束流发射度和亮度与束流密度分布的关系

束流发射率和束流亮度是表征加速器束流品质的主要指标。理论和实验研究都已发现,它们与束流空间电荷的非均匀分布有密切关系。     

加速器束流发射度测量

一、引言加速器束流发射度是束流本身的一个重要特性参量,它完整地描述了束流的径向性能。发射度的测量,为加速器输出束流的使用提供了确切的依据,特别是对于束流的传输来说,有效发射度及其σ矩阵是计算传输过程中束流包络所必不可少的初始条件。     

北京质子直线加速器的束流测量探头

本文介绍了北京质子直线加速器的束流测量探头如荧光靶探头,束流变压器,发射度测量探头,束流截面测量探头,能散度测量探头,法拉第筒,减能器等的作用,机械结构及加工工艺。     

用于核物理实验研究中的束流脉冲调制器

描述了一台用于核物理实验研究中的束流脉冲调制器,它已成功地用于兰州重离子加速器（HIRFL）的放射性离子束流线（RIBLL）的两个核物理实验中。     

BEPCⅡ直线加速器束流位置探测器零点误差的测量

本工作测量了BEPCⅡ直线加速器条形束流位置探测器(BPM)的电中心与四极铁中心的偏差。简述了BEPCⅡ直线加速器的轨道校正系统及其在束流轨道校正在线反馈控制中的作用,说明了BPM零点误差的意义,叙述了利用在线束流进行BPM零点误差测量的原理和方法,并给出测量结果,说明这种测量方法是行之有效的。     

环形单针双束流截面测量技术

利用一个三维环形探针对离子束进行旋转扫描，可以同时测量到两个束流截面的大小和位置，估算出二截面附近的聚焦梯度以及束腰的移动。     

束流位置探头的理论设计

加速器的束流位置通常采用四个纽扣形电极的束流位置探测器(BPM)进行测量。本文主要探讨了一种BPM的理论设计方法。首先利用有限元方法对BPM电极的感应电荷进行理论计算，得到四个电极感应的电信号与位置信号的理论关系；利用最小二乘法原理对此结果进行多项式拟合，求出标定系数。在此基础上通过更改BPM的几何参数，求出相应的标定系数，即可得到不同性能的BPM。经优化处理得到所需的束流位置探测器设计参数。     

DG系列大功率工业辐照电子加速器

中国科学院近代物理研究所成功研制了DG系列中频变压器型工业电子加速器,其中DG-2.5型加速器能量范围1.0-2.5 MeV,最大束流功率90 kw,束流扫描有效宽度1000 mm,适用于各种辐照领域;DG-1.2型能量范围0.8-1.2 MeV,最大功率50 kw;这两种型号加速器均通过了长时间测试,工作稳定、故障率低,采用计算机自动控制,并可与束下传动系统连锁,完全达到了工业应用的标准.     

新型电子直线加速器测试与改进

一种新型的省略电子枪的小型直线加速器被研制成功。高功率速调管的用毕束流被引出作为注入电子,从而取代了传统的电子枪部分。装置在调试完成后开始运行,我们对获得加速后的电子束性能做了初步测量,并与模拟结果进行了对比。结果表明,加速器输出流强远低于设计目标。运用Parmela程序详细分析了电子束流损失的主要因素,针对减少束流损失,提高加速器输出流强,提出了新的改进方案。通过计算分析,得出了该方案良好的可行性。     

Small-scale Experiment on Subcooled Water Jet Injection into Molten Alloy by Using Fluid Temperature-Phase Coupled Measurement and Visualization

The plunging water jet behavior into a pool of a molten lead-bismuth alloy is experimentally investigated. The mixing and interactions of fluids were detected by measuring the fluid temperature as well as the fluid phase distinction by the newly developed bifunctional probes.

In general knowledge of fuel-coolant interactions, the film boiling of water is caused immediately after the first contact of high-temperature melt and water, but the vapor film is locally collapsed by some reasons and the direct contact is extensively propagating in some cases which may produce the explosive vapor generation. In the melt-injection mode previously investigated by numerous researchers, the triggering of explosive interactions is considered as a local rewetting caused by instabilities of the vapor film as the melt temperature decrease. In the coolant-injection mode discussed by the present study, on the other hand, the water temperature poured into bulk melt continues to rise for penetration, in general, that should be effective to stabilize the film boiling. The present experiments showed, however, that the explosive boiling occurred in a condition that both water and melt initial temperatures were high enough for maintaining stable film boiling on the melt-water interface that is clearly different manner of the melt injection mode. Such unstable phenomena are observed when the instantaneous interfacial contact temperature exceeds the homogeneous nucleation temperature of water and the amount of saturated water is accumulated in a melt pool.     

