Hollow cathode plasma contactors have an extensive history as spacecraft neutralizers, but questions remain on whether the technology can neutralize significant positive charging in tenuous space plasmas. Simulations and a representative semianalytical model (which we term the ion emission model) predict effective neutralization in these scenarios as ion current is emitted from the surface of the quasi-neutral

The “magnetic window” is considered to be an effective technique for alleviating a vehicle’s atmospheric reentry blackout, whereas the dynamic variation characteristic of the plasma sheath is critical for the vehicle’s communication. In this article, the effects of dynamic plasma sheath on electromagnetic wave propagation and the bit error rate (BER) of two typical modulation signals under an external

A steady-state kinetic model of argon–helium high-pressure radio frequency dielectric barrier discharge is developed using a simplified reaction rate package appropriate for pressures ranging from 200 to 500 torr. Electron production and loss rates are analyzed as a function of pressure and Ar–He mixture, highlighting the importance of the Ar 2 * dimer for higher pressures and Ar rich mixtures. As

A cathode-less radio frequency (RF) thruster is a plasma-based system for space propulsion. It consists on a source for plasma generation driven by an RF antenna and a magnetic nozzle for the acceleration of the exhausted plasma stream. A parametric analysis has been conducted in order to evaluate the influence of some key design parameters on the performances of such a thruster. Specifically, the

A mathematical model is presented for quantifying the ion number density over a range of discharge current in microplasma discharges. The ion number density is determined from measured discharge voltage, current, pulsing frequency, and trace impurity that is injected into the system deliberately. Experiments are conducted in pure helium with nitrogen being introduced as the trace species. The ion number

A spoof surface plasmon (SPP) transmission line (TL)-based low-cost near-field imaging system is proposed. Its signal processing part uses a compressive sensing algorithm, which is able to accurately image a sparse scene. Unlike conventional multiple antenna-based imaging, a single-radiator system requires a highly dispersive element. Utilizing this dispersion of radiated pattern, frequency diversity

High-intensity short-pulse lasers have made possible the generation of energetic proton beams, unlocking numerous applications in high energy density science. One such application is uniform and isochoric heating of materials to the warm dense matter (WDM) state. We have developed a new experimental platform to simultaneously create and probe WDM at the matter in extreme conditions (MEC) end station

This study presents two 3-D atmospheric plasma spray models, namely, internal and external powder injections, by using the computational fluid dynamics technique to study the status of the melting of a particle and its in-flight velocity during a porous ceramic layer fabrication process. A bulk fluid model, which solves the time-dependent standard ${k}$ - $\varepsilon $ model, is used in combination

Objective: Nonthermal plasma at atmospheric condition using dielectric barrier discharge (DBD) is reported to be useful in many applications. Here, we have developed a strategy to generate nonthermal atmospheric plasma (NTAP) at ambient conditions for potential biomedical applications. Methods: We have explored the active ingredients of the nonthermal plasma using atomic emission spectroscopy. The

The distribution and dissipation of neutral atoms are crucial for understanding the dielectric recovery process after interrupting direct current (DC) vacuum arcs. This article aims to investigate the dissipation of copper atoms after a forced extinction of the vacuum arc experimentally, adopting the plane laser-induced fluorescence method. The change in the 2-D distribution of copper atoms with time

$Z_{\mathrm {eff}}$ is measured by two visible bremsstrahlung diagnostics on HL-2A tokamak, one of which uses a high spectral resolution spectrometer coupled with an electron multiplied CCD (temporal resolution of 100 Hz), and the other uses a filterscope system (temporal resolution of 1 MHz). The bremsstrahlung brightness measured by them coincides with each other very well. $\bar {Z}_{\mathbf {eff}}$

Vacuum arc evaporation is a prospective technique to fabricate hard and wear material due to its high ion energy and plasma density. Nevertheless, target tends to be poisoned by the compound layer in common reactive gases such as acetylene. Then the coating deposition rate and the properties of the coatings would be strongly influenced. Thus, the formation of the compound layer has to be inhibited

Investigations have been carried out into the mechanisms leading the initial breakdown of trigatron switches. The experimental work identifying effects of two different igniting factors are described and carried out in detail. One mechanism is when only the UV radiation generated from the ignition gap (gaps between the pin and adjacent electrodes) is applied to the main gap (gaps between the adjacent

Linear induction motors (LIMs), applied in the field of electromagnetic emission, due to end effect, show the characteristics of thrust rapid decline, and current asymmetry increasing in the process of high-speed movement. This article studies the effect of stator winding connections on thrust and current asymmetry of six-phase shifted 30° LIM considering the static and the longitudinal end effect

