT, whose input and output impedances are 4.5 and $40.5~\Omega $ , respectively, was developed with the transmission lines. The experimental results show that the three-stage transformer based on the low-impedance and low pulse drop design transmission lines can achieve a voltage gain factor of almost 3.0. [ABSTRACT FROM AUTHOR]

The so-called plasma window is a dc cascaded arc whose function, in this paper, is to greatly restrict gas flow from high pressure (upward of 40 kPa) chamber to a low-pressure side (order of 10 Pa). This is motivated by its potential to contain a gas charge stripper on a beamline of a high-intensity heavy-ion accelerator without the need for solid windows that would obstruct beam passage and not survive the beam’s intensity. At the National Superconducting Cyclotron Laboratory (NSCL), a test stand for this plasma window has been developed to study how this flow rate restriction is impacted by plasma physical properties and window geometry. Proposed mechanisms for this flow rate restriction are, first, a significant increase in temperature causing greatly enhanced viscosity in the plasma channel, and second, a choked flow condition being established through gas speed reaching supersonic conditions. The study in this paper is limited to pure Ar gas. Optical emission spectroscopy demonstrates the plasma that has an electron temperature of about 1.7 eV and an electron density of about 1016 cm–3. [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]

In the process of electromagnetic launch, the initial contact pressure distribution of armature/rail (A/R) contacts interface is uneven, and the actual contact area is obviously different from the perfect contact. The uneven contact pressure leads to uneven contact resistance distribution, affecting the magnetic diffusion process and changing the A/R interface current distribution. Therefore, it is necessary to consider the influence of contact pressure on the current distribution. In the past, the simulation studies usually considered the contact between rails and armature as the perfect contact, and the result obtained may be different from the actual situation. This paper uses the finite element software COMSOL to perform coupling simulation analysis on the electromagnetic module and solid mechanics module in the initial stage of electromagnetic launch. At the initial stage of electromagnetic launch, the contact pressure is mainly provided by the prepressure generated by the interference fit. In this paper, the influence of contact pressure on current distribution and the influence of magnitude of interference on contact position, contact pressure, and current distribution are analyzed. [ABSTRACT FROM AUTHOR]

The advances of high-frequency vacuum electron devices (VEDs) in China are reviewed in this paper, including traveling-wave tubes (TWTs) based on novel slow-wave structures (SWSs), high harmonic TWT amplifier, gyrotrons, Smith–Purcell (SP) radiation sources, surface plasmon polaritons (SPPs) sources, and terahertz (THz) radiation sources in ion-focused beam-plasma system. As one of the most widely used VEDs, TWTs based on folded type SWSs, planar SWSs, and grating type SWSs are studied theoretically and experimentally from Ka-band to R-band. Using folded type SWSs, two TWT amplifiers are developed. As high-power millimeter wave and THz wave sources, gyrotron TWTs, gyrotron oscillators, and gyroklystrons are presented. Moreover, this paper shows SP radiation sources, SPPs sources, and THz radiation sources in ion-focused beam-plasma system open good prospects for developing high-frequency VEDs with new mechanisms, which undoubtedly brings about innovative changes for the development of VEDs. [ABSTRACT FROM AUTHOR]

Corona discharge is extensively researched due to the wide applications in the fields of electrostatic precipitator, flow control, thermal management, and so on. Previous researches observe that the characteristics of the corona discharge, such as the average current in the Trichel pulse regime, could be influenced by the airflow velocity. In this paper, the effect of the airflow rate on the corona discharge is further investigated by using a needle-mesh discharge structure. The experimental results show that the discharge is transferred from a large amplitude, long pulse interval time condition to a small amplitude, short interval time condition when increasing the airflow rate and, at the same time, the discharge region is shrunk toward the centerline of tube channel (i.e., shrinking regime). However, after a stable regime around a certain airflow rate, the above-mentioned parameters are changed toward the opposite direction and the discharge region is expanded, when further increasing the airflow rate (i.e., expanding regime). This nonmonotonous phenomenon has not been observed in literature before, and we further investigate it under different tube channel diameters. It is found that, under a larger tube channel diameter, the transition point (corresponding to the minimum pulse amplitude and interval time) moves toward a larger gas flow rate. The physical mechanisms for this phenomenon are analyzed by considering the transport effect by airflow under different Reynolds numbers. It can be caused by a comprehensive effect of the mass transfer, heat transfer, movement process of particles, and frictional loss in the discharge space. The phenomenon revealed in this paper is possibly utilized to improve the application of corona discharge under airflow. [ABSTRACT FROM AUTHOR]

