Formation of electron transport barriers under ECR control of the q(r) profile in the T-10 tokamak

Razumova, K. A.; Alikaev, V. V.; Бондаренко, И. С.; Borschegovskii, A. A.; Vershkov, V.A.; Gorshkov, A. V.; Gott, Yu. V.; Dnestrovskij, Yu. N.; Dreval, V. V.; Dremin, M. M.; Eliseev, L.G.; Kirnev, G.; Kislov, A. Ya.; Klimanov, I.; Kozachok, A. S.; Komarov, A. D.; Krupin, V.A.; Krupnik, L. I.; Krylov, S.V.; Лысенко, С. Е.; Medvedev, A. A.; Melnikov, A. V.; Myalton, T.B.; Notkin, G.E.; Novikov, Alexander; Pavlov, Yu.D.; Petrov, D.P.; Poznyak, V. I.; Roy, I. N.; Savrukhin, P. V.; Sannikov, V. V.; Soldatov, S.; Sushkov, A. V.; Trukhin, V. M.; Khrebtov, S. M.; Chistyakov, V. V.; Shelukhin, D. A.

doi:10.1134/1.1364546

Cited by 11 publications

(6 citation statements)

References 1 publication

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“…Our results show that, in order to efficiently increase the electron temperature inside the magnetic island by localized rf heating, the radial location of the rf power deposition should be as close to the rational surface as possible, and the radial deposition width of rf power should be as narrow as possible, as expected and seen from experimental results [11][12][13][14][15][16].…”

Section: ⅳ Discussion and Summerysupporting

confidence: 81%

“…Magnetic islands due to neoclassical tearing modes (NTMs) have been successfully suppressed by electron cyclotron current drive (ECCD) on ASDEX Upgrade [11], JT-60 [12], and DIII-D [13]. Alternatively, Electron cyclotron resonance heating (ECRH) is also able to reduce the island size or to slow down the island growth on TEXTOR [14], FTU [15], ASDEX Upgrade [15], and T10 [16]. To stabilize magnetic islands more efficiently, the modulated technique to deposit the rf power around the island's O-point has been utilized in experiments [11][12][13][14][15].…”

Section: ⅰ Introductionmentioning

confidence: 99%

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Study of the change of electron temperature inside magnetic island caused by localized radio frequency heating

Yang

Zhu

et al. 2010

Physics of Plasmas

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The change of the electron temperature inside magnetic island caused by localized radio frequency (rf) heating is studied numerically by solving the two-dimensional energy transport equation, to investigate the dependence of the temperature change on the location and width of the rf power deposition along the minor radius and the helical angle, the island width, and the ratio between the parallel and the perpendicular heat conductivity. Based on obtained numerical results, suggestions for optimizing the island stabilization by localized rf heating are made.

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Section: ⅳ Discussion and Summerysupporting

confidence: 81%

Section: ⅰ Introductionmentioning

confidence: 99%

Study of the change of electron temperature inside magnetic island caused by localized radio frequency heating

Yang

Zhu

et al. 2010

Physics of Plasmas

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“…Other experiments in various tokamaks showed that having an inner region with low magnetic shear was indeed sufficient to obtain ITBs [1,4]. In particular, in the case of Razumova et al observations [4], the formation of electron ITBs was correlated with some local flattening of the otherwise monotonically growing q-profile, that is to the creation of a low-shear region. In this work, our interest will be put in this later case.…”

Section: Motivationsmentioning

confidence: 92%

Modifying locally the safety profile to improve the confinement of magnetic field lines in tokamak plasmas

Constantinescu¹,

Firpo²

2012

Nucl. Fusion

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Using Hamiltonian models for the magnetic field lines, we propose a methodology to improve their confinement through the creation of transport barriers. A local modification of the safety profile creating a low-shear zone is shown to be sufficient to locally enhance drastically the regularity of the magnetic field lines without requesting a reversed shear. The optimal benefits of low-shear are obtained when the value q 0 of the safety profile in the low-shear zone is sufficiently far from the main resonance values m/n with low m and n, in the case of large enough values of those (m, n) mode amplitudes. A practical implementation in tokamak plasmas should involve electron cyclotron current drive to locally modify the magnetic shear.

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“…It is convenient, and physically relevant, to consider the large M case for which the derivation of the symplectic mapping associated to ( 5) is immediate through the use of the periodic-δ distribution. For computational purposes, we used a symmetric version [18,26] of the later mapping that yields a very accurate modeling of the continuous dynamics (5) with H(ψ) = 2ψ/(1 + ψ). The physical motivation to consider this specific form of magnetic perturbation was discussed in Ref.…”

Section: Detrimental Effect Of Low Shear In the Vicinity Of Resonance...mentioning

confidence: 99%

“…In this way, they were able to demonstrate that the electron confinement could be modified significantly solely by perturbing the current density profile. Other experiments in various tokamaks showed that having an inner region with low magnetic shear was indeed sufficient to obtain ITBs [2,5].…”

Section: Introductionmentioning

confidence: 96%

Study of the interplay between magnetic shear and resonances using Hamiltonian models for the magnetic field lines

Firpo

Constantinescu

2011

Physics of Plasmas

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International audienceThe issue of magnetic confinement in magnetic fusion devices is addressed within a purely magnetic approach. Using some Hamiltonian models for the magnetic field lines, the dual impact of low magnetic shear is shown in a unified way. Away from resonances, it induces a drastic enhancement of magnetic confinement that favors robust internal transport barriers (ITBs) and stochastic transport reduction. When low-shear occurs for values of the winding of the magnetic field lines close to low-order rationals, the amplitude thresholds of the resonant modes that break internal transport barriers by allowing a radial stochastic transport of the magnetic field lines may be quite low. The approach can be applied to assess the robustness versus magnetic perturbations of general (almost) integrable magnetic steady states, including non-axisymmetric ones such as the important single helicity steady states. This analysis puts a constraint on the tolerable mode amplitudes compatible with ITBs and may be proposed as a possible explanation of diverse experimental and numerical signatures of their collapses

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Formation of electron transport barriers under ECR control of the q(r) profile in the T-10 tokamak

Cited by 11 publications

References 1 publication

Study of the change of electron temperature inside magnetic island caused by localized radio frequency heating

Study of the change of electron temperature inside magnetic island caused by localized radio frequency heating

Modifying locally the safety profile to improve the confinement of magnetic field lines in tokamak plasmas

Study of the interplay between magnetic shear and resonances using Hamiltonian models for the magnetic field lines

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