氘离子轰击钼靶的二次电子发射系数测量

设计了一套二次电子测量装置,采用间接测量法,利用中子发生器产生的氘离子束,对氘离子束轰击下钼靶的二次电子发射系数进行了实验研究,获得了钼的二次电子发射系数随不同入射氘离子能量的变化趋势,氘离子束能量为170 keV时的二次电子发射系数最大,约为2.33.     

半价层法测量电子束能量的模拟计算和分析

采用模拟计算电子-光子耦合输运的蒙特卡罗程序EGS4来模拟计算半价层测量能量方法的过程。得到的半价层数值在一定范围内与Varian公司给出的建议数据和实际测量数据基本吻合。分析了半价层测量的各种影响因素,同时给出了测量能量时应注意的事项,并为实际应用提供了参考数据。     

由中子注量率空间分布形状测量确定反应堆次临界度的方法研究

从堆物理的基础理论出发,提出了通过堆内中子注量空间分布的测量来确定反应堆次临界度的一种新方法,并通过对我国启明星1 号次临界实验装置的数值模拟,初步说明了该方法的可行性.     

高能闪光X射线能谱的空间分布特征

高能闪光X射线是闪光X射线照相的主要手段,而高能闪光X射线的属性参数会影响到闪光X射线照相的实际结果,其中最为重要的属性便是能谱.能谱的空间分布特征可以有效地帮助实际测量装置的结构设计,获取最佳的测量效果.Geant4是国际上通用的高能物理模拟系统,在轫致辐射理论的基础上,使用其对实际场景进行了细致模拟,从而得到高能闪光X射线能谱在空间上的分布特征.     

地层因素对D-D次生γ源空间分布的影响研究

在D-D可控源密度测量中,为研究不同地层条件对次生γ源空间分布的影响,首先分析D-D可控源密度测量原理,在此基础上,采用蒙特卡罗方法模拟研究不同含氢指数、岩性和矿化度地层条件下的次生γ源空间分布特征,最后对其影响因素进行归纳总结。结果表明:次生γ源的空间位置和强度易受各种地层因素的影响,其中地层含氢指数、岩性和矿化度对次生γ源的空间分布都有影响,但影响程度不同。其中地层含氢指数的影响最大,主要影响空间位置,特别是当含氢指数在0～0.1变化时,俘获γ的空间位置变化最大。并且随着地层含氢指数增高,地层含氢量增高,对快中子的减速能力增强,更多的γ射线向中子源靠近,同时γ射线强度也逐渐增强。相比较而言,岩性和矿化度对次生γ源的强度影响较大,空间位置影响相对较小,岩性不同,地层中主要元素的种类和含量不同,热中子俘获截面不同,俘获γ强度也不相同;矿化度高的地层,氯元素含量相对较高,更多的热中子被俘获,γ射线强度增强。本研究对于D-D次生γ源的影响校正提供了基础数据,也为建立精度较高的D-D可控源密度测量方法提供依据。     

中子场空间分布特性研究

采用Monte-Carlo方法,以高斯聚变中子谱和麦克斯韦裂变中子谱为源谱,进行了中子在大气中输运的理论模拟,给出了不同源高度,空问不同位置处的中子注量、能谱和吸收剂量,并总结了中子场的空问分布特性。     

管长对UTSG倒流管空间分布的影响分析

自然循环条件下,自然循环U型管蒸汽发生器(UTSG)并联倒U型传热管内存在非均匀流动,部分传热管出现倒流;现有研究对倒流管的空间分布存在不同认识。通过建立一维、稳态条件下的传热管内流动换热模型,发现传热管管长对并联倒U型管间的流量压降对比关系产生影响,进而对倒流管的空间分布产生影响。传热管管长较小的UTSG,短管将先于长管发生流量漂移;反之,长管将先于短管发生流量漂移。采用最佳评估程序RELAP5/MOD3.3对研究结果进行了验证。     

