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The dispersion relation of plasma and plasma-dielectric photonic multilayer structures is approached in terms of a one-dimensional Particle-in-Cell simulation. For several plasma-dielectric configurations, the system response is obtained using a pulsed excitation and a subsequent two-dimensional frequency analysis. It is first shown that the dispersion relation of a single, homogeneous plasma slab is well described by the cold-plasma model even at a low pressure of 1 Pa. The study is extended to the simulation of plasma photonic crystals with a variety of configurations based on the work of Hojo and Mase [J. Plasma Fusion Res. 80, 89 (2004)]. Considering a one-dimensional plasma photonic crystal made from alternating layers of dielectric and homogeneous plasma slabs, it is shown that the assumption of a cold-plasma description is well justified also in this case. Moreover, in this work, the results are reformatted and analyzed in a band diagram representation, in particular, based on the lattice constant a. Based on these considerations, a scaling invariant representation is presented, utilizing a generalized set of parameters. The study is completed with an exemplary comparison of three plasma-dielectric photonic crystal configurations and their corresponding band diagrams. [ABSTRACT FROM AUTHOR]

Surface-dielectric-barrier discharges (SDBDs) can be applied for a wide range of applications, such as ozone generation, surface treatments, and air-pollutants removal. An important advantage of the SDBD plasma is that relatively low high-voltage (HV) pulses (<10 kV) are needed to generate the plasma. They are effective in removing a wide range of pollutants. Despite their high energy efficiency, plasma decomposition generally results in the reaction by-products and the formation of ozone and nitrogen oxides. This drawback can be overcome by combining the SDBD plasma with catalysis. In this paper, a novel plasma-catalytic topology is proposed for the purpose of on-demand air purification. The main idea of the plasma-catalytic reactor is that both the plasma and the catalytic function are configured as planar structures which are positioned in parallel to each other. The plasma is generated along a planar dielectric structure. We use an SDBD for this purpose. Plates coated with the catalytic material are positioned in parallel to the SDBD plates. The air to be treated is flushed along the plates. There are no restrictions to the type or combination of catalysts used; the catalysts and their specifications can be chosen freely. We have developed a modular plasma-catalytic SDBD reactor to handle large flows, which can be scaled up and scaled down easily. To energize the plasma, an SDBD power modulator was developed. The modulator is able to generate a HV output pulse over an SDBD plasma load with a magnitude adjustable from 4.78 to 6.95 kV. The pulse rise time is about $1~\mu \text{s}$ and its ramp is about 6 kV/ $\mu \text{s}$. The energy per pulse then ranges from 1.1 to 17.4 mJ. The output power can be adjusted up to 48 W at a repetition rate of 5.5 kHz. The maximum possible pulse repetition rate is 22 kHz, but it is limited to 5.5 kHz due to the limited current rating of the available dc power supply. The total energy efficiency of the power modulator is 68%. A single modulator unit can power up to two SDBD reactor plates of $100\times 150$ mm size, having plasma at both sides of the plate. The operational efficiency of the developed SDBD catalytic reactor has been investigated by studying the removal of NOx and ethylene. The removal efficiency of NOx and ethylene is determined as a function of energy density and operational parameters, such as their initial concentrations and the gas flow rate. [ABSTRACT FROM AUTHOR]

A tunable transverse electric (TE) and transverse magnetic (TM) wave splitter using one-dimensional plasma dielectric photonic crystal which consists of plasma arranged periodically in a host dielectric medium is proposed. We performed a detailed study to explore the phenomena of reflection and transmission that occurs on obliquely incident electromagnetic wave propagating in the proposed plasma dielectric photonic crystal. We exactly calculated the transmittance based on the transfer matrix method. We find that if the parameters are selected appropriately, in the TE-stop or TM-stop frequency region, the other polarized component TM or TE wave is totally transmitted. The results also show that the dielectric constant, plasma thickness, incident angle and the applied magnetic field have significantly changed the properties of the TE/TM wave splitter. Moreover, the external magnetic field can be used as a kind of tunable method once the splitter is fabricated. Parameter dependence of the effects for the TE/TM wave splitter is calculated and discussed. [ABSTRACT FROM AUTHOR]