As one of the most important electrified railway components, the pantograph-catenary (PC) system plays a key role in the energy transfer for the train through the sliding electric contact. However, the performance of the PC system is severely limited by pantograph arcing, and the study on the dynamic characteristics of pantograph arcing is still far away from satisfactory. In this article, a magnetohydrodynamic

Atmospheric pressure needle-to-plane negative corona discharges have been studied considering the effect of photoionization in electrode gap spacing from 2.9 to 3.9 mm. Trichel pulses, spatial distributions of electron density and electric field, pulse duration time, and pulse frequency under different gap spacing were investigated in this work. It is found that peak value and duration time of the

The objective of this article is to determine the influence mechanism of the cathode materials on the transition process of the arc modes in high-current drawn vacuum arcs under the external axial magnetic field (AMF). Six kinds of pure metal of Cu, W, Mo, Fe, Cr, and Al were selected as the cathode materials. A high-speed charge-coupled device (CCD) video camera was selected to record the arc appearance

A novel numerical method has been developed that incorporates electrically conducting objects into particle-in-cell simulations of electrostatic plasma. The method allows multiple objects connected by voltage and current sources in an arbitrary circuit topology. Moreover, by means of an unstructured mesh, the objects can have arbitrary shapes. The electric potential of the objects is solved self-consistently

Corona discharges on conductors are unavoidable in high-voltage direct current (HVDC) transmission lines. The cross-section geometry of the conductor is an important factor which significantly affects the positive corona discharges of dc transmission lines. Here, an improved fluid model is proposed to simulate the dc positive corona discharges on conductors with different cross-section geometries.

The rotational motion of a strongly coupled unmagnetized 1-D-dusty plasma ring was studied. The particles rotated within the ring-shaped potential that was formed using a circular grooved electrode with a center post. Particle position data from the rotating dust ring were analyzed and the angular velocity of the particles was calculated. The rotation rate of the ring depended on the number of particles

Helium helicon wave plasma (He-HWP) wall conditioning was performed with a specially designed antenna system on the Experimental Advanced Superconducting Tokamak (EAST) under strong magnetic field (0.5–1 T). The maximum effective RF power $P_{\mathrm {eff}}$ was 30 kW at 27 MHz, and the He pressure was fixed at ~0.27 Pa. Charge-coupled device (CCD) images indicated that toroidal homogeneous but poloidal

The mechanism that the author’s recently developed for plasma fusion at kiloelectron volts (keV) has been extended from the D- 3 He fusion with extremely heated 3 He ions to the D-T fusion with extremely heated tritons. Two major significances of this extension are that the D-T fusion has the highest reactivity and the plasma does not need H ions, which do not participate in the fusion, because the

The coaxial cavity can rarefy the mode spectrum and restrain the mode competition, which is beneficial to the mode selection of high-frequency and high-power gyrotron. However, the misaligned insert would result in frequency shift and a decrease in interaction efficiency. Besides, the ohmic loss on the cavity walls would become uneven, which deteriorates the long pulse operation of the gyrotron. In

The in-vessel structures of tokamak devices sustain large electromagnetic force due to both induced eddy current and halo current. The coupling effect between the electromagnetic field and the mechanical vibration of the structures has a significant influence on the structural dynamic response. To assess the coupled mechanical behavior of in-vessel structures, a numerical method was proposed in this

The current control of the breech pulsed power cables and the stability of the total current are important factors which have an influence on the performance of the electromagnetic railgun system. In order to achieve these two targets, a two-objective optimization model through the genetic algorithms and weighted combination method is established. An optimization example of 20-mm railgun with 1-MJ

In this study, a simple, economical and efficient preionization system (2.45 GHz, 1 kW) was constructed to assist the current startup in Taban tokamak ( $B_{T}= 0.7$ T, $R = 0.45$ m, a = 0.15 m). Power pulse transformer is a part of the preionization circuit, and its removal from the system can have impact on the performance of microwave duration and plasma preionization. In the present system, the

Monolithic U-type armature is one of the most important armatures in electromagnetic railgun. First, based on the traditional U-shaped armature, this article proposes a new structural design of the armature with interference at both ends. In addition, based on the calculation results of the interference fit module, a railgun multiphysical field coupling model is established. Second, through the interference

A W-band folded waveguide traveling wave tube (FWTWT) with lowered 19.4-kV operation voltage and improved gain flatness was investigated and developed. In this article, design methodology, fabrication, and test results were presented and discussed. Two kinds of slow-wave circuits with the positive and negative period stepping were chosen to carry out the contrastive study. A folded waveguide automatic

Keeping good electrical contact at the armature/rail interface and the structural integrity of the armature during electromagnetic launching is critical to its performance. In this article, the influence of armature height on the erosion of armature’s tail is studied through experiments. The results of the armature current melt erosion (CME) of different linear current densities are summarized. For

