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In this work, we propose some numerical schemes for linear kinetic equations in the diffusion and anomalous diffusion limit. When the equilibrium distribution function is a Maxwellian distribution, it is well known that for an appropriate…

Numerical Analysis · Mathematics 2015-03-17 Nicolas Crouseilles , Hélène Hivert , Mohammed Lemou

This study delves into Microtearing Modes (MTMs) in tokamak plasmas, employing advanced simulations within the BOUT++ framework. The research, centering on collisional MTMs influenced by the time-dependent thermal force, enhances our…

Plasma Physics · Physics 2024-04-15 Kaixuan Fan , Xue-Qiao Xu , Ben Zhu , Chao Dong , Tianyang Xia , Zeyu Li

Nonlinear electromagnetic stabilization by suprathermal pressure gradients found in specific regimes is shown to be a key factor in reducing tokamak microturbulence, augmenting significantly the thermal pressure electromagnetic…

The Fokker-Planck Equation, applied to transport processes in fusion plasmas, can model several anomalous features, including uphill transport, scaling of confinement time with system size, and convective propagation of externally induced…

Plasma Physics · Physics 2007-11-05 D. F. Escande , F. Sattin

Trajectory-based methods that propagate classical nuclei on multiple quantum electronic states are often used to simulate nonadiabatic processes in the condensed phase. A long-standing problem of these methods is their lack of detailed…

Chemical Physics · Physics 2023-02-22 Graziano Amati , Johan E. Runeson , Jeremy O. Richardson

A two-fold analysis of electromagnetic core tokamak instabilities in the framework of the gyrokinetic theory is presented. First principle theoretical foundations of the gyrokinetic theory are used to explain and justify the numerical…

Starting from the equations of collisionless linear gyrokinetics for magnetised plasmas with an imposed inhomogeneous magnetic field, we present the first known analytical, closed-form solution for the resulting velocity-space integrals in…

Plasma Physics · Physics 2023-04-27 P. G. Ivanov , T. Adkins

A nonequilibrium distribution function of microscopic thermal current is studied by a direct numerical simulation in a thermal conducting steady state of particle systems. Two characteristic temperatures of the thermal current are…

Statistical Mechanics · Physics 2009-04-01 Satoshi Yukawa , Takashi Shimada , Fumiko Ogushi , Nobuyasu Ito

First-principles numerical simulations are used to describe a transport bifurcation in a differentially rotating tokamak plasma. Such a bifurcation is more probable in a region of zero magnetic shear than one of finite magnetic shear…

Plasma Physics · Physics 2015-05-28 E. G. Highcock , M. Barnes , F. I. Parra , A. A. Schekochihin , C. M. Roach , S. C. Cowley

We present a numerical model and a set of conservative algorithms for Non-Maxwellian plasma kinetics with inelastic collisions. These algorithms self-consistently solve for the time evolution of an isotropic electron energy distribution…

Plasma Physics · Physics 2017-12-12 H. P. Le , J. -L. Cambier

Deuterium-tritium (DT) burning requires a long energy confinement times compared to collision times, so the particle distribution functions must approximate local-Maxwellians. Non-equilibrium thermodynamics is applicable, which gives…

Plasma Physics · Physics 2023-06-14 Allen H Boozer

The paper reports a new electrostatic-confinement based fusion approach, where, a new non-equilibrium distribution function for an ion-beam, compressed by an external electric force, has been derived. This distribution function allows the…

Plasma Physics · Physics 2013-07-02 R. K. Paul

We investigate the ExB diffusion of fusion born \alpha particles in tokamak plasmas. We determine the transport regimes for a realistic model that has the characteristics of the ion temperature gradient (ITG) or of the trapped electron…

Plasma Physics · Physics 2017-02-01 A. Croitoru , D. I. Palade , M Vlad , F Spineanu

Recent gyrokinetic stability calculations have revealed that the spherical tokamak is susceptible to tearing parity instabilities with length scales of a few ion Larmor radii perpendicular to the magnetic field lines. Here we investigate…

Plasma Physics · Physics 2012-05-15 D J Applegate , C M Roach , J W Connor , S C Cowley , W Dorland , R J Hastie , N. Joiner

Models of the continuum radiation from accreting hot plasmas typically assume that the plasma heating mechanism produces energetic particles distributed in energy either as a Maxwellian (the ``thermal'' models) or as an extended power law…

Astrophysics · Physics 2007-05-23 Paolo S. Coppi

The transport of heat out of tokamak plasmas by turbulence is the dominant mechanism limiting the performance of fusion reactors. Turbulence can be driven by the ion temperature gradient (ITG) and suppressed by toroidal sheared flows.…

Plasma Physics · Physics 2017-03-20 Ferdinand van Wyk

Strong electric fields in the auroral and equatorial electrojets can distort the background ion distribution function away from Maxwellian. We developed a collisional plasma kinetic model using the Boltzmann equation and a simple BGK…

Plasma Physics · Physics 2024-08-13 Rattanakorn Koontaweepunya , Yakov S. Dimant , Meers M. Oppenheim

The diffusion approximation to the Fokker-Planck equation is commonly used to model the transport of solar energetic particles in interplanetary space. In this study, we present exact analytical predictions of a higher order telegraph…

Space Physics · Physics 2014-10-07 Frederic Effenberger , Yuri E. Litvinenko

The possible occurrence of equilibrium off-equatorial tori in the gravitational and electromagnetic fields of astrophysical compact objects has been recently proved based on non-ideal MHD theory. These stationary structures can represent…

High Energy Astrophysical Phenomena · Physics 2015-06-17 Claudio Cremaschini , Jiří Kovář , Petr Slaný , Zdeněk Stuchlík , Vladimír Karas

We discuss a family of Vlasov-Maxwell equilibrium distribution functions for current sheet equilibria that are intermediate cases between the Harris sheet and the force-free (or modified) Harris sheet. These equilibrium distribution…

Plasma Physics · Physics 2020-06-24 T. Neukirch , F. Wilson , O. Allanson