Kinetic simulation of the sheath dynamics in the intermediate radio-frequency regime

The dynamics of temporally modulated plasma boundary sheaths is studied in the intermediate radio frequency regime where the applied radio frequency and the ion plasma frequency are comparable. Two kinetic simulation codes are employed and their results are compared. The first code is a realization of the well-known scheme, Particle-In-Cell with Monte Carlo collisions (PIC/MCC) and simulates the entire discharge, a planar radio frequency capacitively coupled plasma (RF-CCP) with an additional heating source. The second code is based on the recently published scheme Ensemble-in-Spacetime (EST); it resolves only the sheath and requires the time resolved voltage across and the ion flux into the sheath as input. Ion inertia causes a temporal asymmetry (hysteresis) of the sheath charge-voltage relation; also other ion transit time effects are found. The two codes are in good agreement, both with respect to the spatial and temporal dynamics of the sheath and with respect to the ion energy distributions at the electrodes. It is concluded that the EST scheme may serve as an efficient post-processor for fluid or global simulations and for measurements: It can rapidly and accurately calculate ion distribution functions even when no genuine kinetic information is available

Collective excitations in electron-hole bilayers

We report a combined analytic and Molecular Dynamics analysis of the collective mode spectrum of an electron-hole (bipolar) bilayer in the strong coupling quasi-classical limit. A robust, isotropic energy gap is identified in the out-of-phase spectra, generated by the combined effect of correlations and of the excitation of the bound dipoles; the in-phase spectra exhibit a correlation governed acoustic dispersion for the longitudinal and transverse modes. Strong nonlinear generation of higher harmonics of the fundamental dipole oscillation frequency and the transfer of harmonics between different modes is observed. The mode dispersions in the liquid state are compared with the phonon spectrum in the crystalline solid phase, reinforcing a coherent physical picture.Comment: 4 pages, 5 figure

Kinetic Interpretation of Resonance Phenomena in Low Pressure Capacitively Coupled Radio Frequency Plasmas

The kinetic origin of resonance phenomena in capacitively coupled radio frequency plasmas is discovered based on particle-based numerical simulations. The analysis of the spatio-temporal distributions of plasma parameters such as the densities of hot and cold electrons, as well as the conduction and displacement currents reveals the mechanism of the formation of multiple electron beams during sheath expansion. The interplay between highly energetic beam electrons and low energetic bulk electrons is identified as the physical origin of the excitation of harmonics in the current

Simulation benchmarks for low-pressure plasmas: capacitive discharges

Benchmarking is generally accepted as an important element in demonstrating the correctness of computer simulations. In the modern sense, a benchmark is a computer simulation result that has evidence of correctness, is accompanied by estimates of relevant errors, and which can thus be used as a basis for judging the accuracy and efficiency of other codes. In this paper, we present four benchmark cases related to capacitively coupled discharges. These benchmarks prescribe all relevant physical and numerical parameters. We have simulated the benchmark conditions using five independently developed particle-in-cell codes. We show that the results of these simulations are statistically indistinguishable, within bounds of uncertainty that we define. We therefore claim that the results of these simulations represent strong benchmarks, that can be used as a basis for evaluating the accuracy of other codes. These other codes could include other approaches than particle-in-cell simulations, where benchmarking could examine not just implementation accuracy and efficiency, but also the fidelity of different physical models, such as moment or hybrid models. We discuss an example of this kind in an appendix. Of course, the methodology that we have developed can also be readily extended to a suite of benchmarks with coverage of a wider range of physical and chemical phenomena

Vergleich von artenreichen Begrünungsmischungen in ungarischen Weingebieten

Intensive mechanical soil cultivation and herbicide treatment was often the preferred technology in vineyards in the second half of the 20th century. In the last decades we increasingly experienced the disadvantages of these technologies: soil degradation, erosion and deflation damages. The use of well-adapted cover-crop mixtures could be an alternative. In 2012 we started to study three different species-rich cover crop mixtures (Biocont-Ecovin, Legume mixture, Grass-herb mixture) in Hungarian vineyards. For 2013 we detected lower weed coverage in the inter-rows sown with the Grass-herb and Legume mixtures, while in control and Biocont-Ecovin inter-rows we detected increasing weed coverage. In the third year (2014) we found in case of every plot that the grass-herb mixture-covered inter-rows were the least weedy. The most successful species in the inter-rows are: Coronilla varia, Lotus corniculatus, Medicago lupulina, Onobrychis viciifolia, Plantago lanceolata, Trifolium repens, Trifolium pratense

