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-2A偏滤器位形的边缘等离子体特性

本实验利用主真空率和偏滤器靶板上的静电探针阵列直接测量边缘和偏滤器室的等离子体参数，即边缘温度Tea，密度nea，悬浮电位Фf，径向电场Er及其梯度dEr／dr，极向电场Ep，径向流速vr，极向流速vp.     

HL-2A装置YAG激光汤姆逊散射测量电子温度的初步结果

 叙述了激光汤姆逊散射的实验原理,介绍了HL-2A装置上改进后的激光汤姆逊散射系统。高脉冲功率Nd：YAG激光光源发出的1 064 nm的激光能很好地满足测量等离子体电子散射光的要求,硅雪崩光电二极管和窄带干涉滤波片组成的多色仪的使用,大大提高了散射光的测量效率。数据处理方法采用按测量误差进行权重分析的查表法,提高了数据处理的速度。最后介绍了各种放电条件下的单空间点电子温度的测量结果。     

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HL-2A和HL-1M装置采用了激光吹气注入高Z杂质来缓减大破裂中的等离子体电流衰竭,并给出了初步实验结果。在HL-2A装置上建立了利用MHD扰动的参量预报放电破裂先兆的报警系统,研制了MHD实时检测与处理系统,实现了放电破裂先兆的预报、快速触发激光吹气、形成阻性高辐射等离子体、消耗热能和磁能,缓减大破裂。实验证明,这是一种使得大型聚变实验装置在放电破裂之前显著减少等离子体中热能和磁能,而且能安全终止放电的简单、快速和有效的途径。     

汤姆逊散射技术在HL-2A装置上的应用进展

非相干激光汤姆逊散射诊断只需要假设电子速度满足Maxwell分布,测量得到的等离子体电子温度与电子密度的数据准确可靠,是托卡马克和其他磁约束核聚变研究装置上重要的诊断工具,并朝着高可靠性、高空间分辨和高重复测量频率的方向发展,其中高可靠性是前提。电子的汤姆逊散射截面很小,其总截面为σ_T=6.65×10^-25 cm²,通常使用电光调Q的Nd∶YAG激光器作为散射光源,激光脉冲宽度约10 ns、脉冲能量约3 J,用5～8通道的光谱仪对散射光谱进行测量与分析。如何对光电探测模块输出的散射脉冲进行数据采集,是激光散射诊断的关键问题之一。以前使用电流积分式的数据采集器(Q-ADCs,如CMC080模块),在一个确定的时间宽度(如50 ns)将散射脉冲信号积分在采样电容器上,从而得到散射信号的强度值,这种方法很难排除电路噪声和外来干扰。该研究通过使用高速数据采集器(纵向分辨率≥10 bits、采样频率f≥1 GS·s^-1,如V1742B模块)在包含散射信号在内的时间段(如300～500 ns)进行采集,获得散射...     

Preliminary analysis of impurity transport in HL-2A ohmic discharges

This paper describes the behaviour of impurity transport in HL-2A ohmic discharges. In 2005, small quantities of metallic impurities （A1, Ni and Ti） were successfully injected into HL-2A plasmas by laser blow-off technique, and their progression was followed by the soft x-ray cameras with good spatial and temporal resolutions. The impurity confinement time is estimated from the characteristic decay time of the soft x-ray signal of the injected impurities, and it is about 30-60 ms. The transport coefficients of impurities （including diffusion coefficient and convection velocity） in radial different region have been derived by using a one-dimenslonal impurity transport code, the results present that diffusion coefficient is much smaller in the central region of plasmas than the outside of it, and it is much larger than that of neoclassical theory predictions; namely, it is anomalous.[第一段]     

Observation of chaotic ELMs in HL-2A tokamak

The high confinement mode(H-mode) operation is recently obtained in HL-2A divertor configuration,the corresponding edge localized mode(ELM) is recognized as being of type III.Time intervals in ELM time series are analysed to obtain the information about the ELM process.Signatures of unstable periodic orbits(UPOs) are detected,which are indicators of chaos and may be used to control the big ELM events.     

微悬臂梁传感器对中药成分的非标记检测

利用微悬臂梁传感技术对两种中药成分(青蒿素与马兜铃酸)抗原抗体的特异性结合进行检测。首先用巯基化二抗将青蒿素或马兜铃酸抗体通过自组装法修饰到微悬臂梁的金面上,再加入不同浓度的青蒿素或马兜铃酸抗原,采用光杠杆原理监测微悬臂梁的实时变形。该系统能够检测出至少100ng/ml浓度的青蒿素与500ng/ml的马兜铃酸标准样品,并与ELISA实验所得的活性标准曲线趋势相对应。由于青蒿素抗体活性比马兜铃酸抗体活性强,因此检测出的青蒿素极限浓度较低。结果表明,利用微悬臂梁传感技术对中药成分的检测是可行的。     

人工神经网络在HL-2A装置汤姆逊散射数据处理中的应用

人工神经网络是一种强大的非线性数据分析算法,其中的感知器神经网络第一次被用于处理HL-2A装置上汤姆逊散射系统的电子温度数据。采用输入层、隐藏层和输出层等三层神经网络结构,输入层为标定数据或测量数据,隐藏层使用sigmoid函数作为传递函数,输出层为电子温度值。从数据处理结果可以看出,该计算方法与传统的χ²最小值方法计算的结果吻合,能够得到可靠的电子温度数据。而且由于计算温度时采用矩阵计算,计算速度比使用χ²最小值法提高20倍以上,为将来利用汤姆逊散射测量的电子温度数据实现等离子体剖面实时反馈控制提供了可能。     

Properties of plasma radiation during discharges with improved confinement on HL-2A Tokamak

In the recent experiment on the HL-2A tokamak,two types of improved confinement regimes have been achieved in different configurations.One is the improved confinement regime in limiter configuration during electron cyclotron resonant heating (ECRH),characterized by a sharp decrease in H α emission accompanied by an increase in the total radiation of plasma,the line averaged electron density and the stored energy of plasma.The other is high confinement regime (H-mode) in divertor configuration during a combination of ECRH and Neutral beam injection (NBI) heating,characterized with edge localized modes (ELMs) besides the features mentioned above.The ELMs are found to be localized on the plasma edge (r/a ≥ 0.8),causing average losses of particles and stored energy in the ranges of about 1-3% and 3-5% respectively during a single ELM event.So far,the ELMs observed in the HL-2A are type III ELMs with low amplitude and high repetition frequency in a range from 200 Hz to 350 Hz.An investigation of the radiated power density profiles shows that radiative cooling effect plays a significant role in the transition back to the L-mode and the triggering of ELM events.