HT-7超导托卡马克边缘涨落谱特征及湍流输运研究

用郎缪尔三探针对HT-7超导托卡马克边缘等离子体涨落进行了高时空分辩测量.给出了欧姆放电下涨落幅度的径向分布、谱特征及传播特性.实验观察表明,在由E_r×B确定的极向旋转速度剪切层附近,等离子体电位、电子温度和电子密度的相对涨落水平和两两间的相干系数均有明显下降,其极向互相关函数亦减小,这说明剪切层对涨落具有去相关作用.由涨落驱动的径向局域粒子输运通量Γ_tur测量显示出湍动输运具有时间上的阵发特性。将悬浮电位涨落φ_f2的自动率谱P_{( 关键词： 托卡马克 边界涨落 湍流输运}     

HL-1M托卡马克边缘参数和雷诺胁强的径向分布

利用多组马赫/郎缪尔探针测量了HL-1M装置刮离层和边缘静电雷诺胁强，等离子体极向旋转，径向和极向电场的径向分布，在低杂波电流驱动，超声分子束注入，多发弹丸注入和中性束注入实验中，给出了雷诺胁强和极向流的关系。结果表明，由于雷诺胁强的径向变化，托卡马克等离子体可以自发地产生剪切极向流。     

HL-2Aƫ����λ�εı�Ե������������

通过中平面活动10探针组、往复快速扫描4探针和低杂波天线口的固定4探针测量了主等离子体边缘的温度、密度、悬浮电位、径向和极向电场、雷诺协强、径向和极向等离子体流速及其径向分布。用偏滤器靶板上的14组嵌入式静电3探针阵列测量了同一环向截面的内外中性化板上的电子温度、密度、悬浮电位及其分布。比较了在孔栏位形和偏滤器位形下边缘等离子体特性的差异,特别是两种位形下边缘温度和密度衰减长度的变化。分析了在多脉冲超声分子束加料和低杂波注入条件下的边界等离子体特性,以及雷诺协强的径向梯度与极向流和径向电场梯度与湍流损失的相互关系。     

HL-2A��Ե�������估�����˵�ʵ���о�

在一次稳定放电过程中利用快速扫描气动探针系统得到电子温度、密度、等离子体电位、极向电场以及它们的涨落、粒子通量、能量通量在径向的分布。研究了HL-2A装置边缘的静电涨落及其输运。实验结果指出,在等离子体边缘涨落量不服从玻耳兹曼关系,存在由于等离子体空间电位的梯度所产生的径向电场剪切层。分析了涨落对边缘约束的影响。     

HL—1M装置LHCD和ECRH实验的边缘流速和电场测量

在聚变装置中等离子体边界条件对整个等离子体约束性能的影响是非常敏感的。L－H模转换机制与边界径向电场Er,Er的梯度及极向旋转速度等参数密切相关。同时,边缘等离子体的径向输运与边缘极向电场Eθ的变化有关。在HL－1M装置中利用低杂波（LHW）注入和电子回旋加热（ECRH）实验,观测边缘等离子体流速和电场的径向分布和变化来研究改善约束性能与Eθ、Er,dEr/dr及边界涨落的关系。     

东方超环上低杂波驱动等离子体环向旋转实验研究

旋转和旋转剪切能抑制磁流体不稳定性和增强等离子体约束.低杂波电流驱动作为未来聚变堆上可能的旋转驱动手段,探索低杂波在现有托卡马克装置上驱动等离子体旋转的驱动机制,可以为未来的聚变堆上旋转预测提供重要参考.在东方超环托卡马克装置上,早期发现了2.45 GHz的低杂波能有效驱动等离子体旋转的现象,认为是边界旋转的改变导致芯部旋转的同电流方向的增加造成的.更高频率下4.6 GHz低杂波电流驱动可以更有效地驱动同电流方向的等离子体旋转.本论文分析在欧姆背景等离子体下,不同功率的低杂波对等离子体环向旋转的影响,研究安全因子剖面变化对环向旋转的关系,利用功率调制获得了低杂波驱动旋转实验中的环向动量输运系数变化情况,发现环向动量扩散系数(χφ)、环向动量箍缩系数(Vpinch)的数值大小趋势是从芯部向靠外的区域逐渐变大.这与低杂波驱动环向旋转时,环向旋转速度由靠外的区域向芯部传递的特性吻合.     

