RF current drive by electron cyclotron waves in the presence of magnetic islands

Rosa, Paulo Ricardo da Silva; Giruzzi, G.

doi:10.1088/0741-3335/42/7/302

Cited by 20 publications

(17 citation statements)

References 29 publications

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“…For example, under some conditions, the cross-field heat conductivity has been found to be strongly reduced inside the island [30,31]. Theoretical and numerical works have shown that the different magnetic topologies due to the presence of a magnetic island can have important consequences for the flux-surface averaged quasilinear diffusion and the consequent power density deposition profile as well as drive current density profile [32][33][34]. These points will be the subject of future work.…”

Section: Discussionmentioning

confidence: 91%

Consequences of finite transport on the effectiveness of ECCD for neoclassical tearing mode stabilization in ITER

Bertelli

Westerhof

2009

Nucl. Fusion

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One of the main aims of the ITER electron cyclotron resonance heating (ECRH) system, in particular of the Upper Port Launcher, is the control of magnetohydrodynamics instabilities. This control typically requires non-inductively driven currents with a high degree of localization, i.e. with a very narrow profile. A numerical analysis of the effect of the radial diffusion of the EC driven current carrying electrons has been performed in order to estimate the effectiveness of electron cyclotron current drive (ECCD) for neoclassical tearing mode (NTM) stabilization. In particular, Fokker–Planck calculations including radial diffusion for the case of the ITER ECRH Upper Port Launcher are presented. These show a significant decrease in the local current density when radial diffusion at a rate of only 1 m2 s−1 is included and consequently a broadening of the profile with a drop in the predicted efficiency for NTM control. Furthermore, it is shown that a simple formula combining the effect of the radial diffusion and the width of the EC power deposition profile reproduces quite accurately the maximum EC driven current density, which is the more relevant number in determining the NTM suppression figure of merit, for typical ITER parameters.

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Section: Discussionmentioning

confidence: 91%

Consequences of finite transport on the effectiveness of ECCD for neoclassical tearing mode stabilization in ITER

Bertelli

Westerhof

2009

Nucl. Fusion

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“…For cases where the NTM is suppressed using ECCD aimed at the resonant q surface, the changes in the current profile that stabilize the magnetic island are also found from the MSE measurements. (Note that the possible effect of the magnetic island on the ECCD profile [11,12] is not considered in this paper.) In these H-mode plasmas heated primarily by co-current neutral beam injection (NBI), the magnetic island rotation frequency (10-30 kHz) is much faster than the MSE (no aliasing) bandwidth (1 kHz), so only the time-averaged (i.e.…”

Section: Spatiotemporal Changes In Pressure-driven Currents From Ntmmentioning

confidence: 99%

“…B y = δB y cos ky. (11) Perturbations in the toroidal magnetic field are negligible and are not considered. For a tearing mode located at radius r s with poloidal mode number m, periodicity requires k = m/r s .…”

Section: Direct Analysis Of Mse Signals Including Helical Perturbatiomentioning

confidence: 99%

Local formulae for combinatorial Pontryagin classes

Gaifullin¹

2004

Izv. Math.

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Using direct analysis of the motional Stark effect (MSE) signals, an explicit measurement of the 'missing' bootstrap current density around the island location of a neoclassical tearing mode (NTM) is made for the first time. When the NTM is suppressed using co-electron cyclotron current drive, the measured changes in the current profile that restore the bootstrap current are also directly found from the MSE measurements. Additionally, direct analysis of helical perturbations in the MSE signals during slowly rotating 'quasi-stationary' modes shows the first explicit measurement of the deficit in the toroidal current density in the island O-point.

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“…We take for the tearing-mode structure a fundamental linear mode with ψ = δψ cos ky. The standard linear tearing-mode picture has magnetic field perturbations of B x = δB x sin ky, (10) B y = δB y cos ky. (11) Perturbations in the toroidal magnetic field are negligible and are not considered. For a tearing mode located at radius r s with poloidal mode number m, periodicity requires k = m/r s .…”

Section: Direct Analysis Of Mse Signals Including Helical Perturbatio...mentioning

confidence: 99%

Spatiotemporal changes in the pressure-driven current densities on DIII-D due to magnetic islands

et al. 2011

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Using direct analysis of the motional Stark effect (MSE) signals, an explicit measurement of the ‘missing’ bootstrap current density around the island location of a neoclassical tearing mode (NTM) is made for the first time. When the NTM is suppressed using co-electron cyclotron current drive, the measured changes in the current profile that restore the bootstrap current are also directly found from the MSE measurements. Additionally, direct analysis of helical perturbations in the MSE signals during slowly rotating ‘quasi-stationary’ modes shows the first explicit measurement of the deficit in the toroidal current density in the island O-point.

show abstract

RF current drive by electron cyclotron waves in the presence of magnetic islands

Cited by 20 publications

References 29 publications

Consequences of finite transport on the effectiveness of ECCD for neoclassical tearing mode stabilization in ITER

Consequences of finite transport on the effectiveness of ECCD for neoclassical tearing mode stabilization in ITER

Local formulae for combinatorial Pontryagin classes

Spatiotemporal changes in the pressure-driven current densities on DIII-D due to magnetic islands

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