共查询到19条相似文献,搜索用时 390 毫秒
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利用具有极向和径向结构的三探针在HL-2A装置等离子体边缘最后闭合磁分界面以内5cm左右,对静电湍流的谱特征进行了实验研究。空间二级关联分析指出,静电湍流主要是由具有低频和长波长的波胞组成,波胞以内都是相关结构;波在极向的传播主要是沿电子逆磁漂移方向,偶尔也会由于多谱勒频移造成在离子逆磁漂移方向的频率分量。静电波在径向向外传播,其速度的大小与极向相速度相当,这个特征意味着径向模对横越磁场的输运有重要的影响。 相似文献
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利用四探针方法系统地研究了KT-5C托卡马克边缘等离子体的湍流性质。实验结果指出,在限制器内0.5cm处,有一自然产生的径向电场剪切层,由Er×B引起的等离子体整体的极向旋转在剪切层外沿着离子逆磁漂移方向,而在剪切层内则是沿着电子逆漂移方向的。 相似文献
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用可见光谱测量HL—1M等离子体的旋转速度 总被引:1,自引:1,他引:0
用SKD高分辨光谱仪测量系统测量了CⅢ、CⅡ、OⅡ及Ha等谱线辐射的多勒位移,给出了HL-1M托卡马克等离子体旋转速度,结果表明:环向旋转速度vψ右到22km·s^-1,角向旋转速度vθ在等离子体内部与电子逆磁漂移方向同向,在r=22cm附近转变为离子逆磁漂移方向,存在极大值9.6km·s^-1,氢弹丸注入时角向旋转反向,在接近孔栏处又变为电子逆磁漂移方向。激光吹气注入杂质时,vθ减小。低杂波注入 相似文献
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利用高分辨光谱测量系统,根据杂质离子谱线OⅡ464.2nm,CⅢ464.7nm和氢Hα谱线的多普勒位移,测量了CT-6B托卡马克等离子体角向转动速度的径向分布.结果表明:杂质离子的角向转动速度的方向在等离子体内部为电子逆磁漂移方向,其线速度在小半径约9cm处达到极大值3.5km/s;在接近孔阑r=10cm处,反转为离子逆磁漂移方向.由此导出等离子体内部的径向电场向里,其最大值为18V/cm.中性氢原子只存在其方向为电子逆磁漂移方向的角向转动分量,其数值较杂质离子谱线所得结果要低.最后对所得的结果作了初步的讨论
关键词: 相似文献
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对等离子体湍流速度场的有效探测,有助于更加深入了解磁约束等离子体湍流以及实现对某些理论预言现象和结构(如带状流)的充分辨识.本文将基于动态程序规划的时间延迟估算技术成功应用于直线磁化等离子体装置中热阴极放电条件下的漂移波湍流角向速度涨落的实验分析,并且其结果清晰再现了漂移波湍流中通过非线性能量耦合自发产生的带状流结构.通过对采用不同频段等离子体湍流涨落通过基于动态程序规划的时间延迟估算分析所再现的带状流结构特征进行比较,进一步就该算法对载波信号中非相干噪声相对水平的抗干扰能力进行了定性评估.这些工作的成功开展,对于通过采用基于动态程序规划的时间延迟估算分析技术更为深入有效探索磁约束等离子体湍流行为特征,尤其是速度涨落场的演化提供了重要的借鉴和参考价值. 相似文献
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首次报导了托卡马克等离子体边缘与湍流相关的极向剩余胁强剖面的测量结果。采用外中平面往复式静电探针阵列对HL-2A托卡马克边缘的极向湍流动量输运进行研究。在没有外部动量注入的欧姆放电下,剩余胁强为有限值、且其空间剖面在等离子体边缘具有明显的径向梯度,表明托卡马克等离子体边缘存在极向动量源。由动量源产生的动量主要以扩散形式向与剩余胁强相反的方向传播,最终的结果是等离子体边缘存在有限的雷诺胁强。在最后闭合磁面以内0.5~2cm区域,剩余胁强的梯度提供自发旋转的力矩,由该力矩引起的动量产生与由速度梯度引起的动量扩散共同导致了雷诺胁强出现负梯度,造成动量沉积,从而驱动极向平衡流。 相似文献
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Hamada Y Watari T Yamagishi O Nishizawa A Narihara K Kawasumi Y Ido T Kojima M Toi K;JIPP T-IIU Group 《Physical review letters》2007,99(6):065005
When Ohmically heated low-density plasmas are additionally heated by higher-harmonics ion-cyclotron-range-of frequency heating, heated by neutral beam injection, or strongly gas puffed, the intensity of zonal flows in the geodesic acoustic mode frequency range in the tokamak core plasma decreases sharply and that of low-frequency zonal flow grows drastically. This is accompanied by a damping of the drift wave propagating in the electron diamagnetic drift direction, turbulence by trapped electron mode (TEM), and the increase of the mode propagating to ion diamagnetic drift direction (ITG). In the half-radius region, TEM and high-frequency zonal flows remain intense in both OH and heated phases. ITG and low-frequency zonal flows grow in heated plasmas, suggesting a strong coupling between ITG and low-frequency zonal flow. 相似文献
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The poloidal rotation velocity of neutral hydrogen atoms is measured using the Doppler shift of the Hα spectral line emitted in the CT-6B tokamak. The poloidal rotation of hydrogen atoms is generated through the collisions and charge-exchanges with main ions (protons). Therefore, the rotation direction of main ions can be deduced from that of neutral hydrogen atoms. The experimental results show that the main ions rotate in the electron diamagnetic drift direction, the same as the impurity ions, in the plasma core. The neutral hydrogen atoms rotate also in the electron diamagnetic drift direction in the edge region of the plasma. However, the rotation direction of main ions in the edge region cannot be judged from the experimental result due to the long mean free path of hydrogen atoms in the edge region. An inward diffusion flux of hydrogen atoms toward the torus inside with a velocity of the same order of magnitude as their poloidal rotation is also observed. 相似文献
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The recently discovered properties of the I-confinement Regime are explained as resulting from the excitation of a heavy particle mode. The theoretically predicted mode phase velocity in the direction of the electron diamagnetic velocity and the induced confinement of impurities at the edge of the plasma column have been confirmed by the experiments. The direction of the mode phase velocity is consistent with that (opposite) of the spontaneous rotation in the plasma core. The mode is of the “ion-mixing” type, in that it does not produce any electron transport across the fields and it involves significant poloidal magnetic field fluctuations. 相似文献
