A new ignition method of the spark gap based on plasma ejection is proposed in this paper, as the conventional trigatron spark gap performs poorly under the low working coefficient (the ratio of the charging voltage to the self-breakdown voltage) in air. The plasma is generated by the capillary discharge, which has high pressure, high temperature and high velocity. The capillary discharge device is placed inside the low voltage electrode. As long as the triggering signal is sent to the device, a column of the plasma flow is ejected in axial direction and develops rapidly towards the high voltage electrode. Subsequently, the gap is broken down and a high resistive channel is formed, where the thermal ionization takes place and the arc across the whole gap is generated and develops into a well conductive channel. The process of the thermal ionization of the high resistive channel varies with the change of the spark gap distance. The breakdown delay and the delay jitter of the spark gap increase with the spark gap distance, as both parameters are mainly determined by the developing process of the plasma ejection. The characteristics of the plasma flow determine the possibility of the breakdown of the spark gap under the low working coefficient. The ignition method based on capillary plasma ejection has been proved by the preliminary experiments, which indicate that under the gap length of 8 cm and the working coefficient of less than 3%, the effective ignition is still achievable.

A simple Semi-Analytical method used to fit the experimentally recorded current of the closed switch discharge circuit into the free running under damped LC oscillator model and the arc plasma conductivity, electron density of the plasma and efficiency of the spark gap switch energy transfer have been driven from the model by some simple calculations. The charging voltage, switch pressure and the spark gap has been changed between 6 to 15 kV, 1 to 1.5 bar and 1.4 or 2.8 mm, respectively. The obtained values for plasma conductivity and electron density of plasma are (5-25)(Ω mm)^{–1}, (0.5–3.5)·10^{24}m^{–3}, respectively. The efficiency of the switch is plotted Vs. Pd and E/P which in both cases the peak value has been about 80 present.

The nonlinear dynamics of a circularly polarized laser pulse propagating in magnetized plasma contains hot nonextensive *q* -distributed electrons and ions is studied theoretically. A nonlinear equation which describes the dynamics of the slowly varying amplitude electromagnetic wave is obtained using the relativistic two-fluids model. Some nonlinear phenomena include modulational instability, self-focusing, soliton formation, and longitudinal and transversal evolutions of laser pulse in nonextensive plasma medium are investigated. Results show that the nonextensivity of particles can substantially change the nonlinearity of medium. The external magnetic field enhances the modulation instability growth rate of right-hand polarization wave but for the left-hand polarization the growth rate decreases. The spot size of the laser pulse is strongly affected by the plasma nonextensivity. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The most accurate models of the capillary Z-pinches used for excitation of soft X-ray lasers and photolithography XUV sources currently are based on the magnetohydrodynamics theory (MHD). The output of MHD-based models greatly depends on details in the mathematical description, such as initial and boundary conditions, approximations of plasma parameters, etc. Small experimental groups who develop soft X-ray/XUV sources often use the simplest Z-pinch models for analysis of their experimental results, despite of these models are inconsistent with the MHD equations. In the present study, keeping only the essential terms in the MHD equations, we obtained a simplified MHD model of cylindrically symmetric capillary Z-pinch. The model gives accurate results compared to experiments with argon plasmas, and provides simple analysis of temporal evolution of main plasma parameters. The results clarify the influence of viscosity, heat flux and approximations of plasma conductivity on the dynamics of capillary Z-pinch plasmas. The model can be useful for researchers, especially experimentalists, who develop the soft X-ray/XUV sources. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The nonlinear properties of two dimensional low-frequency electrostatic excitations of charged dust particles (or defects) are studied in a collisionless, unmagnetized dusty plasma. A fully ionized three-component model plasma consisting of kappa distributed electrons, Maxwellian ions, and negatively charged massive dust grains is considered. In this regard, the well known reductive perturbation technique is used to the hydrodynamical equations and the Poisson equation, obtaining the cylindrical Kadomtsev–Petviashvili (CKP) equation. A parametric investigation indicates that the structural characteristics of these nonlinear excitations (width, amplitude) are significantly affected by the plasma nonthermality as well as by the relevant plasma parameters, such as dust concentration and dust temperature. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The electrostatic fluid accelerator (EFA) generates ionic wind with a simple structure that barely obstructs the free air stream or produce excessive noise. This paper presents the velocity characteristics of an EFA under a high speed free air stream to simulate an EFA-powered propulsor. The results show that when the EFA generates identical velocity to the free air stream, the EFA contributes 25% of the resultant velocity. When the EFA is replaced by a rotary fan that generates identical velocity to the free air stream, the fan contributes only 13.4% of the resultant velocity. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

