Showing papers in "Contributions To Plasma Physics in 2014"

Clinical Plasma Medicine: State and Perspectives of in Vivo Application of Cold Atmospheric Plasma

Abstract: Driven by extensive basic research on plasma effects on living cells and microorganisms, plasma medicine has been developed as innovative medical research field during the last years. Besides partially established applications of plasma to treat materials or devices to allow effective medical applications with respect to biocompatibility or microbiological safety, respectively, the primary focus of plasma-medical research is the direct application of plasma as part of therapeutic concepts. Even if a huge number of atmospheric pressure plasma sources for biomedical applications are described in the literature and characterized by in vitro microbiology and cell biology, there is only a limited number of in vivo experience with animals or human beings up to now. Research in plasma medicine has been mainly focused on applications in dermatology and aesthetic surgery with the aim to support tissue regeneration to improve healing of infected and/or chronic wounds as well as to treat infective and inflamed skin diseases. In general, there are four cold atmospheric plasma sources which were tested comprehensively in animals as well as human beings with respect both to its therapeutic potential and the safety of its application. Three clinical trials with cold atmospheric pressure plasma sources have been carried out yet. All three studies realized in Germany are focused on ulcer treatment. Two cold atmospheric pressure plasma sources got a CE marking as medical device in 2013. This marks a very important step to bring plasma medicine into the clinical daily routine! In future, it will become a general practical requirement to adapt special plasma sources to specific medical applications. Consequently, it is one of the main requirements for the physical and technical field of research and development in plasma medicine to find solutions for modular and flexible plasma devices which are adaptive to some extent e.g. to variable target areas. Based on this as well as together with comprehensive basic research to get much more insight into detailed mechanisms of plasma-induced effects on living structures and the particular role of single plasma components, further fields of plasma application in vivo will be opened or extended, respectively, with both new targets like cancer treatment or new application sites like teeth, lung, eyes, nasal cavity or gastrointestinal tract. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Recent Improvements in the EMC3-Eirene Code

Abstract: The EMC3-Eirene code is improved in many aspects. Ad hoc boundary conditions for intrinsic impurities at the SOL-core interface are removed by implicitly coupling to a 1D core model. Non-uniform cross-field transport coefficients are allowed in the new code version. A particle splitting technique is implemented for improving the Monte Carlo statistic in low-temperature ranges of most interest. Domain splitting, which was possible for the toroidal direction only, is now feasible for all three directions, facilitating mesh optimization for any specific divertor configuration. Stellarator-specific constraints on mesh construction have been relaxed. Axisymmetric neutral-facing components have been moved to cylindrical coordinates. All these features have improved the code performance and capability significantly. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Plasma Applications: A Dermatological View

Abstract: The ability to produce cold plasma at atmospheric pressure conditions was the basis for the rapid growth of plasma related application areas in biomedicine. Plasma comprises a multitude of active components such as charged particles, electric current, UV radiation, and reactive species which can act synergistically. The antiitch, antimicrobial, and anti-inflammatory effect was already demonstrated in in vivo and in vitro experiments and until now no resistance of pathogens against plasma treatment was observed. The combination of the different active agents and their broad range of positive effects on various diseases, especially easily accessible skin diseases, render plasma quite attractive for applications in medicine. Hence, plasma medicine as an independent and promising medical field has been emerged recently. For medical applications two different types of cold plasma are suitable; indirect (plasma jet, plasma torch) and direct plasma sources (dielectric barrier discharge - DBD). So far, no standards and norms are defined for any of these plasma sources. Also, no convenient criteria for standardization of the quality rating of plasma in the view of dermatological applications exist. Although various cold plasma studies have been performed the results are hardly comparable, as physical parameters of the plasma devices, experimental conditions, and organisms used vary greatly. Therefore, standardized risk analyses are necessary for the assessment of different plasma sources. In this review two plasma sources are described and possible risk factors are discussed to estimate the safety of plasma used as a therapeutic tool in dermatology. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

3D Properties of Edge Turbulent Transport in Full‐Torus Simulations and their Impact on Poloidal Asymmetries

