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In this paper we present results for reduced ionization coefficients (α/N, N—gas density) obtained from the breakdown voltage and emission profile measurements in low-pressure dc discharges in two freons: 1,1,1,2-tetrafluoroethane (R134a) with the chemical formula CH2F–CF3 and 2,3,3,3-tetrafluoropropene (HFO1234yf) with the chemical formula CH2=CFCF3. Our results for α/N are determined from the axial emission profiles in low-current Townsend discharge and lay in the intervals of reduced electric fields E/N (E—electric field, N—gas density), from 2.7 to 5.9 kTd for R134a and from 5 to 23 kTd for HFO1234yf. We also provide a comparison of our experimental results with those from the available literature. [ABSTRACT FROM AUTHOR]

In this paper, we show and discuss a set of cross sections for electron collisions with dimethyl ether (DME, C2H6O) obtained by the standard swarm analysis of experimental data for drift velocities and ionization coefficients measured in pure DME and its mixtures with Ar and Ne by E. Oettinger and coworkers. While the existing cross section set gave relatively good predictions for drift velocities, it proved necessary to modify the inelastic cross sections in order to achieve a better agreement with drift velocities in gas mixtures and a good agreement for the ionization coefficient. Furthermore, the derived set of cross sections was used to calculate the electron transport and rate coefficients under the influence of a constant electric field and crossed electric and magnetic DC and RF orthogonal configuration fields. The effect of the magnitude and frequency of the fields on electron transport was studied separately. Our work has resulted in a database of collision and transport data which can be used in modeling of both DC and RF discharges and plasma applications containing pure DME and its mixtures. [ABSTRACT FROM AUTHOR]

In this work we extend a multi term solution of the Boltzmann equation for electrons in neutral gases to consider the third-order transport coefficient tensor. Calculations of the third-order transport coefficients have been carried out for electrons in noble gases, including helium (He), neon (Ne), argon (Ar), krypton (Kr) and xenon (Xe) as a function of the reduced electric field, E/n0 (where E is the electric field while n0 is the gas number density). Three fundamental issues are considered: (i) the correlation between the longitudinal component of the third-order transport tensor and the longitudinal component of the diffusion tensor, (ii) the influence of the third-order transport coefficients on the spatial profile of electron swarm, and (iii) the errors associated with the two term approximation for calculating the third-order transport coefficients for electron swarms in noble gases. It is found that a very strong correlation exists between the longitudinal components of the third-order transport coefficient tensor and diffusion tensor for the higher values of E/n0. The effects of the third-order transport coefficients on the spatial profile of electron swarms are the most pronounced for noble gases with the Ramsauer-Townsend minimum in the cross sections for elastic scattering. The largest errors of two term approximation are observed in the off-diagonal elements of the third-order transport coefficient tensor in Ar, Kr and Xe for the higher values of E/n0. [ABSTRACT FROM AUTHOR]

In this paper, we explain the difference in sign of the flux and bulk drift velocities of a swarm of electrons in constant direct current (dc) and in radio frequency (RF) electric fields under conditions which lead to negative absolute mobility. We have studied (0.5%) F2/Ar decaying plasma. It was shown that there is a spatial separation of groups of electrons with high and low energy and as a result there is a localization of electron attachment in the region of low energy. Finally, we show that the positive value of the bulk mobility and its delay in RF fields may be explained by a wave of localized attachment that changes the center of mass of the electron swarm. [ABSTRACT FROM AUTHOR]

Abstract: A Monte Carlo simulation technique is used to investigate electron transport in N2O in crossed RF electric and magnetic fields. Our work has resulted in a database of transport parameters which can be used for correct implementation in modeling RF discharges. A behavior of transport coefficients under the influence of the magnitude and the frequency of the fields was studied separately revealing some complex features in the time dependence, most notably anomalous anisotropic diffusion and time-resolved negative differential conductivity. [Copyright &y& Elsevier]