Transport in stellarators

Maaßberg, H.; Brakel, R.; Burhenn, R.; Gasparino, U.; Grigull, P.; Kick, M.; Kühner, G.; Ringler, H.; Sardei, F.; Stroth, U.; Weller, A.

doi:10.1088/0741-3335/35/sb/026

Cited by 61 publications

(50 citation statements)

References 33 publications

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“…The neoclassically predicted ambipolar radial electric field is generally in agreement with observations in the core of CHS [26] and W7-AS [27,28,29,30] in the 'ion root' regime. Agreement has also been obtained in plasmas with net toroidal current and significant magnetic shear in W7-AS [31], and qualitative agreement has been reported in TJ-II [32].…”

Section: Neoclassical Transport In Stellarators: Theory and Experimentssupporting

confidence: 82%

Assessment of Transport in NCSX

Mikkelsen

Maaßberg

Zarnstorff

et al. 2007

Fusion Science and Technology

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We explore whether the energy confinement and planned heating in NCSX are sufficient to test MHD stability limits, and whether the configuration is sufficiently quasi-axisymmetric to reduce the neoclassical ripple transport to low levels, thereby allowing tokamak-like transport. A 0-D model with fixed profile shapes is related to global energy confinement scalings for stellarators and tokamaks; neoclassical transport properties are assessed with the DKES, NEO, and NCLASS codes; and a power balance code is used to predict temperature profiles. Reaching the NCSX goal of =4% at low collisionality will require H_ISS-95=3, which is higher than the best achieved in present stellarators. However, this level of confinement is actuallỹ 10% lower than that predicted by the ITER-97P tokamak L-mode scaling. By operating near the stellarator density limit, the required H_ISS-95 is reduced by 35%. The high degree of quasiaxisymmetry of the configuration and the self-consistent 'ambipolar' electric field reduce the neoclassical ripple transport to a small fraction of the neoclassical axisymmetric transport. A combination of neoclassical and anomalous transport models produces pressure profile shapes that are within the range of those used to study the MHD stability of NCSX. We find that =4% plasmas are 'neoclassically accessible', and are compatible with large levels of anomalous transport in the plasma periphery. 7-2

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Section: Neoclassical Transport In Stellarators: Theory and Experimentssupporting

confidence: 82%

Assessment of Transport in NCSX

Mikkelsen

Maaßberg

Zarnstorff

et al. 2007

Fusion Science and Technology

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“…with exponential decay towards the center of the plasma. This choice is supported by W7-AS results [15], where the anomalous heat diffusivity obtained from power balance analysis decreases with increasing n e at the edge.…”

Section: Iib X2 Heating From Lfs In the Equatorial Planementioning

confidence: 66%

Electron Cyclotron Heating for W7-X: Physics and Technology

Erckmann

Brand

Braune

et al. 2007

Fusion Science and Technology

182

127

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Abstract:The W 7-X Stellarator (R = 5.5 m, a = 0.55 m, B<3.0 T), which is presently being built at IPP-Greifswald, aims at demonstrating the inherent steady state capability of stellarators at reactor relevant plasma parameters. A 10 MW ECRH plant with cwcapability is under construction to meet the scientific objectives. The physics background of the different heating-and current drive scenarios is presented. The

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“…For this purpose two simulations are carried out. To put the results of the simulation with the ITG model in relation, the first simulation employs for comparison an empirical anomalous transport model which has been obtained from W7-AS where the diffusion coefficient scales with the absorbed power and inversely with the density, a ∼ P 3/4 n −1 [24,25]. For this first simulation the diffusion coefficient has been adjusted to be on the order of 1 m 2 /s at the plasma edge.…”

Section: Plasma Transportmentioning

confidence: 99%

HELIAS module development for systems codes

Warmer

Beidler

Dinklage

et al. 2015

Fusion Engineering and Design

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a b s t r a c tIn order to study and design next-step fusion devices such as DEMO, comprehensive systems codes are commonly employed. In this work HELIAS-specific models are proposed which are designed to be compatible with systems codes. The subsequently developed models include: a geometry model based on Fourier coefficients which can represent the complex 3-D plasma shape, a basic island divertor model which assumes diffusive cross-field transport and high radiation at the X-point, and a coil model which combines scaling aspects based on the HELIAS 5-B reactor design in combination with analytic inductance and field calculations. In addition, stellarator-specific plasma transport is discussed. A strategy is proposed which employs a predictive confinement time scaling derived from 1-D neoclassical and 3-D turbulence simulations.This paper reports on the progress of the development of the stellarator-specific models while an implementation and verification study within an existing systems code will be presented in a separate work.This approach is investigated to ultimately allow one to conduct stellarator system studies, develop design points of HELIAS burning plasma devices, and to facilitate a direct comparison between tokamak and stellarator DEMO and power plant designs.

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Transport in stellarators

Cited by 61 publications

References 33 publications

Assessment of Transport in NCSX

Assessment of Transport in NCSX

Electron Cyclotron Heating for W7-X: Physics and Technology

HELIAS module development for systems codes

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