Abstract: The 3D fluid turbulence code TOKAM3X is used to investigate the 3D properties of edge turbulent transport and their impact on poloidal asymmetries. Simulations are run in circular limited plasmas in a domain covering both closed and open flux surfaces. Turbulence characteristics exhibit large inhomogeneities both in the radial and poloidal directions reminiscent of experimental observations. The low field side mid-plane in particular is found to be locally more fluctuating and intermittent than the rest of the Scrape-Off-Layer (SOL). As a consequence of this asymmetry, radial turbulent transport, that represents 80 to 90% of the total radial flux, is strongly ballooned, with 75% of the flux flowing through LFS. The equilibrium of the edge plasma is impacted by this asymmetry through the existence of large amplitude asymmetric parallel flows as well as through the development of poloidally asymmetric radial decay lengths making it impossible to define a single SOL width. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

First EMC3-EIRENE Simulations with Divertor Legs of LHD in Realistic Device Geometry

Abstract: An extended mesh system for EMC3-EIRENE has been developed to simulate peripheral plasma including the ergodic and the divertor leg regions of LHD. Both the open and the closed divertor configurations are available. A series of simulations for 8MW input power, five different electron densities at the LCFS (last closed flux surface) and the open/closed configurations were carried out. Approximately 10 times larger neutral pressure was observed under the dome structure compared with the open configuration, which is in good agreement with experimental measurements. In the case of the closed configuration, the leg regions have a large contribution of ionization to hydrogen recycling. In the case of high density discharges, however, electron temperature in the legs becomes low and the major contribution of ionization moves to the ergodic region. Significant influence of configurations is observed in the inboard side of LHD, where closed divertor components are installed but little influence is seen near the LCFS. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Quantum Breathing Mode of Trapped Particles: From Nanoplasmas to Ultracold Gases

Abstract: Particles spatially confined in trapping potentials have attracted increasing interest over the recent decade. Of particular importance are systems of charged particles, such as non-neutral plasmas, nanoplasmas, electrons in metal clusters, electrons in quantum-confined semiconductor structures (“artificial atoms”), electrons on the surface of liquid helium, ions in traps or highly charged particles (grains) in dusty plasmas. A second example of recent interest are systems with other kinds of pair interactions, including dipole interaction, which is important for excitons in quantum wells or ultracold Fermi and Bose gases in traps and optical lattices. Trapped systems are fundamentally different from macroscopic systems since they are dominated by strong spatial inhomogeneity and finite size effects (the properties depend on the exact particle number). Furthermore, by changing the strength of the confinement potential, the many-particle state of the system can be externally controlled—from weak coupling (gas-like) to strong coupling (crystal-like). While trapped classical particles are meanwhile well understood and accessible to first-principle computer simulations, their quantum counterparts still pose big challenges, both for experiment and theory. Therefore, collective properties that can be easily measured or computed and allow to diagnose the many-particle state of the system are of prime importance. It has been found that the quantum breathing mode (monopole oscillation) is one of the most important such properties. In recent years a number of theoretical studies has demonstrated that the quantum breathing mode is ideally suited to measure the coupling strength (the degree of nonideality) of a trapped system, its kinetic and interaction energy and other key observables. This give rise to a novel kind of “spectroscopy” of trapped systems. In this review these developments are summarized. The quantum breathing mode is studied for trapped fermions and bosons with Coulomb and dipole interaction, respectively. A systematic description of collective oscillations and especially the breathing mode is provided. Making use of time-dependent perturbation theory, it is shown how the corresponding breathing frequencies are connected to the properties of the initial equilibrium system. This gives rise to the application of the quantum mechanical sum rules. It is demonstrated how an improved version of the conventional sum rule formulas is suitable for an accurate description of the breathing mode in small systems. Finally, the dependence of the breathing mode on the particle number N is analyzed and the limit of large N is studied for one-dimensional and two-dimensional systems. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Direct Plasma Potential Measurements by Ball-Pen Probe and Self-Emitting Langmuir Probe on COMPASS and ASDEX Upgrade

Abstract: Experimental investigations of the plasma potential by means of a ball-pen probe and self-emitting Langmuir probe technique were performed on the tokamaks COMPASS and ASDEX Upgrade. A spontaneous transition between the cold and self-emitting Langmuir probe has been observed during the deep reciprocation in the vicinity or even inside the last closed flux surface (LCFS) of both tokamaks. These measurements of the plasma potential allow us to compare two independent probe techniques based on heating and non-heating processes. The observed different conditions of the spontaneous transition can be ascribed to different physical mechanisms. Nevertheless, the comparison of the power spectra of ball-pen probe and self-emitting Langmuir probe indicates very good agreement in all measurements and therefore these two probe techniques are interchangeable. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

