Quasi-coherent modes and electron-driven turbulence

被引：55
作者：
Arnichand, H. [1 ]
Sabot, R. [1 ]
Hacquin, S. [1 ]
Kraemer-Flecken, A. [2 ]
Garbet, X. [1 ]
Citrin, J. [1 ,3 ]
Bourdelle, C. [1 ]
Hornung, G. [1 ,4 ]
Bernardo, J. [5 ]
Bottereau, C. [1 ]
Clairet, F. [1 ]
Falchetto, G. [1 ]
Giacalone, J. C. [1 ]
机构：
[1] CEA, IRFM, F-13108 St Paul Les Durance, France
[2] Forschungszentrum Julich, Inst Energy Res Plasma Phys, D-52425 Julich, Germany
[3] FOM Inst DIFFER, Dutch Inst Fundamental Energy Res, Nieuwegein, Netherlands
[4] Univ Ghent, Dept Appl Phys, B-9000 Ghent, Belgium
[5] Univ Tecn Lisboa, Inst Super Tecn, Inst Plasmas & Fusao Nucl, P-1049001 Lisbon, Portugal
来源：
NUCLEAR FUSION | 2014年 / 54卷 / 12期
关键词：
turbulence; micro-instabilities; ohmic confinement; reflectometry; CONFINEMENT; TRANSPORT;
D O I：
10.1088/0029-5515/54/12/123017
中图分类号：
O35 [流体力学]; O53 [等离子体物理学];
学科分类号：
070204 ; 080103 ; 080704 ;
摘要：
This letter reports on quasi-coherent (QC) modes observed in fluctuation spectra from Tore Supra and TEXTOR reflectometers. QC modes have characteristics in between coherent and broad-band fluctuations as they oscillate around a given frequency but have a wide spectrum. They are ballooned at the LFS midplane and appear usually on a frequency ranging from 30 to 120 kHz. In ohmic plasmas from both tokamaks, QC modes are detected only in linear ohmic confinement (LOC) regime and disappear in saturated ohmic confinement (SOC) regime. Linear simulations from Tore Supra predict that the LOC and SOC regimes are dominated by electron and ion modes respectively. Measurements of the perpendicular velocity of density fluctuations have been made from the top of TEXTOR by poloidal correlation reflectometry. They suggest that QC modes have a phase velocity similar to 400 ms(-1) higher in the electron diamagnetic direction than lower frequency fluctuations. Additionally, the onset of QC modes during electron cyclotron resonance heating has been observed in a Tore Supra region where turbulence is suspected to be driven by electron modes. These experimental results and instability calculations show a correlation between onsets of QC modes and predictions of trapped electron modes.
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页数：7
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