Body composition and venison quality of farmed red deer (<i>Cervus elaphus</i>) hinds reared on grass, <i>papilionaceous</i> or mixed pasture paddocks

Red deer (Cervus elaphus) hinds (n=3×10) of identical initial body weight (BW, ca. 68&thinsp;kg) were reared on a monocotyledonous grass (G group), on a grass–papilionaceous (GP group) or on pure papilionaceous pasture each of 2&thinsp;ha (P group) for 219 d. At the end of the experiment carcass tissue composition was assessed by means of computer tomography, slaughter value and meat quality were characterized and tissue – longissimus thoracis et lumborum (LTL), thigh and liver – samples were taken for fatty acid composition analysis. The primary aim was to assess nutrition-driven differences. Hinds of group P provided higher final BW (101&thinsp;kg vs. 90 and 91.9&thinsp;kg in groups G and GP, respectively) and higher BW gain (32.6&thinsp;kg during the total period vs. 22.4 and 22.1&thinsp;kg). The carcass weight exceeded those of the other groups significantly (68.8&thinsp;kg vs. 59.3 and 63.2&thinsp;kg), while there was no difference among groups in the perirenal fat weight and red color tone (a*) of the LTL. Groups G and P differed significantly in the LTL weight (highest in P), its dripping loss (lowest in G), lightness (L; highest in P) and yellow color tone (b*). In the thigh muscle, LTL and liver the highest proportion of fatty acid CLA9c11t was reached on the G pasture, and the same trend was true for docosahexaenoic acid (DHA , C22:6 n3) in the muscles. The n6&thinsp;∕&thinsp;n3 fatty acid ratio was the highest on the P pasture in the liver and both muscles. The liver incorporated the highest proportion of linoleic acid (C18:2 n6) and converted it rather effectively to arachidonic acid (C20:4 n6), coupled with the lowest α-linolenic acid presence. In conclusion, concerning muscle mass production, group P proved to be the most advantageous pasture; meanwhile LTL meat quality factors (dripping loss, DHA proportion, pH, color) were more favorable on the G pasture.</p

Effect of genotype and hens' starting body fat content on the changes in the body fat content of the hens and on the weight and composition of the eggs produced in the first egg laying period

The aim of this study was to examine the effect of genotype and hens’ starting body fat content on the changes in the body fat content of the hens and on the weight and composition of the eggs produced in the first egg laying period. The experiment was carried out with altogether 30 hens (15 TETRA SL brown egg layers and 15 TETRA BLANCA white egg layers), which were chosen from altogether 45 TETRA SL and 45 TETRA BLANCA hens based on their CT (computer tomography) predicted body fat content at 20 weeks of age (hens with the highest (n=5), hens with the lowest (n=5) and hens with average (n=5) body fat content in both genotype). For the in vivo determination of changes in the body composition of these hens, computer tomography (CT) measurements were carried out at every fourth week between the 20th and 72nd week of age. During the CT measurements hens were fixed with belts in a special plexiglass container without using any anaesthetics. The measurements covered the whole body of the hens using overlapping 10 mm slice thickness on a Siemens Somatom Emotion 6 multislice CT scanner. After collecting, weighing and breaking the eggs produced by the experimental birds on the days of the CT measurements their yolk ratio was determined. Based on the results, it was established that the body fat content of the hens increased continuously in both of the genotypes in the first phase of the experimental period, while it did not change further in the second phase of the experiment. It was also observed at all examination days, that the body fat content of the white egg layers was higher than that of the brown egg layers. Hens with the highest starting body fat content had the highest body fat content in both genotypes during the whole egg laying period. The egg production of the hens was not influenced by the body fat content of the birds, but it was affected by the genotype. The TETRA SL hens produced significantly more eggs than the TETRA BLANCA hens. The hens with average body fat content produced lighter eggs than the hens with low or high body fat content