An Efficient Procedure to Identify and Quantify New Molecules for Insulating Gas Mixtures

Abstract: In this contribution, a new procedure to systematically identify and quantify novel molecular gases with low global warming potential for application in high voltage insulation as gas mixtures is presented. The attention is focused on highly efficient procedures to be able to scan a large number of candidate gases. To identify new molecules, we derived an empirical correlation between the electric strength of a gas and certain molecular properties, like polarizability or dipole moment, which can be calculated by means of density functional theory. The swarm parameters of these pre-selected molecules in mixtures with buffer gases is then quantified, using a newly set-up Pulsed Townsend experiment. The setup operates with a high degree of automation to enable systematic evaluation of gas mixtures not to miss possible synergistic effects. Key element of this PT setup is a new photocathode that works with a high quantum efficiency and long lifetime even when exposed to reactive species during the measurements. Moreover, for an automated operation it is important to know precisely in which range the experiment can be operated, i.e. for example to know up to which electron density space charge effects can be neglected. Finally, the measured swarm parameters need to be translated into breakdown voltage strengths of different electrode arrangements and different applied voltage wave shapes. For this, a model of the the streamer to leader transition in SF6 will be applied to other strong electronegative gases in future studies to test if the model is universally valid. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Progress with the COGENT Edge Kinetic Code: Implementing the Fokker‐Planck Collision Operator

Abstract: Here, COGENT is a continuum gyrokinetic code for edge plasma simulations being developed by the Edge Simulation Laboratory collaboration. The code is distinguished by application of a fourth-order finite-volume (conservative) discretization, and mapped multiblock grid technology to handle the geometric complexity of the tokamak edge. The distribution function F is discretized in v∥ – μ (parallel velocity – magnetic moment) velocity coordinates, and the code presently solves an axisymmetric full-f gyro-kinetic equation coupled to the long-wavelength limit of the gyro-Poisson equation. COGENT capabilities are extended by implementing the fully nonlinear Fokker-Plank operator to model Coulomb collisions in magnetized edge plasmas. The corresponding Rosenbluth potentials are computed by making use of a finite-difference scheme and multipole-expansion boundary conditions. Details of the numerical algorithms and results of the initial verification studies are discussed. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Plasma‐Based Pollutant Degradation in Gas Streams: Status, Examples and Outlook

Abstract: The status of the research into and the application of non-thermal plasmas for the pollutant degradation in gases is discussed, including some fundamental topics and engineering issues. Two reactor concepts, both based on dielectric barrier discharges (DBDs), are presented and investigated for various tasks. The DBD-stack reactor shows a very good scalability and was investigated for the oxidation of NO in combustion gases (shipping diesel engine exhausts). The oxidation processes were significantly enhanced by the admixture of hydrocarbons. Significant NO conversion at low specific energy densities below 100 J/L were achieved in laboratory and test bench studies. The water falling film reactor demonstrated its feasibility for the removal of hydrocarbon pollutants from gases. Undecane, a long-chain, harmful hydrocarbon, was decomposed. The conversion of non-soluble compounds into soluble ones (formic acid) is a promising development towards a compact plasma-assisted scrubbing technology. These approaches are good progress not only in the field of environmental plasma application, but also for indoor air quality, hygiene, and plasma synthesis. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Plasma Parameters in the COMPASS Divertor During Ohmic Plasmas

Abstract: This paper reports on probe measurements of the electron energy distribution function and plasma potential in the divertor region of the COMPASS tokamak during D-shaped plasmas. The probe data have been processed using the novel first-derivative technique. A comparison with the results obtained by processing the same data with the classical probe technique, which assumes Maxwellian electron energy distribution functions is presented and discussed. In the vicinity of the inner and outer strike points of the divertor the electron energy distribution function can be approximated by a bi-Maxwellian, with a dominating low-energy electron population (4-7 eV) and a minority of higher energy electrons (12-25 eV). In the private flux region between the two strike points the electron energy distribution function is found to be Maxwellian with temperatures in the range of 7-10 eV. The comparative analysis using both techniques has allowed a better insight into the underlying physical processes at the divertor region of the COMPASS tokamak. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Plasma‐Substrate Interaction during Plasma Deposition on Polymers

