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Edge-Localized-Mode (ELM) suppression by resonant magnetic perturbations (RMPs) generally occurs over very narrow ranges of the plasma current (or magnetic safety factor q95) in the DIII-D tokamak. However, wide q95 ranges of ELM…

Plasma Physics · Physics 2020-08-03 Q. M. Hu , R. Nazikian , B. A. Grierson , N. C. Logan , D. M. Orlov , C. Paz-Soldan , Q. Yu

A general methodology is proposed to differentiate the likelihood of energetic-particle-driven instabilities to produce frequency chirping or fixed-frequency oscillations. The method employs numerically calculated eigenstructures and…

Disruptions continue to pose a significant challenge to the stable operation and future design of tokamak reactors. A comprehensive statistical investigation carried out on the ADITYA-U tokamak has led to the observation and…

This overview presents a tutorial introduction to the theory of magnetic plasma confinement in toroidal confinement systems with particular emphasis on axisymmetric equilibrium geometries, and tokamaks. The discussion covers three important…

Plasma Physics · Physics 2015-09-30 Fatemeh Dini , Reza Baghdadi , Reza Amrollahi , Sina Khorasani

Microinstabilities drive turbulent fluctuations in inhomogeneous, magnetized plasmas. In the context of magnetic confinement fusion devices, this leads to an enhanced transport of particles, momentum, and energy, thereby degrading…

Plasma Physics · Physics 2024-03-20 Georgia Acton , Michael Barnes , Sarah Newton , Hanne Thienpondt

For realistic values of Lundquist number in tokamak plasmas, the 1/1 magnetic island leads to the formation of secondary thin current sheet, which breaks up into a chain of small magnetic islands, called plasmoids. The role of plasmoid…

Plasma Physics · Physics 2019-06-26 A. Ali , P. Zhu

A challenging and fundamental research problem is the better understanding and control of the turbulent transport of heat in present-day tokamak fusion experiments. Recent developments in numerical methods along with enormous gains in…

Plasma Physics · Physics 2008-02-03 Jeremy Kepner , Scott Parker , Viktor Decyk

We study the motion of a charged particle in a tokamak magnetic field and discuss its chaotic nature. Contrary to most of recent studies, we do not make any assumption on any constant of the motion and solve numerically the cyclotron…

Chaotic Dynamics · Physics 2014-12-05 Benjamin Cambon , Xavier Leoncini , Michel Vittot , Rémi Dumont , Xavier Garbet

We investigate tearing modes (TM) driven by current density gradient in collisionless tokamak plasmas by using the electromagnetic gyrokinetic simulation code ORB5. We elucidate the TM width by simulations for flat profiles, as the absence…

The effect of small deviations from a Maxwellian equilibrium on turbulent momentum transport in tokamak plasmas is considered. These non-Maxwellian features, arising from diamagnetic effects, introduce a strong dependence of the radial flux…

Plasma Physics · Physics 2013-08-09 M. Barnes , F. I. Parra , J. P. Lee , E. A. Belli , M. F. F. Nave , A. E. White

Although lower hybrid waves have been shown to be effective in driving plasma current in present-day tokamaks, they are predicted to strongly interact with the energetic alpha particles born from fusion reactions in eventual tokamak…

Plasma Physics · Physics 2016-02-09 Ian E. Ochs , Nicola Bertelli , Nathaniel J. Fisch

Based on the analysis of a large number of high-fidelity nonlinear gyrokinetic simulations, we propose a novel strategy to improve confinement in spherical tokamak plasmas by combining up-down asymmetric flux surface shaping with the Low…

Recently-proposed tokamak concepts use magnetic fields up to 12 T, far higher than in conventional devices, to reduce size and cost. Theoretical and computational study of trends in plasma behavior with increasing field strength is critical…

Plasma Physics · Physics 2019-02-19 E. A. Tolman , N. F. Loureiro , P. Rodrigues , J. W. Hughes , E. S. Marmar

We show that in a neutral magnetized plasma there exist microscopic oscillatory modes, with wavelengths of the order of magnitude of the mean interparticle distance, which become unstable when the electron density exceeds a limit…

Plasma Physics · Physics 2010-06-24 M. Marino , M. Zuin , A. Carati , E. Martines , L. Galgani

In the study of plasma, particularly in applications involving strong laser-plasma interactions, the propagation of a strong electromagnetic wave induces relativistic velocities in the electron flow. Given such conditions, the wave…

Access conditions for full suppression of Edge Localised Modes (ELMs) by Magnetic Perturbations (MP) in low density high confinement mode (H-mode) plasmas are studied in the ASDEX Upgrade tokamak. The main empirical requirements for full…

Modern Tokamaks have evolved from the initial axisymmetric circular plasma shape to an elongated axisymmetric plasma shape that improves the energy confinement time and the triple product, which is a generally used figure of merit for the…

An investigation is made into the effect of the reduction in anomalous perpendicular electron heat transport inside the separatrix of a magnetic island chain associated with a neoclassical tearing mode in a tokamak plasma, due to the…

Plasma Physics · Physics 2017-05-24 Richard Fitzpatrick

A mechanism is presented that suggests shielded 3-D magnetic perturbations can destabilize microinstabilities and enhance the associated anomalous transport. Using local 3-D equilibrium theory, shaped tokamak equilibria with small 3-D…

Plasma Physics · Physics 2015-06-11 Thomas Bird , Chris Hegna

Field-line localized ballooning modes have been observed at the edge of high confinement mode plasmas in ASDEX Upgrade with rotating 3D perturbations induced by an externally applied n = 2 error field and during a moderate level of edge…