Anomalous Diffusion in Axisymmetric Toroidal Systems

Liu, Chuan S.; Baxter, David C.; Thompson, William B.

doi:10.1103/physrevlett.26.621

Cited by 17 publications

(5 citation statements)

References 7 publications

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“…Several studies concerning the possibility of inward particle transport (particle pinch) in tokamaks have been carried out an attempt to understand particle transport and particle pinches in present day experiments. Studies of the basis of particle pinches include an examination of neoclassical transport, 4 an extension of the neoclassical study to include turbulence effects, 5 pinches resulting from ion temperature gradient (ITG) drift waves, 6,7 and the Weiland model describing strong particle pinch in the core due to electron trapping. 8 The Weiland model provided the first description of a particle pinch that was strong enough to account for the density peaking in tokamak experiments with only edge fuelling.…”

Section: Introductionmentioning

confidence: 99%

Reversal of particle flux in collisional-finite beta tokamak discharges

Wang

Weiland

et al. 2015

Physics of Plasmas

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The mixed gradient method [Zhong et al. Phys. Rev. Lett. 111, 265001 (2013)] is adopted and effects of collisions and finite beta are included in the Weiland 9-equation fluid model. The particle flux and particle pinch, obtained using the Weiland anomalous transport fluid model, are compared with Tore Supra experimental results. Particle transport is also studied using predictive simulation data for an experimental advanced superconducting tokamak discharge in which neutral beam heating is utilized. The effects of collisions on particle transport are studied by turning collisions on and off in the Weiland model. It is found that the particle pinch region is related to the mode structure. The particle pinch region coincides with the region where the strong ballooning modes are present due to large gradients. The general properties of the fluid model are examined by finding regions where collisions can enhance the particle pinch. V

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Section: Introductionmentioning

confidence: 99%

Reversal of particle flux in collisional-finite beta tokamak discharges

Wang

Weiland

et al. 2015

Physics of Plasmas

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“…In a low collisionality tokamak, plasmas in which the primary mode of transport is due to the interaction of particles with turbulent electrostatic fields, the time and space evolutions of the particle distribution function can be described by a diffusion equation which is derived from the Vlasov equation expressed in Lagrangian type co-ordinates [14][15][16][17][18][19][20] or the actions. The co-ordinates chosen are the three approximate invariants, µ, J and Ψ, and their action angles.…”

Section: Derivation Of Particle Fluxmentioning

confidence: 99%

Development of optical breakdown on the surfaces of semiconductors subjected to two laser beams of different frequencies

Vigant¹,

Kulikov²,

Lur'e³

et al. 1988

Sov. J. Quantum Electron.

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Many theoretical models show a direct connection between energy transport and particle transport. For a complete understanding of transport processes both energy and particle transport must be understood. A discussion is presented of how energy and particle transport should be related in terms of the relative importance of the diagonal and off-diagonal terms in the equation for the fluxes. A model for particle transport is discussed and it is shown that this model can describe measured density profiles in the DIII-D tokamak under a wide range of DIII-D parameters. This model is obtained from a Lagrangian formulation of the kinetic equation and utilizes the assumption that transport takes place while approximately conserving the first and second adiabatic invariants. The measured results utilize the improved diagnostic capability of DIII-D with an improved capability of measuring current density profiles and particle density profiles. This model is then extended to include energy transport. It is experimentally observed that the particle diffusivity and the thermal diffusivity do not differ greatly and have roughly the same radial dependence. This is discussed and compared with the model. A brief discussion of the effect of internal transport barriers is included.

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“…In a tokamak, electrons streaming parallel to field lines will average potential fluctuations and therefore have only a weak response to electrostatic turbulence 5,12 . Furthermore deeply trapped particles react more strongly with eigenmodes that are localized in the low field "bad" curvature region of the torus.…”

Section: Introductionmentioning

confidence: 99%