有益的、负责任的、可持续的

国际原子能机构为帮助着手发展核电的国家明智地、有益地、安全地和可靠地发展核电做好充分准备     

测量气体放射性的电离室的灵敏度的估计

空气中所含气态放射性物质的测量,在一般剂量测量中常用充以待测气体的电离室来进行。如复估计此种装置对不同能量的β放射性气体的灵敏度或刻度常数,可以利用下面的简单公式及曲线图。     

常规的与浸泡的金属离子植入的比较

可以把真空弧产生的金属等离子体用作常规金属离子植入用的离子源中离子的原材料，或可用作等离子体浸泡离子植入的浸泡等离子体。在两种情况下，产生等离子体的基本方法是一样的；方法是简单折、有效的，并可与各种金属一起使用。不同种类的真空弧离子源由本文作者及其他人研制出来，它们作为金属离子植入工具的适用性已为人们公认。金属等离子体浸泡表面处理是一种刚出现的方法，它的性能和应用是本研究的课题。不论在所使用的工序     

金的热中子吸收截面的测量

本文介绍利用中子晶体谱仪和4π-MnSO_4溶液探测器测量金的热中子吸收截面的方法和结果;讨论了某些对测量结果有影响的因素,并引进了相应的修正。金的热中子(E=0.0253电子伏)吸收截面的测量结果为σ_a=98.8±1.7靶,这个结果与国外近年来发表的测量结果符合得较好。     

铀的生产法的改进

美国在国外的生产铀的公司,当与美国原子能委员会签定的合同满期之后,正在面临着失去他们市场的威胁。有鉴于此,这些公司正在企图以改进工艺的办法来降低生产的成本,从而达到保持他们     

铀的宏观浸蚀的研究

本文研究出一种醋酸-铬酸-水溶液电解浸蚀显露金属铀宏观组织的方法,效果良好,并与过去常用的几种方法进行了比较。     

科罗拉多高原的铀的指示植物

在科罗拉多高原采用了两种植物找铀的方法。第一种方法建立在对深根植物的化学分析基础上,这种植物的根能延展至矿体并从其中吸附铀;该法所探测的是通过植物根部所吸附的但可分析的元素量。第二种方法包括绘制指     

Transport characteristics of space charge-dominated multi-species deuterium beam in electrostatic low-energy beam line

The transport characteristics of a space chargedominated multi-species deuterium beam consisting of D_1~+,D_2~+, and D_3~+ particles in an electrostatic low-energy beam line are studied. First, the envelope equations of the primary D_1~+ beam are derived considering the space charge effects caused by all particles. Second, the evolution of the envelope of the multi-species deuterium beam is simulated using the PIC code TRACK, with the results showing a significant effect of the unwanted beam on the transport of the primary beam. Finally, different injected beam parameters are used to study beam matching, and a new beam extraction system for the existing duoplasmatron source is designed to obtain the ideal injected beam parameters that allow a D_1~+ beam of up to 50 m A to pass unobstructed through the electrostatic low-energy beam transport line in the presence of an unwanted(D_2~+, D_3~+)beam of 20 m A; at the same time, distortions of the beam emittance and particle distributions are observed.     

MC法模拟多路平行束准直器对比度

采用MC法模拟设计了用于SPECT成像的多路平行束(MPB)准直器,将MPB系统重建的模具图像与平行束(PB)系统重建图像进行对比。用OS-EM迭代算法重建图像并计算对比度、信噪比、归一化标准偏差三个指标用于评价图像质量。结果表明:随着迭代次数增加,MPB系统重建图像中热源的对比度高于PB系统,对于小半径热源这个差值更明显,但是冷源的对比度低于PB系统;两个系统有可比较的重建图像收敛速度,随着迭代次数增加,MPB系统的噪声特性略差于PB系统。     

Testing of actively cooled mock-ups in several high heat flux facilities—An International Round Robin Test

Several electron beam and ion beam facilities are involved in high heat flux testing of plasma-facing components for next step fusion devices. Up to a certain degree, these machines are comparable, but differences concern, e.g. beam generation, beam sweeping, calibration techniques and diagnostics. In order to get an information if tests in the different facilities are really comparable, a set of actively cooled CFC monoblocks has been heated in four electron beam and one ion beam facility at comparable power densities. The temperature response during these loadings has been registered and used as a criteria for assessment.     