In this article, a $3\pi $ band-edge dual frequency oscillator using a novel half-period staggered folded waveguide (FWG) is proposed. Simulation results from CST Particle Studio show that the half-period staggered FWG could form a stopband at $3\pi $ phase shift with a high coupling impedance, enabling the device operating at two frequencies. A prototype oscillator was then designed and fabricated

One of biggest obstacles for the development of terahertz (THz) science and technology is the lack of the THz sources, especially, when the requirement of the power reaches to kilowatts. Among all the existing sources, the gyrotron is the most promising one which can generate high-power THz radiation. Recently, a THz detection system is under development in the THz Research Center, University of Electronic

In the above article [1] , on page 2159, there were some errors introduced to the text during the production process.

Presents the table of contents for this issue of the publication.

Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.

In recent years, helicon plasma sources have attracted much attention from scientific centers and industry. In this regard, the power coupling is of particular importance for the production of dense plasma in these systems. Therefore, in order to achieve maximum efficiency in these types of plasma sources, it is necessary to analyze the key parameters affecting plasma power absorption such as magnetic

The background pressure of vacuum chamber determines operation and performance of ion thrusters. In order to present the neutral plume and temperature distribution of a 30-cm-diameter ion thruster working under rated condition and in a large vacuum facility, theoretical calculation and numerical simulation are used to investigate the characteristics of thruster neutral plume. The results show that

This article by employing a zero-dimensional model investigates vacuum ultraviolet (VUV) emission from a xenon–neon microdischarge. The effects of the pressure, the input voltage, and the neon fraction are carefully studied. For specific input voltages, the microdischarge operates in an oscillatory regime which is called the self-pulsing regime. The self-pulsing frequency is mainly affected by the

This article presents the development of a dual-state Ku -band gyrotron traveling-wave tube (gyro-TWT) dual-state curved-profile magnetic injection gun (MIG) generating high-quality electron beams, in which the pitch factor is up to 1.2 and 1.35 for the pulse wave (PW) state and the continuous wave (CW) state, separately. A multiobjective genetic algorithm (MOGA) is applied in the profile optimization

A novel method is proposed to reduce the ultra-wideband (UWB) far-end crosstalk (FEXT) of the parallel microstrips (MSs), in which subwavelength periodically loaded transmission lines (PLTLs) with discontinuous structured guard lines (DSGLs) are appropriately used. The motivation is to innovate a structure to eliminate the FEXT for devices in microwave and millimeter-wave band. In the scheme, the single

In this article, the oversized substrate-integrated waveguide (OS-SIW) is proposed, analyzed, and experimentally demonstrated. The physical parameters and the effect of material surface roughness on the attenuation and the SIW power capability lead to the exploitation of wider and thicker waveguides, as an alternative to enhance the power-handling capability (PHC) and reduce the losses. The resulting

This article investigates the effects of ion-channel guiding, axial magnetic fields, helical wiggler magnetic fields (HWMFs), and self-fields on trajectories of the elliptical relativistic electron beam. Two equations for the average axial velocity and the function $\Phi $ are calculated for an electron in the considered fields by solving the motion equation. In the meantime, the effects of elliptical

A novel concept of the mass ratio of negative to positive ions has been introduced to explore its effect on the sheath structure in three electronegative cold plasmas, namely, CF 4 , O 2 , and C 60 plasmas, for spherical geometry with different probe radii. The magnitudes of velocity of positive ions and potential at the sheath edge are found to modify with the mass ratio, electronegativity, and probe

Corona-based atmospheric pressure cold plasma reactors can be applied to material processing, bacteria inactivation, plasma medicine, etc. Knowledge generated in this article can be used to optimize such reactors when they use electrodes consisting of arrays of needles. The experiment used a gas admixture of helium and dry air and an applied 60-Hz ac voltage of 6.5-kV rms, with an electrode gap of

Diamond-like carbon (DLC) films were grown on Si substrates by high-density helicon wave plasma (HWP) generated under low pressure, with the help of CH 4 as an important single-source precursor. The influence of magnetic field ( ${B}_{0}$ : 1200–2400 Gs) on the film structure, morphology, composition, and mechanical properties has been studied. The high deposition rate of the films exhibits a maximum

In natural clouds, water droplets grow by condensation in a supersaturated environment. Under subsaturated conditions, water droplets normally keep evaporating until they eventually disappear. In this article, we study the effect of corona discharge on water droplet growth under both supersaturated and subsaturated conditions. It is shown that the formation of mist visible to the naked eyes could be

An experimental study of the velocity field in a three-electrode arrangement of a plasma-chemical surface dielectric barrier discharge (SDBD) reactor designed for plant seed’s treatment was carried out. The effect of polarity and magnitude of the extraction voltage (potential of the third electrode), configuration of the SDBD system (5- and 10-mm distances between the strips were observed) and the

