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High-frequency (HF) oil-immersed transformers with small size and light weight have been paid wide attention by researchers. Its oil–paper insulation frequently withstands HF over-voltages at frequencies of several kilohertz and above, resulting in the too early failure of oil–paper insulation. In order to investigate the effect of HF on oil–paper insulation, this article investigates the partial discharge (PD) characteristics of oil–paper insulation under HF stress. The experimental results show that a frequency-induced inflection point is existed near 10 kHz and the PD parameters of HF voltages is much higher than that ac voltages. Besides, the theoretical mechanism is expounded to interpret and understand the formation process of frequency-induced inflection points more easily. It can be found that the change in frequency causes the change in the charge decay time constant and the residual charge on the insulating surface, resulting in the formation of the frequency-induced inflection point at HF. These results might contribute to determine the characteristics of PDs between HF voltages and ac voltages. It can provide references for the research and production of HF transformers. [ABSTRACT FROM AUTHOR]

The space charge effect of transformer insulating paper will distort its internal electric field, and its space charge effect will be more prominent under extremely complex working conditions. At present, the micromechanism of charge transport and electric field distortion characteristics of paperboard are not clear under complex working conditions. So in this article, based on the bipolar carrier transport (BCT) model and the dynamic carrier balance model, the effects of high temperature, aging degree, moisture content, and bent degree on charges accumulation in paperboard are studied under dc high voltage by numerical simulation and the measured data needed for simulation. The results show that the higher temperature strengthens the carrier migration, deepens the injection depth of the charge, and aggravates the distortion of electric field intensity in paperboard. The more extended the aging time of paperboard, the greater the internal trap density and the deeper the trap depth, which lead to charges migration difficultly. Increasing water content in the paperboard will accelerate space charges to reach a steady state, while further increasing it will slow down this process, which is related to the shallow trap getting deeper. When the critical part of paperboard is extruded, many traps are introduced, resulting in charges accumulation seriously. The research results can reference the design of paperboard and the maintenance of transformer insulation system. [ABSTRACT FROM AUTHOR]

The Second International Conference on Advances in Plasma Science and Technology (ICAPST-21) was held during May 27–29, in 2021, at the Sri Shakthi Institute of Engineering and Technology, Coimbatore, India. As Dr. K. Navaneetha Pandiyaraj, the Organizing Chair of the Conference, states in the Preface of the conference’s Book of Abstracts: [ABSTRACT FROM AUTHOR]

The article discusses the International Conference on Plasma Science held in Atlantic City, New Jersey, U.S. in 2017.

The IEEE International Conference on Plasma Science (ICOPS) is held annually, sponsored by the Plasma Science and Applications Committee (PSAC) of the IEEE Nuclear and Plasma Science Society (NPSS). The 47th IEEE NPSS ICOPS was organized ONLINE from December 06 to 10, 2020, by the National Institute of Education, Nanyang Technological University, Singapore. The ICOPS2020 was co-organized together with the 2nd Asia-Pacific Conference on Plasma and Terahertz Science (APCOPTS) which is envisioned as the future Asian version of the ICOPS series of conferences. The ICOPS2020 was initially planned as an onsite physical conference from May 24 to 28, 2020, at Marina Bay Sands, Singapore. However, due to the COVID-19 pandemic, it was shifted to online virtual conference. The conference’s technical program included a wide range of plasma science and technology topics, which ranged from basic and fundamental research to traditional and emerging technology applications. Since the ICOPS2020 was co-organized with APCOPTS, it also had a very strong coverage of fields related to terahertz science and applications. A total of 627 presentations from scientists and participants from over 41 countries were made at ICOPS2020 with a record total registration of 754. All presentations were recorded and were available to the registered participants for 90 days after the conference was over. The program also included a women-in-engineering talk by Jackie Y. Ying from A* Star Singapore and a young professionals networking symposium on “Plasma Entrepreneurship” with the theme “Plasma entrepreneurship—Active translation of cutting-edge research to commercially viable product.” [ABSTRACT FROM AUTHOR]

The objectives of this tutorial are as follows: 1) to help students and researchers develop a basic understanding of how pulsed-power systems are used to create high-energy-density (HED) matter; 2) to develop a basic understanding of a new, compact, and efficient pulsed-power technology called linear transformer drivers (LTDs); 3) to understand why LTDs are an attractive technology for driving HED physics (HEDP) experiments; 4) to contrast LTDs with the more traditional Marxgenerator/ pulse-forming-line approach to driving HEDP experiments; and 5) to briefly review the history of LTD technology as well as some of the LTD-driven HEDP research presently underway at universities and research laboratories across the globe. This invited tutorial is part of the Mini-Course on Charged Particle Beams and High-Powered Pulsed Sources, held in conjunction with the 44th International Conference on Plasma Science in May of 2017. [ABSTRACT FROM AUTHOR]