Abstract: The initial stage of film growth during plasma deposition on polymers determines many film properties such as morphology and structure, interphase formation and adhesion. Therefore, the plasma-substrate interaction is investigated regarding the energy density during film growth, which is defined by the energy flux per depositing atom. The flux of film-forming species and the flux of energetic particles were determined for metal sputtering (silver films) and plasma polymer deposition (amino-functional hydrocarbon films). It is shown that enhanced energy densities can be obtained during the initial film growth due to reduced deposition rates and mixing with the polymer substrate (interphase formation). Thus, good adhesion on polymers such as polyethylene terephthalate (PET) has been achieved. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Particle in Cell/Monte Carlo Collision Method for Simulation of RF Glow Discharges: Effect of Super Particle Weighting

Abstract: Middle East Technical University, Ankara, TurkeyReceived 24 August 2013, revised 05 October 2013, accepted 13 October 2013Published online 09 December 2013Key words Glow discharge, particle-in-cell method, plasma simulations, Monte Carlo methods.A parallel Particle in Cell/Monte Carlo Collision (PIC/MCC) numerical code for glow discharge plasma sim-ulations is developed and verified. This method is based on simultaneous solution of the Lorentz equations ofmotion of super particles, coupled with the Poisson’s equation for electric field. Collisions between the par-ticles are modelled by the Monte Carlo method. Proper choice of particle weighting is critically important inorder to perform adequate and efficient PIC simulations of plasma. Herein, effects of particle weighting on thesimulations of capacitive radio-frequency argon plasma discharges are studied in details.

Diagnostic of Plasma Produced by a Spark Plug at Atmospheric Pressure: Reduced Electric Field and Vibrational Temperature

Abstract: The electric discharge generated between the electrodes of a classic spark plug could not assure a fast and total combustion of the air – hydrocarbon mixture. To be able to improve the quality of the combustion process through the ignition system improvement it is necessary to have a complete diagnostic of the discharge produced by a spark plug, from physical and chemical point of view. This work presents a comparative study of the reduced electric field and the vibrational temperature for a classic spark produced in air at atmospheric pressure, as functions of pulses widths applied by the power supply. The reduced electric field was calculated by using the rotational temperature values established by a previous study, considering them as temperature plasma gas temperatures. The vibrational temperature was determined by using the N2second positive molecular emission spectra. The spark plug was supplied with trains of pulses containing one or two pulses having variable widths provided by a special power supply. The results obtained for the vibrational temperature of nitrogen molecules are close to these obtained for the rotational temperature calculated by using a spectroscopic diagnostic method based on the OH UV molecular band spectra (between 2000 and 3500 K). The electron temperature values, imposed by the reduced electric field (up to 2000 Td), are superior to 10000 K. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Generation of Large-Area Highly-Nonequlibrium Plasma in Pure Hydrogen at Atmospheric Pressure

Abstract: Diffuse Coplanar Surface Barrier Discharge (DCSBD) is a novel type of atmospheric-pressure plasma source developed for high-speed large-area surface plasma treatments. Basic characteristics of DCSBD burning in pure atmospheric-pressure hydrogen were measured using optical and emission spectroscopy methods, and its potential for the surface treatment application was demonstrated by hydrogen plasma reduction of Cu2O thin layers. The discharge generates a thin layer of diffuse non-equilibrium plasma with a high power density of 75W.cm^-3 . The mean electron density and electron temperature derived by the spectroscopy data were 1.3x10^16 cm^-3 and 19x10^3 K, and the surface Cu2O layers forming a weak boundary were reduced to metallic copper within several seconds.

