Coated boron layers by boronization and a real-time boron coating using an impurity powder dropper in the LHD

In the Large Helical Device(LHD),diborane(B2H6)is used as a standard boron source for boronization,which is assisted by helium glow discharges.In 2019,a new Impurity Powder Dropper(IPD)system was installed and is under evaluation as a real-time wall conditioning technique.In the LHD,which is a large-sized heliotron device,an additional helium(He)glow discharge cleaning(GDC)after boronization was operated for a reduction in hydrogen recycling from the coated boron layers.This operational time of 3 h was determined by spectroscopic data during glow discharges.A flat hydrogen profile is obtained on the top surface of the coated boron on the specimen exposed to boronization.The results suggest a reduction in hydrogen at the top surface by He-GDC.Trapped oxygen in coated boron was obtained by boronization,and the coated boron,which has boron-oxide,on the first wall by B-IPD was also shown.Considering the difference in coating areas between B2H6 boronization and B-IPD operation,it would be most effective to use the IPD and B2H6 boronization coating together for optimized wall conditioning.     

Spatially-resolved flat-field soft X-ray spectrometer on experimental advanced superconducting tokamak

A space- and time-resolved flat-field soft X-ray spectrometer with the wavelength range of 1–13 nm has been developed to study impurity behavior on the Experimental Advanced Superconducting Tokamak (EAST). Using an entrance slit, a varied line spacing grating (2400 grooves/mm at the grating center), and a charged coupled device (CCD) system, time evolution of profiles of impurity line emissions were recorded. The spectral resolution of the spectrometer is 0.006 nm at 5 nm when the width of entrance slit is set at 0.03 mm. The best spatial resolution obtained is 24.5 mm with the height of slit at 1.0 mm. The spectrometer is placed 8000 mm away from the plasma center and the observed spatial range covers 0–450 mm from the equatorial plane of EAST. The first experimental results were obtained from the recent EAST campaign. The system was shown to be capable of observing spectral lines from both intrinsic low-Z impurities (C, O, et al.) and highly ionized medium- and high-Z impurities (Fe, Cr, Ni, Cu, et al.). Spectral lines from the full wavelength range (1–13 nm) can be obtained by moving the position of the CCD. Spectra with the wavelength intervals of 1–2 nm show strong metal lines for H-mode discharges. Time evolutions of C VI (3.373 nm) and O VIII (1.897 nm) lines are presented and detail analysis is performed combining electron density intensity, D_α and soft X-ray and extreme ultraviolet (XUV) radiation intensities. Evolutions of profiles of C VI (3.373 nm) and O VIII (1.897 nm) at core plasma were also shown, indicating that the spectrometer can be applied for impurity transport studies,     

Impurity Measured by VUV Spectrometer and OMA on HL-2A Tokamak

Impurity is one of the key issues on a great impact to the quality of tokamak plasma.HL-2A is the first divertor tokamak in China. In this paper the experimental results are presented on impurity through the line emission measurement in the campaign in 2003 under the limiter and divertor configurations. The low-Z impurities such as carbon and oxygen are the most important components in the plasma, but their content are not so high to affect the discharge quality. The high-Z impurities such as copper and ferrum are not essential. The emission intensity of impurity is clearly decreased during the divertor configuration formed.     

基于SOPC技术的EAST定时与同步系统

定时与同步系统是托卡马克装置实现等离子体放电流程实时控制的基础。基于SOPC技术研制的EAST分布式定时与同步系统可为各子系统提供精确时钟和同步触发信号,使装置各子系统按照预先设定好的流程运行,实现EAST等离子体放电实验时序的精确控制。EAST定时与同步系统的时序精度高于1μs,可以满足当前EAST实验的需要。     