Surrounding air pollution is one of the important warnings to human health. It is necessary to detect hazardous pollutant gases in the air. The gas sensor is the candidate for such detection. Progress of smart and flexible sensors has been receiving growing curiosity in recent years because of their enormous sensing applications. Such smart and flexible sensors can be manufactured by depositing conducting materials, such as conducting polymer, carbon nanotube (CNT), graphene oxide, and metallic nanoparticles, onto nonconducting polymeric flexible substrates, such as paper, plastic films, and textiles. Most of the flexible polymeric substrates, such as polyethylene, polyester, nylon, and polypropylene, have low surface energy and poor wettability, which weakens the adhesion between conducting material and flexible substrate. Plasma surface modification is a novel technique to enhance surface properties to produce stable composites. This review focuses on various types of plasmas for surface modification and their effects on the surface after plasma treatment to improve the grafting and adhesion of the sensing layer with the substrate. The aim of this article is to systematically overview the development of plasma-enhanced smart and flexible gas sensors to date and to envisage their future progress. [ABSTRACT FROM AUTHOR]

An intention to organize this Special Issue was born at the International Congress on Energy Fluxes and Radiation Effects (EFRE), which is held every two years in Tomsk under the technical sponsorship of the IEEE. The Congress brings together four conferences, namely, the Symposium on High Current Electronics (SHCE), the Conference on Modification of Materials With Particle Beams and Plasma Flows (CMM), the Conference on Radiation Physics and Chemistry of Condensed Matter (RPC), and the Conference on New Materials and High Technologies (NMHT). Conferences have joined the Congress in different years, but the oldest one is SHCE, which was organized for the first time in 1973, four years before the establishment of the Institute of High Current Electronics (IHCE) in Tomsk. The Symposium on High Current Electronics anticipated the name of the Institute for High Current Electronics due to the fact that the scientific direction of the Institute was laid in the late 60s–early 70s of the last century by the scientific team headed by Prof. Gennady Mesyets, who organized IHCE, SHCE, and subsequently EFRE. The Congress covers a wide range of problems, from pulse power to nanoelectronics, but the unifying canvas is the high-energy impact on materials and environments. In 2020, EFRE Proceedings have published 302 conference papers that the reader can find in the IEEE Xplore digital library. This is why this Special Issue was not intended to publish extended versions of the four-page Congress papers. This special issue was open to the publication of articles by authors regardless of their participation in the EFRE community. The idea of the Special Issue was to collect and analyze the scientific and engineering interests of the community related to the plasma of high-current electric discharges. [ABSTRACT FROM AUTHOR]

These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal. [ABSTRACT FROM AUTHOR]

These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal. [ABSTRACT FROM AUTHOR]

These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal. [ABSTRACT FROM AUTHOR]

These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal. [ABSTRACT FROM AUTHOR]

These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal. [ABSTRACT FROM AUTHOR]

These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal. [ABSTRACT FROM AUTHOR]

These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal. [ABSTRACT FROM AUTHOR]

These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal. [ABSTRACT FROM AUTHOR]

This article introduces an optimal design method for a multistage induction coil launcher. Considering the magnetic coupling and the effect of the armature’s resistance, the basic criteria to select the structure of the driving coil and armature are proposed, and the genetic algorithm is introduced to optimize the pending parameters. Based on the principle that the current in the driving coil matches the movement state of the armature, the design method of optimal capacitor parameters is deduced. The results show that the design error is less than 1%. For a multistage induction coil launcher, the optimization is carried out stage by stage. The effect of the stage spacing between driving coils is analyzed, and it is found that changing the direction of the current in driving coils helps to improve the system efficiency. Finally, based on the above optimal design method, a multistage induction coil launcher is designed, and the energy conversion efficiency of the system is close to 40%. [ABSTRACT FROM AUTHOR]

These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal. [ABSTRACT FROM AUTHOR]

Presents the table of contents for this issue of the publication. [ABSTRACT FROM AUTHOR]

Presents the table of contents for this issue of the publication. [ABSTRACT FROM AUTHOR]

Presents the table of contents for this issue of the publication. [ABSTRACT FROM AUTHOR]