Microwave Plasmas at Atmospheric Pressure

Abstract: Microwave plasmas at atmospheric pressure are used for surface treatments like for example cleaning, sterilization or decontamination purposes, for a pre-treatment to increase the adhesion of lacquer, paint, or glue, and for the deposition of different kind of layers and coatings. Micro plasma jets can also be applied for biomedical applications and for treatment of small and complex geometries like for example the inside of capillaries. Larger plasma torches which exhibit higher gas temperatures can also be used for chemical syntheses like waste gas decomposition, methane pyrolysis, or carbon dioxide dissociation and for plasma spraying purposes. In the present publication an overview on the development and the investigation of the operating principle of two atmospheric pressure microwave plasma torches at frequencies of 2.45 GHz and 915 MHz will be presented. The plasma sources are based on a cylindrical resonator combined with coaxial structures. To explain how these plasma sources work, simulations of the electric field distribution will be discussed. Furthermore, some physical characteristics of an air and an Ar/H2 atmospheric plasma like gas temperatures, excitation temperatures and densities as well as the heating of the plasma by the microwave will be investigated. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Appropriate generation rate constraint (GRC) modeling method for reheat thermal units to obtain optimal load frequency controller (LFC)

Abstract: This paper focuses on choosing a suitable dynamic model for simulation of generation rate constraint (GRC) for load frequency control (LFC) of an interconnected realistic reheat thermal-thermal power system. Two different dynamic models for simulation of the GRC are investigated in details which are named as open loop and closed loop GRC models. These models have been used widely in literature interchangeably without any further description to the reason of selected modeling method and its suitability. This paper makes an attempt to help in choosing more effective and appropriate GRC structure pertained to reheat thermal units based on dynamic simulations to obtain optimal LFC. Reheat thermal units are examined with different GRC models. Then, integral of time multiplied squared error (ITSE) performance index is minimized by an improved particle swarm optimization (IPSO) algorithm to optimize proportional-integral-derivative (PID) controller parameters. All simulations are performed in MATLAB/SIMULINK environment. The results of eigenvalue analysis, dynamic simulations, and robustness analysis reveal the appropriate GRC modeling method for thermal units to attain high-performance and optimal LFC design.

Ultra‐Precision Surface Machining with Reactive Plasma Jets

Abstract: Atmospheric Plasma Jet Machining (PJM) is a technology for non-mechanical ultra-precision surface shape generation, shape error correction and smoothing based on atmospheric plasma jets. PJM is favorably applied to generate optical surfaces like aspheres, acylinders, or free-forms but also to improve the surface shape accuracy in a very fast and cost-efficient way. For that purpose a mainly fluorine containing plasma jet is brought into contact with a surface to locally remove material by a chemical reaction forming volatile products. Hence, the technology is limited to materials like silicon, fused silica and similar, or silicon carbide. Furthermore, the etch profile results from a convolution of the radical and the temperature distribution at the surface. Since the temperature distribution is also influenced by the plasma jet this leads to a non-linear dependence of the removal function of the plasma tool on its velocity. Using the dwell-time algorithm for deterministic surface machining by superposition of the local removal function of the plasma tool an advanced process simulation is necessary. In a first local approximation the velocity dependence of the removal function, which has to be determined previously, must be incorporated. Second order thermal effects due to inhomogeneous heating caused by the part geometry and the tool path can be managed by a sophisticated calculation of the surface temperature evolution during machining based on the Finite Element Method (FEM). With the help of this procedure the accuracy and convergence of the machining process can be significantly improved. In the article several examples of surface processing using plasma jet machining are presented. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Langmuir Probe Evaluation of the Plasma Potential in Tokamak Edge Plasma for Non-Maxwellian EEDF

Abstract: The First derivative probe technique for a correct evaluation of the plasma potential in the case of non-Maxwellian EEDF is presented and used to process experimental data from COMPASS tokamak. Results obtained from classical and first derivative techniques are compared and discussed. The first derivative probe technique provides values for the plasma potential in the scrape-off layer of tokamak plasmas with an accuracy of about ±10%. Classical probe technique can provide values of the plasma potential only, if the electron and ion temperatures are known as well as the coefficient of secondary electron emission. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Electrostatic Ion Thrusters - Towards Predictive Modeling

Abstract: The development of electrostatic ion thrusters so far has mainly been based on empirical and qualitative knowhow, and on evolutionary iteration steps. This resulted in considerable effort regarding prototype design, construction and testing and therefore in significant development and qualification costs and high time demands. For future developments it is anticipated to implement simulation tools which allow for quantitative prediction of ion thruster performance, long-term behavior and space craft interaction prior to hardware design and construction. Based on integrated numerical models combining self-consistent kinetic plasma models with plasmawall interaction modules a new quality in the description of electrostatic thrusters can be reached. These open the perspective for predictive modeling in this field. This paper reviews the application of a set of predictive numerical modeling tools on an ion thruster model of the HEMP-T (High Efficiency Multi-stage Plasma Thruster) type patented by Thales Electron Devices GmbH. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Effect of Anisotropic Ion Pressure on Solitary Waves in Magnetized Dusty Plasmas

