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Trapped electron mode turbulence is studied by gyrokinetic simulations with the GYRO code and an analytical model including the effect of a poloidally varying electrostatic potential. Its impact on radial transport of high-Z trace…

Plasma Physics · Physics 2013-04-04 A. Mollén , I. Pusztai , T. Fülöp , S. Moradi

Charge transport in topological insulators is primarily characterised by so-called topologically projected helical edge states, where charge carriers are correlated in spin and momentum. In principle, dissipation-less current can be carried…

Mesoscale and Nanoscale Physics · Physics 2022-10-05 Jesse A. Vaitkus , Cong Son Ho , Jared H. Cole

Carbon and nitrogen impurity transport coefficients are determined from gas puff experiments carried out during repeat L-mode discharges on the Mega-Amp Spherical Tokamak (MAST) and compared against a previous analysis of helium impurity…

We study radial particle transport in stellarator plasmas using cryogenic pellet injection. By means of perturbative experiments, we estimate the experimental particle flux and compare it with neoclassical simulations. Experimental evidence…

Helical edge modes of 2D topological insulators are supposed to be protected from time-reversal invariant elastic backscattering. Yet substantial deviations from the perfect conductance are typically observed experimentally down to very low…

Mesoscale and Nanoscale Physics · Physics 2019-02-12 V. D. Kurilovich , P. D. Kurilovich , I. S. Burmistrov , M. Goldstein

Conventional neoclassical theory in the Pfirsch-Schl\"{u}ter regime fails to accurately model collision-induced transport in toroidal plasmas with high density gradients. In this scenario, we find that collision suppresses the return flow,…

Plasma Physics · Physics 2024-01-18 Jianyuan Xiao , Huishan Cai , Jian Liu , Zhi Yu , Yifeng Zheng

We review in a tutorial fashion some of the causes of impurity density variations along field lines and radial impurity transport in the moment approach framework. An explicit and compact form of the parallel inertia force valid for…

Poloidal asymmetries in the impurity density can be generated by radio frequency heating in the core and by neoclassical effects in the edge of tokamak plasmas. In a pedestal case study, using global neoclassical simulations we find that…

Plasma Physics · Physics 2015-10-28 István Pusztai , Matt Landreman , Albert Mollén , Yevgen O. Kazakov , Tünde Fülöp

A large diffusive turbulent contribution to the radial impurity transport in Wendelstein 7-X (W7-X) plasmas has been experimentally inferred during the first campaigns and numerically confirmed by means of gyrokinetic simulations with the…

We reported a new result of the neutral impurity scattering of holes that has impact on the charge drift mobility in high purity p-type germanium crystals at 77 Kelvin. The charge carrier concentration, mobility and resistivity are measured…

Instrumentation and Detectors · Physics 2017-02-01 H. Mei , D. -M. Mei , G. -J. Wang , G. Yang

Magnetic nozzles are a key component of electrodeless plasma thrusters, acting as their main acceleration stage. Non-stationary phenomena common to the entire range of $E \times B$ devices, such as oscillations and instabilities, are likely…

Plasma Physics · Physics 2024-12-16 Matteo Ripoli , Eduardo Ahedo , Mario Merino

A systematic study of the impact of impurities on the turbulent heat fluxes is presented for the stellarator Wendelstein 7-X (W7-X) and, for comparison, the Large Helical Device and ITER. By means of nonlinear multispecies gyrokinetic…

Plasma Physics · Physics 2024-09-09 J. M. García-Regaña , I. Calvo , F. I. Parra , H. Thienpondt

We present experimental inferences of cross-field impurity transport coefficients for Alcator C-Mod plasmas using a novel forward model for the entire Ca K-alpha spectrum, including satellite lines within the spectral range, to compare to…

The impact of neutral impurity scattering of electrons on the charge drift mobility in high purity n-type germanium crystals at 77 Kelvin is investigated. We calculated the contributions from ionized impurity scattering, lattice scattering,…

Instrumentation and Detectors · Physics 2017-08-02 H. Mei , G. -J. Wang , G. Yang , D. -M. Mei

We consider the thermodynamic effects of an electrically charged impurity immersed in a two-dimensional two-component plasma, composed by particles with charges $\pm e$, at temperature $T$, at coupling $\Gamma=e^2/(k_B T)=2$, confined in a…

Statistical Mechanics · Physics 2015-06-22 Alejandro Ferrero , Gabriel Téllez

A burning fusion plasma has a large inwards flux of fuel and outwards flux of ash. Existing impurity transport theories do not account for a steady-state environment of such large fluxes. In this paper, we extend classical transport theory…

Plasma Physics · Physics 2021-04-07 E. Litvinova Mitra , E. J. Kolmes , I. E. Ochs , M. E. Mlodik , T. Rubin , N. J. Fisch

We study the transport of ultracold impurity atoms immersed in a Bose-Einstein condensate (BEC) and trapped in a tight optical lattice. Within the strong-coupling regime, we derive an extended Hubbard model describing the dynamics of the…

Quantum Physics · Physics 2008-03-11 M. Bruderer , A. Klein , S. R. Clark , D. Jaksch

This paper discusses the influence of the channel impurity distribution on the transport and the drive current in short-gate MOSFET. In this purpose, a careful description of electron-ion interaction suitable for the case of discrete…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 P. Dollfus , A. Bournel , S. Galdin , S. Barraud , P. Hesto

We propose and study theoretically a new mechanism of electron-impurity scattering in doped seminconductors with large dielectric constant. It is based upon the idea of \textit{vector} character of deformations caused in the crystalline…

Mesoscale and Nanoscale Physics · Physics 2022-09-26 Khachatur G. Nazaryan , Mikhail Feigel'man

In this work, the first nonlinear particle-in-cell simulations carried out in a stellarator with the global gyrokinetic code EUTERPE using realistic plasma parameters are reported. Several studies are conducted with the aim of enabling…