The air circuit breaker (ACB) is required to switch off the short current at various frequencies in the permanent magnet wind power generation system. The movable contact of ACB consists of multiple parallel contacts, and the arc will be ignited when the short-circuit current appears. This paper focuses on the effect of frequency on arc motion in multiple parallel contacts’ system. A 3-D magnetohydrodynamic (MHD) model of a multiple parallel contacts’ structure is built. In this model, the anode consists of five parallel contacts. The difference in voltage between the near-anode layer and the near-cathode layer is considered. The nonlinear B–H curve of the splitter plate is taken into account. The time-varying electromagnetic field induced by the current loop including electrodes and arc column is calculated. The arc evolution process and effect of frequency on arc motion in multiple parallel contacts’ system are analyzed by the arc voltage and the current density distribution. This paper is expected to provide the theoretical references for the optimal design of arc quenching chamber of ACBs. [ABSTRACT FROM AUTHOR]

In classical gun and satellite launching systems, noise, flame, and hazardous gasses occur during the explosion of gunpowder, and it is possible to change the muzzle velocity of projectile only during the production phase. In addition, negative aspects of classical guns include the storage of munitions, their decay in time, high amount of their mass, and their high cost. In this paper, “A New Electromagnetic Coilgun” is designed to allow acceleration of a ferromagnetic projectile with the help of instantaneous alternate current applied on four sequential stator coils without using any mechanical boosters. programmable interface controllers microcontroller software and Delphi software were used to obtain the data from optic systems placed at the beginning of stator coils for gradual velocity measurement of the projectile, to process the same, and to perform triggering checks. Furthermore, such Delphi-based software allowed to improve the muzzle velocity by changing the triggering time for coils and, thus, to optimize the system. This paper is distinguished from other studies in the literature in terms of the software used and the design of accelerating coil. Data communication was ensured through the serial port of the PC during the launching process. The study examined the effects of variables such as the voltage applied on coils, number of turns of the coil, and the number of capacitors on the maximum muzzle velocity that may be obtained through the launcher and these were discussed in detail in the scope of the paper. [ABSTRACT FROM AUTHOR]

As a natural result of the electrified integration and electrical energy revolution, the electromagnetic launch (EML) technology will be inevitably used for future launch missions. This paper has summarized research focuses in this field according to the published papers on EML in China during the past decade and mainly introduced the current research and progress in several key technologies, including launcher, integrated launch package, high-power high-density supply, and overall control/maintenance. Some common pressing problems are pointed out to provide direction for the application of EML technology in engineering and many other fields, such as launcher life, miniaturization of power supply, and improvement of energy availability. [ABSTRACT FROM AUTHOR]

The pulse current can raise the bulk temperature of rails in the electromagnetic rail launcher (EMRL) during each shot. Quantifying the energy deposited in the rails and implementing an effective thermal management system are the key to tactical applications of the EMRL. This paper acquired the spatial distribution characteristics of total heat in the rails by using an analytical model and a multiphysics coupled model based on the hybrid finite-element/boundary-element method. The rail segment that produces the most heat is located where the armature arrives near the end time of the rising edge of pulse current. Since the rails suffer the severest stress when the armature passes, the key to the thermal management is to control their residual temperature rise when the armature passes. Therefore, the horseshoe cooling grooves dug on the back of the rails, which have low-stress concentration effect and good engineering feasibility avoiding internal drilling problem, are enough to effectively cool the rails. The experimental data measured by the fiber Bragg grating sensors in the tests of a single shot and a rapid firing of two agree well with the simulation results, which verifies the validity of the thermal management strategy. Furthermore, through prediction, the maximum residual temperature rise is only 2.57 K in the stage of heat balance at a sustained firing rate of 12 shots per minute for the 30 mm $\times30$ mm rectangular caliber launcher presented in this paper. These conclusions are also adaptive to large-scale launchers and have guiding significance to the engineering application of the EMRL. [ABSTRACT FROM AUTHOR]