An apparatus was designed for generating plasma in ethanol solution. The plasma was generated on the top of the electrode by applying microwave radiation of 2.45 GHz. The results showed that ignition power decreased with increasing temperature of ethanol solution. However, ignition power increased with increasing pressure and point electrode radius of curvature. Plasma and bubbles were generated periodically in the same manner. The electron temperature of the plasma increased with increasing power, while it decreased with increasing pressure. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Shock ignition as an alternative scheme of the laser fusion has the potential of achieving efficient implosion. However, hot electrons produced in result of ignitor-corona interaction may penetrate deep into the fuel making the compression less effective. Transport and energy deposition of hot electron beam into the dense pre compressed of HiPER target by means of Monte Carlo approach are discussed considering the influence of real density and electron beam characteristics. The target parameters before igniting the hot spot have been extracted from a fluid code and used as the initial profile for Monte Carlo simulations. In comparison with simplified step like density profile, electrons penetrate slightly deeper in the case of real shaped density profile. In addition, deposition zone of a broad spectrum electron beam is wider while, monoenergetic electrons depose their energy locally resulting more maximum energy deposition value. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Excitation of highly charged ions in plasmas under the action of ultrashort electromagnetic pulses is investigated theoretically in the frame of perturbation theory. The study is based on analytical expression for probability of bound-bound transition which is derived for Gaussian pulse and Doppler broadening of spectral line shape of the transition. Electronic transitions from the ground state of hydrogen-like ions are considered with account for fine splitting of upper energy levels. The main attention is paid to the dependence of the excitation probability on pulse duration for various ion charges and carrier frequencies of the pulse. The results obtained are of interest for plasma diagnostics based on ion excitation from ground state by ultrashort pulses. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Discharge current voltage (IV) curves are directly measured at the target of a high impulse power magnetron sputtering (HiPIMS) plasma for the target materials aluminium, chromium, titanium and copper. These discharge IV curves have been correlated with ICCD camera images of the plasma torus. A clear connection between the change in the discharge IV curve slopes at specific currents and the appearance of localized ionization zones, so-called spokes, in a HiPIMS plasma is identified. These spokes appear above typical target current densities of 2 A/cm^{2}. The slope of the discharge IV curves, at current densities when spokes are formed, depends on the mass of the target atoms with a higher plasma conductivity for higher mass target materials. This is explained by the momentum transfer from the sputter wind to the argon background gas, which leads to higher plasma densities for heavier target materials. The change in the VI curve slope can be used to identify the spokes regime for HiPIMS plasmas, as being mandatory for deposition of good quality materials by HiPIMS. Consequently, the discharge IV curve slope monitoring can be regarded an essential control approach of any industrial HiPIMS process, where discharge IV curves are much easier accessible compared to more complex diagnostics such as time and space resolved ICCD camera measurements. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Shaded plot for voltage distribution. Figure 10 of the paper by A. EL-Tayeb et al.

In many-body systems the convolution approximation states that the 3-point static structure function, *S*^{(3)}(**k**_{1}, **k**_{2}), can approximately be “factorized” in terms of the 2-point counterpart, *S*^{(2)}(**k**_{1}). We investigate the validity of this approximation in 3-dimensional strongly-coupled Yukawa liquids: the factorization is tested for specific arrangements of the wave vectors **k**_{1} and **k**_{2}, with molecular dynamics simulations. With the increase of the coupling parameter we find a breakdown of factorization, of which a notable example is the appearance of negative values of *S*^{(3)}(**k**_{1,} **k**_{2}), whereas the approximate factorized form is restricted to positive values. These negative values – based on the quadratic Fluctuation-Dissipation Theorem – imply that the quadratic part of the density response of the system changes sign with wave number. Our simulations that incorporate an external potential energy perturbation clearly confirm this behavior. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The heat diffusion across the stochastic magnetic field is studied numerically. The stochastic field is generated by the overlap of two magnetic islands. The parameter *w/w _{c}*, is found tobe an important parameter in charactering the transport, where

Stray light formed by the reflection of photons on inner wall from a bright divertor region can be a serious issue in spectroscopic measurement systems in ITER. In this study, we propose a method to mitigate the influence of stray light using a ray tracing analysis. Usually, a ray tracing simulation requires a time consuming runs. We constructed transfer matrices based on the ray tracing simulation results and used them to demonstrate the influence of stray light. It is shown that the transfer matrix can be used to reconstruct the emission profile by considering the influence of the stray light without any additional ray tracing runs. Mitigation of the stray light in ITER divertor impurity monitor was demonstrated, and a method of prediction of the stray light level for the scrape off layer spectroscopy from divertor region was proposed. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Calculation of the total dielectronic recombination (DR) rates was done in the frame of a statistical model of atoms. The model is based on the idea of collective excitations of atomic electrons with the local plasma frequency, which depends on atomic electrons density distribution. The electron density is described in a frame of the Thomas-Fermi model of atoms. Simple scaling laws for temperature *T _{e}* and nuclear charge