脉冲堆功率分布及绝对功率的测量

本文简要介绍了在脉冲堆零功率实验装置上,利用“中子通量自动测量装置”进行的功率分布、中子通量不均匀系数和绝对功率的测量工作。     

一种新型的液滴分布测量方法

介绍了一种新型液滴空间分布测量技术及实验装置,该技术可测得气-水系统中气泡在自由液面处破裂产生液滴的空间分布及运动轨迹。本工作利用染色液滴撞击到水敏试纸(熟宣纸)即被吸收这一原理记录液滴运动位置。通过设计一系列不同直径的纸筒,统计同一大小气泡破裂产生液滴分别在这些圆纸筒上的撞击位置,运用数理统计原理对得到的所有数据进行综合分析,得到气泡破裂产生液滴的空间分布和运动轨迹。     

Validity Analysis of Spatial Distribution Measurement of Secondary Electron by Solving Eigenmatrix Method

In order to measure the secondary electron spatial distribution of different materials in the actual environment accurately, a new type of secondary electron emission spatial distribution measurement structure was designed. The experimental measurement principle was given, and the measured data were analyzed by solving the eigenmatrix method to obtain the required secondary electron spatial distribution. The validity of proposed measurement method by simulation calculation was verified, and the simulation result was consistent with the assumed secondary electron spatial distribution function. It indicates that the measurement method is reliable and accurate. The prototype of measurement system will be developed based on this new design.     

不同带电情况下介质材料二次电子发射特性研究

空间材料二次电子发射特性是决定航天器表面带电速率和充电平衡电位水平的重要参数。本文利用1~5keV的脉冲电子束开展了聚酰亚胺(kapton)、玻璃盖片和光学太阳反射镜(OSR)材料的二次电子发射系数(δ)测试,并完成了介质材料表面不同充电情况下的二次电子发射特性研究。研究结果表明,在入射电子能量为1~5keV范围内材料二次电子发射系数随入射电子能量上升而下降,同时当二次电子发射系数大于1时,材料表面将累积正电荷,二次电子发射系数下降,当二次电子发射系数小于1时,材料表面将累积负电荷,二次电子发射系数将增加。     

Spatial Distribution of Bremsstrahlung in Water and Water-Iron by 22-MeV Electron Bombardment Measured with Activation Detectors

The spatial distributions of bremsstrahlung in water (1 m thick) and water (60 cm thick)-iron (6.3 cm thick) bombarded by 22-MeV electrons were measured by using a new activation method which we developed. These informations are useful for studying shielding, residual activity and radiation damage of accelerator and target materials.

From the measured activities, the bremsstrahlung spectra in water were evaluated with the LYRA and the SAND-II unfolding codes. The evaluated spectra were in good agreement with the analytical calculation by the DIBRE code, except for the higher energy ends. The longitudinal and the lateral distributions of bremsstrahlung flux in water were obtained by integrating the evaluated spectra above 8 MeV. The agreement of the experimental and the calculated flux distributions was very good except for a large angle to beam direction. The total photon number crossing a plane normal to the beam axis attenuates exponentially along the axial depth. The iso-flux contour of bremsstrahlung flux was given by interpolating the flux distribution curves.

Only the saturated activities of gold detectors were obtained for water-iron in good experimental accuracy. The spatial distribution of gold saturated activities in water-iron clearly shows the attenuating effect due to strong absorption in iron.     

Electron Temperature Measurement by Floating Probe Method Using AC Voltage

This study presents a novel floating probe method to measure electron temperatures using a hollow cathode-type discharge tube. The proposed method detects a shift in the floating potential when an AC voltage is applied to a probe through an intermediary blocking capacitor.The shift in the floating potential is described as a function of the electron temperature and the applied AC voltage. The floating probe method is simpler than the Langmuir probe method because it does not require the measurement of volt-ampere characteristics. As the input AC voltage increases, the electron temperature converges. The electron temperature measured using the floating probe method with an applied sinusoidal voltage shows a value close to the first(tail)electron temperature in the range of the floating potential.     