Azimuthal surface waves are electromagnetic eigenwaves of cylindrical plasma-dielectric waveguides which propagate azimuthally nearby the plasma-dielectric interface across an axial external stationary magnetic field. Their eigenfrequency in particular can belong to the electron cyclotron frequency range. Excitation of azimuthal surface waves by rotating relativistic electron flows was studied in detail recently in the case of the zeroth radial mode for which the waves' radial phase change within the layer where the electrons gyrate is small. In this case, just the plasma parameters cause the main influence on the waves' dispersion properties. In the case of the first and higher radial modes, the wave eigenfrequency is higher and the wavelength is shorter than in the case of the zeroth radial mode. This gain being of interest for practical applications can be achieved without any change in the device design. The possibility of effective excitation of the higher order radial modes of azimuthal surface waves is demonstrated here. Getting shorter wavelengths of the excited waves in the case of higher radial modes is shown to be accompanied by decreasing growth rates of the waves. The results obtained here are of interest for developing new sources of electromagnetic radiation, in nano-physics and in medical physics. [ABSTRACT FROM AUTHOR]

In this study, the characteristic properties and plasma parameters of capacitive radio frequency (RF) argon (Ar) discharge and supplementary discharge at low pressure are investigated with optical emission spectroscopy (OES). The wavelengths of spectral lines from OES are obtained between 650-900 nm. Using OES lines and related experimental data, the electron temperatures for different RF power, flow, and measurement periods are determined. Eventually, the properties of plasma including the electron temperature are identified. In addition, the numerical modelling of the discharge parameters is carried out by using the 'extended' fluid model for plasma, and consistency between numerical and experimental results is discussed. [ABSTRACT FROM AUTHOR]

Hot plasma dielectric response models, which are now used in most linear full wave codes, are formulated in Fourier space assuming that particle's Larmor radius is much smaller than the scale of spatial nonuniformity of magnetic field. Such approximation assumes that the spatial scale of plasma dielectric response to the RF field is limited to a few Larmor radii, which is accurate for a limited range of wave frequencies ω. The scale of plasma dielectric response along the magnetic field line could be comparable to the scale of the magnetic field nonuniformity when ω is close to the particle's cyclotron frequency ωc or when ω is much smaller than ωc, which requires the use of a more accurate model. In the present approach, the hot plasma dielectric response is formulated in configuration space without limiting approximations by numerically calculating the plasma conductivity kernel based on the solution of the linearized Vlasov equation in nonuniform magnetic field. Results of the conductivity kernel calculation in hot collisionless plasma are presented for 1-D mirror and 2-D tokamak magnetic field configurations for ω ~ ωc. Selfconsistent simulation of RF fields using the calculated conductivity kernel of 1-D mirror magnetic field is made. A new parallel full wave RF code, based on the presented approach of accurate selfconsistent modeling of plasma dielectric response in configuration space, is under development. [ABSTRACT FROM AUTHOR]

The propagation of an ultrawideband electromagnetic signal in the ionosphere-a plasma medium with spatially nonuniform characteristics-is studied analytically in the high-frequency approximation. The effect of the plasma dielectric properties and angular divergence on the shape and frequency spectrum of the propagating signal is investigated. It is shown that the spectral energy density of the signal is preserved if collisions of ionospheric plasma electrons are neglected. [ABSTRACT FROM AUTHOR]

Reactive ion etching was used to study bismuth zinc niobate (BZN) thin films etching in SF/Ar plasma as a function of pressure. The etch rate increases as the pressure increases from 1 to 20 mTorr and decreases when the pressure exceeds 20 mTorr. The film surfaces were analyzed to determine the etching mechanism using X-ray photoelectron spectroscopy. Pressure is found to have an effect on etch reaction and non-volatile etch by-products removal through different ion density and energy, thus resulting in varying compositions, element chemical binding states on the film surface. Dielectric properties of the film, modified by SF/Ar plasma, show an obvious variation with pressure. The permittivity shows a slight decrease in the range of 1-20 mTorr but a sharp decrease at 30 mTorr. Instead, the dielectric loss variation exhibits an opposite trend. [ABSTRACT FROM AUTHOR]