A high nitrogen oxides (NO x ) removal rate under fluctuating temperature condition still remains a challenge to be solved. The plasma can be a potential solution to overcome this problem. This article reported catalytic NO x removal coupled with plasma in a wide temperature range below 350 °C. Silver (Ag) and copper (Cu) supported on ZSM5 zeolite were used as the catalysts to remove NO x . The results

Cold plasma generated from a gas admixture of helium and dry air with 60-Hz ac voltage at 6.50-kV rms was utilized to process biochar. Reactive oxygen and nitrogen species (RONS) were generated in the cold plasma and these chemical radicals modified the biochar. Plasma-processed biochar samples were immersed in distilled water after which the pH of the solid/water mixture was measured. This pH test

This article presents a numerical model and simulation results for the flow stabilization problem behind a solid cylinder. Four dielectric barrier discharge actuators are attached to the cylinder surface, each consisting of two tape electrodes. The surface-exposed electrodes are supplied with a high sinusoidal voltage, whereas the embedded ones are electrically grounded. A surface low-temperature plasma

2-D particle-in-cell simulations of free charge creation by collisional ionization of C12 and C60 molecules immersed in plasma for the parameters of relevance to plasma gasification are presented. Our main findings are that: 1) in uniform plasmas with smooth walls, two optimal values that emerge for free electron production by collisional ionization (i.e., a most efficient discharge-condition creation)

Beam plasma directly forms the thrust of single-stage helicon plasma thrusters and its properties are the input parameters of the two-stage helicon thruster. Therefore, the spatial distribution of the beam plasma is vital for both single-stage and two-stage helicon thrusters. Using an optical emission spectroscope with a radial resolution of 5 mm, the spatial distribution of the beam plasma parameters

One of the challenges that International Thermonuclear Experimental Reactor (ITER) will face during plasma operation is to determine the absolute divertor surface temperature of the actively water-cooled (70 °C, 3 MPa) tungsten plasma-facing units (PFUs) to ensure their integrity. The expected steady-state heat flux up to 10 MW/m 2 is close to the operational limit and so one of the goals of the thermographic

Instrumentation used in the diagnostic of signals in fusion experiment needs protection against surges in signal power, which emerges from the electron cyclotron resonance heating (ECRH). In this article, a design methodology for the development of selective single notch waveguide is presented. The design of the notch filter is a circular corrugated waveguide that has been modeled based on the second-order

The noncontact diagnosis methods of discharge plasma include spectrum, electromagnetic wave, ultraviolet image, and high-speed nanosecond image analyses, but there are few studies on the visible image diagnosis method. With the development of digital cameras, the number of pixels in a visible image is far greater than that of ultraviolet, infrared, and high-speed cameras; the image contains a considerable

The switching behavior of gas-filled contactors was investigated using a model switch. High-speed imaging and spectroscopy provided information regarding the characteristics of the arc plasma. The impact of external magnetic fields, fill gas, fill pressure, and current amplitude was investigated. The most important factor, influencing the switching behavior for currents below 100 A, is provided by

For metallized film capacitors (MFCs), the pulsed current would lead to the electrode fracture, the process might be accelerated under the repetitive pulsed current, and finally leading to the failure of MFCs. In order to study the mechanism of electrode fracture and its influencing factors, an experiment platform based on metallized film is established to observe electrode fracture by using a microscope

The use of lasers to initiate the closure of high-power gas switches was initially explored soon after the development of suitable high-power pulsed lasers in the 1960s. The low jitter, excellent triggering range, and galvanic isolation provided by laser triggering have been extensively exploited in the triggering of megavolt switches in large pulsed power machines. The fact that the lasers and optical

Inductive pulsed power supply (IPPS) is considered as an alternative to capacitive one due to its higher energy density. An opening switch is necessary for an IPPS because it interrupts the charging circuit and transfers the stored energy to the load. A major technical challenge inherent to the IPPS is the overvoltage across the opening switch, i.e., the open-circuit voltage. Moreover, obtaining a

This article intends to design, simulate, and implement a dummy load coil, a very significant element, in the Loran transmitter system. In order to ensure the impedance matching, the solenoid coil is designed with an inductance range from 200 to 300 $\mu \text{H}$ . Analytical and finite-element methods are deployed as the most common practice solutions to calculate and simulate the coil inductance

The design and operation of many pulsed-power devices are affected by surface flashover of insulator, resulting in reduction of voltage and current output; therefore, the physical research under the corresponding parameter is limited. Since the primary electron emission plays a critical role in the flashover process, methods that can prohibit electron emission from the cathode are expected to improve