强脉冲离子束横截面分布的测量

强脉冲离子束在靶上的横截面能量密度分布和束流焦点位置是束流分析和辐照效应研究中重要的技术参数.利用红外成像诊断技术,可以以较高的空间分辨率和能量密度分辨率对束流的横截面分布进行测量,并可以实现对束流焦点的测量和束流传输特性的分析.通过该实验,可以使学生掌握强脉冲加速器诊断的基本技能,加深对加速器原理及脉冲束流分布和传输特性的认识.     

Relations between compositional modulation and atomic ordering degree in thin films of ternary III—V semiconductor alloys

This paper derives the expressions for the ordering degree and the modulation factor of A and B atoms in A_xB_1-xC epilayers of ternary III--V semiconductor alloys. Using these expressions, it identifies quantitatively the alternating atom-enhanced planes, compositional modulations, atomic ordering degree on the group-III sublattices and the fine structure of NMR spectra.     

Nucleon--nucleon interactions in the double folding model for fusion reactions

Nucleus--nucleus potentials are determined in the framework of double folding model for M3Y--Reid and M3Y--Paris effective nucleon--nucleon (NN) interactions. Both zero-range and finite-range exchange parts of NN interactions are considered in the folding procedure. In this paper the spherical projectile--spherical target system ¹⁶O+²⁰⁸Pb is selected for calculating the barrier energies, fusion cross sections and barrier distributions with the density-independent and density-dependent NN interactions on the basis of M3Y--Reid and M3Y--Paris NN interactions. The barrier energies become lower for Paris NN interactions in comparison with Reid NN interactions, and also for finite-range exchange part in comparison with zero-range exchange part. The density-dependent NN interactions give similar fusion cross sections and barrier distributions, and the density-independent NN interaction causes the barrier distribution moving to a higher position. However, the density-independent Reid NN interaction with zero-range exchange part gives the lowest fusion cross sections. We find that the calculated fusion cross sections and the barrier distributions are in agreement with the experimental data after renormalization of the nuclear potential due to coupled-channel effect.     

强脉冲离子束辐照金属材料表面热力学效应计算

 简要讨论了强脉冲离子束与金属靶材料相互作用的理论模型,以此为基础应用数值计算的方法模拟计算了离子能量为1.0 MeV和300 keV,束流密度分别为10 A/cm²、50 A/cm²、100 A/cm²的质子束与金属铝靶材料相互作用时的热力学效应,给出了铝在辐照后内部的温度分布、温度梯度分布,以及温度变化速率（加热速率与冷却速率）、热激波的产生与传播过程及与应力等模拟计算结果。     

利用双折叠模型对弹核为α的熔合垒高度和位置的系统学分析

本文系统分析了α粒子与不同的靶核熔合时, 势垒高度和位置与相互作用核的电荷数和均方根半径的关系. 通过基于密度依赖的核子-核子相互作用(CDM3Y6)的双折叠模型来计算核势. 得到了当弹核为α时垒高度和位置的参数化公式. 通过分析质量数从16到238的原子核表明, 参数化公式可以精确地再现弹核为α的熔合反应的垒高度和位置, 其精确度在±1%以内. 此外, 其结果还能很好地和实验值, 经验值, Royer, KNS, AW和亲近势的结果相符合.     

赝火花脉冲电子束的特征

基于电场递增效应理论,讨论了多极板赝火花脉冲电子束的特征.通过电子束对固体变色片和金属靶的轰击,对赝火花电子束的不稳定性、细丝效应和自箍缩效应等现象做了研究和分析.The characteristics of pulsed electron beam generated by multiplate pseudospark chamber (MPC) on the basis of field escalation effects have been described in this paper. The phenomena such as instability, filament effect, and self-pinch effect of pseudospark electron beam were studied and analyzedby the bombardment of solid evident films and metal targets.     

