scholarly journals Surface transport coefficients for three-dimensional topological superconductors

2015 ◽  
Vol 91 (2) ◽  
Author(s):  
Hong-Yi Xie ◽  
Yang-Zhi Chou ◽  
Matthew S. Foster
Keyword(s):  
Transport Coefficients ◽  
Three Dimensional ◽  
Surface Transport ◽  
Topological Superconductors

Experimental and simulation study of impurity transport response to RMPs in RF-heated H-mode plasmas at EAST

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Germán Vogel ◽  
Hongming Zhang ◽  
Yongcai Shen ◽  
Shuyu Dai ◽  
Youwen Sun ◽  
...  
Keyword(s):  
Inner Core ◽  
Extreme Ultraviolet ◽  
Transport Coefficients ◽  
Three Dimensional ◽  
Line Emission ◽  
Core Region ◽  
Emission Mitigation ◽  
One Dimensional ◽  
Impurity Transport ◽  
Transport Code

Spatial profiles of impurity emission measurements in the extreme ultraviolet (EUV) spectroscopic range in radiofrequency (RF)-heated discharges are combined with one-dimensional and three-dimensional transport simulations to study the effects of resonant magnetic perturbations (RMPs) on core impurity accumulation at EAST. The amount of impurity line emission mitigation by RMPs appears to be correlated with the ion Z for lithium, carbon, iron and tungsten monitored, i.e. stronger suppression of accumulation for heavier ions. The targeted effect on the most detrimental high-Z impurities suggests a possible advantage using RMPs for impurity control. Profiles of transport coefficients are calculated with the STRAHL one-dimensional impurity transport code, keeping $\nu /D$ fixed and using the measured spatial profiles of $\textrm{F}{\textrm{e}^{20 + }}$ , $\textrm{F}{\textrm{e}^{21 + }}$ and $\textrm{F}{\textrm{e}^{22 + }}$ to disentangle the transport coefficients. The iron diffusion coefficient ${D_{\textrm{Fe}}}$ increases from $1.0- 2.0\;{\textrm{m}^2}\;{\textrm{s}^{ - 1}}$ to $1.5- 3.0\;{\textrm{m}^2}\;{\textrm{s}^{ - 1}}$ from the core region to the edge region $(\rho \gt 0.5)$ after the onset of RMPs. Meanwhile, an inward pinch of iron convective velocity ${\nu _{\textrm{Fe}}}$ decreases in magnitude in the inner core region and increases significantly in the outer confined region, simultaneously contributing to preserving centrally peaked $\textrm{Fe}$ profiles and exhausting the impurities. The ${D_{\textrm{Fe}}}$ and ${\nu _{\textrm{Fe}}}$ variations lead to reduced impurity contents in the plasma. The three-dimensional edge impurity transport code EMC3-EIRENE was also applied for a case of RMP-mitigated high-Z accumulation at EAST and compared to that of low-Z carbon. The exhaust of ${\textrm{C}^{6 + }}$ toward the scrape-off layer accompanying an overall suppression of heavier ${\textrm{W}^{30 + }}$ is observed when using RMPs.

scholarly journals Thermoelectric Relations in the Conformal Limit in Dirac and Weyl Semimetals

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 814
Author(s):  
Vicente Arjona ◽  
Juan Borge ◽  
María A. H. Vozmediano
Keyword(s):  
Chemical Potential ◽  
Transport Coefficients ◽  
Three Dimensional ◽  
Anomalous Behavior ◽  
Conformal Anomaly ◽  
Electronic Systems ◽  
Electric Transport ◽  
Thermo Electric ◽  
Weyl Semimetals ◽  
Band Crossing

Dirac and Weyl semimetals are three-dimensional electronic systems with the Fermi level at or near a band crossing. Their low energy quasi-particles are described by a relativistic Dirac Hamiltonian with zero effective mass, challenging the standard Fermi liquid (FL) description of metals. In FL systems, electrical and thermo–electric transport coefficient are linked by very robust relations. The Mott relation links the thermoelectric and conductivity transport coefficients. In a previous publication, the thermoelectric coefficient was found to have an anomalous behavior originating in the quantum breakdown of the conformal anomaly by electromagnetic interactions. We analyze the fate of the Mott relation in the system. We compute the Hall conductivity of a Dirac metal as a function of the temperature and chemical potential and show that the Mott relation is not fulfilled in the conformal limit.

scholarly journals Adjoint approach to calculating shape gradients for three-dimensional magnetic confinement equilibria

2019 ◽  
Vol 85 (2) ◽  
Author(s):  
Thomas Antonsen ◽  
Elizabeth J. Paul ◽  
Matt Landreman
Keyword(s):  
Figure Of Merit ◽  
Transport Coefficients ◽  
Three Dimensional ◽  
Direct Calculation ◽  
Flux Surface ◽  
Shape Gradient ◽  
Onsager Symmetry ◽  
Mhd Equilibria ◽  
Gradient Based ◽  
Adjoint Approach