The dual-mode characteristics of the Buneman instability are investigated in a slab plasma, including the geometric effects. The dual symmetric and anti-symmetric dispersion modes of the Buneman instability are obtained by the plasma dielectric function with the spectral reflection conditions for the slab geometry. The result shows that the magnitudes of the growth rate for the symmetric mode are always greater than those for the anti-symmetric mode. It is also found that the geometric effect suppresses the position of the maximum growth rate for the Buneman instability in bounded slab plasmas since the maximum conditions for the symmetric and anti-symmetric modes of the Buneman instability are given by 0:60 < kzv0=pe < 0:65. The physical characteristics and properties of the dual modes of the Buneman instability are also discussed. [ABSTRACT FROM AUTHOR]

The effective potential theory is a physically motivated method for extending traditional plasma transport theories to stronger coupling. It is practical in the sense that it is easily incorporated within the framework of the Chapman-Enskog or Grad methods that are commonly applied in plasma physics and it is computationally efficient to evaluate. The extension is to treat binary scatterers as interacting through the potential of mean force, rather than the bare Coulomb or Debye-screened Coulomb potential. This allows for aspects of many-body correlations to be included in the transport coefficients. Recent work has shown that this method accurately extends plasma theory to orders of magnitude stronger coupling when applied to the classical one-component plasma model. The present work shows that similar accuracy is realized for the Yukawa one-component plasma model and it provides a comparison with other approaches. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The nonthermal and geometric effects on the propagation of the surface dust acoustic waves are investigated in a Lorentzian dusty plasma slab. The symmetric and anti-symmetric dispersion modes of the dust acoustic waves are obtained by the plasma dielectric function with the spectral reflection conditions the slab geometry. The variation of the nonthermal and geometric effects on the symmetric and the anti-symmetric modes of the surface plasma waves is also discussed. [ABSTRACT FROM AUTHOR]

Temperature variation of a catalytic metal surface exposed to ozone produced in an atmospheric-pressure dielectric barrier discharge is examined by using a very thin thermocouple. The metal sheet is heated initially to a certain temperature ( T1) using a resistive heater and, then, the ozone concentration is increased with the heater current unchanged. When T1 is room temperature, the temperature of the metal sheet remains almost constant independent of ozone concentration. When T1 is increased up to 80 °C, the temperature of the metal sheet decreases clearly with increasing ozone concentration due to enhanced catalytic dissociation of ozone at the metal surface. The rate of decrease in temperature for a stainless steel sheet is increased from nearly 0% to $\sim 5.7$ % with increasing T1 from room temperature to 80 °C, while that for a platinum sheet is increased further to $\sim 17.5$ % at 80 °C due to stronger catalytic activity of platinum. The results confirm that the sensitivity for ozone is improved with a stronger catalytic metal heated to a higher temperature as the sensor body. [ABSTRACT FROM PUBLISHER]

This paper develops a novel symmetric dielectric barrier discharge (DBD) plasma as an ion source for environmental mass spectrometry (MS) applications. The conventional linear-type DBD plasma generator suffers the drawback of floating voltage at the plasma outlet. This paper develops an innovative symmetric T-shaped DBD plasma generator to produce atmospheric plasma with zero-floating potential for high-sensitivity MS analysis. By changing the geometric configuration and the drive phase of the symmetric T-shaped DBD plasma generator, the resulting symmetric structural design can fully cancel the floating potential and noise signal. Therefore, the main objective of this paper is to compare the differences between traditional linear-type DBD and the symmetric T-shaped DBD designs using MS, spectroscopy, and some basic electrical measurements. The most suitable parameters are determined by changing the electrode design, voltage, temperature, gas flow rate, diameter, and other parameters of the plasma tube. The symmetric T-shaped design generator produces the zero-potential plasma that generates fewer ambient gas molecules to form ozone, NOx, water clusters, and other strong oxidizing molecules such that less damage to the MS samples occurs. This in turn results in a less fragmented ion signal and higher sensing performance for rapid MS applications. In addition, the proposed system can directly ionize gas, liquid, and solid samples at more than 10^7 -cm ^-3 ion concentration. Results show that more information-rich spectra can be obtained with the developed symmetric T-shaped DBD plasma generator compared with the typical linear-type DBD generator. [ABSTRACT FROM PUBLISHER]