EAST全超导托卡马克装置失超保护检测技术的现状及发展

EAST装置是九五国家重大科学工程项目之一,做为世界上第一个全超导托卡马克装置,其纵场和极向场线圈全部由超导磁体组成,进行安全,准确,有效的失超保护是装置安全运行的首要环节。如何在全超导托卡马克装置这样复杂的电磁环境进行失超检测在世界上也无先例可寻。EAST上失超检测系统经过几十轮单饼超导线圈实验及两轮装置正式放电实验后逐步建立和完善起来,并已通过工程验收达到装置实验运行要求。主要介绍了EAST超导装置失超检测系统的基本结构和检测原理,同时还简述失超检测技术的发展并给出了实验结果。     

EAST等离子体电子密度测量与处理算法设计

介绍EAST托卡马克中HCN 激光干涉仪测量等离子电子密度基本原理,给出了等离子体电子密度HCN信号处理算法,该算法能准确地去零漂并有效的进行信号翻转处理,并利用小波分析的方法对信号进行去噪处理,获得了高精度低噪音的HCN信号.该算法同样可用于HT7托卡马克五道HCN信号处理中,利用好的HCN信号可以更加准确地反演等离子体密度空间分布,这种密度处理算法是行之有效的.     

Observation of the Two-Dimensional Distribution of Impurity Line Emissions Using a Space-Resolved EUV Spectrometer in LHD

A space-resolved EUV spectrometer for measuring the one-dimensional distribution of impurity line emissions in Large Helical Device (LHD) has been upgraded to measure two- dimensional distributions of impurity line emissions with an extension of working wavelength range to 30～650 A. The two-dimensional measurement is performed by scanning the observation chord horizontally. A rectangular plasma region of 520 × 700 mm 2 in vertical and horizontal sizes can be observed during a single horizontal scan. The horizontal scan requires a time duration of 5 s at least. The spatial resolution is 10 mm in the vertical direction when a spatial-resolution slit of 0.2 mm in width is adopted. Although a spatial resolution in the toroidal direction is 75 mm, it is a function of CCD exposure time and horizontal scanning speed. Two-dimensional distribution of EUV line emissions from several impurities has been successfully observed for the first time from steady discharges in LHD. In this paper two-dimensional distributions of He II (303.78 A), C V (40.27 A), C VI (33.73 A) and Fe XX (132.85 A) located at different radial positions are presented with simple analysis on the magnetic field structure of LHD.     

EAST安全联锁监管系统设计

全超导托卡马克装置(FullSuperconductingTokamak,FST)所有主要磁体均为超导磁体,其运行风险大大高于现有的其它超导托卡马克。EAST(ExperimentalAdvancedSuperconductingTokamak)是一个全超导托卡马克装置,为了避免人员和装置出现意外事故,建立了联锁系统与安全系统。安全联锁监管系统位于EAST联锁系统与安全系统的顶层,协调各分控系统的安全运行。根据EAST安全联锁系统的需求,采用可编程逻辑控制器、联锁信号光纤网和光电转换设备,建立了安全联锁监管系统,实现了事件收集、信号循环扫描、保护动作输出、系统状态和故障日志信息记录和实时监控等功能。该系统实际扫描周期平均值约0.7ms,最大值约3ms,达到了EAST安全联锁系统的要求。     

EAST装置大功率速调管保护系统研制

依据速调管耗散能量的安全值与最大故障电流、电弧电压和电源供电切断时间的关系,介绍了EAST上2.45 G/2 MW低杂波速调管过流保护系统的设计。采用过电流电路触发和引燃管旁路速调管电流的方法来实时保护速调管。经自检测试和在EAST放电实验中的应用表明,该系统能在50μs内完成保护,完全满足设计需求。     

Zeff first measurements in EAST with a multi-channel visible bremsstrahlung new system

A multi-channel visible bremsstrahlung measurement system was developed to measure the ion effective charge (Z_eff) in EAST tokamak. The system has a temporal resolution of 0.05 ms and spatial resolution of 3 cm. The measurement principle and the design of the 8-channel fiber-photomultiplier tubes (PMTs) coupled system are described, including the calibration process of the measurement system with an integrating sphere. Preliminary experimental results of line integrated bremsstrahlung profile and Z_eff derived from the system are reported.