Turbulent Fluctuations in TFTR Configurations with Reversed Magnetic Shear

Mazzucato, E.; Batha, S. H.; Beer, M; Bell, M.G.; Bell, R. E.; Budny, R.; Bush, C. E.; Hahm, T. S.; Hammett, G. W.; Levinton, F. M.; Nazikian, R.; Park, H.; Rewoldt, G.; Schmidt, G. L.; Synakowski, E. J.; Tang, W. M.; Taylor, G.; Zarnstorff, M. C.

doi:10.1103/physrevlett.77.3145

Cited by 199 publications

(156 citation statements)

References 24 publications

Supporting

Mentioning

138

Contrasting

Unclassified

Order By: Relevance

“…[28][29][30][31] Dramatic examples of fluctuation suppression have been observed with the use of reflectometry in the core of fusion plasmas. [32][33][34] The radial correlation length of turbulence has also been studied with this method, and the results are consistent with models of enhanced confinement resulting from the radial decorrelation of turbulent eddies. [35][36][37][38][39] This tutorial covers the basic principles of reflectometry relevant to current experiments in fusion plasmas.…”

Section: Introductionsupporting

confidence: 50%

A tutorial on the basic principles of microwave reflectometry applied to fluctuation measurements in fusion plasmas

2001

Self Cite

View full text Add to dashboard Cite

show abstract

Section: Introductionsupporting

confidence: 50%

A tutorial on the basic principles of microwave reflectometry applied to fluctuation measurements in fusion plasmas

2001

Self Cite

View full text Add to dashboard Cite

show abstract

“…In the enhanced reversed shear ͑ERS͒ modes in the Tokamak Fusion Test Reactor ͑TFTR͒, the reflectometry shows suppression of fluctuation around the barrier location. 73 As for the edge transport barrier formation, the fluctuation suppression is also confirmed in the DIII-D tokamak using a lithium beam probe. 74 It is considered that these suppressions of fluctuation can be realized when the EϫB-shearing rate is beyond the maximum growth rate ␥ max of concerned instabilities, such as trapped electron modes, ion temperature gradient modes and so on.…”

Section: Bifurcation and Transport Barriermentioning

confidence: 84%

Experimental study of the bifurcation nature of the electrostatic potential of a toroidal helical plasma

et al. 2000

View full text Add to dashboard Cite

The bifurcation nature of the electrostatic structure is studied in the toroidal helical plasma of the Compact Helical System ͑CHS͒ ͓K. Matsuoka et al., Proceedings of the 12th International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Nice, 1988 ͑International Atomic Energy Agency, Vienna, 1989͒, Vol. 2, p. 411͔. Observation of bifurcation-related phenomena is introduced, such as characteristic patterns of discrete potential profiles, and various patterns of self-sustained oscillations termed electric pulsation. Some patterns of the electrostatic structure are found to be quite important for fusion application owing to their association with transport barrier formation. It is confirmed, as is shown in several tokamak experiments, that the thermal transport barrier is linked with electrostatic structure through the radial electric field shear that can reduce the fluctuation resulting in anomalous transport. This article describes in detail spatio-temporal evolution during self-sustained oscillation, together with correlation between the radial electric field and other plasma parameters. An experimental survey to find dependence of the temporal and spatial patterns on plasma parameters is performed in order to understand systematically the bifurcation property of the toroidal helical plasma. The experimental results are compared with the neoclassical bifurcation property that is believed to explain the observed bifurcation property of the CHS plasmas. The present results show that the electrostatic property plays an essential role in the structural formation of toroidal helical plasmas, and demonstrate that toroidal plasma is an open system with a strong nonlinearity to provide a new attractive problem to be studied.

show abstract

“…In tokamaks, nonmonotonic forms of g͑y͒ may result from hollow toroidal current profiles, which can be obtained by many experimental techniques and are related with enhanced confinement; for example, this happens when neutral beam injection is applied as a noninductive current drive. 12 It was suggested in Refs. 13 and 14 ͑see also Ref.…”

Section: ͑11͒mentioning

confidence: 99%

Transport properties in nontwist area-preserving maps

Szezech

Caldas

Lopes

et al. 2009

Chaos: An Interdisciplinary Journal of Nonlinear Science

View full text Add to dashboard Cite

Nontwist systems, common in the dynamical descriptions of fluids and plasmas, possess a shearless curve with a concomitant transport barrier that eliminates or reduces chaotic transport, even after its breakdown. In order to investigate the transport properties of nontwist systems, we analyze the barrier escape time and barrier transmissivity for the standard nontwist map, a paradigm of such systems. We interpret the sensitive dependence of these quantities upon map parameters by investigating chaotic orbit stickiness and the associated role played by the dominant crossing of stable and unstable manifolds. © 2009 American Institute of Physics. ͓doi:10.1063/1.3247349͔Nonmonotonic flows with reverse shear are observed in many physical systems. Much previous research indicates that transport properties of such systems can be well described by area preserving maps. Many examples exist, e.g., in the fields of fluid mechanics and plasma physics; in particular, in models that describe zonal flows that occur in geophysics, atmospheric science, and fusion plasma physics. The standard nontwist map (SNM) is a well-known paradigm for investigating transport in reverse shear systems. The nonmonotonicity property of the SNM gives rise to transport barriers due to robust tori (invariant curves) that occur in zonal flows. These tori separate regions of the two-dimensional phase space. Moreover, the influence of these barriers on the transport remains even after the breakup of the tori. This phenomenon, i.e., the difficulty encountered in crossing broken barriers, is explained by examining the stickiness of orbits that occur in some regions of the map phase space. For a certain range of control parameters, these regions emerge near resonances. The presence of stickiness is closely related to the structure of the stable and unstable manifolds of hyperbolic orbits, becoming prevalent when the manifolds reconnect and change from a dominant homoclinic tangle to a combination that includes both homoclinic and heteroclinic tangles.

show abstract

Turbulent Fluctuations in TFTR Configurations with Reversed Magnetic Shear

Cited by 199 publications

References 24 publications

A tutorial on the basic principles of microwave reflectometry applied to fluctuation measurements in fusion plasmas

A tutorial on the basic principles of microwave reflectometry applied to fluctuation measurements in fusion plasmas

Experimental study of the bifurcation nature of the electrostatic potential of a toroidal helical plasma

Transport properties in nontwist area-preserving maps

Contact Info

Product

Resources

About