This paper analyzed the flux characteristics of a single-phase tubular switched reluctance linear motor (TSRLM) based on magnetic equivalent circuit (MEC) method. The single-phase TSRLM is divided into five different parts, which are the teeth of the stator, the yoke of the stator, air gap, the teeth of the mover, and the yoke of the mover. The reluctance of every part is expressed in analytical formulas at five special mover positions. The flux linkages at five special mover positions are calculated by magnet tube method and Gauss–Seidel iteration method which takes the saturation into consideration. A high-order Fourier series method is used to map the nonlinear relationship between flux linkage, current, and mover position with the flux linkage data calculated by the MEC method. The calculated flux linkage is consistent with 3-D finite-element method and experimental results. The dynamic and static performance of the simulation utilized with MEC method is consistent with those in experiments, which verifies the accuracy of the MEC method proposed in this paper. [ABSTRACT FROM AUTHOR]

The iron loss of doubled-sided linear switch reluctance motor (DLSRM) is analyzed and calculated in this paper. Because of the double salient structure of the switched reluctance motor and the nonlinearity of the magnetization curve of the ferromagnetic material, the flux density waveform is nonsinusoidal. So, it is difficult to calculate the iron loss of DLSRM. This paper mainly introduces the calculation method of dynamic magnetic density of the DLSRM, and basing on this, the simulation model of iron loss of DLSRM is built and compared the iron loss in different parts of the total as a percentage of the motor. Finally, an experimental platform based on DLSRM is built to measure the actual iron loss in the motor and verify the correctness of the calculation of iron loss. [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]

Compulsators are popular choices for various high-power electromagnetic launch applications, especially for the electromagnetic railgun. A two-axis-compensated compulsator with lower internal impedance and higher power density was proposed in the authors’ previous paper. The field windings and compensating windings are allocated electrical orthogonally, providing the opportunity to design the direct-axis and quadrature-axis compensations independently. Due to the excitation function of the field windings, as well as field windings and compensating windings at the same rotor periphery, the ratio between $d$ -axis and $q$ -axis compensation is determined not only by the waveform of the air-gap flux density but also by the occupied space of windings, electromagnetic force during discharge and temperature rise and cooling condition. All these aspects mentioned above were analyzed in this paper. Furthermore, the output performance for single pulse discharge of a 2-m railgun with 100-g armature and multiple pulses discharge of a 5-m railgun with 300-g armature was simulated and compared. The results indicated that the two-axis compensation could obtain benefits by introducing more sinusoidal discharge currents for single pulse mission comparing to traditional compensation structure, whereas no obvious advantages for a flat-topped current waveform for multiple pulses mission. [ABSTRACT FROM AUTHOR]

Pulsed alternator (PA) is a kind of high-power pulsed supplies widely applied in the field of electromagnetic (EM) launch. Over the past decades, the self-excited air-core PA is widely studied, but it has the disadvantages of poor heat transfer and high electric field loss. The hybrid excitation PA combined with the advantages of electric excitation and permanent magnet excitation PA, and the output voltage of armature winding can be adjusted by the electric field current. This paper presents double-electric-excitation hybrid excitation compensated PA (DEE-HECPA). In order to improve the adjustable performance for the output voltage of HECPA, the rotor structure is changed and double excitation coils are used in PA. In this paper, the equivalent magnetic circuit model for hybrid excitation region is established and the air-gap flux density is calculated. The dimensional parameters are calculated by the special EM design method for PA, the characteristics of electric excitation are verified by finite-element analysis, and the characteristics of output current for DEE-HECPA are analyzed. The research results demonstrate that DEE-HECPA is a feasible topology for PA. [ABSTRACT FROM AUTHOR]

