100 MeV强流质子回旋加速器超高真空系统研制

中国原子能科学研究院建成了一台强流质子回旋加速器,其引出能量为100 MeV,流强为200 μA。为减小粒子加速时束流损失的目的,其粒子加速腔内工作真空度要求为6.7×10^-6 Pa。由于是紧凑型加速器结构,该加速器能提供给真空系统利用的通路有限,为此主真空系统设计为内置式低温冷板结合商业低温泵的排气方案以增加系统整体的抽气能力。设计、加工完成的真空系统已成功应用于100 MeV强流质子回旋加速器上,为加速器的束流调试和正常供束提供了有利的保障。     

Influence of Gap Distance on Vacuum Arc Characteristics of Cup Type AMF Electrode in Vacuum Interrupters

The greenhouse effect of SFe is a great concern today. The development of high voltage vacuum circuit breakers becomes more important. The vacuum circuit breaker has minimum pollution to the environment. The vacuum interrupter is the key part of a vacuum circuit breaker. The interrupting characteristics in vacuum and arc-controlling techniue are the main problems to be solved for a longer gap distance in developing high voltage vacuum interrupters. To understand the vacuum arc characteristics and provide effective technique to control vacuum arc in a long gap distance, the arc mode transition of a cup-type axial magnetic field electrode is observed by a high-speed charge coupled device （CGD） video camera under different gap distances while the arc voltage and arc current are recorded. The controlling ability of the axial magnetic field on vacuum arc obviously decreases when the gap distance is longer than 40 ram. The noise components and mean value of the arc voltage significantly increase. The effective method for controlling the vacuum arc characteristics is provided by long gap distances based on the test results. The test results can be used as a reference to develop high voltage and large capacity vacuum interrupters.     

基于ARM和DSP的CSR主环电源控制系统

介绍了基于删和DSP的CSR主环磁场电源控制系统的设计和开发.系统以以太网作为连接各个单元的传输介质,以删板卡作为以太网中的一个通信节点,由DSP板卡完成实际的电源控制.实验表明控制效果良好,超过了预期的设计目标.     

Vacuum pumping by the halo plasma

An estimate is made of the effective vacuum pumping speed of the halo plasma in a tandem mirror fusion reactor, and it is shown that, if the electron temperature and line density are great enough, the halo can be a very good vacuum pump. One can probably obtain the required density by recycling the ions at the halo dumps. An array of small venting ports in the dump plates allows local variation of the recycle fraction and local removal of the gas at a conveniently high pressure. This vented-port concept could introduce more flexibility in the design of pumped limiters for tokamaks.     

Vacuum System for HL-2A Tokamak

The vacuum system for HL-2A was built in 2003. The test results indicated that this system is feasible. It consists of three main parts: a pumping system, a pumping divertor and a glow discharge cleaning (GDC) system. For the pumping system, there are three main functions: (1) evacuating the vacuum vessel thus to produce an ultra high vacuum, (2) removal of impurities released during baking and (3) pumping during GDC. The pumping divertor controls the particles at the plasma edge and the GDC system provides a clean wall conditioning. During the first campaign of physical trial experiment on HL-2A, the ultimate pressure reached 4.6 × 10-6 Pa, and the total leakage and outgassing rate in 12 hours was 1.8 × 10-5 Pa·m3/s, which is close to that of ASDEX.     

Arc Behaviours in Vacuum Interrupters with Axial Magnetic Field Electrodes

To improve the limiting current interruption capability and minimizing vacuum interrupter with axial magnetic field （AMF） electrodes, it is significant to investigate the vacuum arc behaviours between the contacts. AMF distributions of the slot type electrodes were studied by both numerical analysis and experiments. Furthermore, the behaviours of vacuum arcs for different parameters of the slot type AMF electrodes were investigated by using high-speed CCD camera. The influences of gap distance, contact diameter and phase shift time between AMF and arc current on the vacuum arc were investigated. The results provide a reference for research and development of vacuum interrupters with slot type or other types of AMF electrode.     

