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]     

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利用多道远红外HCN激光干涉仪实时测量了等离子体中的粒子数增量,首次得到了HL-2A等离子体偏滤器位形和孔栏位形下强场侧和弱场侧SMBI的加料效率,结果与法国Tore Supra装置的SMBI加料效率的范围相一致。     

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在HL-2A装置孔栏位形放电的等离子体实验中,电子回旋辅助加热期间观察到了等离子体约束改善的现象,并对等离子体从低约束模式(L模)向约束改善模式转换时的等离子体线平均电子密度、等离子体储能、分界面内辐射功率、能量约束时间、Hα辐射等进行了研究。同时,分析了电子密度和等离子体辐射功率的空间分布随时间的演化。对改善约束的相关功率(辅助加热、欧姆加热功率和损失功率)进行了分析,并研究了等离子体约束改善转换时的边界净输入功率(阈值)与电子线平均密度和环向磁场的关系。     

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.     

星敏感器光学系统弥散斑测试方法

提出了一种星敏感器光学系统弥散斑尺寸的测试方法,主要是利用平行光管、转台和CCD显微摄像系统组成弥散斑测量系统,采集图像后,采用双三次插值像元细分,提取图像中灰度值,依据瑞利判据计算弥散斑尺寸。通过实际测量和试验验证,光学系统0.8视场弥散斑测量精度可以达到0.5μm,重复测量精度可达0.2μm。     

基于HCN波形数据的等离子体密度计算方法初探

本文介绍基于HCN波形数据的等离子体密度计算方法，内容包括基准电平、相对于零相位点时间的确定方法以及在此基础上的密度计算过程和方法；此外，本文还给出了若干改进处理结果的想法。     

HL-2A装置高密度破裂的实验观测

大破裂发生时，不仅会在第一壁和偏滤器靶板上产生大的热负载沉积。并会由于晕电流而产生强烈电磁力。这种电磁力能够对偏滤器室及真空室内的部件造成损害。因此，如何避免大破裂放电是托卡马克运行中一个重要课题。为了减轻和控制大破裂，必须清楚地认识其产生机制和发生特性。     

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介绍了在HL-2A装置上远红外激光干涉诊断系统第一镜的溅射和沉积实验。比较了实验前后第一镜反射率的变化,分析了污染后的第一镜表面杂质成分,提出了用挡板防护第一镜的方法。     

超声分子束在HL-1M托卡马克等离子体中的消融和穿透

讨论并研究了超声分子束在托卡马克等离子体中的消融和穿透问题，其中包括了分子束的绝热膨胀，团簇的形成和解离，束的静电屏蔽效应和冷通道效应.研究结果表明，在考虑了这些效应以后数值得到的结果与实验结果相近.这些研究对于更好地理解超声分子束与等离子体的相互作用和优化设计加料系统有一定作用. 关键词： 超声分子束 加料 托卡马克等离子体 消融和穿透     

Particle confinement and density profile behaviour on HL-1M

In this paper the density profile behaviour and the particle confinement operation regime on HL-1M have been studied under the pellet injection (PI), supersonic molecular beam injection (SMBI), gas puffing (GP) and lower hybrid current drive experimental situations. The relationships between density profile, particle confinement time and edge safe factor have been explored. The density profile, which is measured by six-channel far-infrared ray laser interferometer has been analysed by using the peaking coefficient calculation code. Changes of the outward and inward diffusion velocities before and after the peaking of the central density profile have been calculated using the global particle balance equations. The particle confinement operation regimes have been discussed. The peaking density profile can be easily obtained under the condition of efficient fuelling. In ohmic discharges, confinement time increases as the peaking density profile factor rises, and is saturated at a critical value related to the fuelling efficiency. The particle confinement time of SMBI lies between the values of GP and PI, and its value is about 3-5 times of the energy confinement time.