This paper proposes some practical methodology and design aids for the linear motion servocontrol systems such as the electromagnetic launchers. Mason’s gain formula was first used in the state space to solve for the transfer function of the complex and multiloop system rapidly and conveniently. The classical feedback control referring to the separation principle, involving a tracking controller and an observer-based compensator, may work well but has limited bandwidth under the constraint of the nominal inertia, and this fact is demonstrated rigorously in this paper and improved by a novel compensation scheme. According to the time-domain performance and Nyquist view, a delicate parameter design of control parameters is made for the tracking controller and the robust observer. The algorithm is verified by use of a rapid control prototype real-time simulation platform. The comparison of the experimental results shows that the proposed control scheme has good properties of trajectory tracking, antidisturbance, and noise suppression. [ABSTRACT FROM AUTHOR]

This paper clearly demonstrates the structure of Experimental Advanced Superconducting Tokamak (EAST) power supply system and analyzes principles of the finite-state machine (FSM) elaborately. Depending on the characteristics of EAST power supply system and the requirements of it, this paper chooses the real-time Linux as system platform and experimental physics and industrial control system (EPICS) as development tool to design a control system of the EAST poloidal field power system supply. This paper utilizes a temporal logic control based on the FSM in order to regulate the operation process of real-time sequence logic control of 12 sets of power controllers. This design is evaluated and tested, and it completely meets the real-time requirement of the poloidal field power supply (PFPS) control system. Several experiments have proved that this design definitely meets the real-time sequence logic control requirement of the PFPS control system in the complex situations under magnetic fields. [ABSTRACT FROM AUTHOR]

The interest in the use of atmospheric-pressure plasma jets (APPJs) is constantly growing. APPJs offer various ranges for applications, such as wound healing, cancer treatment, and dental care. The complex plasma chemistry plays an important role in each of these fields but is often poorly understood. In this paper, the production of atomic oxygen in a radio frequency helium–oxygen plasma is investigated by means of a numerical simulation. A 1-D discharge of an atmospheric-pressure plasma jet is created with the plasma module of COMSOL Multiphysics, using a set of 25 reactions. Many 1-D simulations usually cannot estimate the power deposition in a correct way because of suspected arising losses, such as radiation and inefficiencies of the external circuit. In order to match the experimental power deposition of 13 W, high voltages (855 V) are required in the model. Such high voltages cause changes in the plasma characteristics like a switch in the glow mode. The impact of the voltage on the plasma is investigated by the comparison of a low-voltage (325 V) simulation, which matches the experimental oxygen production, and a high-voltage (855 V) simulation, which matches the experimental power deposition. Outcomes of this paper further support the idea that the power deposition measured in experiments is higher than the actual power deposition coupled to the plasma. [ABSTRACT FROM AUTHOR]

The planned China fusion engineering test reactor (CFETR) needs one or more negative-ion-based neutral beam injectors (N-NBIs) with a beam energy of 500 or even 1000 keV. In order to prepare for CFETR, a prototype of CFETR N-NBI is being designed. The prototype needs an acceleration grid power supply (AGPS) rated at 200 kV/25 A with a maximum pulselength reaches to 3600 s. The AGPS adopted a single-stage inverter-type high-voltage power supply (HVPS). The output voltage ripple is an important specification of the AGPS, which can affect the efficiency and stability of N-NBI system by influencing the beam divergence. However, the conventional methods cannot be used to limit the output voltage ripple of the inverter-type HVPS used as AGPS of CFETR N-NBI prototype. This paper simplified the AGPS to an insulated three-phase three-level (TPTL) dc–dc converter connected with a dual dc link. The working process of the TPTL dc–dc converter with duty-cycle modulation has been analyzed, and two main continuous conduction modes are described. The influence of key parameters such as duty cycle of inverter, leakage inductance of transformer, and output current on output voltage ripple is analyzed. Based on the analysis results, a so-called combined control strategy was proposed to keep the output voltage ripple at a level. The proposed strategy is suitable for the cases where the object output voltage is below 175 kV. Some simulations were carried out by using MATLAB/Simulink. The results showed that the analysis in this paper is reliable and the proposed control strategy has a good performance. [ABSTRACT FROM AUTHOR]

