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6 results on '"electron transport coefficient"'

1. Data-driven discovery of electron continuity equations in electron swarm map for determining electron transport coefficients in argon.

Author

Kawaguchi, S, Takahashi, K, and Satoh, K

Subjects
*ELECTRON transport, *ELECTRONS, *ARGON, *DIFFUSION coefficients, *CONTINUITY, *ION mobility spectroscopy, *ELECTRON diffusion
Abstract

In this study, we develop a novel method for determining electron transport coefficients from electron swarm maps measured by a scanning drift-tube experiment. In our method, two types of electron continuity equations that describe either the spatial or the temporal evolution of an electron swarm are discovered in the electron swarm map. The electron transport coefficients can be determined from the coefficients in the discovered equations. Therefore, we can determine the Townsend ionization coefficient, ionization rate coefficient, center-of-mass drift velocity, mean arrival-time drift velocity, longitudinal diffusion coefficient, and longitudinal third-order transport coefficient. These transport coefficients in argon are determined over a wide range of reduced electric fields, E / N, from 29.7 to 1351.6 Td (1 Td = 10−21 Vm2) using our method. We establish that the consideration of high-order transport coefficients, which have been systematically ignored so far, is important for the proper determination of low-order transport coefficients, specifically the electron drift velocity and longitudinal diffusion coefficient, in the presence of ionization growth. [ABSTRACT FROM AUTHOR]

Published
2023
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2. Examination of Longitudinal Diffusion Coefficient Obtained by Pulse Experiment.

Author

TERASHITA, YUSAKU, SATOH, KOHKI, and ITOH, HIDENORI

Subjects
*DIFFUSION coefficients, *LONGITUDINAL method, *MONTE Carlo method, *ELECTRON transport, *GLOW discharges
Abstract

SUMMARY A pulse experiment was simulated using a Monte Carlo simulation on two model gases with a constant collision frequency. The longitudinal diffusion coefficient [ABSTRACT FROM AUTHOR]

Published
2016
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3. Expression of longitudinal third-order transport coefficient in terms of α parameters and its validity

Author

KAWAGUCHI Satoru, TAKAHASHI Kazuhiro, SATOH Kohki, KAWAGUCHI Satoru, TAKAHASHI Kazuhiro, and SATOH Kohki

Abstract

The relation between the longitudinal third-order transport coefficient ω 3 contained in the continuity equation for electrons and α parameters defined by arrival-time spectra of an electron swarm is deduced. Values of ω 3 and the α parameters in CH4 gas and SF6 gas are calculated by Monte Carlo simulation, and then the values of ω 3 are compared with those of the longitudinal third-order transport coefficient ω'3 which are calculated from the α parameters to examine the validity of the deduced relation. The values of ω'3 are found to excellently agree with those of ω 3 below 500 Td in CH4 gas and from 150 Td to 700 Td in SF6 gas, where the values of the effective ionisation coefficient are nought or quite small. The results suggest that values of ω 3 can be obtained experimentally from arrival-time spectra measured by a double-shutter drift tube.

Published
2018

5. Expression of longitudinal third-order transport coefficient in terms of α parameters and its validity

Author

Satoru Kawaguchi, Kazuhiro Takahashi, and Kohki Satoh

Subjects
010302 applied physics, Physics, Transport coefficient, α parameters, Monte Carlo method, Electron, third-order transport coefficient, Expression (computer science), Condensed Matter Physics, 01 natural sciences, Spectral line, 010305 fluids & plasmas, Third order, Continuity equation, Ionization, electron transport coefficient, 0103 physical sciences, Atomic physics, Monte Carlo simulation
Abstract

The relation between the longitudinal third-order transport coefficient ω 3 contained in the continuity equation for electrons and α parameters defined by arrival-time spectra of an electron swarm is deduced. Values of ω 3 and the α parameters in CH4 gas and SF6 gas are calculated by Monte Carlo simulation, and then the values of ω 3 are compared with those of the longitudinal third-order transport coefficient ω'3 which are calculated from the α parameters to examine the validity of the deduced relation. The values of ω'3 are found to excellently agree with those of ω 3 below 500 Td in CH4 gas and from 150 Td to 700 Td in SF6 gas, where the values of the effective ionisation coefficient are nought or quite small. The results suggest that values of ω 3 can be obtained experimentally from arrival-time spectra measured by a double-shutter drift tube.

Published
2018

6. Electronic Structure and Thermoelectric Properties of Pseudoquaternary Mg2Si1-x-ySnxGey-Based Materials

Author

Kutorasinski, K., Tobola, J., Kaprzyk, S., Khan, A. U., Kyratsi, Theodora, and Kyratsi, Theodora [0000-0003-2916-1708]

Subjects
Electron transport coefficient, Silicon, Electronic structure, Thermoelectric power, Germanium, Boltzmann transport theory, Characterization, Electric power factor, Lattice thermal conductivity, Thermoelectric equipment, Morphological characterization, Thermoelectricity, Energy dispersive spectroscopy, thermoelectric properties, Electron transport properties, Thermal conductivity, Tin, Coherent potential approximation, Energy dispersive x-ray spectroscopy, Carrier concentration, Boltzmann transport, Statistical mechanics, Scanning electron microscopy, semiconductor doping
Abstract

A theoretical study is presented on complex pseudoternary Bi-doped Mg2Si1-x-ySnxGey materials, which have recently been revealed to reach high thermoelectric figures of merit (ZT) of ∼1.4. Morphological characterization by scanning electron microscopy and energy-dispersive x-ray spectroscopy indicated that the investigated samples were multiphase and that the alloy with nominal composition Mg2Si0.55Sn0.4Ge0.05 contained three phases: Mg2Si0.35Sn0.6Ge0.05 (Sn-rich phase), Mg2Si0.65Sn0.3Ge0.35 (Si-rich phase), and Mg2Si0.15Sn0.5Ge0.35 (Ge-rich phase). The electronic structure of all these phases was calculated in the framework of the fully charge self-consistent Korringa–Kohn–Rostoker method with the coherent potential approximation (KKR-CPA) to treat chemical disorder. Electron transport coefficients such as the electrical conductivity, thermopower, and the electronic part of the thermal conductivity were studied by combining the KKR-CPA technique with Boltzmann transport theory. The two-dimensional (2D) plots (as a function of electron carrier concentration and temperature), computed for the thermopower and power factor, well support the large thermoelectric efficiency detected experimentally. Finally, employing the experimental value of the lattice thermal conductivity as an adjustable parameter, it is shown that ZT ≈ 1.4 can be reached for an optimized Bi content near T ≈ 900 K in case of the nominal composition as well as the Sn-rich phase. The question of the effect of disorder on the convergence of the conduction bands and thus the electron transport properties is addressed through detailed examination of the Fermi surfaces. © 2014, The Author(s). 43 3831 3837 3831-3837

Published
2014

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