Dynamic response of a multi-span beam to transverse impact

The general case of impact between a continuous beam on many supports and a moving mass striking the beam transversely at any point has been analysed. Expressions for the deflection of the beam at any point along the beam, the impact force and the duration of impact have been theoretically derived employing the operational method developed by Heaviside. The results are presented in convenient, easily computable form and are applicable for a beam of any number of spans, struck at any point. Experiments have been performed on a three-span beam using a photographic method of measurement. The agreement between the theoretical and experimental results is excellent. The formulations presented are expected to provide the basis for the development of a rapid and reliable method for designing multi-span beams to withstand impact loading.     

微波离子枪离子束光学的数值模拟

用数值模拟方法研究了聚焦离子束系统中微波离子枪的束光学性能，将离子枪看作由源等离子体极和Ｏｒｌｏｆｆ－Ｓｗａｎｓｏｎ透镜组成的双级加速系统，分析了各参对束发射特性的影响。结果展示出引出束光学主要取决于引出导流系数和电势分布，在一定条件下可获得发散度小的离子束。     

Linear hybrid simulations of low-frequency fishbone instability driven by energetic passing particles in tokamak plasmas

A linear simulation study of energetic passing particle-driven low-frequency fishbone instability in tokamak plasmas has been carried out using the global kinetic-MHD (magnetohydrodynamics) hybrid code M3D-K. This work is focused on the interaction of energetic passing beam ions andn=1 mode with a monotonic safety factorqprofile andSpecifically, the stability and mode frequency as well as mode structure of then=1 mode are calculated for scans of parameter values of beam ion beta, beam ion injection energy, beam ion orbit width, beam ion beta profile, as well as background plasma beta. The excited modes are identified as a low-frequency fishbone with the corresponding resonance ofwhereis the beam ion toroidal transit frequency andis the beam ion poloidal transit frequency. The simulated mode frequency is approximately proportional to the beam ion injection energy and beam ion orbit width. The mode structure is similar to that of internal kink mode. These simulation results are similar to the analytic theory of Yuet al.     

Enhanced Raman Scattering of Elliptical Laser Beam in a Collisionless Plasma

This paper presents the Enhanced Raman scattering of a elliptical laser beam in a collisionless plasma. The transverse intensity gradient of a pump beam generates a Ponderomotive force, which modifies the background plasma density profile in a direction transverse to pump beam axis. This modification in density effects the incident laser beam, plasma wave and back-scattered beam. Non-linear differential equations for the beam width parameters of pump laser beam, plasma wave and back-scattered beam are set up and solved numerically. The interplay between the self-focusing of the main beam and SRS has been studied in detail. The analysis clearly shows a coupling between the main beam and the plasma wave, therefore an increase in the self-focusing of the pump beam at lower intensities increases the self-focusing of the plasma wave which inturn leads to an increase in the back-reflectivity of the scattered wave. Further, it is also predicted that strong self-focusing of the pump beam at higher plasma density leads to strong self-focusing of the plasma wave and results in an increase in SRS reflectivity.     

横向和纵向耦合束流系统束流发射度增长分析

分析了初始无关联无耦合的束流通过存在横向和纵向耦合的束流系统后发射度的增长。结果表明，束流的有效发射度随着束流初始条件的变化明显地增长。给出了束流有效发射度的增长关系和边界方程式。     

Self-Focusing of Elliptical Laser Beam in Collisional Plasma and Its Effect on Stimulated Brillouin Scattering Process

This paper presents an investigation of self-focusing of elliptical laser beam in a collisional plasma and its effect on stimulated Brillouin scattering (SBS) process. The non-linearity arising through non-uniform heating leads to redistribution of carriers, which modifies the background plasma density profile in a direction transverse to pump beam axis. This modification affects the incident laser beam, ion-acoustic wave and back scattered beam. Non-linear differential equations for the beam width parameters of the pump laser beam, ion-acoustic wave and back scattered beam are set up and solved numerically. It is observed from the analysis that the focusing of waves greatly enhances the SBS back-reflectivity.     

Diagnosis and dynamics in a simple low energy medium current electron beam channel

We present a simple experimental setup and an associated method enabling both the non-destructive diagnosis and the calculation of the beam evolution in a low energy medium current electron beam channel, where the space-charge and emittance effects are comparable. The diagnosis makes use of an axially symmetric magnetic lens while a second lens is added to increase the flexibility in the beam processing. The paper emphasizes the three steps involved in the method: the evaluation of the lenses' magnetic field by numerical simulation, the beam diagnosis, and the computation of the beam envelope. The calculation of the magnetic field is based on the finite element method. Subsequently, the beam parameters at the electron source exit – emittance and cross-over radius and position – are found with the modified three gradient method. Finally, the beam dynamics are modeled with the K–V equation adapted for the particular case of axial symmetry. The results obtained in this paper can be used to optimize technological processes, such as welding, hardening, cladding, and surface alloying.