Vacuum circuit breakers have an issue of instability arc current and chopping phenomena when the current is cut off from the circuit. To clarify the effect of the instability low-current vacuum arc for circuit breaker development, the instability mechanism of low-current vacuum arc for various parameters was proposed to verify consequent affecting circuit breaker capacity in this paper. This paper used the cathode spot model neglect the transition region between the collisionless sheath and collisional plasma region. The eight equations were used for solving the dependent variable of plasma parameters for both silver and copper electrode materials. The low ionization was supposed in the cathode spot model. The results showed that the changes in the work function and ion current fraction at ambient temperature did not have the main influence on the arc stability limit current both in the silver electrode and copper electrode. On the contrary, the changes in the heat conductivity at ambient temperature affecting the arc stability limit current significantly both in the silver and copper electrodes. Furthermore, the results were found out that the cathode spot can be confirmed unstable current phenomena when the current below 19 A for copper cathode and below 19.4 A for the silver cathode. These phenomena can be explained that the reversed electrons flow from the plasma side to sheath region affecting the electric field at cathode spot become negative zone; thus, the starting noise on the current trace appears before chopping current. [ABSTRACT FROM AUTHOR]

We have studied the two-electron pseudodot (TEPD) system immersed in plasma environments under the influence of a monochromatic linearly polarized laser field. The four different sets, constituted by the potential parameters, of the more general exponential cosine screened Coulomb potential are used to characterize the Debye and quantum plasma environments. The time dependent in the Schrödinger equation arising from the laser field is interchanged to the potential energy term from the kinetic energy term through the dipole approximation and the Kramers–Henneberger transformation. Then, the laser-dressed potential that denotes the effects of the laser radiation field is constituted by using the Ehlotzky approximation. In that case, as the analytical solution is impossible just now due to the complicated form of the Schrödinger equation, the numerical solution is carried out via the asymptotic iteration method. In this paper, the pseudodot system is considered because the quantum dots are very similar to atomic systems, and the pseudoharmonic potential is successful in explaining the atomistic structures. However, it is an important motivation for us that, as well as the importance of the laser–plasma interactions, the laser field is a considerable exciter for radiating, which exhibits remarkable confinement effects. Since, as well as the screening effects exhibited by plasmas on atomic systems, and their significant results, the plasma is a significant experimental argument in manufacturing and modification of the quantum dots, the plasma effects are taken into consideration in this paper. Within these motivations, all parameters that operate on the energies of TEPD system with the laser effect in plasmas are analyzed in detail, and the corresponding results are discussed thoroughly. [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]

The collision frequencies between electrons and air molecules are important parameters when analyzing electrical breakdown. Different values for the collision frequency in atmospheric air have been reported in academic literature; the current analysis method for breakdown in waveguides and filters considers an electric field-independent term. However, some authors have remarked the importance of an electric field dependence of the collision frequency. In this paper, the collision frequency of electrons, accelerated by the presence of an electric field, against air molecules is obtained. The collision frequency is calculated from experimental data, for breakdown voltages at dc in positive polarity in a wide atmospheric pressure range using a plane–plane plates configuration. As waveguide filters are currently designed with a 3-dB tolerance below the electrical breakdown thresholds, this paper analyses the current methods for these breakdown threshold calculations, and proposes a novel correction factor for the collision frequency in order to approximate the analytic calculations to experimental results. [ABSTRACT FROM AUTHOR]

In this paper, a comparative investigation has been performed on the effects of water vapor on electron energy in He/H2O and Ar/H2O plasma jets at atmospheric pressure. The investigation is based on a needle-plane discharge system and the numerical simulation with the use of a 2-D fluid model. The OH production and its correlation with electron energy in the two gases have also been calculated. This paper gives the following significant results. The averaged electron energy in He/H2O keeps basically a constant at water vapor concentrations below about 0.1%, and then it evidently decreases. However, the averaged electron energy in Ar/H2O is hardly changed with the increase in the water vapor concentration. This difference from that in He/H2O is mainly due to different energy thresholds for the electron collision reactions related to helium and argon. The averaged OH densities in He/H2O and Ar/H2O increase with increasing the water vapor concentration, but that for He/H2O is evidently large at water vapor concentrations below about 0.5%, compared to Ar/H2O. The reason for this can be attributed to more electrons participating in the excitation reaction related to H2O and large reaction rate of OH production in He/H2O. Finally, this paper suggests that a proper high water vapor concentration in He/H2O plasma jets may allow an expected electron energy and also generates abundant OH radicals. [ABSTRACT FROM AUTHOR]