The Discharge Development and Arc Modes in Vacuum at A Long Gap Distance in Vacuum Interrupters

The influence of an arc current on the discharge development and the arc modes of a single coil type axial magnetic field （AMF） electrode were investigated by a high-speed charge couple device （CCD） video camera in a long gap distance of 40 mm. The distribution of the axial magnetic field of the single coil type AMF electrode was computed. By computational results, the single coil type AMF electrode could generate higher axial magnetic flux density than the slot type AMF electrode. It was found that the single coil type AMF electrode could perform better than the slot type AMF electrode with the same designing parameters. And the development of the arc modes experienced diffuse mode, constricted but unstable mode, and constricted and stable mode with the amplitude of the arc current increasing. The correlation between the vacuum arc and the noise components of arc voltage was investigated too. The interruption capability could be known in a practical commercial vacuum interrupter by the test results in a demountable vacuum interrupter （DVC） with a electrode diameter of 50 mm and a gap distance of 40 mm.The test results could provide reference to design the high voltage vacuum interrupter adopting the single coil type AMF electrode.     

EAST超导托卡马克核聚变实验装置真空室窗口烘烤及热应力分析

超导托卡马克核聚变实验装置EAST的真空室窗口烘烤系统要求窗口温度达到150℃。为选取加热丝型号及确定其合理布局，采用ANSYS有限元分析软件进行热应力分析。分析结果显示，窗口大部分区域的温度分布及热应力分布较为均匀，并满足要求，按照ASME压力容器评定标准，均在安全系数内。同时，对温度梯度较大的区域提出可行性的附加方案，以降低可能出现的应力集中。     

真空膜蒸馏法处理含铀废水 BR>

采用聚丙烯微孔膜对含铀废水进行真空膜蒸馏(VMD)处理研究,考察了进料铀的温度、质量浓度、流速以及真空侧压力对膜通量及截留率的影响,得到了最佳工艺条件:进料流速,0.5 m/s;进料温度,55℃;真空侧压力,2.66 kPa。在该条件下,当料液中铀的质量浓度为1~9 mg/L时,膜具有良好的分离性能,膜通量为3.5 kg/(m2.h),截留率为99.1%,馏出液中铀的质量浓度低于国家排放标准(0.05 mg/L)。实验结果表明,作为一种新颖的水处理技术,真空膜蒸馏法将在含铀废水处理中发挥重要作用。     

Design of the Vacuum Feedthrough for the EAST ICRF Antenna

Detailed design of the vacuum feedthrough for the Ion Cyclotron Radio Frequency (ICRF) antenna in EAST, along with an electro-analysis and thermal structural analysis, is presented. The electric field, the voltage stand wave ratio (VSWR) and the stresses in the vacuum feedthrough are studied. A method using the rings of oxygen-free copper as the cushion and macro-beam plasma arc welding is applied in the assembly to protect the ceramic from being damaged during welding. The vacuum leak test on the prototype of vacuum feedthrough is introduced.     

Vacuum Poloidal Magnetic Field of Tokamak in Alternating-Current Operation

Vacuum poloidal magnetic field of tokamak in alternating-current (AC) operation is investigated. It is found that the vacuum magnetic field in AC operation is qualitatively different from that in direct-current (DC) operation. In the DC case, the vacuum magnetic field varies along the poloidal direction with one period, while in the AC case, the vacuum magnetic field varies along the poloidal direction with two periods. This implies that two sets of vertical field coil may be needed for the AC operation.     

Repeated Strike Process During Disconnector Operation in Ultra-High Voltage Gas-Insulated Switchgear

Very fast transient over-voltage(VFTO),induced by disconnector operations in gasinsulated switchgears,has become the limiting dielectric stress at ultra-high voltage levels.Much work has been done to investigate single-strike waveforms of VFTO.However,little study has been carried out investigating the repeated strike process,which would influence VFTO significantly.In this paper,we carried out 450 effective experiments in an ultra-high voltage test circuit,and conducted calculations through the Monte Carlo simulation method,to investigate the repeated strike process.Firstly,the mechanism of the repeated strike process is proposed,based on the experimental results.Afterwards,statistical breakdown characteristics of disconnectors are obtained and analyzed.Finally,simulations of the repeated strike process are conducted,which indicate that the dielectric strength recovery speed and polarity effect factor have a joint effect on VFTO.This study enhances the understanding of the nature of VFTO,and may help to optimize the disconnector designed to minimize VFTO.     