Time-Optimal Power-Change Control for Coupled-Core Reactors

The numerical method used in this study is Moving Particle Semi-implicit (MPS) method which is based on moving particles and their interactions. Grids are not necessary. Large deformation of fluids can be calculated without grid tangling. A surface tension calculation model is developed to analyze droplet breakup. This model is verified by the simulation of vibration of an ethanol droplet. Two-dimensional numerical analyses of droplet breakup in liquid-liquid and gas-liquid systems are carried out. The correlation between the Weber number and the breakup mode observed in the calculations agrees with that in the experiments. Breakup behavior of a droplet surrounded by a vapor film is analyzed. Flow in the vapor film is considered, though boiling of water and solidification of the melt droplets are ignored. It is found that the breakup of a droplet is suppressed by the vapor film. The critical Weber number in the vapor film is obtained as 50. Molten core coolability is considered by using this result. The median diameter of stable droplets of the molten core is expected as 5 mm in a typical condition, which is consistent with FARO experiment. This result shows that in Advanced Boiling Water Reactor (ABWR) the debris bed up to 40% of the core can be cooled down in the lower head of the reactor pressure vessel.     

Air-water multidimensional impingement flow on vertical flat wall

The emergency core cooling (ECC) water is supplied from the direct vessel injection (DVI) system in the Advanced Power Reactor 1400 MWe (APR1400) during a postulated large-break loss-of-coolant accident (LBLOCA). The velocity of ECC water exceeds 10 m/s in the early high pressure phase of LBLOCA and then is decreased to 2-3 m/s in the late phase of reflood. During the injection the flow behavior exhibits a complex mode involving impingement, bypass, entrainment, sweepout and condensation in the reactor downcomer. There is currently no model to accurately simulate the local and complicated flow behavior in the APR1400 downcomer during a LBLOCA. This study is aimed at developing models for the water film flow and deformation, both of which are expected to sizably affect the other multidimensional flow characteristics in the downcomer. Experimental studies are conducted to benchmark the predictive model by furnishing the boundary conditions for the analysis resorting to the Accelerated Liquid Phase Hydrodynamics Apparatus (ALPHA) and the Kinetic Aerodynamic Physics Parallelepiped Apparatus (KAPPA). The Poisson equation and potential theory are applied to formulate the behavior of the water film and air flow. In both the experimental and numerical studies, the temperature-dependent thermodynamic properties and the reactor vessel curvature are neglected to render the problem at hand tractable. The model is found to reasonably describe the downward film flow behavior. The water film is developed in proportion to the initial injection velocity of the ECC water. The downward velocity of water film is increased with the heights of injection. Regarding the film deformation the calculated results tend to deviate from the experimental data as the injected air velocity is increased. The disagreement is attributed to limitations inherent in the two-dimensional treatment and point source approach.     

W/BDD薄膜电极制备及其电化学性能研究

利用化学气相沉积（CVD）法研制了一种钨基硼掺杂金刚石（W/BDD）薄膜电极,通过扫描电镜和Raman光谱考察了W/BDD薄膜电极的性能,通过电化学方法测定了其在LiCl-KCl熔盐中的电化学窗口和电化学性能。结果表明,研制的W/BDD薄膜电极的BDD薄膜有较好的微观结构;W/BDD薄膜电极在LiCl-KCl熔盐中的电化学窗口约为3.5 V(-2.5～1.0 V,相对于Ag/AgCl参比极电位);电解过程中,氧离子不与W/BDD薄膜电极表面BDD薄膜层的碳反应,直接被氧化为氧原子;长时间电解不会改变电极表面薄膜层的形貌和结构。     

Research on corona discharge suppression of high-voltage direct-current transmission lines based on dielectric-film-covered conductor