In this paper, a cylindrical dielectric barrier discharge (DBD) plasma reactor is analyzed and investigated at normal environmental conditions. The stressed voltage is varied up to 40 kV peak-to-peak with a variable frequency of up to 4 kHz. In order to compare the experimental findings with the simulation results, an equivalent electrical circuit model is used. To simulate the dynamic microdischarge inside the plasma reactor, a voltage-controlled current source is implemented. The reactor is filled with aluminum oxide to enhance its operation. An equivalent configuration is proposed to model the region of alumina pellets inside the reactor and to calculate the corresponding equivalent capacitance. It is found that the measured voltage, discharge current, and voltage–charge waveforms are consistent with the simulated results. The quantitative comparison of the experimental and simulated data confirms the validity of the developed electrical circuit model of the plasma reactor. [ABSTRACT FROM AUTHOR]

The degradation of 4-chlorobenzoïcacid (4-CBA) in waterwas performed using an innovative plasma dielectric barrier discharge(DBD) process. The influence of the electrode material directly incontact with the solution was examined. The roles of power and frequencydischarge on the treatment efficiency were also evaluated. The hydrodynamicbehavior of the solution and physical aspect of the discharge werestudied by contact angle measurements and intensified charge-coupleddevice (iCCD) acquisition, respectively. Analyses showed that theuse of stainless steel (SS) resulted in a better efficiency of theprocess compared with the use of brass (B). The degradation of 4-CBAwas 80 and 50% for SS and B, respectively, after 1 h of plasma discharge.The presence of NOxin the plasma dischargeand corrosion reaction occurring on the brass surface limited thedegradation of the 4-CBA. It was possible to observe two main byproductsand identify the 4-chlorosalicylic acid or 4-chlorohydroxybenzoïcacid. Ultimately, the discharge frequency was reduced to limit theproduction of NOxspecies. [ABSTRACT FROM AUTHOR]

Abstract: We present the results of analytical studies and numerical simulations of a plasma-dielectric wakefield accelerator (PDWFA). The plasma-dielectric structure under investigation is a dielectric-lined circular waveguide that has a transport channel filled with isotropic plasma. In the linear theory approximation (overdense plasma) the total field is represented as a sum of the plasma wave, the eigenwaves of the dielectric waveguide, and the quasistatic field of the bunch. It is shown that at a certain plasma density the superposition of the plasma wave and the dielectric waves allows the acceleration of the witness bunch by the field of the dielectric wave together with simultaneous focusing by the plasma wave. For the overdense plasma regime the results of analytical investigations coincide well with results of particle-in-cell (PIC) simulations. Also, we carried out a PIC simulation of the underdense (blowout) regime of wakefield excitation in the unit. In this regime a focusing is provided by ions remaining in the drift channel after pushing out from it plasma electrons. [Copyright &y& Elsevier]

A method of plasma density measurement based on microwave resonant cavity perturbation (by Kornegay [14]) is described. Resonant cavity theory was analyzed and a resonant cavity with special structure was designed for measuring the low density plasma. In the middle of the closed cavity, there were cut-off tubes which were extended a little into the cavity to get through the plasma. It was found that the distribution of the electrical field intensity was the densest near the cut-off tubes when the cylindrical cavity operating with TM010 mode. By using the method of resonant equivalent circuit analysis, both the amplitudes and phases of the Scattering matrices (S matrices) were obtained before the plasma came and at the time of the plasma passing through. Then the electron line density (Ne) and the electron-molecule collision frequency for momentum transfer (vm) were calculated. A modified formula was proposed based on our simulation which was conducted in HFSS and experimental results. With the comparison of our results and Kornegay's, it was found that the accuracy of the plasma dielectric constant calculation was improved about 5 percent. [ABSTRACT FROM AUTHOR]

