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1.
为了拓宽等离子体参数测量范围,对EAST极向弯晶谱仪(PXCS)进行了升级改造。配合高通量大面积水冷固体探测器,提高了极向弯晶谱仪系统的光子计数率、时间分辨率、空间探测范围以及长时间运行稳定性,并在EAST装置上成功运行。实验结果表明,升级后的谱仪获得了高信噪比的类氦氩离子的母线及其一系列伴线谱,通过光谱拟合分析给出了等离子体温度时间演化及其剖面信息,测量结果与切向弯晶谱仪的数据一致,验证了极向弯晶谱仪的升级结果和数据测量的可靠性,并且在EAST长脉冲实验运行也能够稳定地提供全时间的参数分布。  相似文献   
2.
The effect of passive plates on vertical displacement control in the EAST tokamak is investigated by open loop experiments and numerical simulations based on a rigid displacement model.The experiments and simulations indicate that the vertical instability growth rate is reduced by a factor of about 2 in the presence of the passive plates,where the adjacent segments are not connected to each other.The simulations also show that the vertical instability growth rate is reduced by a factor of about 10 if all adjacent segments on each passive plate loop are connected to each other.The operational window is greatly enlarged with the passive plates.  相似文献   
3.
利用径向可移动朗缪尔三探针和马赫探针对HT-7超导托卡马克边界等离子体参量及其涨落进行了空时空分辨测量.给出了欧姆放电及其与低杂波电流驱动共同作用下边界等离子体电位φp、电子温度Te和电子密度ne及其涨落的径向分布.实验表明,在限制器附近,存在一由Er×B确定的极向旋转速度剪切层.在剪切层内,Te和ne分布较陡,且φp,Te和ne的相对涨落水平下降明显.这说明剪切层对边界区的等离子体涨落具有抑制作用.低杂波驱动使径向电场梯度变陡,从而使剪切程度加深但对剪切层宽度无影响.此外,测量表明等离子体环向速度马赫数Mφ存在径向梯度.环向流的这种径向梯度可能是形成径向电场所需的平均极向流的一种重要驱动源 关键词: 托卡马克 边界涨落 低杂波驱动  相似文献   
4.
用勒让德级数处理Abel变换   总被引:1,自引:0,他引:1       下载免费PDF全文
阮怀林  万宝年  张先梅  刘建坤 《物理学报》2001,50(12):2393-2397
提出了一种处理弱非中心对称Abel变换的新方法.把测量的积分值用Yasutomo的方法分成奇、偶两部分.非对称的原函数被表达为一个权函数和一个中心对称函数之积.对称函数用勒让德级数展开.级数的系数通过用最小二乘法来决定 关键词: Abel变换 勒让德级数 测试函数 对称 非对称  相似文献   
5.
Lower hybrid current drive (LHCD) experiments for investigating the interaction between lower hybrid (LH) wave and residual dc electric field were performed in extensive plasma parameter ranges in the HT-7 superconducting tokamak. The experimental results are well fitted to the Karney-Fisch theory on the efficiency of LH waves energy converted to poloidal magnetic field energy. The fraction of absorbed LH power is about 0.75 for the HT-7 machine, and the upshift of the LH-wave parallel refraction index during LHCD experiments have been derived by the optimizing fitting parameters. The LH wave is also used for the transformer recharging when the plasma current is maintained unchanged. The highest efficiency about 7% has been achieved in HT-7 machine.  相似文献   
6.
More than 70% of the total plasma current is sustained by the bootstrap current and current drive during the synergy of lower hybrid current driving (LHCD) and ion Berstein wave (IBW) heating on the HT-7 tokamak.The lower hybrid non-inductive current source is off-axis and well localized, and more than 35% bootstrap current plasma has been obtained. The IBW in controlling electron pressure profile can be integrated into the LHCD target plasma. The largest steep gradient of the electron pressure profile in the region ρ - 0.5-0.7 mostly comes from the electron temperature profile, which may induce the large fraction bootstrap current. The large off-axis bootstrap current can help to create negative magnetic shear, and the good plasma confinement is achieved.  相似文献   
7.
通过对托卡马克中模拟积分器积分误差的分析,设计了一种由数字信号处理部件动态抑制这些误差的斩波式积分器,并在实验中获得了长时间、低漂移的积分效果。  相似文献   
8.
周倩  万宝年  吴振伟  黄娟 《中国物理》2005,14(12):2539-2545
The line-integrated optical measurement of impurity radiation profiles for the study of light impurity transport is performed in the HT-7 tokamak. The carbon impurity line emissivity is obtained by Abel inversion. The radial transport behaviours of carbon impurities at different central line averaged electron densities ne are investigated in ohmic discharges. The diffusion coefficient Dk(r), the convection velocity Wk(r) and the total flux of the impurity ions Fk decrease with the increase of ne, which shows a reduction in the impurity particle transport at higher electron densities.  相似文献   
9.
By applying ion Bernstein wave (IBW) heating into the lower hybrid current drive (LHCD) plasma, improved confinements have been obtained in the HT-7 tokamak. The central electron temperature was doubled and the storage energy was increased significantly. The core electron density and temperature were broadened and ther profiles near the edge were steepened. A transport barrier has been formed in the vicinity of the limlter radial location. An enhanced shear in poloidal phase velocity was found in the same region with reduction of the fluctuation levels and the coherences between fluctuations. The results suggest that the improved confinement in the IBW and LHCD plasma is at least partially due to the modification of shear in poloidal velocity and then the suppression of fluctuations and fluctuation induced fluxes via de-correlation effect.  相似文献   
10.
It is the first time so far as we know that two arrays of multi-channel soft x-ray detectors are used to generate twodimensional (2D) images of sawtooth oscillation on the HT-7 tokamak using the Fourier-Bessel harmonic reconstruction method, and using the singular value decomposition to analyse the data from soft x-ray cameras. By these two arrays, 2D image reconstruction of soft x-ray emissivity can be obtained without assumption of plasma rigid rotation. Tomographic reconstruction of the m=1 mode structure is obtained during the precursor oscillation of the sawtooth crash. The crescent-shaped mode structure appearing on the contour map of the soft x-ray emissivity is consistent with the quasiinterchange mode. The characteristics of the m=1/n=1 mode structure observed in the soft x-ray tomography are as follows: the magnetic surface is made up of the crescent-shaped “hot core” and the circular “cold bubble”. The structure of the magnetic surface rotates in the direction of the electron diamagnetic drift and the rotation frequency is the oscillation frequency of soft x-ray signals.  相似文献   
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