Comment on “Guiding center plasma models in three dimensions” [Phys. Plasmas 15, 092112 (2008)]

Krommes, John A.

doi:10.1063/1.3206670

Cited by 9 publications

(9 citation statements)

References 14 publications

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“…Calculating the third and fourth order moments of their distribution (skewness and kurtosis) helps identify the underlying distribution and identify processes which drive such features [20,21] (although it has been argued that in fact the universality of non-Gaussian features in edge simulations without full magnetic geometry, etc. would suggest such features are not a "sensitive probe of the underlying physical mechansims" [22]) .…”

Section: Skewness and Kurtosismentioning

confidence: 99%

Pedestal and edge electrostatic turbulence characteristics from an XGC1 gyrokinetic simulation

Churchill

Chang

et al. 2017

Plasma Phys. Control. Fusion

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Abstract. Understanding the multi-scale neoclassical and turbulence physics in the edge region (pedestal + scrape-off layer) is required in order to reliably predict performance in future fusion devices. We explore turbulent characteristics in the edge region from a multiscale neoclassical and turbulent XGC1 gyrokinetic simulation in a DIII-D like tokamak geometry, here excluding neutrals and collisions. For an H-mode type plasma with steep pedestal, it is found that the electron density fluctuations increase towards the separatrix, and stay high well into the SOL, reaching a maximum value of δne/ne ∼ 0.18. Blobs are observed, born around the magnetic separatrix surface and propagate radially outward with velocities generally less than 1 km/s. Strong poloidal motion of the blobs is also present, near 20 km/s, consistent with E × B rotation. The electron density fluctuations show a negative skewness in the closed field line pedestal regions, consistent with the presence of "holes", followed by a transition to strong positive skewness across the separatrix and into the SOL. These simulations indicate that not only neoclassical phenomena, but also turbulence, including the blobgeneration mechanism, can remain important in the steep H-mode pedestal and SOL. Qualitative comparisons will be made to experimental observations.

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Section: Skewness and Kurtosismentioning

confidence: 99%

Pedestal and edge electrostatic turbulence characteristics from an XGC1 gyrokinetic simulation

Churchill

Chang

et al. 2017

Plasma Phys. Control. Fusion

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“…variations of the coordinate q), but also variations of the two other non-gyro-angle coordinates p and ϕ, as in Eq. (13). Since this refinement is useless here, for the following we will set f 1 = f 2 = 0 and remain with only the connection R g .…”

Section: Intrinsic Counterpart Of the Anholonomymentioning

confidence: 99%

“…The fast coordinate that measures the Larmor gyration of the particle around the magnetic-field lines is the so-called gyro-angle. It plays a leading role in guiding-center theory, but its standard definition raises several questions, both from a mathematical and from a physical point of view [11][12][13][14][15] . For instance, when can the gyro-angle be globally defined?…”

Section: Introductionmentioning

confidence: 99%

On an intrinsic approach of the guiding-center anholonomy and gyro-gauge arbitrariness

Guillebon

Vittot

2013

Physics of Plasmas

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In guiding center theory, the standard gyro-angle coordinate is associated with gyro-gauge dependence, the global existence problem for unit vectors perpendicular to the magnetic field, and the notion of anholonomy, which is the failure of the gyro-angle to return to its original value after being transported around a loop in configuration space. We analyse these three intriguing topics through the lens of a recently proposed, global, gauge-independent gyro-angle. This coordinate is constrained and therefore necessitates the use of a covariant derivative. It also highlights the intrinsic meaning and physical content of gyro-gauge freedom and anholonomy. There are, in fact, many possible covariant derivatives compatible with the intrinsic gyro-angle, and each possibility corresponds to a different notion of gyro-angle transport. This observation sheds new light on Littlejohn's notion of gyro-angle transport and suggests a new derivation of the recently discovered global existence condition for unit vectors perpendicular to the magnetic field. We also discuss the relationship between Cartesian position-momentum coordinates and the intrinsic gyro-angle. V C 2013 AIP Publishing LLC. [http://dx.

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“…The amplitude of both is the same and treated as an independent perturbation parameter different from ε. Since this method is mainly adopted by the following researchers to solving the electromagnetic and electrostatic perturbation [18,14,29,30], our analysis focuss on this method, which is called modern GT in this paper.…”

Section: Introductionmentioning

confidence: 99%

Deriving the trajectory equations of gyrocenter with a multi-parameter Lie transform method

Zhang

2016

Preprint

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It's pointed out that the values of the generators derived by the modern gyrokinetic theory are inappropriately amplified by the pullback transform with the existence of electromagnetic perturbation, and the trajectory equations of the gyrocenter include terms containing the perturbative magnetic vector potential not in the form of its curl. These terms are not physical ones, as the perturbative magnetic vector potential could include an arbitrary gauge term. In this paper, instead of the single-parameter Lie transform method utilized by the modern gyrokinetic theory, a multi-parameter Lie transform method is utilized. All characteristic scales of the system can be taken into account. With the assistance of a kind of linear cancellation rule, the new method can decouple the gyroangle θ from the remaining degrees of freedom up to the second order of the parameter as the ratio between the Larmor radius and the transverse length scale of the equilibrium magnetic field. With this new method, those nonphysical terms don't appear anymore in the trajectory equations.

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Comment on “Guiding center plasma models in three dimensions” [Phys. Plasmas 15, 092112 (2008)]

Abstract: A dynamical theory of electron transfer: Crossover from weak to strong electronic coupling

Cited by 9 publications

References 14 publications

Pedestal and edge electrostatic turbulence characteristics from an XGC1 gyrokinetic simulation

Pedestal and edge electrostatic turbulence characteristics from an XGC1 gyrokinetic simulation

On an intrinsic approach of the guiding-center anholonomy and gyro-gauge arbitrariness

Deriving the trajectory equations of gyrocenter with a multi-parameter Lie transform method

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