HT-7诊断中性束评价系统温升特性分析

本文介绍了HT-7诊断中性束装置束评价系统的基本结构和工作原理;分析靶板采样孔的遮挡效应、束腰位置和前、后靶上采样铜柱的温升比值的关系,解释了相同参数下后靶板温升较高的实验现象;根据前、后靶板的平均温升比值,计算了装置运行中的束流焦距,结果显示其误差不大于5%.     

HT-7 诊断中性束电源控制系统设计

本文介绍了HT-7托卡马克实验装置上研制的基于脉宽调制（PWM）的诊断中性束电源系统的组成、结构和控制需求,以及控制系统的组成和控制功能等。经实际调试与多轮HT-7实验运行,验证了该套电源控制系统的稳定性与可靠性。     

大功率NBI系统的PLC时序控制应用

论述了利用PLC逻辑关系对放电实验控制运行的工作原理,介绍了PLC梯形图应用程序和VB6.0环境下上位机监控程序的开发以及良好的人机操作界面,通过上位机监控界面来实时监控各电源及设备的运行状态.PLC控制系统的应用保障了实验装置的安全运行,极大地方便了实验中对放电参数的改变和设置.     

Performance of Diagnostic Neutral Beam for the HT-7 Tokamak

Diagnostic neutral beam (DNB), combined with spectral diagnostics, is employed to measure the ion temperature in HT-7. The factors affecting the extracted beam are studied in the experiment for the high performance diagnostic neutral beam. A 6.5 A extracted hydrogen current at 43 keV of 100 ms was obtained after optimization. The extracted beam has a proton ratio as high as 40%, and can penetrate into the core plasma after neutralization to measure the ion temperature effectively.     

HT-7超导托卡马克装置上中子通量分布的实验研究

本文介绍了HT-7超导托卡马克装置上中子通量分布的测量实验.在实验中,使用了两种有较强抗伽马能力的中子探测系统:BF3和3He正比计数管及其相应的电子学与数据采集.在2005年春季实验中,在相同实验条件下,细致测量并比较研究了真空室外不同水平位置、垂直位置的中子通量.实验研究了真空室窗口和变压器铁芯的存在对测量结果的影响,验证了测量结果与三维数值计算的一致性.本项工作为更深入的物理研究奠定了基础.     

HT-7超导托卡马克上聚变中子产额和中子注量率分布计算

利用所编制的三维托卡马克中子计算程序,计算了HT-7装置上中子产额随等离子体中心离子温度与密度的变化.同时计算了中子注量率及其在空间不同位置与方位角的分布特性.考虑了离子温度与密度分布的形状因子不同所带来的误差.计算结果为中子诊断和中子辐射防护等提供了依据.     

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.     

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.     

Logical and Timing Control for Diagnostic Neutral Beam Injection on HT-7

The timing and master control logic （MCL） units are the most important function units of the diagnostic neutral beam （DNB） power supply control system. The units control the operation of nine power supply subsystems of the DNB system, and provide protection for the DNB system from faults such as beam source arc down. Based on the characteristics of the DNB power supply system, the timing and MCL units have been designed, fabricated and tested. Experiments prove that the timing unit is convenient, flexible and reliable, and the MCL is functional.     

Analysis on Pressure Distribution in HT-7 Neutral BeamInjection System

Neutral Beam Injection (NBI) is an effective way to improve the efficiency of tokamak heating system. This article primarily introduces a work on the pressure distribution inside the tank of NBI heating system, especially inside the neutralizer, which is got by selecting a proper mathematical model and constructing a series of rational calculating formulas on pressure distribution. Furthermore, we simulate the pressure distribution by the Monte Carlo method. Comparing the result of simulation with that of theoretical calculation, we find that both the results are very close each other, showing their mutual validity.     

放疗加速器束流剂量实时成像系统

介绍了一种放疗加速器束流剂量实时成像系统，采用数字化脉冲X射线成像技术获取放疗加速器的束流强度分布图像，并利用数字图像处理技术生成实时3D剂量图。利用该系统可以实时、直观地获得加速器束流强度的相对分布曲面，给出任意剖面的束流强度分布曲线和FWHM、半影、峰值、对称度、均整度等参数。利用本系统的实时性，在国内首次实现了放疗加速器动态楔形剂量分布和束流过渡过程的测量。给出了系统配置和实测的放疗加速器束流强度分布图像。     

Achievement of 1000 s plasma generation of RF source for neutral beam injector

A radio frequency(RF) ion source was developed for neutral beam injector in Institute of Plasma Physics, Chinese Academy of Sciences(ASIPP). A cylindrical driver based RF plasma source was tested and optimized for long pulse operation. Recently, the plasma source achieved 1000 s stable plasma discharge with RF power of 35 k W and source pressure of 0.7 Pa for the first time.The heat loading on each of driver components such as the Faraday shield(FS), RF coil and expansion chamber was measured by the water flow calorimeter system. The experiment results showed that FS is the component with highest heat loading and the heat loading on FS was about 65.8% of total heat loading on source. The details of the long pulse operation of RF plasma source are presented in this paper.     