The results presented in this article relate to the work conducted to verify the existence of anode-induced phenomena, predominantly anode vaporization and consequent prebreakdown (PBD) current enhancement due to the impact of positive ions and microparticles over a relatively larger area at the cathode (presumably ion-assisted field (I-F) emission like). The verification of this hypothesis is attempted using a three-electrode arrangement. One electrode is comprised of a needle insulated from and projecting through a plane electrode (collector) of 40-mm diameter. It was surmised that if the positive ion beam from the anode spot (due to electron beam impact) were to be macroscopically diffuse, at least the collector would gather a part of it. However, no currents could be detected in the collector circuit even at voltages close to breakdown. The needle currents continued to display the typical characteristics of PBD currents under alternating voltages. The needle currents depended on the spacing between the needle tip and the plane of the collector and the polytetrafluoroethylene (PTFE) insulation used to prevent emission from the immediate vicinity of the needle evaporated significantly. Typical broad-area electrode behavior displayed by needle currents indicated that I-F emission, if any, is limited to the needle itself, which is certainly broad compared to the positive ion beam. Dependence of the PBD currents and breakdown voltages on the melting point of the anode material lend support to such anode-triggered electrode phenomena. [ABSTRACT FROM AUTHOR]

In recent years, all-solid-state high-voltage pulse generators have been widely used in irreversible electroporation for tumor ablation technology. However, high voltage may cause the breakdown of loads that leads to short circuits. The short circuit of loads will generate high short-circuit currents that will affect the performance of semiconductor switches. To improve the reliability and lifetime of solid-state pulse generators, a passive synchronous isolated gate drive circuit with short-circuit protection based on decreasing the gate–source voltage is proposed in this article. To verify the overcurrent protection during the breakdown of loads, a solid-state Marx generator prototype using the drive circuit was built and tests were carried out. The experimental results show that the 205-A short-circuit current was clamped with 90 A in less than 500 ns, while the transient voltage can be neglected. Besides, the response time, the maximum transient voltage, and the maximum current amplitude can all be adjusted. [ABSTRACT FROM AUTHOR]

Cancer is a devastating and life-threatening disease. It is the second leading cause of death worldwide after heart diseases. While science has significantly advanced to improve the treatment outcome and quality of life in cancer patients, there are still many issues with the current therapies, such as toxicity and the development of resistance to treatment. Among the novel tools to overcome these limitations is nonthermal plasma (NTP) and its treatment regimens. Recent progress in NTP devices with ion temperatures close to room temperature demonstrated significant potential in cancer therapy. NTP devices provide a unique combination of reactive oxygen species (ROS), reactive nitrogen species (RNS), photons, and electric fields that exhibit desirable properties of triggering cell death pathways, selectively for cancer cells. While in principle NTP is nonnecrotic and gentle to the tissue, but reactive oxygen and nitrogen species (RONS)-triggered tumor cell death exhibited to have pro-immunogenic properties. Many in vitro and in vivo experiments have demonstrated antitumor effects of direct NTP, synergistic applications of NTP with anticancer drugs/treatments, and plasma-conditioned medium (PCM) applications against a variety of cancer cells. The latest results and findings in this field are the subject of this review along with a brief lay-reader-explanation of cancer and immunology. In this review, initially, we give an overview of the literature that deals with studies on the use of NTP for cancer treatment. Subsequently, we present typical results from that literature to illustrate the advances of NTP in oncology. Finally, we discuss some challenges and future scopes offered by NTP for cancer treatment. [ABSTRACT FROM AUTHOR]

Plasma gas injection as one of the non-thermal plasma (NTP) technologies has a free-standing gas-phase plasma reactor outside the polluted target and can efficiently degrade contaminants by injecting plasma gas containing a large number of reactive species. This approach has been utilized in various fields of pollutants treatment, because of its structural advantage of indirect contact between pollutants and electrodes and its ability to produce strong oxidizing species. This article first expounds on the principle of the plasma gas injection and then progresses to a discussion of its application for pollutants degradation, mainly focusing on the treatment effect and degradation mechanisms. It is believed that plasma gas injection is considered to be a very practical, clean, efficient, and environmentally friendly method for pollution control. [ABSTRACT FROM AUTHOR]