Abstract: The propagation of linear and nonlinear dust ion acoustic waves (DIAWs) are studied in a collisionless magnetized plasma which consists of warm ions having anisotropic thermal pressure, nonthermal (energetic) electrons and static dust particles of positive and negative charge polarity. The anisotropic ion pressure is defined using double adiabatic Chew-Golberger-Low (CGL) theory. In the linear regime, the propagation properties of the two possible modes are investigated via ion pressure anisotropy, dust particle polarity and nonthermality of electrons. Using reductive method Zakharov-Kuznetsov (ZK) equation is derived for the propagation of two dimensional electrostatic dust ion acoustic solitary waves in dusty plasmas. It is found that both compressive and rarefactive solitons are formed in presence of nonthermal electrons using Cairn's distribution [R.A. Cairns, A.A. Mamun, R. Bingham, R.O. Dendy, R. Bostrom, C.M.C. Nairn and P.K. Shukla, Geophys.Res. Lett. 22, 2709 (1995)] in the system. The ion pressure anisotropy, nonthermality of electrons and charge polarity of the dust particles have significant effects on the amplitude and width of the dust ion acoustic solitary waves in such anisotropic nonthermal magnetized dusty plasmas. The numerical results are also presented for illustration. Our finding is applicable to space dusty plasma regimes having anisotropic ion pressure and nonthermal electrons. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Development of the Backflow Model for Simplified Impurity Exhaust in Monte-Carlo Calculation

Abstract: The Monte-Carlo (MC) approach has a lot of flexibility in impurity transport modeling in the SOL and divertor region. However, in the divertor plasma simulation with the noble impurity seeding, characteristic time of the impurity transport especially in the sub-divertor chamber is long because the MC calculation of the impurity gas transport can be finished only by exhaust. The impurity MC calculation for such long exhaust processes is difficult in a series of the iterative calculation of a suite of integrated divertor codes SONIC. In order to overcome such a problem, a backflow model has been developed. Amount of the backflow flux from the sub-divertor chamber to the divertor region is evaluated in advance, and then simulating impurity flux is injected from the exhaust slot to the divertor region like a backflow. By this model, the MC calculation time is reduced significantly and iterative calculation of SONIC becomes possible within a reasonable calculation time. As a demonstration, the SONIC code with the backflow model has been applied to investigation of power handling in JT-60SA divertor. The SONIC simulation showed that low divertor heat load (< 10 MW/m2) with the low SOL density (< 1.5 × 1019m–3), which is required in the full non-inductive current drive scenario, was achieved by the Ar gas puffing of 0.86 Pa m3/s. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Atmospheric Pressure Plasma Application for Pollution Control in Industrial Processes

Abstract: Economic application of atmospheric pressure plasma technology for industrial pollution control requires fulfilling two propositions: First application of pollution control technologies needs to result in clear environmental, health, or safety benefits motivating political measures. Second plasma technology needs to be competitive as compared to other available pollution control technologies. Thus in this article methods for the evaluation of atmospheric plasma application for industrial pollution control are reviewed: Examples of emission regulations and emission control technologies are given. Requirements of industrial scale emission control and of thermal and non-thermal exhaust gas treatment technologies are described. The potential of various non-thermal plasma reactor concepts for cost effective treatment of industrial scale gas flows is analyzed, and methods for the evaluation of plasma energy balance and plasma chemical kinetics are given for them. How to deal with shortcomings of atmospheric pressure plasmas such as lack of plasma-chemical selectivity is addressed in a section about plasma-catalytic hybrid processes. Further the progress made recently in electrostatic precipitation is reviewed, and the importance of electro-hydrodynamic effects for the reactor design both for electrostatic precipitation and for plasma chemical pollution control is considered. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Density and Temperature Correlations in the SOL; Implications for Gas Puff Imaging of Turbulence

Abstract: Using a two-dimensional turbulence model, a strong linear correlation is found between density and electron temperature within scrape-off layer fluctuations. This has important implications for gas puff image interpretation for two commonly used lines, Dα and HeI (587.6 nm). Dα emission responds approximately linearly to proportional changes in the underlying plasma density and electron temperature, making image interpretation relatively straightforward. However, above ∼25 eV, HeI (587.6 nm) emission is approximately constant with proportional changes in density and electron temperature, so underlying plasma perturbations may go unseen. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Density Regimes and Heat Flux Deposition in the WEST Shallow Divertor Configuration

