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.     

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.     

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.     

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.     

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。     

HT-7诊断中性束装置真空远程监控系统设计

本文介绍了真空实时远程监控系统的设计要求,讨论了该系统的硬件设计、软件设计及其工作原理,给出了部分实验结果。系统成功地应用于实验并获得理想的实验结果,为诊断中性束稳态运行提供可靠保障。     

诊断中性束装置离子源起弧实验的多元非线性回归分析

通过调节影响诊断中性束离子源弧流的进气量、灯丝电流和弧压三个参量，进行了三组离子源起弧实验。建立了多元非线性回归模型，得到了三个参量对弧流的回归方程。回归分析表明，弧流对进气量和灯丝电流相当敏感，且有趋于饱和的特征，这与实验结果相吻合。在进气针阀开度492、灯丝总电流469A、弧压190V时重复起弧，均得到弧流170A以上、脉宽150ms的稳态放电，满足了诊断中性束流对弧流的要求。     

DNB束功率测量系统设计

设计了测量诊断中性束(DNB)束功率及束密度剖面的束功率测量方案,采用热电偶测量束线轰击功率测量靶板后靶面的温升信号,经热电偶信号调理器调制放大后,由数据采集卡采集到现场计算机中进行数据处理,以及功率大小和功率密度剖面分布的计算,计算值通过光纤链路传输到控制室终端计算机加以复现.实验证明,DNB束功率测量系统工作稳定可靠,实现了对束线轰击靶板后靶面温升的实时测量,和对束线功率大小及功率密度剖面的良好复现.     

液氮温度下JX-6型椰壳炭的性能测试

活性炭是NBI低温吸附泵吸附面的关键组成部分,其性能是决定NBI低温泵抽气性能的关键因素之一.本文选取JX-6型椰壳活性炭,用全自动比表面积及孔径分析仪(ASAP2020)在液氮温度下对其性能进行了测试,并对实验数据进行了分析.实验结果表明,该活性炭具有良好的孔隙结构和较强的吸附性能,其最大吸附量达到252 cm3/g STP.为进一步研究NBI低温泵的低温吸附抽气提供了理论依据.