Electron heat transport in improved confinement discharges in DIII-D

被引:100
作者
Stallard, BW [1 ]
Greenfield, CM
Staebler, GM
Rettig, CL
Chu, MS
Austin, ME
Baker, DR
Baylor, LR
Burrell, KH
DeBoo, JC
deGrassie, JS
Doyle, EJ
Lohr, J
McKee, GR
Miller, RL
Peebles, WA
Petty, CC
Pinsker, RI
Rice, BW
Rhodes, TL
Waltz, RE
Zeng, L
机构
[1] Lawrence Livermore Natl Lab, Livermore, CA 94550 USA
[2] Gen Atom Co, San Diego, CA 92186 USA
[3] Univ Calif Los Angeles, Los Angeles, CA USA
[4] Univ Texas, Austin, TX 78712 USA
[5] Oak Ridge Natl Lab, Oak Ridge, TN USA
[6] Univ Wisconsin, Madison, WI USA
关键词
D O I
10.1063/1.873494
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
In DIII-D [J. L. Luxon and L. G. Davis, Fusion Technol. 8, 441 (1985)] tokamak plasmas with an internal transport barrier (ITB), the comparison of gyrokinetic linear stability (GKS) predictions with experiments in both low and strong negative magnetic shear plasmas provide improved understanding for electron thermal transport within the plasma. Within a limited region just inside the ITB, the electron temperature gradient (ETG) modes appear to control the electron temperature gradient and, consequently, the electron thermal transport. The increase in the electron temperaturegradient with more strongly negative magnetic shear is consistent with the increase in the ETG mode marginal gradient. Closer to the magnetic axis the T-e profile flattens and the ETG modes are predicted to be stable. With additional core electron heating, FIR scattering measurements near the axis show the presence of high k fluctuations (12 cm(-1)), rotating in the electron diamagnetic drift direction. This turbulence could impact electron transport and possibly also ion transport. Thermal diffusivities for electrons, and to a lesser degree ions, increase. The ETG mode can exist at this wave number, but it is computed to be robustly stable near the axis. Consequently, in the plasmas we have examined, calculations of drift wave linear stability do not explain the observed transport near the axis in plasmas with or without additional electron heating, and there are probably other processes controling transport in this region. (C) 1999 American Institute of Physics. [S1070-664X(99)95505-2].
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页码:1978 / 1984
页数:7
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