Dynamics and dependencies of the configuration-dependent 1-2 kHz fluctuation in W7-X

被引:9
作者
Ballinger, S. B. [1 ]
Terry, J. L. [1 ]
Baek, S. G. [1 ]
Beurskens, M. [2 ]
Brunner, K. J. [2 ]
Fuchert, G. [2 ]
Knauer, J. [2 ]
Killer, C. [2 ]
Pasch, E. [2 ]
Rahbarnia, K. [2 ]
Schilling, J. [2 ]
Scott, E. [2 ]
von Stechow, A. [2 ]
Thomsen, H. [2 ]
Grulke, O. [2 ,3 ]
Wurden, G. [4 ]
Kocsis, G. [5 ]
Szepesi, T. [5 ]
Zsuga, L. [5 ]
机构
[1] MIT, Plasma Sci & Fus Ctr, 77 Massachusetts Ave, Cambridge, MA 02139 USA
[2] Max Planck Inst Plasma Phys, Greifswald, Germany
[3] Tech Univ Denmark, Lyngby, Denmark
[4] Los Alamos Natl Lab, Los Alamos, NM USA
[5] Wigner Res Ctr Phys, Budapest, Hungary
关键词
SYSTEM;
D O I
10.1016/j.nme.2021.100967
中图分类号
TL [原子能技术]; O571 [原子核物理学];
学科分类号
0827 ; 082701 ;
摘要
A 1-2 kHz electromagnetic mode is present in a large fraction of W7-X discharges in the standard magnetic field configurations with 5/5 edge island structure. The power in the mode is significantly reduced in other magnetic configurations. The mode can appear spontaneously and persist for the full duration of a discharge. Its full width at half maximum is typically 100-300 Hz. The 1-2 kHz mode was first observed in visible light emissions from the divertor [1] Matching spectral peaks were found in measurements of both global and edge plasma parameters, including line-integrated density, diamagnetic energy, and edge floating potential and ion saturation current [2]. An infrared camera recording shows a temperature modulation of similar to 2.5 K due to this mode on a divertor tile where the average temperature was 600 degrees C. Separate correlation analyses of the highspeed camera recordings, Langmuir probe signals, and Mirnov coil signals all indicate a poloidal velocity of 0.5-10 km/s and m = 2 as a likely poloidal mode number. Langmuir probes mounted on the Multi-Purpose Manipulator show that the fluctuation is present in one of the magnetic islands over a radial distance of at least 5 mm. A database of various diagnostic measurements and dB/dt signals from a Mirnov coil was created using a majority of the discharges from the 2018 campaign on W7-X, in order to shed light on the plasma parameters that are correlated with the existence of the 1-2 kHz mode. The power in the mode is positively correlated to the toroidal current, total external heating power, and core electron temperature. It is negatively correlated with plasma density.
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页数:9
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