scholarly journals Landauer-Datta-Lundstrom Generalized Transport Model for Nanoelectronics

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Yuriy Kruglyak
Keyword(s):  
Electron Transport ◽  
Band Structure ◽  
Free Path ◽  
Power Law ◽  
Linear Response ◽  
Transport Model ◽  
Transport Coefficients ◽  
Mean Free Path ◽  
Linear Dispersion ◽  
Thermoelectric Transport

The Landauer-Datta-Lundstrom electron transport model is briefly summarized. If a band structure is given, the number of conduction modes can be evaluated and if a model for a mean-free-path for backscattering can be established, then the near-equilibrium thermoelectric transport coefficients can be calculated using the final expressions listed below for 1D, 2D, and 3D resistors in ballistic, quasiballistic, and diffusive linear response regimes when there are differences in both voltage and temperature across the device. The final expressions of thermoelectric transport coefficients through the Fermi-Dirac integrals are collected for 1D, 2D, and 3D semiconductors with parabolic band structure and for 2D graphene linear dispersion in ballistic and diffusive regimes with the power law scattering.

An extended analytical solution of the Boltzmann equation for non-homogeneous fusion and astrophysical plasmas

1988 ◽  
Vol 40 (3) ◽  
pp. 441-453 ◽  
Author(s):  
S. Cuperman ◽  
D. Zoler
Keyword(s):  
Boltzmann Equation ◽  
Analytical Solution ◽  
Free Path ◽  
Density Gradient ◽  
Transport Coefficients ◽  
Spherical Geometry ◽  
Mean Free Path ◽  
Astrophysical Plasmas ◽  
Electron Plasmas ◽  
Gravitational Fields

The perturbative Chapman-Enskog procedure for solving Boltzmann's equation, holding when f1 ≪ f0 (f = f0 + f1 + …), is replaced by a method that is free of such a limitation. This work represents an extension to the case of strongly anisotropic plasma systems and the spherical geometry of that of Campbell (1984, 1986). The solution obtained here is expressed in terms of prescribed ratios of mean free path for collisions, as well as electric and gravitational fields, to the temperature- and density-gradient lengths. This solution is also used to discuss the limitation of the conduction transport coefficients in electron plasmas.

Electron transport in dense gases: limitations on the Ioffe-Regel and Mott criteria

1986 ◽  
Vol 64 (9) ◽  
pp. 1810-1816 ◽  
Author(s):  
Norman Gee ◽  
Gordon R. Freeman
Keyword(s):  
Carbon Dioxide ◽  
Electron Transport ◽  
Gas Phase ◽  
Free Path ◽  
Mean Free Path ◽  
Repulsive Interaction ◽  
Dense Gases ◽  
Localized State ◽  
The Mean ◽  
Nonspherical Molecules

In the gas phase, the Ioffe–Regel criterion that electron transport becomes modified when the mean free path equals the electron wavelength (L = λ) applies clearly only to helium and hydrogen, which have a net repulsive interaction with electrons. The Mott criterion, that when L = λ/2π the electron is in a localized state, also applies to these two gases. The two criteria are less effective for molecules that have net attractive interactions with the electrons, because the interactions are not simply additive. They are not useful for xenon gas. The criteria are also assessed for: (a) several highly polarizable, spherical and nonspherical molecules; (b) polar molecules; (c) nitrogen and carbon dioxide, which form transient anions.

scholarly journals Diffusive transport of energetic electrons in the solar corona: X-ray and radio diagnostics

2018 ◽  
Vol 610 ◽  
pp. A6 ◽  
Author(s):  
S. Musset ◽  
E. P. Kontar ◽  
N. Vilmer
Keyword(s):  
Solar Corona ◽  
Free Path ◽  
Electron Distribution ◽  
Transport Model ◽  
Imaging Spectroscopy ◽  
Mean Free Path ◽  
Diffusive Transport ◽  
X Rays ◽  
Energetic Electrons ◽  
X Ray

Context. Imaging spectroscopy in X-rays with RHESSI provides the possibility to investigate the spatial evolution of X-ray emitting electron distribution and therefore, to study transport effects on energetic electrons during solar flares. Aims. We study the energy dependence of the scattering mean free path of energetic electrons in the solar corona. Methods. We used imaging spectroscopy with RHESSI to study the evolution of energetic electrons distribution in various parts of the magnetic loop during the 2004 May 21 flare. We compared these observations with the radio observations of the gyrosynchrotron radiation of the same flare and with the predictions of a diffusive transport model. Results. X-ray analysis shows a trapping of energetic electrons in the corona and a spectral hardening of the energetic electron distribution between the top of the loop and the footpoints. Coronal trapping of electrons is stronger for radio-emitting electrons than for X-ray-emitting electrons. These observations can be explained by a diffusive transport model. Conclusions. We show that the combination of X-ray and radio diagnostics is a powerful tool to study electron transport in the solar corona in different energy domains. We show that the diffusive transport model can explain our observations, and in the range 25–500 keV, the scattering mean free path of electrons decreases with electron energy. We can estimate for the first time the scattering mean free path dependence on energy in the corona.

