The axial dependency of the central-axis value of the heavy particle density and temperature of surface-wave plasmas is studied using Rayleigh scattering (RyS). The plasma is generated at a frequency of 2.45 GHz in argon by a surfatron operating under the standard settings of a power of 45 W, a flow rate of 50 sccm and a pressure of 20 mbar. To investigate the effect of the pressure on the gas temperature, we also investigated 6 and 10 mbar plasmas. By using a two-dimensional intensified CCD array we could determine and eliminate the influence of false stray light, a major disturbing factor in the determination of the Rayleigh signal. In order to trace the energy fluxes that determine the gas temperature, we performed Thomson scattering so that the properties of the electron gas are known. It is found that the gas temperature, Ta, depends on the wall temperature and the product of the gas pressure and the electron pressure. The latter implies that Ta follows the electron density axially, meaning that it is highest at the launcher and decreases monotonically in the wave propagation direction. The maximum gas temperature of around Ta = 800 K is found close to the launcher for the highest gas pressure of 20 mbar. For lower pressures we find lower Ta values. The extrapolation of Ta toward the end of the plasma column leads to a temperature of about 320 K. This study reveals that, for the argon plasmas under study, the central-axis values of the gas temperature are determined by the balance between the heating of the gas by means of elastic electron collisions and the cooling due to heat conduction from the center to the wall.

The goal of this work was to investigate the potential of sliding spark plasma to excite from dielectrics emission spectra that have utility in direct trace quantitative analysis of non-conducting materials in air at atmospheric pressure. The sliding spark is a special variety of pulsed plasma specularly discharging across a dielectric surface enforced between a pair of electrodes. Analysis of the emission spectra measured between 212 ≤ λ ≤ 511 nm using CCD spectrometer showed that the sliding spark is accompanied by prompt atomic and molecular emission over a broad wavelength range. Each dielectric is characterized by unique spectral features composed of mostly overlapping atomic, ionic and molecular lines and a complex background that results from the plasma species, cathode material, operating environment and the major components of the sample matrix including their reaction products. Among the measured lines a number (depending on the oxidation state of the element in the matrix) of atomic and ionic lines were found to be free from spectral interference and with good signal-to-noise ratio, which indicates their potential for direct trace quantitative analysis utilizing a new technique: sliding spark spectroscopy. Mostly ionic lines are optically thin. In the UV range the lines are especially not broadened and are identifiable against a weak continuum.

RF sputtered Zn metal films were processed at O2 plasma at various process conditions. The surface morphology of the processed films was characterized using SEM and AFM techniques. Dense and continuous film surface with good surface morphology were observed in all plasma processed films. The microstructure of processed Zn films was very much dependent on the process parameters especially the plasma power and gas flow rate. The effect of these parameters on particle size and surface roughness was examined carefully. The particle size of all processed films lay in between 23 and 70 nm. Noticeable change on surface morphology, particle size and surface roughness was observed with respect to process parameters. The observed sheet resistance was an evidence of the influence of process parameters especially process time on the electrical properties of processed films. In addition, the influence of surface roughness and particle size on electrical resistance was also discussed.

Documents decontamination using dry methods, less invasive than the wet ones implying toxic nocuous substances for cellulose-based materials, has been the object of numerous studies. In recent years mixed researchers teams have been studying the possibility of one-step document decontamination performed by a dry treatment, the risks of repeated wet manipulation thus being reduced. Among physical methods appropriate to this end, high-frequency cold plasma and corona effect can be mentioned. Our studies were carried out on samples taken from ancient books with no cultural heritage value. The decontamination efficiency and the impact on paper of the two types of treatments were determined by: microbiological analysis, scanning electron microscopy, FTIR, chromatic alterations and gloss determination. The above-mentioned procedures eliminate the use of chemical conservation substances, nocuous for the paper support. At the same time the health risk for conservators, restorers, archivists or archive’s users is removed.

To fulfill the transport applications, either for traction or on-board auxiliaries systems, a power generator based on fuel cell needs significant power. For this purpose, long fuel cell stacks, either mono- or multi-stack systems, are already implemented as technological solutions. Long stacks though may be affected by spatial discrepancies (fluidics, temperature) causing possible failures. The latter often occur on localized stack sections. A corrective action has to be taken to quickly restore the fuel cell’s state of health. As an alternative to fluidic action, segmented electric action is explored in this paper. First, an “All or Nothing” solution achieved with electrical by-pass circuits is analyzed: it proved simple to implement but restrictive to exploit. Consequently, a “gradual” action is proposed by using the power electronics converter associated to the fuel cell. Hence, the present work investigates the approach consisting in individually driving the electric power delivered by each segment of a long polymer electrolyte membrane fuel cell stack. Each segment is controlled independently according to its state of health. To achieve this objective, the article provides an extended multi-criteria analysis of several power converter topologies. The converter topology has to be in agreement with transportation specifications: simple, compact, having a high efficiency and should be adapted to manage fuel cell degraded modes. Among several studied topologies, resonant isolated boost stands out as a candidate topology. The related multi-port architecture and algorithm structure are analyzed by numerical simulations, taking into account degraded modes and technology considerations.