Angular Distribution of Gadolinium Vapor Produced by Electron Beam Heating

Static corrosion tests were performed for the glass phase of a simulated waste form of non-combustible radioactive low-level waste to study a basic aqueous corrosion behavior. The waste form, which was fabricated from simulated waste sample by use of in-can type induction-heated melting, consists of two separated phases; a glass phase and a metal phase. Tests were performed for the glass phase from two types of the waste form with different chemical composition at 35°C and S/V ratio of 2,600 m^?1. The glass phase with both types showed an incongruent dissolution similar to conventional high-level radioactive waste (HLW) glasses, i.e., the normalized elemental mass loss (NL_i) for soluble elements such as B and Na continued to increase after the saturation of insoluble elements such as Si, A1 and Ca. The NL_i for B increased in proportion to the square root of time except for early stage, which suggests that the rate of the long-term dissolution or alteration may be controlled by a diffusion process. Potential secondary phases forming as the results of incongruent dissolution were estimated to be kaolinite and calcite by comparison of the measured solution data with the thermodynamically calculated phase stability relationships. These results suggest that the glass phase has a potential chemical durability not so different from conventional HLW glasses.     

Electron Heat Diffusivity Measurement by Perturbative Method on HT-7 Tokamak

Spatio-temporal evolutions of the sawteeth activities are measured simultaneously with a 16 channel high spatio-temporal resolution electron cyclotron emission （ECE） heterodyne radiometer on HT-7 and the evolutions of the sawteeth are found to be diffusive in character. By a perturbative analysis, the electron heat diffusivity Хe inferred by time-to-peak method and Fourier transform shows a good agreement. The value of electron heat diffusivity shows radial asymmetry between the low magnetic field side （LFS） and the high magnetic field side （HFS）. It is observed that with the increase in plasma density, the electron heat diffusivity decreases and the confinement of energy is improved. By comparing with Хe^pb inferred by static power balance analysis, the result indicate that Хe^hp is larger than Хe^pb by a factor ranging from 2 to 10.     

微波零相位法测量超导加速器ps级电子束纵向长度

本文基于微波零相位法,将中国工程物理研究院太赫兹自由电子激光(CTFEL)2×4-cell超导加速器的下游腔作为零相位腔,测量了上游腔增能后的电子束纵向长度,并通过束流动力学模拟证明,当两个超导腔正常工作时,上游腔出口处的电子束纵向长度与下游腔出口处的接近。实验结果表明,CTFEL 2×4-cell超导加速器能实现半高宽小于6.8 ps的电子束,满足装置出光要求。     

水堆安全壳内气体分布模拟计算

本工作采用TH3SL程序对水堆事故后安全壳内的气体分布及蒸汽冷凝进行了随机模拟。校验计算表明 :此程序的模拟结果是可信的     

使用活化探测器和成像盘技术相结合的方法测量混凝土屏蔽体内中子空间分布

描述了一种联合使用活化探测器和成像盘技术（IP）探测中子注量的方法。利用这种方法测量了高能中子束线装置KENS（KEKspallationneutronsourcefacility）中混凝土屏蔽体内中子的空间分布。高能中子注量衰减的实验结果与使用蒙特卡罗程序MARS14模拟计算的结果符合很好。结果表明，联合使用活化探测器和成像盘技术可以同时测量多个位置的中子注量，直观展现出混凝土屏蔽体内中子强度的分布情况。     

Spatial Characteristics of Thomson Scattering in a Linearly Polarized Laser Field

The spatial characteristics of Thomson scattering in a linearly polarized laser field are investigated. The results show that the electron＇s motion and spatial distributions of Thomson scattering depend sensitively on the phase η0 at which the electron is injected to the laser field. When η0 equals to 0 or π, the electron motion is a zigzag motion and the spatial distributions of the emission show fourfold or twofold symmetry. In other cases of phases, there is a steady drift motion of electron in the transverse direction, which results in the absence of the zigzag motion and a breakdown of the symmetry of the spatial distributions as well.