High spatial sampling global mode structure measurements via multichannel reflectometry in NSTX

被引:56
作者
Crocker, N. A. [1 ]
Peebles, W. A. [1 ]
Kubota, S. [1 ]
Zhang, J. [1 ]
Bell, R. E. [2 ]
Fredrickson, E. D. [2 ]
Gorelenkov, N. N. [2 ]
LeBlanc, B. P. [2 ]
Menard, J. E. [2 ]
Podesta, M. [2 ]
Sabbagh, S. A. [3 ]
Tritz, K. [4 ]
Yuh, H. [5 ]
机构
[1] Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA
[2] Princeton Plasma Phys Lab, Princeton, NJ 08543 USA
[3] Columbia Univ, Dept Appl Phys & Appl Math, New York, NY 10027 USA
[4] Johns Hopkins Univ, Baltimore, MD 21218 USA
[5] Nova Photon, Princeton, NJ 08540 USA
关键词
NEOCLASSICAL TEARING MODES; TOROIDAL ALFVEN EIGENMODES; EXCITATION; PHYSICS; INSTABILITIES; SPECTRUM; LOSSES;
D O I
10.1088/0741-3335/53/10/105001
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
Global modes-including kinks and tearing modes (f <similar to 50 kHz), toroidicity-induced Alfven eigenmodes (TAE; f similar to 50-250 kHz) and global and compressional Alfven eigenmodes (GAE and CAE; f >similar to 400 kHz)-play critical roles in many aspects of plasma performance. Their investigation on NSTX is aided by an array of fixed-frequency quadrature reflectometers used to determine their radial density perturbation structure. The array has been recently upgraded to 16 channels spanning 30-75 GHz (n(cutoff) = (1.1-6.9) x 10(19) m(-3) in O-mode), improving spatial sampling and access to the core of H-mode plasmas. The upgrade has yielded significant new results that advance the understanding of global modes in NSTX. The GAE and CAE structures have been measured for the first time in the core of an NSTX high-power (6MW) beam-heated H-mode plasma. The CAE structure is strongly core-localized, which has important implications for electron thermal transport. The TAE structure has been measured with greatly improved spatial sampling, and measurements of the TAE phase, the first in NSTX, show strong radial variation near the midplane, indicating radial propagation caused by non-ideal MHD effects. Finally, the tearing mode structure measurements provide unambiguous evidence of coupling to an external kink.
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页数:18
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