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Very low frequency (50 to 500 Hz) self-excited electrostatic waves are detected in a cylindrical argon plasma column with a weak axial magnetic field (10 to 100 G). The waves propagate azimuthally with a phase velocity in the electron diamagnetic drift direction, but with a speed at least an order of magnitude less than the ion acoustic speed. A number of known plasma instabilities are considered as possible explanations, though most of them do not seem to account for the observed characteristics of the waves. 相似文献
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Xu Y Weynants RR Jachmich S Van Schoor M Vergote M Peleman P Jakubowski MW Mitri M Reiser D Unterberg B Finken KH;TEXTOR Team 《Physical review letters》2006,97(16):165003
Systematic measurements on the edge turbulence and turbulent transport have been made by Langmuir probe arrays on TEXTOR under various static Dynamic Ergodic Divertor (DED) configurations. Common features are observed. With the DED, in the ergodic zone the local turbulent flux reverses sign from radially outwards to inwards. The turbulence properties are profoundly modified by energy redistribution in frequency spectra and suppression of large scale eddies. The fluctuation poloidal phase velocity changes direction from electron to ion diamagnetic drift, consistent with the observed reversal of the Er x B flow. In the laminar region, the turbulence is found to react to an observed reduced flow shear. 相似文献
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In this Letter we report an experimental study of fully developed anisotropic magnetic turbulence in a laboratory plasma. The turbulence has broad (narrow) spectral power in the perpendicular (parallel) direction to the local mean magnetic field extending beyond the ion cyclotron frequency. Its k[see symbol] spectrum is asymmetric in the ion and electron diamagnetic directions. The wave number scaling for the short wavelength fluctuations shows exponential falloff indicative of dissipation. A standing wave structure is found for the turbulence in the minor radial direction of the toroidal plasma. 相似文献
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Electron temperature fluctuation in the HT-7 Tokamak plasma observed by electron cyclotron emission imaging 下载免费PDF全文
The fluctuation of the electron temperature has been measured by
using the electron cyclotron emission imaging in the Hefei Tokamak-7
(HT-7) plasma. The electron temperature fluctuation with a broadband
spectrum shows that it propagates in the electron diamagnetic drift
direction, and the mean poloidal wave-number $\bar{k}_{\theta}$is
calculated to be about 1.58 cm-1, or
\bar{k}θ ρs≈ 0.34. It indicates that the
fluctuation should come from the electron drift wave turbulence. The
linear global scaling of the electron temperature fluctuation with
the gradient of electron temperature is consistent with the mixing
length scale qualitatively. Evolution of spectrum of the fluctuation
during the sawtooth oscillation phases is investigated, and the
fluctuation is found to increase with the gradient of electron
temperature increasing during most phases of the sawtooth
oscillation. The results indicate that the electron temperature
gradient is probably the driver of the fluctuation enhancement. The
steady heat flux driven by electron temperature fluctuation is
estimated and compared with the results from power balance
estimation. 相似文献
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Conway GD Borba DN Alper B Bartlett DV Gormezano C von Hellermann MG Maas AC Parail VV Smeulders P Zastrow KD 《Physical review letters》2000,84(7):1463-1466
Correlation of density turbulence suppression and reduced plasma transport is observed in the internal transport barrier (ITB) region of JET tokamak discharges with optimized magnetic shear. The suppression occurs in two stages. First, low frequency turbulence and ion transport are reduced across the plasma core by a toroidal velocity shear generated by intense auxiliary heating. Then with the ITB formation, high frequency turbulence and electron transport are reduced locally within the steep pressure gradient region of the ITB. 相似文献
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D. L. Brower N. C. Luhmann Jr. W. A. Peebles Ch. P. Ritz E. J. Powers 《International Journal of Infrared and Millimeter Waves》1986,7(3):447-457
Summary The wave propagation direction of microturbulence in a tokamak plasma has been accurately measured by application of a new homodyne spectroscopy technique. This method has been used in conjunction with a collective far-infrared laser scattering experiment on TEXT. The low-frequency density fluctuations are observed to propagate primarily in the electron diamagnetic drift direction, however, the broadband spectra also possess an appreciable level of fluctuations traveling in the ion drift direction. Application of the homodyne spectroscopy technique represents an inexpensive and easily implemented alternative to the more technically demanding heterodyne schemes available in the far-infrared. 相似文献