HL-1M装置边缘等离子体结构研究

描述HL-1M装置上几种典型放电中的边缘等离子体物理实验结果.利用马赫/朗缪尔6探针组、静电4探针组、20组三探针阵列研究了低杂波电流驱动、超声分子束注入、多发弹丸注入和中性束注入放电中的粒子约束性能、等离子体旋转和边缘静电雷诺胁强的变化对改善约束的影响.给出了雷诺胁强和极向相速度的关系.结果表明，雷诺胁强的径向变化可以自发产生托卡马克等离子体的剪切极向流.LHCD能使低密度放电的粒子约束增加1至2倍.弹丸注入后，粒子约束时间和极向旋转至少可增加1倍，而SMBI可使粒子约束时间增加约一个数量级并取得高性能等离子体. 关键词： 粒子约束 雷诺胁强 极向流剪切 马赫/朗缪尔6探针组     

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。     

KT—5C边缘等离子体湍流性质的实验研究

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。     

HL-2A 装置的边缘参数测量

HL-2A 装置中平面边缘的等离子体特性通过磁力传动的马赫/ 雷诺协强/ 朗缪尔10 探针组进行了研究。10 探针组安装在可径向向里和向外移动, 并可绕轴旋转360^o 的传动杆上, 用于测量主等离子体边缘的温度、密度、悬浮电位、空间电位、径向和极向电场、湍流的雷诺协强、径向和极向等离子体流速及其径向分布。HL- 2A 装置的实验结果表明, 边缘等离子体扰动诱发的雷诺协强产生了边缘极向流; 雷诺协强的径向梯度驱动带状流抑制了湍流输运。     

Direct Measurements of E×B Flow and Its Impact on Edge Turbulence in the CASTOR Tokamak Using an Optimized Gundestrup Probe

New experimental evidence of the correlation between edge sheared E×B flow and reduction of turbulence has been measured in the CASTOR tokamak (R = 0.4 m, a = 0.085 m, B _T = 1 T). A biasing electrode is placed at the separatrix in a configuration which has demonstrated strongly sheared electric fields and consequent improvement of the global particle confinement. A set of movable electrostatic probes (rake, Langmuir, Gundestrup, and rotating Mach) provide redundant, simultaneous measurements of poloidal flow, toroidal flow, electron temperature, density, and radial electric field with high temporal resolution and at the same poloidal location. Particular effort has been made in the optimization of the Gundestrup probe collector geometry in order to reduce the relative uncertainty of Mach number measurements in plasmas with weak flow (M , M < 0.1). The measurements from the rake, Gundestrup, and rotating Mach probes give three independent radial profiles of E×B shear in ohmic and biased modes. Good agreement is obtained both for the profile shape and its absolute magnitude. The plasma flows, especially the poloidal E×B drift velocity, are strongly modified in the sheared region, reaching Mach numbers as high as half the sound speed. The corresponding shear rates (5×10⁶ s^-1) derived from both the flow and electric field profiles are in excellent agreement and are at least an order of magnitude higher than the growth rate of unstable turbulent modes as estimated from fluctuation measurements. In addition, we compare the measured E×B ion mass flow with the phase velocity of fluctuations moving poloidally across the Gundestrup collectors. Given the poloidal separation of the collecting plates and the sampling frequency (5 MHz), the maximum detectable phase velocity turns out to be rather modest compared to the measured bulk poloidal flow speed. Therefore the two quantities are only compared when the poloidal speed is low; in that case, they show similar behaviour in response to the applied bias.     

