Study of internal transport barriers in the initial phase of Ohmic discharges in TUMAN-3M

Askinazi, L. G.; Bulanin, V. V.; Vildjunas, M. I.; Golant, V.E.; Gorokhov, M. V.; Kornev, V. A.; Krikunov, S. V.; Лебедев, С. В.; Петров, А. В.; Rozhdestvensky, V. V.; Tukachinsky, A. S.; Zhubr, N. A.

doi:10.1088/0741-3335/46/5a/005

Cited by 9 publications

(8 citation statements)

References 9 publications

(12 reference statements)

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“…The rotation shear (ω ) is calculated from the turbulence rotation, assuming that the turbulence rotation equals the plasma rotation (see section 4.2), and is defined by [29] In general, it is found that the rotation shear increases for a region with reduced transport [28]. Without the DED, ω is flat in the investigated region and only a small increase at the plasma edge is observed (see figure 13(b)).…”

Section: Ded In the 3/1 Configuration With Counter-injection (Scenarimentioning

confidence: 99%

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Reflectometry measurements during operation of the dynamic ergodic divertor at TEXTOR

Krämer–Flecken

Soldatov

Busch³

et al. 2006

Nucl. Fusion

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The O-mode correlation reflectometer at TEXTOR is used for the investigation of the propagation and the properties of the turbulence at the plasma edge. The multi-horn antenna setup allows the investigation of the correlation properties of the turbulence and its rotation. Turbulence and plasma rotation for different plasma conditions are found to be in agreement and based on this comparison the radial electric field is estimated. In addition the density fluctuation level is estimated from the standard deviation of the phase of the reflected signal. The influence of a magnetic perturbation field, generated by the dynamic ergodic divertor (DED), on the turbulence and transport properties is studied and compared with plasmas without such a field perturbation. The strength and radial range of the perturbation field can be widely varied. Together with tangential neutral beam injection in coand counter-current directions, the turbulent transport is investigated. The combination of neutral beam injection and the DED enables the modification of the plasma rotation profile. It can lead either to the generation of a locked mode or the formation of a transport barrier.

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Section: Ded In the 3/1 Configuration With Counter-injection (Scenarimentioning

confidence: 99%

“…The rotation shear (ω ) is calculated from the turbulence rotation, assuming that the turbulence rotation equals the plasma rotation (see section 4.2), and is defined by [29] • denotes operation without DED and with DED. For 0.8/a 0.9 the rotation is decreased by the DED.…”

Section: Ded In the 3/1 Configuration With Counter-injection (Scenari...mentioning

confidence: 99%

Reflectometry measurements during operation of the dynamic ergodic divertor at TEXTOR

Krämer–Flecken

Soldatov

Busch³

et al. 2006

Nucl. Fusion

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“…In the TUMAN-3M tokamak detailed measurements of plasma rotation, radial electric field and electrostatic potential during the burst of MHD activity were performed. The characteristic parameters in the experiments [1][2][3] for Ohmic shots [13] are: major radius R = 53 cm, minor radius, restricted by bulk limiter, a = 22 cm, plasma current I p = 100-130 kA, toroidal magnetic field at the axis B tor = 0.7 T, n| r=18 cm = (0.5 ± 0.3)10 19 m −3 , T e | r=18 cm = 80±40 eV, T i | r=18 cm = 20±10 eV. Magnetic islands corresponding to the MHD activity have the poloidal/toroidal mode numbers 2/1, 3/1, 4/1; they appear around r ≈ 17-18 cm and the largest has the width of the order of 2-3 cm.…”

Section: Comparison With the Experimentsmentioning

confidence: 99%

Interpretation of the observed radial electric field inversion in the TUMAN-3M tokamak during MHD activity

Rozhansky

Тендлер

2008

Nucl. Fusion

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A theoretical model for the toroidal rotation spin-up and generation of a positive radial electric field during the stochastization of plasma edge is put forward. Equations for the toroidal velocity and for modification of the core radial electric field have been derived. A detailed comparison of the model results with the radial electric field and plasma potential measurements during MHD activity in the TUMAN-3M tokamak is presented.

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“…Assuming that the turbulence is frozen in the plasma, as indicated in [12] for the 2/1 mode, the poloidal rotation shear [14] ω = ∆v Θ /∆r c , with v Θ = Ω Θ r c can be estimated. As shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

Turbulence investigations during ergodic divertor operation with induced 2/1 tearing mode

et al. 2005

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Within the last year of TEXTOR operation a major part of the experiments were dedicated to the interaction of the ergodized plasma edge, induced by the dynamic ergodic divertor (DED), with the core plasma. Systematic experiments are performed in the 3/1 configuration of the DED. Depending on β, the DED generates a locked 2/1 mode in the plasma at a critical current in the DED coils. Different diagnostics were used to measure the plasma response in the core and edge. The investigations in this paper are focused on the measurement of density fluctuation and the analysis of the coherent-mode structure outside the q = 2 surface using O-mode poloidal correlation reflectometry. A reduction of the quasi-coherent mode amplitude and frequency is observed, caused by the 2/1 mode together with a decrease of the density scale length. Moreover, the deduced poloidal rotation velocity at the q = 3 surface changes from the electron to the ion diamagnetic drift direction with the onset of the 2/1 island. Also a reduction of the density fluctuations is observed as well as a decrease in the poloidal correlation length. From Ar-injection a delayed inward propagation of the emission maximum is observed for different Ar ionization stages when the 2/1 mode is generated.Similar experiments with a slowly rotating DED show that the steepened density gradients are spatially localized and confirm the hypothesis that the 2/1 mode is responsible for the observations. PACS : 52.25. Gj, 52.30.Cv, 52.35.Ra, 52.55.Fa, 52.55.Tn

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Study of internal transport barriers in the initial phase of Ohmic discharges in TUMAN-3M

Cited by 9 publications

References 9 publications

Reflectometry measurements during operation of the dynamic ergodic divertor at TEXTOR

Reflectometry measurements during operation of the dynamic ergodic divertor at TEXTOR

Interpretation of the observed radial electric field inversion in the TUMAN-3M tokamak during MHD activity

Turbulence investigations during ergodic divertor operation with induced 2/1 tearing mode

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