This article examines the mechanical design tolerances for the Scorpius injector using a 3-D particle-in-cell (PIC) code. In order to meet its objective as a high-fidelity, multipulse flash X-ray source, the accelerator has requirements for the electron beam in order to minimize the spot size of the beam focused onto a foil target to create high fluence X-rays at energies greater than 10 MeV. The requirements for alignment of the cathode, anode beam pipe, focusing solenoids, and transport solenoids specified using Trak and AMBER are independently verified using a 3-D electrostatic/magnetostatic model of the Scorpius injector, including transverse magnetic field errors that arise from mechanical alignment errors. It is predicted that the injector will meet the performance requirements for radiographic operation and has a design margin to correct for potentially unforeseen operating conditions. [ABSTRACT FROM AUTHOR]

Role of streaming speeds of ions ($u_{i0}$) and relativistic electrons ($u_{e0}$) together with the immobile dust charge ($Z_{d}$) to form dust-ion acoustic (IA) compressive and rarefactive relativistic solitons in this multispecies plasma model for immobile dusty plasma are investigated. In this new investigation of dust-IA waves with positive ions and relativistic electrons in presence of immobile dust, it is noteworthy to mention that only compressive Korteweg-de Vries (KdV) solitons are seen to produce for some pairs of initial streaming of ions and relativistic electrons. Whereas for some other pairs of ion and relativistic electron streaming speeds, rarefactive solitons of either increasing or decreasing character are seen to produce. The presence of dust charge of immobile dust, present in the plasma, plays a very crucial role to form compressive and rarefactive KdV solitons which is a salient feature of this theoretical investigation. The presence of massive dust particles in the stationary background of the plasma, andthe lighter ions and relativistic electrons get appreciable initial drifts which makes a great change in the growth of solitons which is a salient feature of this new investigation. The results of this finding may be great useful in space plasma and applications of this plasma model in space plasmas are also discussed in brief. [ABSTRACT FROM AUTHOR]

The present technical note is dedicated to an experimental study to determine the efficiency of energy transfer from chemical to acoustic pressure impulse for an underwater aluminum exploding wire. The study is part of a larger project aimed at developing a repetitive exploding wire powerful pressure source for industrial applications. This article presents the experimental arrangement, the diagnostics used, and the main results obtained. The experiments reported include the accurate measurement of the acoustic pressure impulse generated by both aluminum and gold underwater exploding wires. Based on previously published work, a straightforward interpretation of the results allows the efficiency of the energy transfer from chemical to acoustic pressure impulse for an underwater aluminum exploding wire to be estimated as 2.2%. [ABSTRACT FROM AUTHOR]

We describe the design, operation, and qualification of a coaxial plasma gun (CPG) in a low-pressure environment with a gas puff inlet. This infrastructure enables a CPG to operate in the deflagration mode followed by snowplow plasma sheath formation. These modes inject radially expanding and axially propagating plasma sheaths into a low-pressure residual background. This manuscript details the pulse power delivery circuit, including automatic logic control of subcircuits. High-speed camera images (12800 frames/s) of the formed plasma elucidate the ionization of an axially propagating plasma. Long-exposure images (1.3 s) capture the full propagation distance of the plasmoid. Rogowski coil current diagnostics elucidate the timing of a self-crowbar discharge that delineates between deflagration and snowplow modes. An empirically determined 50-ms gas puff duration resulted in a maximum plasma propagation distance of $\approx 23$ cm. Shorter durations did not ionize a sufficient amount of gas for elongated axial propagation, whereas longer durations suppressed axial plasma sheath expansion. This type of gas injection CPG device is now qualified for use in CPG experiments that require the snowplow mode and maximum mean free path of fast ions resulting from various plasma heating mechanisms. These include CPG operation within external magnetic fields in which significant plasma propagation distance is required, including solar physics experiments and space propulsion development. [ABSTRACT FROM AUTHOR]

We report the deposition of nanocrystalline graph- itic films on Cu foil in a roll-to-roll (R2R) plasma-enhanced chemical vapor deposition (PECVD) system. The influence of discharge modes on the graphitic film synthesis is studied in radio frequency (RF) capacitively coupled Ar/H2/CH4 plasma. First, electrical and spectroscopic characterizations supported with modeling are carried out to study the properties of hybrid and gamma modes in Ar plasma at an excitation frequency of 80 kHz. A hybrid mode, which exhibits both alpha and gamma characteristics, exists at 950 Pa for Ar plasma at powers up to 1100 W. However, Ar plasma transitions at 1380 Pa from hybrid to gamma mode when the power is greater than 750 W. Second, the quality of the nanocrystalline graphitic films, which is assessed with Raman spectroscopy, is correlated with the characteristics of hybrid and gamma modes in Ar/H2/CH4 plasma. The hybrid mode in Ar/H2/CH4 plasma has relatively less ion bombardment. However, the gamma mode in Ar/H2/CH4 plasma provides abundant intermediate carbon species and heats the Cu substrate directly to around 1193 K. Hence, thin films of nanocrystalline graphite with different qualities can be produced at a web feed rate of 30 mm/min without supplemental heating by adjusting the discharge modes. [ABSTRACT FROM AUTHOR]