In this paper, the capacitances of the two-stage bushing that is installed in the 1-MV test bed for neutral beam injectors in the future fusion reactors are calculated by modeling the bushing in a 3-D electrostatic code. One of the modeling results is the stored energy in the bushing, which corresponds to 1/2 CV2. After evaluating the bushing capacitance, a MATLAB/Simulink model is presented to model the possible breakdown in the bushing and between the electrodes in the 1-MV test bed. When a breakdown occurs between anode and cathode, an overcurrent is drawing that can cause damage in the electrode surfaces while an overvoltage takes place when the breakdown happens between the bushing stages. Such damage has been observed experimentally in the past. This paper also presents some of the possible protection against the breakdown in the 1-MV test bed to dissipate the stored energy in order to protect the electrode surfaces and the bushing. The suggested protections presented in this paper are damping resistors, surge arrester individually, and both of them. Also, a coil can be added to the DR either in series or in parallel. [ABSTRACT FROM AUTHOR]

This paper is focused on using plasma as element of a frequency selective surface (FSS). FSSs have been used for filtering electromagnetic waves for many years. Conventional FSSs use metal patch pattern as periodic element. This paper takes the plasma tube as a substitution for metal patch. The 3-D finite-difference time-domain method with periodic boundary condition is utilized to simulate the interaction of incident wave and plasma FSS. Numerical calculation results in that electron number density of plasma can dominate the resonance frequency obviously. The resonance frequency increases as the increasing of electron number density of plasma to the limit of that of perfectly electric conductor. Thus, the FSS can be designed to be tunable by changing the ionized electron number density. Both of the noncollision and collisional plasma model are introduced to study the FSS characteristics. The numerical calculation results show that the collision frequency only influences the reflectivity while has no effect on the resonant frequency. The resonant frequency and transmitted power ratio can be tuned by assigning the plasma’s electron number density and collision frequency. Thus, plasma elements offer the possibility of improved shielding effect along with reconfigurability. Plasma FSS can also be made transparent by tuning the plasma off which makes the use of FSS more versatile. [ABSTRACT FROM AUTHOR]

In this paper, a complete flux scheme (CFS) has been implemented in 1-D fluid model for simulating the pulsed dielectric barrier discharge (DBD) in pure argon at atmospheric pressure. The characteristic quantities of the pulsed DBD have been systematically calculated by using the CFS and presented in comparison with those by using the exponential difference scheme (EDS). This paper shows the following results. There is the two-pulse discharge mode in the present simulation. The two discharge currents obtained using the CFS and EDS converge to the same result in good agreement with the experiment as spatial step length decreases, but the CFS has a fast convergence performance compared to the EDS. With a small grid number, the numerical scheme has an evident effect on the characteristic quantities in the time region corresponding to the first discharge pulse. This paper suggests that in the pulsed DBD, the usage of the CFS with a properly small grid number can give more accurate result and also presents a high calculation efficiency. [ABSTRACT FROM AUTHOR]

This paper represents a contribution toward finding a complete set of electron collision cross sections for the methane molecule by revising all of the collision cross sections and adding the partial collision cross sections data relating to dissociation by electron impact. For the latter, there are no available measurements data for each channel of dissociation and no validated recommended data for use in the modeling, although these data are very important in order to determine different species in a methane plasma. The rate coefficients of the partial dissociative collisions into neutrals and the partial ionization collisions are also calculated, and when fitted, these can be used as input for fluid models. This paper is concluded by the validation of our set of data through a comparison between the transport coefficients calculated by using our data and the measurements of the transport coefficients that already exist in the literature. [ABSTRACT FROM AUTHOR]

