scholarly journals The Contribution of Phonons to the Thomson Coefficient

1954 ◽  
Vol 7 (3) ◽  
pp. 520 ◽  
Author(s):  
PG Klemens
Keyword(s):  
Temperature Gradient ◽  
Electric Current ◽  
Fermi Energy ◽  
Unit Volume ◽  
Transport Coefficients ◽  
Thomson Coefficient

An electric current of density j flowing in a temperature gradient \1T gives up heat in a reversible way; the amount of heat thus liberated per unit volume and unit time is given by -p.j\1T, (1) p. being the Thomson coefficient, which can be shown to be T d r l(Kl )' p.=-e dT(P Ko -~ 5' (2) where ~ is the Fermi energy, and the K's are the usual transport coefficients as defined by Mott and Jones (1936, p. 306, equation (99)), or more generally by Wilson (1953, p. 305).

scholarly journals Gyrokinetic simulations of electric current generation in ion temperature gradient driven turbulence

2021 ◽  
Vol 28 (11) ◽  
pp. 112303
Author(s):  
Xiang Chen ◽  
Zhixin Lu ◽  
Huishan Cai ◽  
Lei Ye ◽  
Yang Chen ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Electric Current ◽  
Ion Temperature ◽  
Ion Temperature Gradient ◽  
Current Generation ◽  
Gyrokinetic Simulations

Transport coefficients for a two-temperature equal-mass plasma in a uniform magnetic field

1994 ◽  
Vol 52 (2) ◽  
pp. 309-319 ◽  
Author(s):  
S. Y. Abdul-Rassak ◽  
E. W. Laing
Keyword(s):  
Magnetic Field ◽  
Heat Flux ◽  
Electric Current ◽  
Uniform Magnetic Field ◽  
Transport Coefficients ◽  
Equal Mass ◽  
Temperature Ratio ◽  
Fokker Planck Equations ◽  
Two Temperature ◽  
Fokker Planck

Transport coefficients for electric current and heat flux have been calculated for a two-temperature equal-mass plasma for several values of the temperature ratio R in the range 1 < R ≤ 100. Transport coefficients have been obtained using the linearized Fokker—Planck equations.

Transport coefficients for an equal-mass plasma in a uniform magnetic field

1993 ◽  
Vol 50 (1) ◽  
pp. 125-144 ◽  
Author(s):  
S. Y. Rassak-Abdul ◽  
E. W. Laing
Keyword(s):  
Magnetic Field ◽  
Heat Flux ◽  
Electric Current ◽  
Uniform Magnetic Field ◽  
Transport Coefficients ◽  
Parallel Transport ◽  
Equal Mass ◽  
Particle Species ◽  
Hall Parameter ◽  
Fokker Planck Equations

Cross–field transport coefficients for the electric current and heat flux have been calculated for an equal–mass plasma for various values of the Hall parameter Ωr in the range Ωr ≥ 1. Coefficients have also been calculated for parallel transport. These have been obtained using the linearized Fokker–Planck equations for both particle species, taking advantage of the mass symmetry, which leads to remarkable cancellations in the collision terms.

scholarly journals Short-Circuit Current in Polymeric Membrane-Based Thermocells: An Experimental Study

Membranes ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 480
Author(s):  
V. María Barragán
Keyword(s):  
Temperature Gradient ◽  
Electric Current ◽  
Short Circuit ◽  
Electrical Power ◽  
Short Circuit Current ◽  
Membrane System ◽  
Polymeric Membrane ◽  
Experimental Point ◽  
Maximum Output ◽  
Alkali Chloride

Thermocells are non-isothermal electrochemical cells used to convert thermal energy into electricity. In a thermocell, together with the ion flux, heat is also transferred, which can reduce the temperature gradient and thus the delivered electric current. A charged membrane used as a separating barrier in the electrolyte liquid could reduce this problem. Therefore, the use of ion-exchange membranes has been suggested as an alternative in terms of thermoelectricity because of their high Seebeck coefficient. Ion transfer occurs not only at the liquid solution but also at the solid membrane when a temperature gradient is imposed. Thus, the electric current delivered by the thermocell will also be highly dependent on the membrane system properties. In this work, a polymeric membrane-based thermocell with 1:1 alkali chloride electrolytes and reversible Ag|AgCl electrodes at different temperatures is studied. This work focuses on the experimental relation between the short-circuit current density and the temperature difference. Short-circuit current is the maximum electric current supplied by a thermocell and is directly related to the maximum output electrical power. It can therefore provide valuable information on the thermocell efficiency. The effect of the membrane, electrolyte nature and hydrodynamic conditions is analysed from an experimental point of view.

