Control System of Neutral Beam Injection on HT-7

Neutral Beam Injection control system (NBICS) is constructed to measure the plasma current, Magnet current, vacuum pressure, cryopump temperature, control water cooling, filament voltage, and power supply， etc. The NBICS, consisting mainly of a Programmable Logic Controller (PLC) subsystem, data acquisition and processing subsystem and cryopump and vacuum pressure monitoring subsystem, has successfully been used on a NBI device. In this article, the design of NBICS on HT-7 is discussed and each subsystem is described in particular.In addition, some experimental results are reported which are very important data for further research related to the HT-7 tokamak.     

中性束注入器Tank充气特性对离子源放电的影响

利用对PV-10型压电阀定标实验,研究了中性束注入器Tank内补充气体的参数对离子源放电弧电流的影响,对比压电阀脉冲电源的脉宽和幅值,显示后者对Tank内补充气体量具有更显著的线性关系.据此进行的中性束注入器离子源放电实验结果表明,采用压电阀定标值计算获得的参数,可以稳定重复地获得最大放电脉宽达到400 ms的等离子体弧电流,为下一步向托卡马克装置注入高能中性粒子束奠定了应用基础.     

Thermal analysis of EAST neutral beam injectors for long-pulse beam operation

Two sets of neutral beam injectors(NBI-1 and NBI-2) have been mounted on the EAST tokamak since 2014. NBI-1 and NBI-2 are co-direction and counter-direction, respectively. As with indepth physics and engineering study of EAST, the ability of long pulse beam injection should be required in the NBI system. For NBIs, the most important and difficult thing that should be overcome is heat removal capacity of heat loaded components for long-pulse beam extraction. In this article, the thermal state of the components of EAST NBI is investigated using water flow calorimetry and thermocouple temperatures. Results show that(1) operation parameters have an obvious influence on the heat deposited on the inner components of the beamline,(2) a suitable operation parameter can decrease the heat loading effectively and obtain longer beam pulse length, and(3) under the cooling water pressure of 0.25 MPa, the predicted maximum beam pulse length will be up to 260 s with 50 keV beam energy by a duty factor of 0.5. The results present that, in this regard, the EAST NBI-1 system has the ability of long-pulse beam injection.     

Using Adaptive Discrete-Time Gas Supply Control for Long Pulse Arc Discharge of Ion Source on NBI

A control model of gas supply system is introduced for ion source and an adaptive discrete-time control algorithm to regulate the hydrogen injection. A real-time feedback control system （RFCS） is designed to control the gas supply for ion source based on the control model and the discrete-time control algorithm. The experimental results have proved that RFCS could regulate the gas supply smoothly, suppress the arc＇s abrupt over-current at the end of the ion source discharging, prolong the discharge pulse and stabilize the ion concentration. With RFCS, the ion source for neutral beam injection has reached its longest pulse with a length of 4.5 seconds in a stable status.     

Experimental Study of Diagnosis Neutral Beam for HT-7 Tokamak

Parametrical effect on plasma discharge and beam extraction in the diagnosis neutral beam （DNB） system for HT-7 tokamak was studied experimentally. Useful results with an improved beam quality were obtained.     

支持多种温度传感器的多通道低温测量系统的设计

中性束注入(neutral beam injector, NBI)系统的低温泵上必须设置一组温度测量点以监控其工作状态;为满足NBI温度测量需求,设计了一种支持多种温度传感器的多通道低温测量系统;系统采用24位Σ-Δ模数转换(analog-to-digital converter, ADC)芯片AD7193执行模数转换,采用控制器STM32F103ZET6控制设定恒流源、切换测量通道、ADC、以太网通信、串口通信、温度数据处理以及其他控制电路;该温度测量电路的设计可以用于由恒流源驱动的四线制低温温度测量领域。     

EAST-NBI用差分式低温冷凝泵的设计

为了维持EAST-NBI内的真空环境以满足中性束生成与传输过程对真空压力分布的要求,设计了EAST-NBI用差分式低温冷凝泵.本文概述了中性束注入加热的原理以及EAST-NBI真空系统的组成,详细阐述了EAST-NBI用差分式低温冷凝泵的结构设计,抽速和冷凝面积的确定,液氦系统和液氮系统热负荷的计算等关键问题.该差分式低温冷凝泵通过在EAST-NBI综合测试台上进行大量实验验证,完全满足EAST-NBI对真空系统的要求.     

射频负离子源关键参数测量系统研制

强流离子源是大功率中性束注入系统的关键部件之一,为了实现中性束注入系统的稳态运行,需要开展射频负离子源的实验研究。射频负离子源的负离子引出电流、引出总电流和引出电子流等关键参数的测量是射频离子源实验理论分析的基础,本系统通过信号调理隔离传输实现射频负离子源关键参数的测量。实验结果表明,系统测量采集数据精准可靠,运行稳定。     

静电场分析法优化设计负离子源中性束注入系统高压仓结构

为探究最为合理的负离子源中性束注入(NNBI)装置高压仓(HVD)结构,采用有限元静电场分析方法,对不同结构高压仓进行仿真计算分析,在考虑分布电容影响的前提下,优化设计了高压仓的主体和外形结构,并确定了安全绝缘距离,对高压仓的工程研制提供了理论指导,为NNBI的安全稳定运行奠定了基础。     

EAST中性束注入器稳态偏转磁铁的参数设计与估算研究

中性束注入器偏转磁铁是剥离束流中剩余离子的关键设备,它与剩余离子吞食器等内部部件构成了中性束注入器的束偏转系统。束偏转系统的性能对中性束注入器束流的品质及其束传输效率发挥着重要作用。本文根据EAST(Experimental Advanced Superconducting Tokamak,EAST)中性束注入器对束偏转系统的要求,对其偏转磁铁各性能参数进行了估算。为中性束注入器设计了一台用以剩余离子180°偏转的偏转磁铁。该偏转磁铁采用H型二极电磁铁结构;其磁极端面设计为138cm×47cm的圆角矩形结构;其线圈设计为每侧2饼,每饼2层,每层8根的串联结构,导线选用外方内圆空心铜导体,以满足偏转磁铁稳态运行的需要。该设计的偏转磁铁在370 A励磁电流条件下,可提供80keV氘离子束偏转所需的磁场。实验测试结果显示:500 A励磁电流稳态运行条件下,偏转磁铁线圈冷却水温升约21.5℃,该设计结构的偏转磁铁满足EAST中性束注入器满参数稳态运行和未来运行参数逐步提高的需要。