A review of internal transport barrier physics for steady-state operation of tokamaks

Connor, J. W.; Fukuda, T.; Garbet, X.; Gormezano, C.; Mukhovatov, V.; Wakatani, Masahiro; Physics, Internal Barrier

doi:10.1088/0029-5515/44/4/r01

Cited by 341 publications

(365 citation statements)

References 272 publications

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“…Of primary interest in the study of poloidal rotation is understanding the impact of rotational shear on the formation of internal transport barriers. 57,58 In this regard, a description of possible stable flow profiles should provide insight into what role poloidal rotation can play in both triggering as well as sustaining transport barriers. Future work will be oriented toward the development of a self-consistent transport model to better understand the types of flow structures which can be described within the framework of this simple description of turbulently driven poloidal flows.…”

Section: ͑76͒mentioning

confidence: 99%

Poloidal rotation and its relation to the potential vorticity flux

et al. 2010

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A kinetic generalization of a Taylor identity appropriate to a strongly magnetized plasma is derived. This relation provides an explicit link between the radial mixing of a four-dimensional ͑4D͒ gyrocenter fluid and the poloidal Reynolds stress. This kinetic analog of a Taylor identity is subsequently utilized to link the turbulent transport of poloidal momentum to the mixing of potential vorticity. A quasilinear calculation of the flux of potential vorticity is carried out, yielding diffusive, turbulent equipartition, and thermoelectric convective components. Self-consistency is enforced via the quasineutrality relation, revealing that for the case of a stationary small amplitude wave population, deviations from neoclassical predictions of poloidal rotation can be closely linked to the growth/damping profiles of the underlying drift wave microturbulence.

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Section: ͑76͒mentioning

confidence: 99%

Poloidal rotation and its relation to the potential vorticity flux

et al. 2010

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“…38 The question of the role of low-q surfaces in confinement has a long history. [39][40][41][42][43] Low-q surfaces have in the past been associated with microtearing modes, magnetic islands of unexplained origin, etc., all with the aim of providing a physical basis for the notion of profile consistency. Previous work 44 has also suggested that spikes or humps in the fluctuation intensity profile may sit at low-q resonances, and that these localized intensity gradients may drive sheared poloidal flow via the Reynolds stress.…”

Section: ͑49͒mentioning

confidence: 99%

Multiscale interaction of a tearing mode with drift wave turbulence: A minimal self-consistent model

McDevitt

Diamond

2006

Physics of Plasmas

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A minimal self-consistent model of the multiscale interaction of a tearing mode with drift wave turbulence is presented. A tearing instability in a cylindrical plasma interacting with electrostatic drift waves is considered, for reasons of simplicity. Wave kinetics and adiabatic theory are used to treat the feedback of tearing mode flows on the drift waves via shearing and radial advection. The stresses exerted by the self-consistently evolved drift wave population density on the tearing mode are calculated by mean field methods. The principal effect of the drift waves is to pump the resonant low-m mode via a negative viscosity, consistent with the classical notion of an inverse cascade in quasi-two-dimensional turbulence. This process can occur alone or in synergy with current gradient drive of the low-m mode. Speculations of the relation of this multiscale process to the more general issue of the fate of energy transferred to large scales by an inverse cascade are presented. The existence of nonlinearly driven vortices pinned to low-q surfaces as a class of highly anisotropic dissipative structures which terminate the inverse cascade is proposed. The evolution of a finite size magnetic island is discussed.

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“…In particular the E × B velocity shear may lead to a reduction in the amplitude of turbulent fluctuations, even to their suppression, or to a decrease in the radial correlation lengths [11]. Although there are experimental observations supporting this scenario, the overall experimental evidence up to date is rather complicated, not universal in the various tokamak machines and has not made clear whether the magnetic shear or the sheared flow (toroidal or poloidal) are more important for the ITB formation.…”

Section: Introductionmentioning

confidence: 99%

Two-fluid tokamak equilibria with reversed magnetic shear and sheared flow

Poulipoulis

Throumoulopoulos

Tasso³

2007

J. Plasma Phys.

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The aim of the present work is to investigate tokamak equilibria with reversed magnetic shear and sheared flow, which may play a role in the formation of internal transport barriers (ITBs), within the framework of two-fluid model. The study is based on exact self-consistent solutions in cylindrical geometry by means of which the impact of the magnetic shear, s, and the "toroidal" (axial) and "poloidal" (azimuthal) ion velocity components, v iz and v iθ , on the radial electric field, E r , its shear, |dE r /dr|, and the shear of the E × B velocity, ω E×B ≡ |d/dr(E × B/B 2 )|, is examined. For a wide parametric regime of experimental concern it turns out that the contributions of the v iz , v iθ and pressure gradient (∇P i ) terms to E r , |E ′ r | and ω E×B are of the same order of magnitude. The contribution of the ∇P i term is missing in the framework of magnetohydrodynamics (MHD) [G. Poulipoulis et al. Plasma Phys. Control. Fusion 46 (2004) 639]. The impact of s on ω E×B through the ∇P i term is stronger than that through the velocity terms; in particular for B z = constant, the contributions of the ∇P i and velocity terms to ω E×B at the point where dE r /dr = 0 are proportional to (1 − s)(2 − s) and (1 − s), respectively. The results indicate that, alike MHD, the magnetic shear and the sheared toroidal and poloidal velocities act synergetically in producing electric fields and therefore ω E×B profiles compatible with ones observed in discharges with ITBs; owing to the ∇P i term, however, the impact of s on E r , |E ′ r | and ω E×B is stronger than that in MHD.

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A review of internal transport barrier physics for steady-state operation of tokamaks

Cited by 341 publications

References 272 publications

Poloidal rotation and its relation to the potential vorticity flux

Poloidal rotation and its relation to the potential vorticity flux

Multiscale interaction of a tearing mode with drift wave turbulence: A minimal self-consistent model

Two-fluid tokamak equilibria with reversed magnetic shear and sheared flow

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