Poloidal Structure of the Turbulence and the Turbulent Flux During Edge Plasma Biasing in the Castor Tokamak

The poloidal structure of the turbulence and the turbulent particle flux in the scrape-off layer (SOL) of the CASTOR tokamak are analysed by means of a poloidal ring of 124 probes distributed uniformly along the whole poloidal circumference. Fluctuation measurements are performed in standard ohmic regime as well as in discharges when a biased electrode is inserted either into the SOL or deeper into the confinement region. It is found that in both cases a strongly sheared radial electric field is created in the SOL, which de-correlates the density and radial velocity fluctuations and reduces their levels. Consequently, the turbulent flux is reduced. However, no phase shift is observed between density and radial velocity fluctuations. When the electrode is localized in the confinement region, all the above effects are less pronounced because of a smaller shear. In addition, the increase of the E × B velocity at biasing leads in both cases to the formation of oscillations in the temporal correlation function. These oscillations are specifically associated to the poloidal mode (m = q), which is created for a limited time and rotates poloidally. This mode does not modify the phase between density and radial velocity fluctuations and has no further effect on the turbulent flux.     

Observations of Edge Plasma on HL-2A Tokamak

The edge plasma characteristics are studied by a movable array of Mach/Reynolds stress/Langmuir 10-probes and fast reciprocating 4-probes in the boundary region. These probes can measure edge plasma temperature, density, poloidal electric field, radial electric field, Reynolds stress, poloidal rotation velocities and their profiles obtained by changing the radial positions of the probe array in different discharges. Measurement resuits are used to analyze plasma confinement, turbulent fluctuations and their correlation. The fixed flush 3-probe arrays are mounted on the 4-divertor neutralization plates at the same toroidal cross-section in divertor chamber. These probes are used to measure the profiles of the electron temperature, density and float potential in divertor chamber.     

EDGE REYNOLDS STRESS STRUCTURE OF LOWER HYBRID WAVE INJECTION IN THE HL—1M PLASMA

The radial profiles of electrostatic Reynolds stress,plasma poloidal rotations,radial and poloidal electric fields have been measured in the plasma boundary region on the HL-1M tokamak using a multi-array of Mach/Langmuir probes.During experiments of lower hybrid wave current drive,the variations in LHW drive power xill cause changes in the edge electric field,poloidal rotation veloity and Reynolds stress.The results indicate that sheared poloidal flow can be generated in the edge plasma due to radially varied Reynolds stress.     

Experimental study on influence of cooling on glow discharge parameters

The influence of cooling of the discharge tube walls by the liquid nitrogen on some basic parameters of the neon glow discharge positive column is studied. By probe measurements, the longitudinal electrical fieldE _z, the electron concentrationn _e and the electron temperatureT _e are determined. The equation for determination of the radial profile of the relative electron concentration is derived and, on base of experimentally obtained quantities of the radial potentialV(r), this radial profile is computed.     

HL-2A装置中的带状流三维特性研究和探针设计

HL-2A装置边缘等离子体测地声模带状流的三维特征采用外中平面上三组三台阶探针阵列组成具有环向、极向和径向分辨的独特结构的探针系统进行了研究.其中两组具有极向距离为65mm的三台阶5探针阵列组成极向带状流10探针组,另一组电动式带状流6探针阵列与带状流10探针组之间的环向距离为800mm. 此外,采用快速往复气动6探针组研究了磁分界面附近的温度、密度、雷诺协强及其径向分布.在HL-2A装置上同时观测到测地声模带状流(频率f=7kHz)的极向和环向对称性(m≈0,n 关键词： 三台阶式ZF探针 带状流 三维空间结构     

HL-1M装置边缘参数测量

在HL－1M装置上利用马赫／郎缪尔探针分别在欧姆放电,低杂波注入,中性束注入,离子回旋加热和电子回旋加热等情况下测量下刮离层和等离子体边缘的极向流速度和电场,得到了它们的径向分布,研究了LHW,NBI,ICRH和ECRH对改善等离子体约束性能,边缘粒子的径向传输的影响。     

Observation of long-distance radial correlation in toroidal plasma turbulence

This Letter presents the discovery of macroscale electron temperature fluctuations with a long radial correlation length comparable to the plasma minor radius in a toroidal plasma. Their spatiotemporal structure is characterized by a low frequency of ～1-3 kHz, ballistic radial propagation, a poloidal or toroidal mode number of m/n=1/1 (or 2/1), and an amplitude of ～2% at maximum. Nonlinear coupling between the long-range fluctuations and the microscopic fluctuations is identified. A change of the amplitude of the long-range fluctuation is transmitted across the plasma radius at the velocity which is of the order of the drift velocity.