Corona discharge suppression for high-voltage direct-current(HVDC) transmission lines at line terminals such as converter stations is a subject that requires attention. In this paper, a method based on a conductor covered with dielectric film is proposed and implemented through a bench-scale setup. Compared with the bare conductor, the corona discharge suppression effect of the dielectricfilm-covered conductor under positive polarity is studied from the composite field strength and ion current density using a line-plate experimental device. The influences of film thickness and film material on the corona discharge suppression effect are investigated. The charge accumulation and dissipation characteristics of different film materials are also studied. The results show that the conductor covered with dielectric film has excellent ability to inhibit corona discharge. The groundlevel composite field strength of the conductor covered with dielectric film is lower than its nominal field strength, and its ion current density is at the n A m~(-2) level. The corona threshold voltage can be promoted by increasing the film thickness, but the ability to inhibit corona discharge becomes weak.The larger the surface electric field strength, the more charge accumulated, but the faster the charge dissipation rate. Compared with polyvinyl chloride film, cross-linked polyethylene film has stronger charge accumulation ability and slower charge dissipation rate, which can better restrain the corona discharge of HVDC transmission lines.     

超导薄膜粒子探测器

本文介绍了一种新型探测器——超导薄膜粒子探测器。描述了探测机制和探测原理,并对探测器的主要参数、典型特性和应用问题进行了简单讨论。     

溅射功率对磁控溅射制备Bi薄膜结构和性能的影响

采用直流磁控溅射方法在不同功率下制备了铋(Bi)薄膜,对薄膜的沉积速率、表面形貌、生长模式、晶体结构进行了研究,并对其晶粒尺寸和应力的变化规律进行了分析。扫描电镜(SEM)图像显示：薄膜均为柱状生长,平均晶粒尺寸随溅射功率先增大后减小,薄膜的致密度随着功率的增加而降低,在60W时又变得较致密。X射线衍射(XRD)结果表明：Bi薄膜均为多晶斜六方结构,薄膜内应力随功率的增加由张应力变为压应力。     

MHD Stability Analysis and Flow Controls of Liquid Metal Free Surface Film Flows as Fusion Reactor PFCs

Numerical and experimental investigation results on the magnetohydrodynamics(MHD) film flows along flat and curved bottom surfaces are summarized in this study. A simplified modeling has been developed to study the liquid metal MHD film state, which has been validated by the existing experimental results. Numerical results on how the inlet velocity(V), the chute width(W) and the inlet film thickness(d0) affect the MHD film flow state are obtained. MHD stability analysis results are also provided in this study. The results show that strong magnetic fields make the stable V decrease several times compared to the case with no magnetic field,especially small radial magnetic fields(Bn) will have a significant impact on the MHD film flow state. Based on the above numerical and MHD stability analysis results flow control methods are proposed for flat and curved MHD film flows. For curved film flow we firstly proposed a new multi-layers MHD film flow system with a solid metal mesh to get the stable MHD film flows along the curved bottom surface. Experiments on flat and curved MHD film flows are also carried out and some firstly observed results are achieved.     

The application of limiter target electrostatic measurement system in J-TEXT tokamak

The limiter target electrostatic measurement system including limiter grounding current sensors and Langmuir probes have been newly developed for the measurement of the limiter target area on the Joint-Texas Experimental tokamak(J-TEXT).Current sensors fixed between graphite limiters and the vacuum vessel walls are used to measure the currents between limiters and vessel wall.Simultaneously,a rectangular poloidal array containing 54 Langmuir probes is embedded in the graphite tiles of limiters for a more localized measurement.Based on this system,the effect of both the plasma's inherent behavior,including plasma motion and the 2/1 tearing mode,and the electrode biasing on probe and sensor signals have been observed and analyzed in the experiments.     

An Experimental Study of Thermal-hydraulic Phenomena in the Downcomer with a Direct Vessel Injection System of APR1400 during the LBLOCA Reflood Phase

The direct vessel injection (DVI) mode is adopted as a safety injection system in the place of a conventional cold leg injection (CLI) mode in the Advanced Power Reactor 1400MW (APR1400). It is expected that “sweep-out” and “direct ECC (Emergency Core Cooling) water bypass” are two most important bypass mechanisms of ECC water injected through the DVI lines during the LBLOCA reflood phase. Using the test facility of plane-channel type scaled down to 1/7 ratio of the prototype reactor (APR1400), we carry out the following tests for the investigation of the two mechanisms: water film spreading test, sweep-out test, and direct ECC water bypass test. From the water film spreading test, it was found that the curvature effect is negligible and the present modified linear scaling law is more appropriate than the linear scaling law. In the sweep-out test, the continuous onset is used to analyze the water height in the downcomer and the amount of ECC water bypass by sweep-out is compared with the previous correlations. The direct ECC water bypass test is performed in order to understand the ECC water film behavior in the downcomer.