Relativistic magnetron is an important choice for high power microwave (HPM) source because it is relatively small compared with other HPM sources; in this respect, magnetron with diffraction output (MDO) is particularly attractive because its output port is already a horn. Previous experimental studies on MDO were conducted using a short pulse (~25 ns) SINUS-6 accelerator; here, we investigate the dynamical properties of an MDO under long pulse (~100 ns) and high monitored current (25–30 kA) conditions using a commercial particle-in-cell (PIC) code. The results show that MDO operation can be divided into two stages, and both are capable of HPM generation. At 450-kV applied voltage, the first stage happens between 0 and 35 ns when the transparent cathode rods emit electrons and they form spoke motion, and the dominant frequency is 4 GHz. The second stage happens after 35 ns, the spoke rotation in conventional magnetron region continues, but massive particles begin to flow toward the extended vanes region, and the dominant frequency is 2 GHz. If the applied voltage is higher, the stage transition happens sooner. Particle phase space plots show particle propagation toward the output port direction, which is a natural consequence of the pulsed power system and Lorentz force. Placing a cathode endcap on top of the cathode rods cannot stop the particles. The output power is well in the gigawatt (GW) realm and no pulse shortening is observed despite considerable particles are lost through contact with the anode wall in 100-ns pulse. The peak beam to microwave conversion efficiency is not as high as reported experimental value, but still a decent number close to 60%. Overall, the MDO is a suitable choice for certain applications that requires 100-ns pulse in GW range with high energy efficiency. [ABSTRACT FROM AUTHOR]

For the stability of the spinning projectile launched by a railgun, calculation is carried out to analyze the influence of the arm edge effect (AEE). The AEE refers to that when the edge of an arm is in contact with the edge of a rail, it may produce an asymmetric electromagnetic to create an extra rotation torque. Since the current skin effect may change the magnetic field distribution when some current flow through the arm’s edge. A finite element model is established to simulate the AEE. Results show that for the projectile with separated arms, the AEE may cause the rotation torque to reverse, and the rotation torque may vary alternately between positive and negative value. When increasing the number of arms, the variation amplitude of torque is decreasing and closer to the average value. However, increasing the number of arms will also weaken its strength, so this is not a good method. Therefore, this article proposes an improved projectile, which is connecting the rear arms by a ring. This allows the current to enter the ring first and then into the arms, what may keep the rotation torque constant, and increase the strength. This article may have important guiding significance for the research of launching spinning projectile by a railgun. [ABSTRACT FROM AUTHOR]

This report gives prominence to the importance of the traditional Cockcroft–Walton voltage multiplier to the design of pulsed power supplies for dielectric barrier discharge (DBD) applications. Following an inventive concept, a simple Cockcroft–Walton generator is combined with a MOSFET-based switch (in either “push” or “pull” mode). Thus, the to-be-chopped stabilized dc high voltage is produced by a compact, transformer-less, modular unit, having high flexibility in terms of engineering. This approach leads to well-defined, square, high-voltage pulses of variable amplitude, frequency, and duty cycle. Design, implementation, and proof test of such a prototype are here demonstrated. The prototype yields square pulses as high as 10 kV (plateau value), as narrow as 350 ns (variable pulsewidth up to millisecond, depending on the frequency), rising or falling time close to 20 ns, pulse repetition rates up to 4 kHz, and output mean power up to 150 W. The functionality of the system is demonstrated by driving coaxial, ambient air DBDs of variable lengths, while principal electrical and optical parameters are recorded. Peak power values higher than 70 kW are measured on the DBD side, while the voltage multiplier power efficiency factor remains close to 95%. [ABSTRACT FROM AUTHOR]