When asphalt concrete is manufactured incorporating a high percentage (almost 70%) of reclaimed materials from the deconstruction of road surfaces under renovation, and when the corresponding production device is designed specifically to reduce the energy input need (lowering the production temperature), the resulting manufacturing process contributes to the protection of the environment and reduces production costs. However, to meet the quality requirements of the finished product, virgin materials of appropriate quality and quantity must also be added (mineral aggregates and new asphalt binder) and control systems set up to quantify and optimize the parameters involved (thus avoiding the guess work which still often prevails today). It was for this reason that a new experimental technique described here was devised, which will ultimately be used in asphalt concrete production plants. The technique involves lixiviating reclaimed asphalt concrete using a chlorinated solvent; the resulting solute is collected gradually, then the mixture of binders (virgin and reclaimed asphalt concrete) can be characterized and their mass fractions quantified using a combination of UV and IR spectrometry. With this experimental technique we were able to assess the extent to which the reclaimed asphalt pavement binder participates in the agglomeration and cohesion of the reclaimed asphalt concrete. This assessment was made in terms of the main parameters in the production process, temperature of the materials and mixing time.

Magnetohydrodynamics (MHD) describes the physical behavior of inductively coupled plasma (ICP). The goal of this paper is to provide a physical understanding of a process ICP torch using a resistive MHD model. This includes a basic description and derivation of the fluid model. Inductive plasma is treated as a continuous, conducting fluid that satisfies the classical laws of motion and thermodynamics. This model combines fluid equations, similar to those used in fluid dynamics, with Maxwell’s equations. Steady fluid flow and temperature equations are simultaneously solved (direct method) using a finite elements method (FEM). The electromagnetic field equations are formulated in terms of potential vector with applied voltage source, so this model is physically more consistent, a more accurate and a faster simulation. The governing resistive MHD equations for an inductive plasma flow under local thermodynamic equilibrium (LTE) and laminar flow are presented, with appropriate boundary conditions. The model enabled to obtain the electromagnetic fields, temperature and flow velocity distributions also allows the determination of the electric parameters such as impedance of the plasma torch, total power, eddy losses, etc.

The optical beam deflection method and numerical simulation are developed to study laserinduced bubble in the bulk and near a wall. The influence of the distance between the bubble center and the wall and the influence of the wall sizes on the collapse features of the bubble are discussed. The results show that the collapse time of the bubble is proportional to the maximum bubble radius, and the experimental and numerical results are in agreement with theoretical results when the bubble collapses in the bulk. Besides, the maximum radius increases with the laser energy and then begins to level out as the laser energy continues to increase because of the laser plasma shielding. The closer the bubble is to the wall, the larger the maximum radius and the collapse time are. Furthermore, the bubble surface velocity, the liquid jet velocity and the newborn shock wave pressure are larger, which means that the force acting on the wall is larger near small walls than near large ones.

In many areas of soft and hard matter research science, the amount of material to investigate is rather limited. Partly because the fabrication of larger samples is too expensive or not feasible, yet, partly because the interesting features depend on the size. The aim of this work is to develop a neutron reflectometer optimized for small samples and specular measurements. We present a new concept which is based on state-of-the-art neutron optical elements and which allows studies of samples 100 times smaller than with previous instrumentation. The concept is to use an elliptically focusing guide in the sample plane, and a converging beam geometry in the scattering plane. The latter allows for the simultaneous measurement of a wide angle-of-incidence range simultaneously. Here we report on the prototype setup and first measurements, where we reached a reduction of counting time by one order of magnitude. If a complete instrument is built based on the presented principle, another order of magnitude can be expected.

A 3 kJ plasma focus device was used to study the influence of the soft X-ray on live microorganisms. When Saccharomyces cerevisiae – (yeast) was treated with a dose of 65 mSv of the X-ray radiation (14 shots), no difference in the fertility activity between the control probe and the sample was observed. Also no change in the survival enzyme activity was found after irradiation through a 100 μm Al foil of another type of yeast – Kluyveromyces marxiamus. The irradiation of the Chlamydomonas reinhardtii samples by the PF-X-ray emission through 20 μm Al foil with a dose of 11 mSv produces a considerable change of the photosynthesis parameters. This result is similar to the results of previous studies with plasma focus radiation where strong effects were derived with low doses but with a high dose power.

This paper proposes a generally applicable numerical algorithm for the simulation of two dimensional electrode shape changes during electrochemical machining processes. The computational model consists of two coupled problems: an electrode shape change rate analysis and a moving boundary problem. The innovative aspect is that the workpiece shape is computed over a number of predefined time steps by convection of its surface with a velocity proportional and in the direction of the local electrode shape change rate. An example related to the electrochemical machining of a slot in a stainless steel plate is presented here to demonstrate the strong features of the proposed method.