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Identification of m=2 competent mode of complex magneto-hydro-dynamics activities during internal soft disruption based on singular value decomposition and tomography of soft-X-ray emission on the HT-7 tokamak 下载免费PDF全文
In this paper,the singular value decomposition(SVD) method as a filter is applied before the tomographic inversion of soft-X-ray emission.Series of ’filtered’ signals including specific chronos and topos are obtained.(Here,chronos and topos are the decomposed spatial vectors and the decomposed temporal vectors,respectively).Given specific magnetic flux function with coupling m = 1 and m = 2 modes,the line-integrated soft-X-ray signals at all chords have been obtained.Then m = 1 and m = 2 modes have been identified by tomography of simulated ’filtered’ signals extracted by the SVD method.Finaly,using the experimental line-integrated soft-X-ray signals,m = 2 competent mode of complex magnetohydrodynamics(MHD) activities during internal soft disruption is observed.This result demonstrates that m = 2 mode plays an important role in internal disruption(Here,m is the poloidal mode number). 相似文献
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A compound sawtooth with an incomplete relaxation was observed in EAST’s lower hybrid current drive(LHCD)plasma. The sub-crash phase of the compound sawtooth corresponds to a longer-lasting and slower-growing 1/1 mode.Based on the two-dimensional(2D) SXR tomography, the time-dependent 2D image of a compound sawtooth crash is obtained. The island produced during a resistive internal kink mode is observed in the all crash phases of the compound sawtooth. The destabilization of 1/1 long-lasting saturated 1/1 mode is related to the current driven by the LHCD near the q = 1 surface. 相似文献
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利用HT-7装置上建立的多阵列软X射线诊断系统对等离子体放电中的锯齿不稳定性进行研究,发现锯齿的出现及其行为特点与等离子体电子密度Ne、电子温度Te、边界安全因子qα、壁条件等放电参数有密切关系。在低杂波电流驱动等离子体放电条件下,观察到m/n=1/1的中间模振荡出现在锯齿的上升阶段,并迅速发展、饱和、衰减,在锯齿塌陷或先兆振荡出现以前消失。分析和讨论了欧姆加热条件下和低杂波加热条件下的锯齿行为。 相似文献
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Operation of HT-7 tokamak in a multicycle alternating
square wave plasma current regime is reported. A set of AC operation
experiments, including LHW heating to enhance plasma ionization
during the current transition and current sustainment, is described.
The behaviour of runaway electrons is analysed by four HXR detectors
tangentially viewing the plasma in the equatorial plane, within
energy ranges 0.3--1.2~MeV and 0.3--7~MeV, separately. High energy
runaway electrons (\sim MeV) are found to circulate predominantly
in the opposite direction to the plasma current, while the number of
low energy runaway electrons (\sim tens to hundreds of keV)
circulating along the plasma current is comparable to that in the
direction opposite to the plasma current. AC operation with lower
hybrid current drive (LHCD) is observed to have an additional
benefit of suppressing the runaway electrons if the drop of the loop
voltage is large enough. 相似文献
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Repetitive 'Snakes' and Their Damping Effect on Core Toroidal Rotation in EAST Plasmas with Multiple H-L-H Transitions 下载免费PDF全文
Repetitive impurity snake modes are observed after H-L mode transitions (high to low confinement modes) in EAST plasmas exhibiting multiple H-L-H transitions. Such snake modes are observed to lower the core plasma toroidal rotation. A critical impurity strength factor associated with snake-mode formation is estimated to be as high as αz,c = nz,cZ^2/ne - 0.75. These observations have implications for ITER H-mode sustainability when the heating power is only slightly above the H-mode power threshold. 相似文献
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