We present an experimental analysis of the change in the electric field enhancement factor with varying gap size and penetration depth (P.D) of cathode into anode for a coaxial vacuum gap, diagnosed using Fowler–Nordheim analysis and optical imaging via scanning electron microscope (SEM) and time integrated Digital single lens reflex camera (DSLR). Data were collected on the Coaxial Gap Breakdown Machine (240 A, 25 kV, 150 ns, ~0.1 Hz). Experiments using five different gap sizes at nine different P.Ds are compared over runs comprising 50 shots for each case. The results show a strong link between enhancement factor and gap size, with P.D and surface topology. For large gap sizes, 150, 330, and 700 $\mu \mathrm {m}$ , the average enhancement factor value increases with increasing P.D. For smaller gap sizes, 50 and 100 $\mu \mathrm {m}$ , the average enhancement factor decreases with P.D. SEM imaging before and after plasma formation for each gap size allows for quantifying surface finish, microprotrusion growth, average blast diameter, and an estimation of the surface area breakdowns occupy. Time integrated DSLR imaging analysis of the gap at each shot allows for a determination of the distribution of breakdowns about the circumference of the gap for each case tested. The Fowler–Nordheim analysis allows for a quantitative analysis of the surface roughness of all gap sizes tested. Results show that for large gap sizes, the gap geometry and increasing area of breakdown is the main cause for increasing average enhancement factor. For small gap sizes, the dominant driving factor for small average enhancement factors—that subsequently decrease with P.D—is significant changes in surface topology due to an increased number of breakdowns. [ABSTRACT FROM AUTHOR]

This is now the 16th publication of the series of special issues on plasma-assisted technologies. Once more, in this newest installment, the reader will encounter an expansive array of novel and innovative applications and developments in plasma-based systems. The varied range of topics is a tribute to the continued forward progression of the possibilities accessible through plasmas, and builds on the significant success of the previous special issues. [ABSTRACT FROM AUTHOR]

Megavolt-class pulsed gas switches play an important role in large pulsers as transfer switches. This article analyzes the breakdown process and characteristics of a megavolt self-triggered preionized switch under 100-ns pulses based on the optical diagnosis. It is discovered that the triggering spark illumination targeting the main cathode or anode can separately preionize the main gap. The discharge channel is likely to first form between trigger electrodes and the main anode. Based on the above deduction, the streamer velocity is calculated to be $0.54 \times 10^{6}$ – $2.34 \times 10^{6}$ m/s, proportional to the electric field. Also, parameters of the empirical formula for calculating the gas heating time are amended. Influence mechanisms of the switch jitter are also studied. Under pulsed preionization mode, the trigger gap breaks down when the main gap electric field is high enough, and the switch jitter is mainly determined by the self-triggering jitter. Nonetheless, the self-triggering jitter can be partly offset during the breakdown process if the changing rate of mean reduced electric field $d(E/p)$ / dt at the self-triggering time is higher than 1.0 $1.0\left(\mathrm{kV} \cdot \mathrm{ns}^{-1} \cdot \mathrm{cm}^{-1} \cdot \mathrm{MPa}^{-1}\right)$. Under sustaining preionization mode, the trigger gap breaks down prematurely, and the continuous arcing driven by switch leak current preionizes the main gap. Therefore, the influence of the self-triggering jitter on the switch jitter can be eliminated. [ABSTRACT FROM AUTHOR]

The analysis of the possibilities of using the cross-flow plasma-fuel nozzle for supporting stable combustion of gaseous fuel in a combustion chamber of the contact-type gas turbine engine with steam injection is presented. Experimental studies of the plasma-fuel nozzle were carried out, which proved the stability of its operation in a wide range of changes in the flow rates of plasma feedstock air. Indicators of the efficiency of the thermal scheme of the contact-type gas turbine engine as well as the characteristics of a low-emission combustion chamber with plasma assistance are obtained. [ABSTRACT FROM AUTHOR]

This is an overview of existing facilities for testing of thermal protection materials (TPM) for spacecraft based on the inductively plasma (ICP) sources with power over 100 kW. As a chief designer of the ICP plasma torch systems, the author provides the main parameters, describes design of the torches and power supplies, analyzes efficiency of plasma generation, and discusses trends in the ICP-based facilities development with power from 100 kW to 1 MW. The overview is based on data from the open sources and real parameters of APT-100 and −200 plasma systems currently in production by Applied Plasma Technologies, Corporation, Marshall, VA, USA. [ABSTRACT FROM AUTHOR]