Abstract: To support ITER divertor design, the WEST project on Tore Supra aims at studying high heat fluxes on tungsten monoblock during long pulses. In that persective, a particular attention is paid to simulate the edge plasma interaction with complex PFCs using the transport code SOLEDGE2D-EIRENE. The plasma response to a heating and puffing scenario is described as well as the so-called divertor density regimes, characterizing the operational domain of the WEST divertor. These results are compared for two different magnetic configurations: a semi-open double null divertor with the X-point away from the target plates and a shallow divertor configuration with the X-point close to the targets. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Determination of N and O‐atoms and N2 (A) Metastable Molecule Densities in the Afterglows of N2‐H2, Ar‐N2‐H2 and Ar‐N2‐O2 Microwave Discharges

Abstract: Early afterglows of N2-H2, Ar-N2-H2 and Ar-N2-O2 flowing microwave discharges are characterized by optical emission spectroscopy. The N and O atoms and the N2 (A) metastable molecule densities are determined by optical emission spectroscopy after calibration by NO titration for N and O-atoms and measurements of NO and N2 band intensities. If an uncertainty of 30% is estimated on N-atomic density, an inaccuracy of one order of magnitude is obtained on the O and N2 (A) densities. In N2-(0.05-2.5%)H2 and Ar-(1-50%)N2-(0.05-2.5%) H2 gas mixtures, the O-atoms are coming from O2 impurities in the discharge. Concentrations of N and O-atoms and of N2 (A) densities are compared to the ones obtained in Ar-(5-50%)N2-(0.2-2.5%) O2 gas mixtures in which a controlled amount of O2 is added. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Numerical Methods for 3D Tokamak Simulations Using a Flux-Surface Independent Grid

Abstract: A numerical approach for 3D Tokamak simulations using a flux surface independent grid is presented. The grid consists of few poloidal planes with a Cartesian isotropic grid within each poloidal plane. Perpendicular operators can be discretised within a poloidal plane using standard second order finite difference methods. The discretisation of parallel operators is achieved with a field line following map and an interpolation. The application of the support operator method to the parallel diffusion operator conserves the self-adjointness of the operator on the discrete level and keeps the numerical decay rate at a low level. The developed numerical methods can be applied to geometries where an X-point is present. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Propulsive Force in an Electric Solar Sail

Abstract: An electric solar sail (e-sail) is a promising propellantless propulsion concept for the exploration of the Solar System. An e-sail consists of an array of bare conductive tethers at very high positive/negative bias, capable of extracting solar-wind momentum by Coulomb deflection of protons. The present work focuses on the positivebias case with a potential profile that must be correctly modeled. Ion scattering does occur at some point of the profile and the resulting thrust is determined; that thrust scales slower with distance to the Sun, than it was previously suggested in the literature. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Investigating the performance of technical indicators in electrical industry in Tehran's Stock Exchange using hybrid methods of SRA, PCA and Neural Networks

Abstract: According to high application of electrical industry in different industrial branches, generation and distribution of power energy is one of the most challenges of countries. The next step is its appropriate and qualified distribution after generation of electricity in powerhouses. Hence, this paper investigates the efficiency of cable companies in Tehrans Stock Exchange (TSE) according to key effects of providers in power distribution generation. Prediction price indicator movement has always been a challenging task in the exploitation of time series for forecasting. Exact prediction of price indicator movement may offer numerous privileges for investors. As a result of the complexity of stock market data, development of efficient models is often not simple. This research have combined a number of methods namely as Principal Component Analysis (PCA), Stepwise Regression Analysis (SRA) and Artificial Neural Networks (ANN) by technical analysis tools of financial markets. In proceeding, the efficiency of each set in predicting the indicator trend of stocks' total price, have been compared. Data used in this research have been collected from cable companies in the stock exchange between 2007 and 2013. Using empirical results, this research introduces an efficient set of technical indicators for forecasting total price indicator movement in cable companies in TSE. Other results of this research indicate more accuracy of SRA and neural networks in comparison with PCA and neural networks.