Growth of 4H-SiC in Current-Controlled Liquid Phase Epitaxy

2013 ◽  
Vol 740-742 ◽  
pp. 3-6 ◽  
Author(s):  
Takeshi Mitani ◽  
Masayuki Okamura ◽  
Tetsuo Takahashi ◽  
Naoyoshi Komatsu ◽  
Tomohisa Kato ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Temperature Gradient ◽  
Electric Current ◽  
Joule Heating ◽  
Liquid Phase Epitaxy ◽  
Negative Polarity ◽  
Growth Speed ◽  
Positive Polarity ◽  
Current Leads ◽  
Dc Current

4H-SiC crystallization from Si-C solution in electric current-controlled liquid phase epitaxy was investigated. The dependence of growth speed on a DC current shows that dissolution/growth is controlled by the electric current without altering temperature gradient in the furnace. Application of an electric current leads to reduction of growth speed with negative polarity and enhancement of growth speed with positive polarity. The variation of the growth speed with a DC current density has been explained by the combination of the effects of electromigration of C solute and Joule heating.

ANOMALOUS TRANSPORT IN METALS AND SEMICONDUCTORS

2008 ◽  
Vol 22 (01n02) ◽  
pp. 120-120
Author(s):  
A. H. MACDONALD
Keyword(s):  
Electric Fields ◽  
Fermi Energy ◽  
Transport Coefficients ◽  
Hall Conductivity ◽  
Small Contribution ◽  
Ferromagnetic Metals ◽  
Longitudinal Conductivity ◽  
Paramagnetic Materials ◽  
Energy Property ◽  
Spin Hall Conductivity

According to the Kubo formula, the static uniform electric fields in a metal or semiconductor can induce coherence between band states far from the Fermi energy. This interband coherence response appears to be at odds with the normal view that transport is a Fermi-energy property, and is relatively unfamiliar since it makes a negligibly small contribution to the most commonly studied transport coefficients such as the longitudinal conductivity. It has recently been argued that interband coherence response can dominate the anomalous Hall conductivity of ferromagnetic metals and semiconductors and the spin-Hall conductivity of paramagnetic materials. I will review recent theoretical ideas related to the charge Hall conductivity of ferromagnetic materials and the spin Hall conductivity of paramagnetic materials and their relation to recent and future experiments. Note from Publisher: This article contains the abstract only.

Improved Thomson Coefficient Measurements Using an AC Method

2014 ◽  
Vol 1642 ◽  
Author(s):  
Yasutaka Amagai ◽  
Atsushi Yamamoto ◽  
Megumi Akoshima ◽  
Hiroyuki Fujiki
Keyword(s):  
Thermal Conductivity ◽  
Temperature Gradient ◽  
Current Method ◽  
Thin Wire ◽  
Temperature Changes ◽  
Ac Current ◽  
Thomson Coefficient ◽  
Absolute Seebeck Coefficient ◽  
Current Resistance

ABSTRACTWe present an improved AC (Alternating Current) method for the determination of the Thomson coefficient, which can be used for obtaining the absolute Seebeck coefficient. While previous work has focused on DC (Direct Current) methods, we analyze the influence of an AC current in order to derive the Thomson coefficient of a thin wire from measurable quantities. Our expression requires five parameters including AC current, resistance, temperature gradient, and the temperature changes due to the Thomson and Joule effects. Thus, a prior determination of thermal conductivity and sample geometry is not required, unlike DC methods. In order to validate our analysis, the Thomson coefficient of a thin Pt wire has been measured at several frequencies. The results agree with those obtained from a conventional DC method.

Temperature-gradient joining of Ti–6Al–4V alloys by pulsed electric current sintering

2012 ◽  
Vol 535 ◽  
pp. 182-188 ◽  
Author(s):  
Daihua He ◽  
Zhengyi Fu ◽  
Weimin Wang ◽  
Jinyong Zhang ◽  
Zuhair A. Munir ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Electric Current ◽  
Pulsed Electric Current
Sign in / Sign up

Export Citation Format

Share Document