scholarly journals Full inversion of solar relativistic electron events measured by the Helios spacecraft

2019 ◽  
Vol 624 ◽  
pp. A3 ◽  
Author(s):  
D. Pacheco ◽  
N. Agueda ◽  
A. Aran ◽  
B. Heber ◽  
D. Lario
Keyword(s):  
Relativistic Electron ◽  
Free Path ◽  
Transport Model ◽  
Radial Distance ◽  
Mean Free Path ◽  
Time Profile ◽  
Release Time ◽  
The Sun ◽  
Data Set ◽  
Energy Channel

Context. The Parker Solar Probe and the incoming Solar Orbiter mission will provide measurements of solar energetic particle (SEP) events at close heliocentric distances from the Sun. Up to present, the largest data set of SEP events in the inner heliosphere are the observations by the two Helios spacecraft. Aims. We re-visit a sample of 15 solar relativistic electron events measured by the Helios mission with the goal of better characterising the injection histories of solar energetic particles and their interplanetary transport conditions at heliocentric distances <1 AU. Methods. The measurements provided by the E6 instrument on board Helios provide us with the electron directional distributions in eight different sectors that we use to infer the detailed evolution of the electron pitch-angle distributions. The results of a Monte Carlo interplanetary transport model, combined with a full inversion procedure, were used to fit the observed directional intensities in the 300–800 keV nominal energy channel. Unlike previous studies, we have considered both the energy and angular responses of the detector. This method allowed us to infer the electron release time profile at the source and determine the electron interplanetary transport conditions. Results. We discuss the duration of the release time profiles and the values of the radial mean free path, and compare them with the values reported previously in the literature using earlier approaches. Five of the events show short injection histories (<30 min) at the Sun and ten events show long-lasting (>30 min) injections. The values of mean free path range from 0.02 AU to 0.27 AU. Conclusions. The inferred injection histories match with the radio and soft X-ray emissions found in literature. We find no dependence of the radial mean free path on the radial distance. In addition, we find no apparent relation between the strength of interplanetary scattering and the size of the solar particle release.

Inelastic Mean Free Path Data for Si Corrected for Surface Excitation

2005 ◽  
Vol 11 (6) ◽  
pp. 581-585
Author(s):  
Gábor Tamás Orosz ◽  
György Gergely ◽  
Sándor Gurbán ◽  
Miklós Menyhard ◽  
Aleksander Jablonski
Keyword(s):  
Monte Carlo ◽  
Electron Transport ◽  
Free Path ◽  
Photoelectron Spectroscopy ◽  
Electron Spectroscopy ◽  
Mean Free Path ◽  
Thin Layers ◽  
Elastic Peak ◽  
Surface Excitation ◽  
Inelastic Mean Free Path

Surface-sensitive electron spectroscopies, like Auger electron spectroscopy, X-ray photoelectron spectroscopy and elastic peak electron spectroscopy (EPES) are suitable techniques to investigate surfaces and thin layers. A theoretical model for electron transport is needed to process the observed electron spectra. Electron transport descriptions are based on the differential elastic cross sections for the sample atoms and the inelastic mean free path (IMFP) of backscattered electrons. An electron impinging on the sample can lose energy either due to surface or volume excitations. In the present work a Monte Carlo (MC) simulation of the elastic peak of Si, Ag, Ni, Cu, and Au for surface analysis is presented. The IMFP of Si was determined applying the EPES method. The integrated elastic peak ratio of Si with the standard metal reference samples corrected for surface excitation provided IMFP values of Si in the energy range E = 0.2–2.0 keV. Experiments were made with the ESA 31 HSA (ATOMKI) and with the DESA-100 (Staib) spectrometers. Surface correction was based on the application of Chen's model and material parameters. The Monte Carlo simulations of elastically backscattered electron trajectories were made using new EPESWIN software of Jablonski. An improvement of IMFP experimental results was achieved applying the presented procedure.

SIMULATION OF THE TRANSITION BETWEEN MESON-SYSTEM AND QGP IN A TRANSPORT MODEL

2007 ◽  
Vol 16 (07n08) ◽  
pp. 2269-2275 ◽  
Author(s):  
ZHIGUANG TAN ◽  
ALDO BONASERA ◽  
CHUBIN YANG ◽  
DAIMEI ZHOU ◽  
S. TERRANOVA
Keyword(s):  
Free Path ◽  
Finite Temperature ◽  
Transport Model ◽  
Mean Free Path ◽  
Bag Model ◽  
Thermodynamical Properties ◽  
Model Based ◽  
Mit Bag Model ◽  
The Mean ◽  
Meson System

Some thermodynamical properties of the interacting meson system and QGP at finite temperature are discussed. For a pure meson gas the Hagedorn limiting temperature is reproduced when the experimentally observed resonances are included. For QGP our results for different numbers of flavors Nf compare very well to the theoretical ones. A transport model based on the mean free path approach is used to simulate the evolution of the system. During the evolution we use the MIT bag model to perform the transition between meson gas and QGP.

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