A $Q$ -band traveling-wave tube (TWT) with profiled helix pitches and profiled inner diameters of slow wave structure (SWS) is proposed. The transmission characteristics of the $Q$ -band TWT are simulated by the Computer Simulation Technology (CST). In the operating frequency band (36.5–41.5 GHz), the simulated voltage standing wave ratio (VSWR) is less than 1.5. In addition, the beam–wave interaction is simulated to predict the performance of the $Q$ -band TWT when the beam voltage and beam current are 8.5 kV and 60 mA, respectively, and the axial focusing magnetic field is 0.4 T. In the operating frequency band, the self-oscillation is well suppressed, and the device efficiency of the $Q$ -band TWT exceeds 63.5%, and the saturated output power and gain exceed 83 W and 45 dB, respectively, especially the device efficiency can reach the maximum of 69.5% at 37 GHz. When it is backed off 6 dB from the saturation, the device efficiency exceeds 40.5%, up to 42.7% at 39 GHz. Preliminary experiments have confirmed the design. These results show that the proposed $Q$ -band TWT has important applications to the next generation wireless communication system with high efficiency. [ABSTRACT FROM AUTHOR]

The micro-structure miniaturization of vacuum electron devices (VEDs) in terahertz band requires the high precision description of formation and transportation for the ultrahigh density electron beams with the novelty theoretical analysis and simulation. In this article, the 3-D spatial potential of circular electron beam formation is presented by adopting differential geometry and tensor analysis theory. The specific numerical solution of the circular electron beam potential can be obtained by establishing a moving coordinate frame, carrying out numerical calculation, series expansion with adopting of Riemann method. In order to verify the complex theory, a 0.34 THz vacuum electron tube using thin circular electron beam gun and corresponding optical system are designed and analyzed. The beam voltage and current are 23.8 kV and 0.28 A respectively, with beam channel radius of 0.16 mm and magnetic field of 5250 Gs. Using 3-D simulation of CST, the ultrahigh density electron beam can transport 30 mm with good stability. The spatial potential of numerical calculation with the obtained theoretical functions and the simulation model are compared to verify our theoretical description. Both the results are with good consistent which preliminary proves the effectiveness of the theoretical function. Furthermore, we combine the theoretical function potential with the electron beam envelope under the same coordinate frame, the detailed characteristics of ultrahigh density beam formation with the potential function can be directly understood easily, which will give the deep physical mechanics vision for the development of high power and high-efficiency terahertz tube in the future. [ABSTRACT FROM AUTHOR]

In this work, we used the semi-Lagrangian method and the Vlasov code to study the instabilities in a quantum plasma with 1-D temperature anisotropy. Taking the Fermi–Dirac type of distribution function (DF) and using the semi-Lagrangian Vlasov code, we studied the gradual evolution of density and kinetic energy in a degenerate plasma with quantum effects. In this collisionless plasma, adiabatic compression will be along the direction of wave propagation and will lead to temperature anisotropy of the electron distribution that varies along the direction of wave propagation. The findings will find application for dense plasma at finite temperature as in laser-produced plasmas, fusion plasma, as well as solar plasmas. [ABSTRACT FROM AUTHOR]

This study explores the degradation of the reactive Remazol Blue RR (RBRR) as a model textile effluent upon its exposure to non-thermal atmospheric pressure plasma. An extensive comparative study of different combinations of the following plasma/solution treatment environments was conducted: 1) Ar plasma jet (Ar-PJ) alone; 2) Ar/O2 and Ar/N2 plasmas; 3) Ar plasma with O2 or N2 injected (INJ) in the bulk of the Ar plasma afterglow; and 4) Ar plasma with O2 or N2 bubbling (BB) in the RBRR solution. In all conditions, plasma treatment was carried out at a fixed applied voltage of 31 kV and treatment time of 10 min. The degradation efficiency of RBRR in the different plasma-treated solutions was evaluated using UV–visible spectroscopy. Optical emission spectroscopy (OES) was used to examine the generation of excited species in plasma during the degradation processes. Moreover, the concentration of plasma-induced reactive hydroxyl radicals (OH•) and hydrogen peroxide (H2O2) was determined spectroscopically. To further corroborate the results, the pH, conductivity, and total organic carbon (TOC) of the plasma-treated RBRR solutions were assessed. Overall, the results showed that the highest degradation efficiency (45%) was obtained upon exposure of RBRR aqueous solution to Ar plasma with N2 bubbling in the solution. The non-toxic nature of all plasma-treated solutions was confirmed by non-inhibition of bacterial growth (Escherichia coli and Staphylococcus aureus). Overall, plasma treatment in general and Ar plasma accompanied with N2 bubbling in particular constitute an eco-friendly and very promising techniques to degrade/decolorize textile effluent. [ABSTRACT FROM AUTHOR]