Upgrade of plasma density feedback control systemin HT-7 tokamak

The HT-7 is a superconducting tokamak in China used to make researches on the controlled nuclear fusion as a national project for the fusion research. The plasma density feedback control subsystem is the one of the subsystems of the distributed control system in HT-7 tokamak (HT7DCS). The main function of the subsystem is to control the plasma density on real-time. For this reason, the real-time capability and good stability are the most significant factors, which will influence the control results. Since the former plasma density feedback control system (FPDFCS) based on Windows operation system could not fulfill such requirements well, a new subsystem has to be developed. The paper describes the upgrade of the plasma density feedback control system (UPDFCS), based on the dual operation system (Windows and Linux), in detail.     

HT-7托卡马克实验装置上基于PLC控制的中性束诊断电源系统

文章介绍HT-7托卡马克实验装置上的中性束诊断电源系统的组成、结构，以及基于S7-300PLC的逻辑控制系统。实验表明，该系统操作简单，性能稳定可靠。     

Analysis of charge-exchanged neutral particles during IBW heating in the HT-7 tokamak

The charge-exchange neutral particles fluxes and energy distribution in IBW heated plasma were investigated in the HT-7 tokamak. The RF frequency was 30 MHz and with an injecting power up to 200 kW. It is observed that the plasma performance is obviously enhanced by IBW heating. The electron temperature was increased by 0.5 keV and the central line averaged electron density was doubled. The neutral particle fluxes of high-energy increased and the bulk ions were heated during IBW heating. The ion temperature was increased by 0.3 keV and the ion heating efficiency of (2–3) eV kW⁻¹ × 10¹³ cm⁻³ was achieved. The velocity distribution of charge-exchanged neutral particles appears to be Maxwellian without high-energy tail ions up to the maximum RF power.     

On the comparison of three methods of assessing beam quality for broad beam in vitro cell irradiation

The interaction of charged particles with living matter has recently attracted increasing interest in the field of biomedical applications such as hadron therapy, radioprotection and space radiation biology. Particle accelerators are particularly useful in this area.In vitro radiobiological studies with a broad beam configuration require beam homogeneity. The goal is to produce a dose distribution given to a cell population that is as close to uniform as possible.In this paper, we compare the results of three devices used to assess the beam quality for broad beam irradiation: a passivated implanted planar silicon (PIPS) particle detector, a position-sensitive solid state detector, which is camera-like, and a solid state nuclear track detector (CR39).The first device is a PIPS detector of 300 μm nominal depletion depth and an entrance window with a thickness of about 500 Å. It is collimated with a 0.5 mm aperture and mounted in air on an XY moving table as close as possible to the exit window of the beam line.The second device is a CMOS position-sensitive detector (technological process 0.6 μm AMS CUA), 112 × 112 pixels, with 153 × 153 μm² pixel size. It allows the user to rapidly obtain dose uniformity over a surface of 1 × 1 cm². During uniformity and dose rate assessment it is placed in air at the PIPS location.For both detectors, beam profile was obtained for various proton fluxes (from ∼5 × 10⁴ to 10⁶ particles cm⁻² s⁻¹). Preliminary tests were made with CR39 using 4 MeV He⁺⁺ ions.Results are analysed using Poisson distribution and cell hit probability.     

Design of flowing liquid lithium device for HT-7 tokamak

Lithium is a very attractive element due to its very low radiation power, strong H retention as well as strong O getter activity. Flowing liquid lithium (FLiLi) device, to be used as a plasma-facing limiters, has been designed and will be tested in HT-7 tokamak. It is mainly composed of distributor, guide plate, collector, and heater as well as cooling loop. The heater uses heater strip and cooling loop design, to control the temperature of lithium on the guide plate ranging from 200 °C to 400 °C. The distributor attached to feeding pipe, distributes liquid lithium (LiLi) flowing on the guide plate. The collector was designed to reclaim the superfluous LiLi and transport it out of device.The paper focuses on the design of flowing liquid lithium device. In addition to the process of design, thermal analysis has been carried out using finite element method (FEM) for optimizing the structure of heater and cooling loop and results of analysis are presented.     

NBI双潘宁离子源参数的静电探针测量

介绍了静电探针在22cm双潘宁离子源中心等离子体参数测量中的应用.测出了探针的伏安特性曲线,由该曲线求出在弧流为200 A时,电子温度约为6.0 eV,密度约为2×1012 cm-3,这对于调整放电控制条件,获得高效率大功率的离子源有重要的参考价值,并且对于今后实现强而且均匀的中性束束流的引出也有着重要意义.     

计算脉冲电子束辐照下能量沉积剖面的新方案

脉冲电子束辐照材料试验研究中,束流电子具有不同的速度和角度分布。但数值模拟计算一般都考虑电子束垂直入射靶材料,这可能导致数值计算结果与试验结果不符。针对该问题,提出了一种计算电子束辐照下能量沉积剖面的新方案,利用MCNP(Monte Carlo N Particle Transport Code)软件对铝、铜、钽金属材料在电子束辐照下的能量沉积进行模拟,分析了电子束垂直入射与带有角度分布入射时能量沉积的差异,为解释电子束辐照试验测量数据与理论计算结果之间的差异提供了依据。     

诊断中性束电源的数据采集与处理系统

文中介绍了一种用于诊断中性束电源系统的数据采集与处理系统(DPAS).在电源系统的运行过程中,系统需要对18路电流/电压信号进行实时采集.DPAS采用网络技术以客户端/服务器模式进行开发.系统引进了一种高效的压缩算法从而大量地节约了数据存储所需的磁盘空间.系统所采用的数据存储格式与EastScope软件(一款用于查看实验数据的软件)兼容,从而使实验操作人员可以很容易对实验结果进行分析和总结.