In this paper, the finite-element method (FEM) is applied for an exact solution of the dispersion of hybrid electromagnetic waves excited in a novel combined elliptical waveguide. This special configuration is included of an elliptical metallic waveguide filled with a dielectric material, whereas two axial hollows with circular cross section have been created in it. A hollow is placed in one of focuses of the elliptical waveguide and second hollow is located in another focus or shifted from it. Two straight relativistic electron beams with the same currents and velocities in opposite directions are injected inside the hollows. Here, we apply an accurate approach in which the electromagnetic fields described by the FEM and satisfies boundary conditions at the interfaces of different regions. Then, the time growth rate of slow waves amplified by the electron beam is numerically calculated. The excited waves are in microwave range. The effects of accelerating voltage and current density of electron beams, and geometrical parameters such as radius and location of electron beam, on the frequency spectra, the growth rate, and profiles of axial electric and magnetic fields of excited slow waves are studied. Our research shows, the novel waveguide studied in this paper is superior to other waveguide structures in wave amplification with applying minimum input electrical power. [ABSTRACT FROM AUTHOR]

The earth’s magnetosphere is an intricate input–output system, where the inputs are the solar wind parameters and the output measure are the geomagnetic. The disturbance storm time (DST) index is one such quantity measure for the intensity of disturbance in the geomagnetic field due to the magnetic storm. The geomagnetic activities have catastrophic effects on several communication networks and harmful for biological livings. Therefore, it is significant to develop a model for the prediction of disturbance in the geomagnetic field. This paper presents linear as well as nonlinear parametric techniques to model the complex magnetosphere dynamics. Neural network (NN)-based modeling techniques, such as feed-forward NN (FFNN), NN integrated with nonlinear autoregression with exogenous (NARX) inputs, adaptive neuro-fuzzy inference system (ANFIS), and recurrent NN are developed for the prediction of the magnetic storm. Global search algorithms, such as particle swarm optimization and genetic algorithm, also train the developed FFNNs. All the models are trained on 15 years’ real-time series data of solar wind parameters and DST index on a frequency of 1 h. The accuracy of the predicted DST index for multiple intensity levels of the magnetic storm using all developed linear and nonlinear modeling techniques is presented, compared, and analyzed thoroughly. The performance of NN integrated with NARX inputs and ANFIS is higher than rest of methods developed in the paper. Both techniques have the capability to predict mild, moderate, and intense magnetic storm with high degree of accuracy. The comparative analysis with state of the art shows the enhanced accuracy and robustness of developed models in this paper. [ABSTRACT FROM AUTHOR]

In this paper, atmospheric-pressure air and oxygen corona plasma jets under water surface have been used to generate plasma-activated water (PAW) to inactivate colletotrichum gloeosporioides (C. gloeosporioides) suspension. The atmospheric-pressure plasma jets in the water were characterized by measuring: 1) the electrical and optical properties for evaluating the plasma efficiency and 2) the physicochemical properties of PAW, including pH value, oxidation-reduction potential value, and the concentration of hydrogen peroxide, nitrite, and ozone. The aim of this paper is to investigate the effects of long-lived reactive oxygen and nitrogen species (RONS) and environmental factor (acidity) in PAW on fungicidal property. The results of antifungal activity show that the inactivation rate of C. gloeosporioides is higher using air-PAW than oxygen-PAW, and increases with increasing reaction time when preparation time of PAW is fixed as 30 min. This correlates well with measurements of the aqueous-phase long-lived RONS concentration such as nitrate and ozone, suggesting these species play crucial roles in the inactivation process. [ABSTRACT FROM AUTHOR]

In the process of electromagnetic launch, the melting on the armature surface tends to change the state of the armature/rail (AR) contact. Once the contact state is damaged, transition will appear easily. For this reason, it is necessary to analyze the factors affecting the melting characteristics of the armature surface. According to the Reynolds equation listed for the liquid metal film (LMF) on the AR contact interface, and by coupling the temperature, stress, and electromagnetic fields, this paper presents a thermoelastic magnetohydrodynamic model, which is used to analyze effects of the current waveform, and the length and angle of the armature tail on the surface melting rate and LMF thickness. The results show that for the same armature, if we want to achieve the same velocity within the same time range, the smoother the current waveform, the slower the surface melting rate and the thinner the minimum LMF thickness, and that for armatures of different key dimensions, in a certain range, the longer the armature tail, the slower the surface melting rate, but the larger the total melting amount and the thicker the minimum LMF thickness, and that the angle of armature tail has little effect on melting characteristics of the armature surface. What has been done in this paper is of great importance to improving the AR contact state and optimizing the performance of the electromagnetic launcher. [ABSTRACT FROM AUTHOR]