This work researches the possibility of increasing the dye removal efficiency from wastewater using nonthermal plasma. A study for the optimal air gap distance between dual pin and surface of Acid Blue 25 dye solution and thickness of ground plate is carried out using 3D-EM simulator to find maximum electric field intensity at the tip of both pins. The consequences display that the best gap for corona discharge is approximately 5 mm using 15 kV source. In addition, the optimum plate thickness is 0.1 mm. These distance and thickness were mentioned are constant during the study of other factors. Dual pin-to-plate high-voltage corona discharge plasma system is presented to investigation experimentally the gap distance, thickness of ground plate, initial dye concentration, pH solution and conductivity on the amount of Acid Blue 25 dye color removal efficiency from wastewater. There is a large consensus among the simulation and experimental work in the air gap and thickness of ground plate. Where the decolorization for air gap 5 mm is 95.74 at time 35 min compared with 91% and 17% for 1 mm and 20 mm gap distance respectively. Also, the discharge energy at each air gap are calculated. Measurement results for the impact of thickness of an Aluminum ground plate on color removal competence showed color removal efficiencies of 86.3%, 90.78% and 98.06%, after treatment time 15 min for thicknesses of 2, 0.5 and 0.1 mm respectively. The decolorization behavior utilizing dual pin-to-plate corona discharge plasma system display 82% pigment evacuation proficiency inside 11min. The complete decolorization was accomplished within 28min for distinctive examined introductory color focuses 5 ppm up to 100 ppm. Likewise, the impacts of conductivity by utilizing diverse salts as AlCl3, CaCl2, KCl and NaCl and with distinctive focuses have been explored. The rising of the solution conductivity leads to the reduction of decolorization efficiency. The decolorization efficiency and discharge energy are calculated at different concentration molarity for AlCl3, CaCl2, KCl and NaCl. It was observed that the presence of salts at the same concentration level substantially decreased the rate and the extent of decolorization. The results indicate that the optimum pH for the decolorization of Acid Blue 25 dye is in the range between 3 and 6. Furthermore the conductivity and discharge energy were measurement at each value of pH. Energy yield for decolorization and Electrical Energy per Order (EE/O) under different initial pH value were calculated. A kinetic model is used to define the performance of corona discharge system under different value of pH. The model of pseudo -zero, pseudo-first order, and pseudo-second order reactions kinetic are utilized to investigate the decolorization of Acid Blue 25 dye. The rate of degradation of Acid Blue 25 dye follows the pseudo-first order kinetics in the dye concentration. Energy consumption requirements for decolorization was considered. The outcomes will be useful for designing the plasma treatment systems suitable for industrial wastewaters. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

In this paper, an atmospheric pressure dual-frequency (50 kHz/33 MHz) micro-plasma jet was used to deposit organosilicon film. The discharge generated in atmospheric environment. Plasma composition was characterized by optical emission spectroscopy. With introduction of tetraethyl orthosilicate, we observed various spectra, for example Si(251.6 nm), OH(308.9 nm), C(247.8 nm), O(777.5 nm). Abundant reactive radical species which are benefit to film deposition were generated in plasma. The deposited film was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The film is mostly composed of Si and O. The film has Si-O-Si backbone with a small number of organic component (-CHx). (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The long-time evolution of weakly-collisional plasma with application of high voltage positive pulses to an electrode immersed in plasma, with pulse widths less than as well as more than ion plasma periods, is studied. The plasma is produced by electron impact ionization of argon or helium gas, where electrons are coming out from dc biased hot thoriated tungsten filaments. It is observed that during the temporal evolution of argon plasma, a beam component exists along with temporal bulk electrons giving rise to a double hump profile of transient Electron Distribution Function (EDF). However, in the case of temporal evolution of helium plasma, only a bulk electron population is present. The obtained results are explained by understanding the role played by thermionically emitted electrons during the plasma evolution, the role of the difference of ionization rates of helium and argon, and the higher temporal plasma potential. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

This paper presents a scheme for second harmonic generation (SHG) of an intense Cosh-Gaussian (ChG) laser beam in thermal quantum plasmas. Moment theory approach in W.K.B approximation has been adopted in deriving the differential equation governing the propagation characteristics of the laser beam with distance of propagation. The effect of relativistic increase in electron mass on propagation dynamics of laser beam has been incorporated. Due to relativistic nonlinearity in the dielectric properties of the plasma, the laser beam gets self-focused and produces density gradients in the transverse direction. The generated density gradients excite electron plasma wave (EPW) at pump frequency that interacts with the incident laser beam to produce its second harmonics. Numerical simulations have been carried out to investigate the effects of laser parameters on selffocusing of the laser beam and hence on the conversion efficiency of its second harmonics. Simulation results predict that within a specific range of decentered parameter the ChG laser beams show smaller divergence as they propagate and, thus, lead to enhanced conversion efficiency of second harmonics. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)