Numerical Simulation of Low Current Vacuum Arc Supersonic Flow

Based on a two-dimensional axisymmetric magneto-hydrodynamic （MHD） model, low current vacuum arc （LCVA） characteristics are studied. The influence of cathode process under different axial magnetic fields and different anode radii on LCVA characteristics is also simulated. The results show that the influence of both cathode process and anode radii on LCVA is significant. The sign of anode sheath potentials can change from negative to positive with the decrease of anode radii. The simulation results are in part verified by experimental results. Especially, as the effect of ion kinetic energy is considered, ion temperature is improved significantly; which is in agreement with experimental results.     

Eddy Calculation and Vacuum Field Reconstruction on EAST

A new method, by using eigenmodes to reduce the fitting parameters and pre-calculated eddy current based on a lump parameter circuit equation, is applied to reconstruct the vacuum field for EAST plasma startup.     

重离子微束装置中真空窗的研究

中国科学院近代物理研究所（IMP）正在兰州重离子加速器（HIRFL）系统中研制中能重离子微束终端,以对重离子进行准确定位和精确计数。应用有限元分析软件对不同结构、不同材料的真空窗进行受力分析,模拟真空窗的形变和等效应力,运用强度理论考察候选真空窗的安全性;运用SRIM程序模拟离子的小角散射、横向射程,详细计算入射离子的能量、真空窗材料和厚度及空气层对束斑展宽的影响;最后提出真空窗适宜的结构、材料及厚度范围。     

Study of Distortion of a Vacuum Arc at a Long-Gap Distance

Experimental study of the long-gap distance vacuum arc distortion for three types of axial magnetic field (AMF) contacts, by using high-speed charge coupled device (CCD), is presented. The arc current was of a half-cycle sine wave with a frequency of 50Hz, produced by an L-C discharging circuit. The time of appearance and duration of vacuum arc distortion under three conditions were studied. It was found that the gap distance, current and diameter of the electrode affected the characteristics of vacuum distortion at a long-gap distance. Some characteristics of the vacuum arc at a long-gap distance was revealed and the experience and data for further investigation were provided.     

EASTICRF天线真空馈口电特性评估

本文对EASTICRF天线真空馈口进行了相关的电特性分析,获得了真空馈口电场分布、电势分布,以及电压驻波比随加热频率的变化情况,分析结果验证了真空馈口的可行性和合理性,并为真空馈口电特性评估提供理论依据。另外,在相同条件下,运用相同的方法对一种新型结构的真空馈口进行了相同的电特性分析,分析结果验证了新型结构真空馈口的优越性。     

Influce of Initial Opening Speed on Characteristics of a Drawn Vacuum Arc

Influence of the initial opening speed on the characteristics of drawn vacuum arcs for axial magnetic field(MF) vacuum interrupters (VIs) is studied using a high-speed charge- coupled device (CCD) camera. Two values of initial opening speed, 0.5 m/s and 1.5 m/s, were set to make a comparative study. The cup-type electrode was made of Cu-Cr (50%-50% in weight) with a diameter of 30 mm and a gap distance between electrodes of 10 mm. The results show that the transition time decreases by 0.5 ms when the initial opening speed increases from 0.5 m/s to 1.5 m/s at a peak current of 2.5 kA, while the transition time decreases by 1.0 ms when the initial opening speed increases from 0.5 m/s to 1.5 m/s at a peak current of 5.0 kA. The reason why the duration of the transition arc mode decreases is that the e®ect of electromagnetic force and Coulomb force among arcs is increased when the initial opening speed increases.     

EASTICRF天线真空馈口热-结构分析

真空馈口是ICRF天线中的一个重要部件,它对ICRF天线起真空密封作用。鉴于真空馈口的重要性和安全性,运用有限元方法对两种形式的真空馈口进行了热和热-结构分析,给出了两种形式的真空馈口上的温度分布和应力分布。结果显示：镀银的真空馈口上的温度变化和应力均小于未镀银的真空馈口上的温度变化和应力,但两种形式的真空馈口上的应力均小于材料的许用应力。分析结果验证了真空馈口结构设计的可行性和安全性。