A general solution of the ripple-averaged kinetic equation (GSRAKE)

Beidler, C. D.; D’haeseleer, William

doi:10.1088/0741-3335/37/4/007

Cited by 92 publications

(99 citation statements)

References 27 publications

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“…Here, the ripple-trapped particles dominate the radial transport, and their distribution function is nearly symmetric allowing for a bounce-averaged formulation of the DKE for calculating the radial transport; see e.g. [25,26]. In the lmfp-regime, the parallel viscosity evaluated for…”

Section: B Radial Transportmentioning

confidence: 99%

Momentum correction techniques for neoclassical transport in stellarators

Maaßberg¹,

Beidler²,

Turkin³

2009

Physics of Plasmas

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In the traditional neoclassical ordering for stellarators, mono-energetic transport coefficients are evaluated using the simplified Lorentz form of the pitch-angle collision operator which violates momentum conservation. In this paper, the parallel momentum balance with radial parallel momentum transport and viscosity terms is analysed, in particular with respect to the radial electric field. Next, the impact of momentum conservation in the stellarator lmfp-regime is estimated for the radial transport and the parallel electric conductivity. Two different momentum correction techniques are described based on mono-energetic transport coefficients calulated by the DKES code [W.I. van Rij and S.P. Hirshman, Phys. Fluids B 1, 563 (1989)]. The benchmarking of the parallel electric conductivity and of the bootstrap current is presented for a tokamak as well as for two W7-X stellarator configurations [G. Grieger et al., Phys. Fluids B 4, 2081(1992]. Finally, the impact of the momentum correction on the expected total bootstrap current is briefly analysed for two W7-X scenarios.

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Section: B Radial Transportmentioning

confidence: 99%

Momentum correction techniques for neoclassical transport in stellarators

Maaßberg¹,

Beidler²,

Turkin³

2009

Physics of Plasmas

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“…For this reason, stellarator transport at low collisionality is sensitive to small values of E r . A variety of codes have been developed to compute these neoclassical effects in stellarators [5][6][7][8][9][10][11][12][13].…”

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confidence: 99%

Comparison of particle trajectories and collision operators for collisional transport in nonaxisymmetric plasmas

et al. 2014

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In this work, we examine the validity of several common simplifying assumptions used in numerical neoclassical calculations for nonaxisymmetric plasmas, both by using a new continuum drift-kinetic code and by considering analytic properties of the kinetic equation. First, neoclassical phenomena are computed for the LHD and W7-X stellarators using several versions of the drift-kinetic equation, including the commonly used incompressible-E × B-drift approximation and two other variants, corresponding to different effective particle trajectories. It is found that for electric fields below roughly one third of the resonant value, the different formulations give nearly identical results, demonstrating the incompressible E ×B-drift approximation is quite accurate in this regime. However, near the electric field resonance, the models yield substantially different results. We also compare results for various collision operators, including the full linearized Fokker-Planck operator. At low collisionality, the radial transport driven by radial gradients is nearly identical for the different operators, while in other cases it is found to be important that collisions conserve momentum.

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“…The ion diffusivity in the high-T i phase is significantly reduced in the core region. The neoclassical transport was calculated by the GSRAKE code [15]. The radial electric field is provided by the ambipolar condition and is negative (ion-root) in the core region [16].…”

Section: Resultsmentioning

confidence: 99%

Ion Heating Experiments Using Perpendicular Neutral Beam Injection in the Large Helical Device

Nagaoka

Yokoyama

Takeiri

et al. 2008

Plasma and Fusion Research

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A perpendicular neutral beam (P-NB) injector was installed in the Large Helical Device (LHD) and utilized for high-power ion heating and measurement of the ion temperature (T i ) profile by charge exchange spectroscopy. Significant progress was achieved in ion heating experiments using P-NB, and a high T i of 5.2 keV was achieved at the plasma center. A T i peak profile with a steep gradient in the core region was observed, indicating an improved mode of ion transport. The enhancement of toroidal flow in the core region was observed with the T i rise. Transport analysis shows improvement in anomalous transport in the core region, and the neoclassical transport remains unchanged when the high T i is realized.

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A general solution of the ripple-averaged kinetic equation (GSRAKE)

Cited by 92 publications

References 27 publications

Momentum correction techniques for neoclassical transport in stellarators

Momentum correction techniques for neoclassical transport in stellarators

Comparison of particle trajectories and collision operators for collisional transport in nonaxisymmetric plasmas

Ion Heating Experiments Using Perpendicular Neutral Beam Injection in the Large Helical Device

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