The shape gradient quantifies the change in some figure of merit resulting from differential perturbations to a shape. Shape gradients can be applied to gradient-based optimization, sensitivity analysis and tolerance calculation. An efficient method for computing the shape gradient for toroidal three-dimensional magnetohydrodynamic (MHD) equilibria is presented. The method is based on the self-adjoint property of the equations for driven perturbations of MHD equilibria and is similar to the Onsager symmetry of transport coefficients. Two versions of the shape gradient are considered. One describes the change in a figure of merit due to an arbitrary displacement of the outer flux surface; the other describes the change in the figure of merit due to the displacement of a coil. The method is implemented for several example figures of merit and compared with direct calculation of the shape gradient. In these examples the adjoint method reduces the number of equilibrium computations by factors of$O(N)$, where$N$is the number of parameters used to describe the outer flux surface or coil shapes.

Analysis of reactive ion transport in weakly ionized gas mixtures

1991 ◽  
Vol 69 (7) ◽  
pp. 1090-1099 ◽  
Author(s):  
Koichi Iinuma
Keyword(s):  
Ion Transport ◽  
Transport Theory ◽  
Dynamic Equilibrium ◽  
Transport Coefficients ◽  
Three Dimensional ◽  
Reaction Rates ◽  
Gas Mixtures ◽  
Reaction Scheme ◽  
Inelastic Process ◽  
Neutral Gas

A new formulation for the analysis of low density multiple-ion swarms drifting, diffusing, and inter-reacting in a neutral gas is proposed on a transport theory basis. A set of coupled three-dimensional transport equations for an arbitrary number of ion species, which governs the number densities of the ion swarms as functions of time and position coordinates, is exactly solved using a Fourier transform in a matrix representation. A picture of dynamic equilibrium state for hypothetical four ion swarms in a neutral gas is numerically obtained. Also, experimental data of transport coefficients and reaction rates for (Li+, Li+•N2, Li+•2N2)flN2 system are examined in a complete reversible cyclic reaction scheme and compared with a Green's function method. The initial and boundary conditions, the analysis in gas mixtures, and the inelastic process associated with the present formulation are briefly discussed. Key words: ion swarm, cluster ion, transport equation, ion–molecule reaction.

scholarly journals On the Navier-Stokes equations with temperature-dependent transport coefficients

2006 ◽  
Vol 2006 ◽  
pp. 1-14 ◽  
Author(s):  
Eduard Feireisl ◽  
Josef Málek
Keyword(s):  
Stokes Equations ◽  
Transport Coefficients ◽  
Three Dimensional ◽  
Periodic Problem ◽  
Large Data ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Long Time ◽  
Spatially Periodic ◽  
Dependent Transport

We establish long-time and large-data existence of a weak solution to the problem describing three-dimensional unsteady flows of an incompressible fluid, where the viscosity and heat-conductivity coefficients vary with the temperature. The approach reposes on considering the equation for the total energy rather than the equation for the temperature. We consider the spatially periodic problem.

The Effects of Anisotropic Transport Coefficients on Pore Pressure in Shale Formations

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Vahid Dokhani ◽  
Mengjiao Yu ◽  
Stefan Z. Miska ◽  
James Bloys
Keyword(s):  
Pore Pressure ◽  
Fluid Transport ◽  
Drilling Fluid ◽  
Transport Coefficients ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Bedding Plane ◽  
Wellbore Stability ◽  
Coupled Flow ◽  
In Situ Conditions

This study investigates shale–fluid interactions through experimental approaches under simulated in situ conditions to determine the effects of bedding plane orientation on fluid flow through shale. Current wellbore stability models are developed based on isotropic conditions, where fluid transport coefficients are only considered in the radial direction. This paper also presents a novel mathematical method, which takes into account the three-dimensional coupled flow of water and solutes due to hydraulic, chemical, and electrical potential imposed by the drilling fluid and/or the shale formation. Numerical results indicate that the presence of microfissures can change the pore pressure distribution significantly around the wellbore and thus directly affect the mechanical strength of the shale.

Stability of Computational Algorithms Used in Molecular Dynamics Simulations

1995 ◽  
Vol 117 (3) ◽  
pp. 531-534 ◽  
Author(s):  
Akira Satoh
Keyword(s):  
Transport Coefficients ◽  
Three Dimensional ◽  
Divergence Time ◽  
Linear Functions ◽  
Time Interval ◽  
Thermodynamic Quantities ◽  
Number Density ◽  
Time Intervals ◽  
Dynamics Simulations ◽  
The Relationship

The present study focuses on a three-dimensional Lennard-Jones system in a thermodynamic equilibrium in order to discuss divergence processes, the relationship between time intervals and divergence times, and the influence of time intervals on thermodynamic quantities and transport coefficients under various number density and temperature. It is found that the velocities of molecules in a system gradually increase with time until the system suddenly diverges exponentially. The time interval-divergence time relationship can be expressed in approximate terms as linear functions if the data are plotted on logarithmic scales, and the system diverges more easily as temperature or number density increases. Thermodynamic quantities show the influence of large time intervals more clearly than do transport coefficients.

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