Electron temperature fluctuation in the HT-7 Tokamak plasma observed by electron cyclotron emission imaging

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 ρ_s≈ 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.     

Measurements of Reynolds stress and turbulence in the boundary plasma of the HT-7 tokamak

Measurements of electric field fluctuations, Reynolds stress and poloidal flow have been performed in the boundary region of the HT-7 tokamak using a Langmuir probe array.Sheared radial electric field and poloidal flow have been found in the vicinity of the limiter and the turbulence has been clearly modified in this region. Furthermore,the electrostatic Reynolds stress component shows a radial gradient close to the velocity shear layer location.All results here indicate that the radial gradient of Reynolds stress may play an important role in the driving of poloidal flows in the plasma boundary region.     

氢氘比的测量和粒子再循环

利用多道光学分析仪测量了HT－7托卡马克的氢氘比。通过一个简化模型讨论了氢氘比和粒子再循环的关系,并分析了氢氘比不容易控制的原因。     

氢原子能量分布和分子过程

利用多道光学分析仪（ＯＳＭＡ）系统进行了高分辨率的Ｈα的测量,从Ｈα线型分布直接得出氢原子的能量分布,由能量分布可知发生在等离子体边界的原子、分子过程是离子在限制器表面中性化后的反射,以及电子碰撞引起的氢分子的激发离解和电离离解。     

等离子体离子温度和角向旋转速度的测量

 利用多道光学分析仪测量了HT6M托卡马克CV227.1nm谱线线形分布,通过选点拟合得到了等离子体离子温度和旋转速度。     

Bootstrap Current Increment After Siliconization on the HT—7 Tokamak

We present some results for the estimation of the bootstrap current after sillconization on the HT-7 tokamak.After siliconization,the plasma pressure gradient and the electron temperature near the boundary are larger than before siliconization.These factors influence the ratio of the bootstrap current to the total plasma current which increases from several per cent to above 10%.The results are expected to explain the previous experimental phenomena that,after siliconization,the plasma current profile is broadened and the higher current can be obtained easily on the HT-7 tokamak experiment.     

HT–6M托卡马克表面加热实验中的光谱现象

 HT–6M表面加热实验中实现了H模式放电。分析了Ha 谱线，C III和O II谱线在L-H和H-L模转化过程中的变化情况，讨论了边界条件、粒子循环、杂质循环对L-H和H-L转化以及对H模的影响。     

在HT-7托卡马克上密度扫描实验中的边界湍流和输运

在HT-7托卡马克上密度扫描实验中使用一个快速扫描气动朗缪尔探针来研究边界湍流和输运。随着中心弦平均等离子体密度的增加，在等离子体边界观察到径向电场剪切增强，径向电场的增强能够解释边界输运的减小和全局粒子约束的改善。粒子约束时间的增加和垂直扩散系数的减小证明粒子输运降低了。在等离子体边界区域发现电离和辐射驱动湍流的特征，表明电离和辐射在湍流驱动过程中具有重要性。     

光谱法测量等离子体离子温度和旋转速度

分析多普勒展宽和多普勒频移的区别，讨论了弦积分的线形分布和高斯分布的差异，利用光谱多道分析仪测量了碳227．1nm谱线的线形分布，通过选点拟合得出辐射粒子的离子温度和旋转速度径向分布。     

HT－6M托卡马克表面加热实验中的光谱现象

ＨＴ—６Ｍ表面加热实验中实现了Ｈ模式放电。分析了Ｈα谱线，ＣⅢ和ＯⅡ谱线在Ｌ—Ｈ和Ｈ—Ｌ模转化过程中的变化情况，讨论了边界条件、粒子循环。