Spatially localized turbulence measurements using CO<sub>2</sub>laser collective scattering diagnostics on the HT-7

Sun, P. J.; Li, Y D; Li, Q; Zhang, W Y; Zhang, X D; Cao, Guangming; Hu, Liqun; Li, J

doi:10.1088/0031-8949/86/02/025504

Cited by 3 publications

(2 citation statements)

References 19 publications

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“…Microturbulence was measured with collective scattering of electromagnetic waves, which is a powerful technique capable of providing the spectral power of density fluctuations [18,19]. The CO 2 laser collective scattering system has always been employed in the HT-7 tokamak, providing measurement of microturbulence with the wave vectors in the poloidal direction [20,21]. In the campaign of 2012, the tangential CO 2 laser collective scattering system [28] was first installed on the EAST tokamak, as shown in figure 1(a).…”

Section: Methodsmentioning

confidence: 99%

Characterization of core microturbulence in L-mode and H-mode regimes on the EAST superconducting tokamak

Cao¹,

Li²,

Li³

et al. 2015

Phys. Scr.

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The core microturbulence ( ≈ − r a / 0.4 0.5, ρ − ⊥ k ~1.5 4.3 s ) provided by a tangential CO 2 laser collective scattering system on the EAST tokamak, in low (L) and high (H) confinement mode regimes respectively, are presented. We report the change of core microturbulence characteristics from L-mode to H-mode: firstly, the spectrograms of the core microturbulence show the redistribution of microturbulence in the frequency domain after the L-H transition; secondly, the time evolution of the integrated spectral power displays that the amplitude of the core microturbulence in H-mode is much larger than that in L-mode; thirdly, the cross-correlation time-frequency spectrum analysis indicates that the structural characteristics of the core microturbulence in L-mode and H-mode are very different. These results suggest that both the amplitude and the structural characteristics of the core microturbulence change significantly from L-mode to H-mode, although the spatial extent of the transport barrier in H-mode is at the edge, which could be closely related to the changes of the profiles of basic plasma parameters.

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Section: Methodsmentioning

confidence: 99%

Characterization of core microturbulence in L-mode and H-mode regimes on the EAST superconducting tokamak

Cao¹,

Li²,

Li³

et al. 2015

Phys. Scr.

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“…Although ion thermal transport in advanced tokamaks approaches that predicted by the neoclassical theory, electron thermal transport seems to remain anomalous [1][2][3]. The electron temperature gradient (ETG) instability-driven modes are believed to be responsible for the latter [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Evolution of the electron temperature gradient mode in plasmas containing vortex and shear flows

Shi¹,

Chen²,

Yu³

et al. 2013

Phys. Scr.

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Evolution of the electrostatic potential of the electron temperature gradient (ETG) mode in a plasma with shear and vortex flows, as well as impurity ions, is investigated using a local fluid model. The governing equations are obtained through the Bayly nonmodal approach and solved numerically, so that the evolution of the electrostatic potential is obtained directly. It is found that the ETG mode intensity increases with flow shear, and an intensity minimum occurs when the eccentricity of the vortex flow is at a critical value. In general, impurity ions have a stabilizing effect on the flow-shear-induced secondary instability.

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Experimental observation of (intermediate, high)-k micro-turbulence in different type H mode plasmas in EAST

Sun

et al. 2018

Physics of Plasmas

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Both k1 = 12 cm−1 (intermediate-k) and k2 = 22 cm−1 (high-k) micro-turbulence (k⊥ρs ∼ 1–4) in gradient region plasmas were measured simultaneously by the EAST poloidal CO2 laser collective scattering system. Their behaviors have been studied in detail in both ELM-free/type III ELMy and enhanced Da (EDA) H mode plasma discharges. Compared with that in the previous L mode phase, it can be seen obviously that the mean frequency of lower-k (k1) micro-turbulence increases and that of higher-k (k2) decreases during the ELM-free or type III ELMy H mode phase, while frequency-integrated spectral power (Stot) of both k1 and k2 micro-turbulence seems almost the same. On the other hand, both Stot and mean frequency of k1/k2 micro-turbulence show continuous increase during the EDA H mode phase. These results imply that the response of (intermediate, high)-k micro-turbulence on different type H mode is different. Further cross-correlation analysis between k1 and k2 micro-turbulence shows that their cross-correlation value is a little lower in H mode phase than the previous L mode phase. It can also be found that the cross-correlation value decreases gradually during the ELM-free and subsequent type-III ELMy phases, and it is almost zero in the EDA H mode phase. These new results could shed some light on the comprehensive understanding of mechanisms under H mode physics.

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Spatially localized turbulence measurements using CO₂laser collective scattering diagnostics on the HT-7

Cited by 3 publications

References 19 publications

Characterization of core microturbulence in L-mode and H-mode regimes on the EAST superconducting tokamak

Characterization of core microturbulence in L-mode and H-mode regimes on the EAST superconducting tokamak

Evolution of the electron temperature gradient mode in plasmas containing vortex and shear flows

Experimental observation of (intermediate, high)-k micro-turbulence in different type H mode plasmas in EAST

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Spatially localized turbulence measurements using CO2laser collective scattering diagnostics on the HT-7

Cited by 3 publications

References 19 publications

Characterization of core microturbulence in L-mode and H-mode regimes on the EAST superconducting tokamak

Characterization of core microturbulence in L-mode and H-mode regimes on the EAST superconducting tokamak

Evolution of the electron temperature gradient mode in plasmas containing vortex and shear flows

Experimental observation of (intermediate, high)-k micro-turbulence in different type H mode plasmas in EAST

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Spatially localized turbulence measurements using CO₂laser collective scattering diagnostics on the HT-7