纳秒强流脉冲电子束强化金属表面的研究

利用多极板赝火花放电装置产生的高功率脉冲电子束对不同类型的钢, 如45#, 65Mn, T8, 9Cr18和GCr15等进行轰击, 研究其在金属材料表面改性中的应用. 样品表面的显微硬度和耐腐蚀性测试结果以及扫描电子显微镜(SEM)的观察分析表明, 经电子束轰击后, 这些材料在结构、组织和性能上发生了明显的变化, 轰击中心区域的显微硬度和耐蚀性明显提高. 基于一维热传导方程对材料表面的冷却速率进行了估算, 对电子束与金属材料的作用过程进行了理论分析. 结果表明, 高功率密度脉冲电子束与金属材料相互作用, 表面冷却速率高达1. 2×1012 ℃/s, 使材料表面局部瞬间达到熔化, 产生骤热急冷过程. High power density electron beams generated by multiplate pseudospark discharge chamber, have been used to bombard various kinds of steel targets such as 45#, 65Mn, T8, 9Cr18, GCr15, etc, and studyits applications for modification of metal surface. The microhardness and corrosive resistance property have been measured and the morphology was obtained by using SEM analysis. The results showed that the surface properties and structure of the matevials bom barded have been modified; in the bombarded center area, the microhardness as well as corrosive resistance property was improved obviously. The interactions befween the electron beam and metal materials were theoretically considered and discussed on the basis of simple calculation with one dimensional thermal transfer equation. It showed that the cooling rate of metal surface with 1.2×1012 ℃/s was so high that caused the metal surface instant melted, and abrupt cooled.     

Simulation of 200–400 Me V/u 12C+12C elastic scattering on SHARAQ spectrometer

In order to further obtain the information of three-body force(TBF) from 200–400 Me V/u12C+12C elastic scattering, we plan to perform this experiment on a SHARAQ spectrometer. Based on the experimental condition of the Radioactive Ion Beam Factory(RIBF)-SHARAQ facility, a simulation is given to find a compromise between the better energy and angular resolutions, and higher yield by optimizing the target thickness, beam transport mode, beam intensity and angular step. From the simulation, we found that the beam quality mainly limits the improvements of energy and angular resolutions. A beam tracking system as well as a lateral and angular dispersionmatching technique are adopted to reduce the influence of beam quality. According to the two angular settings of SHARAQ as well as the expected cross sections on the basis of the theoretical model, the energy and angular resolutions, and statistical accuracy are estimated.     

Simulation of effects of incident beam condition in p-p elastic scattering

The simulation is performed for the monitors of beam direction and beam position for p-p elastic scattering. We set several variables to simulate the monitors of incident beam condition changes: beam positions at the quadrupole magnet and target in beam line polarimeter (BLP2), distance between quadrupole magnet and target, size of plastic scintillators, distance between the target in BLP2 and the centers of plastic scintillators, and beam polarization. Through the rotation of the coordinate system, the distributions of scattered and recoiled protons in the laboratory system were obtained. By analyzing the count yields in plastic scintillators at different beam positions, we found that the beam incident angular change (0.35°) could be detected when the asymmetry of geometries of left and right scintillators in BLP2 was changed by 6%. Therefore, the scattering angle measured in the experiment can be tracked by these monitors.     

强脉冲离子束辐照薄金属靶的热力学过程研究

在回顾和总结现有强脉冲离子束诊断技术和能量沉积模型的基础上, 结合红外成像诊断分析, 基于能量平衡, 提出了强脉冲离子束在固体靶中功率密度分布模型, 并采用蒙特卡罗方法对其进行计算. 以该功率密度模型作为源项, 使用有限元分析方法模拟强脉冲离子束入射100 μm不锈钢靶后内部温度场在毫秒时间范围内的分布和演化. 结果显示, 在微秒时间范围内, 热场以存在于近表面区域数倍于离子射程范围内的冲击热场为主要特征; 而在毫秒时间范围内, 靶的前后表面(纵向)已达到温度平衡, 且靶后表面温度场和入射前表面的离子束横截面能量密度具有空间分布的相似性. 这证明了, 在采用具有毫秒响应速度的红外拍摄系统的情况下, 背面红外诊断技术可以实现以较高的精度对强脉冲离子束横截面的能量分布进行诊断和分析.