Abstract: In this paper the omni-directional reflection bands in one-dimensional plasma photonic crystal (PPC) have been studied theoretically. We present the study of plasma photonic crystal, having alternate regions of plasma⿿dielectric (Al2O3 or ZnS). Reflectances from this periodic multilayered structure in TE- and TM-modes are calculated for different angles of incidence in microwave region for omni-directional reflection bands. The reflectance is obtained by solving a Maxwell's equation using a translational matrix method. In addition to this, we have also studied the effect of variation of plasma width as well as plasma density on the reflection properties of plasma dielectric photonic crystal in TE- and TM-modes. The study of reflectance bands of such plasma photonic crystals shows that it can be used as omni-directional reflector. [Copyright &y& Elsevier]

SUMMARY The decomposition of hydrogen sulfide (H2S) to hydrogen and sulfur with Al2O3, MoOx/Al2O3, CoOx/Al2O3 and NiO/Al2O3 packed non-thermal plasma dielectric barrier discharge reactor was studied. The reaction was carried out with 5-mm discharge gap during the decomposition of 5 vol.% H2S at 150 ml/min (STP) flow rate. Typical results indicated the conversion of ~50% at a specific input energy of ~0.92 kJ/l H2S and 10% (in length) packed reactor showed the best conversion. Among the catalysts studied, MoOx and CoOx supported on Al2O3 showed high performance, which may be caused by synergy between plasma excitation of the carrier gas molecules and catalytic behaviour of MoOx and CoOx. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The decomposition of mixture of selected volatile organic compounds (VOCs) has been studied in a catalytic non-thermal plasma dielectric barrier discharge reactor. The VOCs mixture consisting n-hexane, cyclo-hexane and p-xylene was chosen for the present study. The decomposition characteristics of mixture of VOCs by the DBD reactor with inner electrode modified with metal oxides of Mn and Co was studied. The results indicated that the order of the removal efficiency of VOCs followed as p-xylene > cyclo-hexane > n-hexane. Among the catalytic study, MnOx/SMF (manganese oxide on sintered metal fibres electrode) shows better performance, probably due to the formation of active oxygen species by in situ decomposition of ozone on the catalyst surface. Water vapour further enhanced the performance due to the in situ formation of OH radicals. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

We have developed a large-volume low-pressure cylindrical plasma reactor with a size that matches industrial reactors for treatment of textiles. It was shown that it efficiently produces plasmas with only a small increase in power as compared with a similar reactor with 50 times smaller volume. Plasma generated at 13.56 MHz was stable from transition to streamers and capable of long-term continuous operation. An industrial-scale asymmetric cylindrical reactor of simple design and construction enabled good control over a wide range of active plasma species and ion concentrations. Detailed characterization of the discharge was performed using derivative, Langmuir and catalytic probes which enabled determination of the optimal sets of plasma parameters necessary for successful industry implementation and process control. Since neutral atomic oxygen plays a major role in many of the material processing applications, its spatial profile was measured using nickel catalytic probe over a wide range of plasma parameters. The spatial profiles show diffusion profiles with particle production close to the powered electrode and significant wall losses due to surface recombination. Oxygen atom densities range from 1019 m-3 near the powered electrode to 1017 m-3 near the wall. The concentrations of ions at the same time are changing from 1016 to the 1015 m-3 at the grounded chamber wall. [ABSTRACT FROM AUTHOR]

For the diagnostics of dense plasmas, photons in the vacuum ultraviolet (VUV) or X-ray domain are required. First experiments have demonstrated the great capacity of X-ray Thomson scattering for the determination of plasma parameters such as density, temperature, and ionization state. For a reliable interpretation of the experimental data, the interaction of energetic photons with the plasma has to be considered. The cross section for Thomson scattering is related to the dynamic structure factor S(k,ω). We improve the usual random phase approximation by including collisions and calculate a dynamic collision frequency in Born approximation. We also study the influence of dynamic screening and the relation to the concept of dynamic local-field corrections to the dielectric function. We give results for a variety of plasma parameters and determine the region where collisions are of relevance. [ABSTRACT FROM PUBLISHER]