In this article, we consider a dense stellar plasma consisting of predominantly electrons, positrons, and ions under the action of the magnetic field of the star. We derived the Korteweg–de Vries Burgers (KdV-Burgers) equations by using the reductive perturbation technique and obtained shock and solitary profiles for magnetoacoustic waves. We further studied the self-interaction of such stationary formations and the amplitude modulated envelope solitons. The possibility of a rogue wave-like structure is also discussed. To understand the physical problem in greater detail, we studied the Hamiltonian formulation to study stability. We studied how modulational instability can lead to the formation of rogue waves by investigating the nonlinear Schrodinger equation. In addition, drift-like instability showing the density and charge separation effects in plasma has been studied. The results will be helpful to interpret magnetoacoustic wave formations in solar corona or other stellar entities and can help in the study of inhomogeneous plasmas in laboratory and fusion reactors. PACS—52.35.Fp, 03.50.De, 41.20.-q, 52.30.Cv, 47.85.Dh, 52.35.Hr, 52.27.Ep, 52.30.-q, 52.35.Tc, and 52.35.Sb. [ABSTRACT FROM AUTHOR]

A multicomponent degenerate quantum plasma comprising nondegenerate warm light ion species, inertial heavy-ion species, and relativistically degenerate electrons are considered to study the large-amplitude degenerate pressure-driven nucleus–acoustic solitary waves (NASWs). Sagdeev’s pseudopotential approach has been adopted for the energy balance equation of large-amplitude NASWs, and the Mach number domain $({M_{l} \le M\le M_{h}})$ is determined numerically in various plasma parameters. It is seen that only compressive (positive pulse) solitary waves can exist in the present plasma system. The effect of different plasma parameters such as the ratio of light-ion species to heavy-ion species number density ($f$), degenerate electron density ($k$), relativistic factor ($\gamma$), temperature ratio ($\sigma$), and Mach number ($M$) on the characteristic of solitary waves is studied. The corresponding phase trajectory is also drawn for the solitons in the existence domain of the Mach number. Our result may be helpful to understand the basic characteristics of nonlinear solitary waves propagating in an astrophysical object such as white dwarfs and neutrons stars. [ABSTRACT FROM AUTHOR]

This work reports the estimation of discharge diameter ($d_{d}$) using “Gaussian fit” method applied on the discharge’s image captured using high–speed camera (HSC). Work was conducted in a rotating gliding arc (RGA) and obtained the $d_{d}$ near the shortest ($\delta $) and longest ($\Delta $) gap between the electrodes, operated under 5 SLPM (transitional) and 50 SLPM (turbulent) flow rates of argon gas at atmospheric conditions. Gaussian fit was verified to be suitable to estimate the thickness of the objects that could be well differentiated from the background in the captured image. Furthermore, the results indicated that the gas flow rate is highly influential on $d_{d}$. The average $d_{d}$ was thinned by ≈28%, from 0.29 to 0.21 mm, when the flow rate was increased from 5 to 50 SLPM, indicating the influence of turbulent eddies at 50 SLPM. The $d_{d}$ was varying along the discharge length under turbulent flow due to discharge’s inhomogeneity in intensity arising due to twisting, curling, and knot formations. This work marks an essential step toward the characterization of the RGA reactor. [ABSTRACT FROM AUTHOR]

Ready-to-eat (RTE) millet grain flakes and puffs are gaining importance in the modern era because of their nutritional and health benefits. In this work, air plasma has been generated and bubbled into pearl millet during soaking, followed by analyzing its flaking and puffing characteristics. The voltage 180, 200, and 220 V with airflow rates of 10 and 12 lph for 1 and 2 h was exposed to treat pearl millet samples. An increase in conductivity, total soluble solids (TSS), and drop in pH of the soaked medium was observed with the bubbling of plasma. The plasma bubbling exhibited an improvement in the pearl millet’s flaking and puffing properties. The noteworthy changes ($P < 0.05$) in expansion volume, bulk density, color, moisture content, crispiness, and hardness were observed in flaked and puffed samples. An increase in the expansion ratio (ER) of pearl millet flakes and puffs from 4.2 to 8.3 and 4.9 to 9.5 decreases in bulk density of flakes and puffs from 0.36 to 0.11 and 0.14 to 0.06 kg/m3, respectively, was noticed with the plasma bubbling. The textural properties like the crispiness of the flakes and puffs elevated, and hardness was reduced with the given treatments. The decrement in yellowness index (YI) and increase in whiteness index (WI) was observed in both flaked and puffed samples with the rise in exposure time. The synergistic effect of plasma reactive species in combination with hydration aids in improving grain properties and helps in diversifying the utilization of millet grains. [ABSTRACT FROM AUTHOR]