Two types of nonthermal plasma processes such as pulsed corona discharge and dielectric barrier discharge were investigated for the decomposition of volatile organic compounds and nitric oxide. The performance equation of the plasma reactor was derived with the assumption that the decomposition rate of the pollutant is directly proportional to the concentration of the pollutant and the discharge power. From this model equation and the experimental decomposition data, the apparent decomposition rate constants of various organic compounds and nitric oxide were determined. Alkene and substituted alkene were found to have much larger decomposition rate constants than aromatics and substituted alkane compounds, which implies that the decomposition of the derivatives of aromatics and alkanes requires more energy. To verify the validity of the model derived, the experimental data in the present study and in the literature were compared with the calculation results, and relatively good agreements were achieved between them [ABSTRACT FROM PUBLISHER]

The steady-state, sheath between a Maxwellian plasma source and a dielectric surface was simulated numerically in the collisionless hypothesis. A method of nonphysical numerical time evolution was investigated to extend the electrostatic particle-in-cell method to a large range of ion masses at low cost in calculation time. Secondary electron emission effects were also considered and all of these results for a Maxwellian plasma were validated by comparison with previous analytical models in the entire range of ion masses and with other numerical simulations in the case of light ions. The occurrence of instabilities resulting from the interaction between the ion and the secondary electron flows was also investigated. The numerical times method was thus validated and its limitations characterized. It is now available to simulate arbitrary distribution functions of electrons, secondary electrons, and ions at low cost in calculation time [ABSTRACT FROM PUBLISHER]

Basic, local kinetic theory of ion temperature gradient driven (ITG) mode, with adiabatic electrons is reconsidered. Standard unstable, purely oscillating as well as damped solutions of the local dispersion relation are obtained using a bracketing technique that uses the argument principle. This method requires computing the plasma dielectric function and its derivatives, which are implemented here using modified plasma dispersion functions with curvature and their derivatives, and allows bracketing/following the zeros of the plasma dielectric function which corresponds to different roots of the ITG dispersion relation. We provide an open source implementation of the derivatives of modified plasma dispersion functions with curvature, which are used in this formulation. Studying the local ITG dispersion, we find that near the threshold of instability the unstable branch is rather asymmetric with oscillating solutions towards lower wave numbers (i.e. drift waves), and damped solutions toward higher wave numbers. This suggests a process akin to inverse cascade by coupling to the oscillating branch towards lower wave numbers may play a role in the nonlinear evolution of the ITG, near the instability threshold. Also, using the algorithm, the linear wave diffusion is estimated for the marginally stable ITG mode. [ABSTRACT FROM AUTHOR]

Cold atmospheric-pressure plasma show promising antimicrobial effects, however the detailed biochemical mechanism of the bacterial inactivation is still unknown. We investigated, for the first time, plasma-treated Gram-positive Bacillus subtilis and Gram-negative Escherichia coli bacteria with Raman and infrared microspectroscopy. A dielectric barrier discharge was used as a plasma source. We were able to detect several plasma-induced chemical modifications, which suggest a pronounced oxidative effect on the cell envelope, cellular proteins and nucleotides as well as a generation of organic nitrates in the treated bacteria. Vibrational microspectroscopy is used as a comprehensive and a powerful tool for the analysis of plasma interactions with whole organisms such as bacteria. Analysis of reaction kinetics of chemical modifications allow a time-dependent insight into the plasma-mediated impact. Investigating possible synergistic effects between the plasma-produced components, our observations strongly indicate that the detected plasma-mediated chemical alterations can be mainly explained by the particle effect of the generated reactive species. By changing the polarity of the applied voltage pulse, and hence the propagation mechanisms of streamers, no significant effect on the spectral results could be detected. This method allows the analysis of the individual impact of each plasma constituent for particular chemical modifications. Our approach shows great potential to contribute to a better understanding of plasma-cell interactions. [ABSTRACT FROM AUTHOR]

Negative refraction in one- and two-dimensional lossless plasma dielectric photonic crystals consisting of plasma and background materials is theoretically investigated and the necessary conditions for negative refraction in these two structures are obtained. The critical frequency ω0 and the bandwidth Δω for negative refraction are explored, and the parameter dependence of effects such as plasma filling factor and the dielectric constant of background materials is also examined and discussed. [ABSTRACT FROM AUTHOR]