直流X射线模拟电缆X射线响应的可行性

本文对电缆X射线辐照响应的机理和模拟方法进行了研究,分析了电缆直流和脉冲X射线辐照响应的异同。建立了带状电缆X射线辐照响应一维计算模型,该模型包含电缆屏蔽层和介质层间隙、介质层瞬态辐射感应电导率等计算模型,模拟了带状电缆直流和脉冲X射线辐照电流响应。模拟结果表明,在X射线注量相同的条件下,电缆直流和方波脉冲X射线响应具有类似的波形特征及相同的间隙电压。因此,在该计算模型描述的电缆X射线辐照响应机制下,可利用直流X射线开展相应的脉冲X射线辐照响应机制模拟。     

屏蔽电缆X射线辐照非线性效应模拟

本文分析了X射线辐照电缆的物理过程,建立了电缆介质层辐射感应电导率(RIC)和间隙效应计算模型,采用有限元方法模拟了电缆X射线辐照非线性效应,给出了诺顿等效电流源(NCD)的非线性响应规律。模拟结果表明,仅考虑RIC效应时,随着X射线注量的增加,NCD幅度存在明显的饱和现象,波形宽度逐渐变窄;仅考虑间隙效应时,NCD幅度近似正比于间隙宽度;当同时考虑两种效应时,间隙效应将会大幅抵消RIC对NCD的影响。因此,在预估核爆环境下屏蔽电缆的X射线辐照响应时,需综合考虑RIC和间隙非线性效应的影响。     

SIP外壳内受X射线激发的电磁干扰环境

本文估算了系统级封装（SIP）外壳内，受脉冲X射线辐照产生的电磁干扰（EMI）环境。首先通过蒙特卡罗数值方法计算了可伐合金及印制电路板（PCB）表面受X射线辐照激发电子的产额和能谱，并基于该计算结果开展了电子自洽运动的数值模拟。利用时域有限差分法（FDTD）和粒子模拟技术（PIC）对电子产生电磁场的过程进行了仿真。计算结果表明，电子的运动使得电子发射面附近的EMI环境最强。此外，从频谱可看出，电磁干扰主要集中在低频部分，且频率取决于X射线的时间参数。通过减小SIP外壳的受辐照面积及高度可降低外壳内的EMI环境强度。     

强流脉冲离子束辐照对钛合金表面相结构的影响

利用X射线衍射(XRD)和能量色散的特征X射线谱(XEDS)扫描,对强脉冲离子束辐照钛合金的表面结构特征和成分分布进行了测试与分析。结果表明,试样钛合金为(α+β)型两相钛合金。当以低能流密度离子束辐照时,材料表面粗糙度的增加导致结构发生明显变化;随着离子束能流密度的增加,材料表面层出现微小非晶相;表面元素呈明显的层状均匀分布;多次脉冲离子束辐照下,表面形成Al2O3等氧化物,从而利于被辐照表面抗氧化性的提高。进一步提高离子束能流密度,多次脉冲辐照,材料表面形成了新相Al6MoTi和AlMoTi2。     

强流脉冲电子束纯铝表面改性过程的热力学模拟

针对强流脉冲电子束表面改性的特点,建立了相应的数学物理模型,以纯铝材表面改性实验为基础,计算了由强流脉冲电子束辐照材料表面所产生快速升降温与熔凝过程,对其中的熔化、蒸发、热应力波等现象分别进行了数值模拟。计算结果表明,熔化深度约在1-10μm,与实验结果接近;蒸发作用影响较小,汽化层厚度仅为纳米量级;热应力波的幅值约在0．1MPa量级,且与脉冲的能量密度大致成正比,但是对材料结构和性能有重要影响。     

SKDll模具钢的强流脉冲电子束辐照改性

本文介绍强流脉冲电子束(HCPEB)材料表面改性原理,采用模具钢SKDll进行辐照处理实验.对处理样品表面进行形貌观察,发现熔坑面密度及粗糙度随脉冲处理次数的增加而减小.X射线衍射分析证实,多脉冲处理条件下表面改性层中碳化物发生溶解,形成高奥氏体含量的重熔组织,而过多的能量注入会使奥氏体发生再度分解.磨损性能测试表明,在低电压(19.8 kV)处理情况下,耐磨损性能得到改善,脉冲次数为8次时处理样品的耐磨性达到最佳,这与表面改性层中碳化物及奥氏体的相对含量变化密切相关.     

SKD11模具钢的强流脉冲电子束辐照改性

本文介绍强流脉冲电子束（HCPEB）材料表面改性原理，采用模具钢SKD11进行辐照处理实验。对处理样品表面进行形貌观察，发现熔坑面密度及粗糙度随脉冲处理次数的增加而减小。X射线衍射分析证实，多脉冲处理条件下表面改性层中碳化物发生溶解，形成高奥氏体含量的重熔组织，而过多的能量注入会使奥氏体发生再度分解。磨损性能测试表明，在低电压（19．8kV）处理情况下，耐磨损性能得到改善，脉冲次数为8次时处理样品的耐磨性达到最佳，这与表面改性层中碳化物及奥氏体的相对含量变化密切相关。     

Kovar封装CMOS器件X射线剂量增强效应研究

在器件的金属化层及封装等结构中，高原子序数材料在低能X射线的辐照下，会在相邻的低原子序数材料中产生剂量增强效应，从而使得器件性能严重退化。主要介绍了柯伐封装的CMOS器件，在X射线和γ射线辐照下，其辐照敏感参数阈值电压和漏电流随总剂量的变化关系。并对实验结果进行了比较，得出低能X射线辐照对器件损伤程度大于γ射线，对剂量增强效应进行了有益的探讨。     

六面体单元中X射线能量沉积算法及其在圆柱壳体结构中应用研究

为了对三维条件下的X射线热击波传播问题进行数值模拟,需首先解决能量沉积计算的问题。本文采用计算能通量矢量在面单元上积分的方法,给出了一种六面体单元中X射线能量沉积算法,并计算了有限长圆柱壳体构形在X射线正入射及斜入射条件下的能量沉积分布。结果表明:对于正入射,沉积能量沿方位角近似呈余弦分布,与理论解吻合,在半径方向上,能量沉积由表层向内部快速递减;对于斜入射,在壳体内外侧及柱体端面均会出现能量沉积区域,整个沉积能量分布呈现出明显的边界效应。     

薄膜锗靶等离子体参量诊断的实验研究

描述了对双脉冲辐照薄膜锗靶形成的等离子体参量诊断的实验研究。使用平晶谱仪和时间分辨X射线晶体谱仪诊断等离子体参量,给出了等离子体的电子密度、电子温度及其时间演变过程。实验结果表明:双脉冲打靶比单脉冲打靶电子温度有较大幅度提高。诊断结果为双脉冲驱动薄膜靶高增益X射线激光实验选择最佳的实验条件提供了实验依据。     

Shock wave interactions arising from near surface displacement cascades

Kaminsky has recently observed during 14 MeV neutron irradiation of a variety of materials that substantial (micron-sized) particles are ejected from the surfaces of the bombarded specimens. Similarities between Kaminsky's observations and the macroscopic phenomena of spall suggested the possibility that shock waves and transient thermal stresses, generated by energetic primary knock-ons, may be in part responsible.A brief discussion of spall phenomena will be presented as background to calculations of the shock wave interactions. The results indicate that cascade generated stresses may be responsible for the emission of such particles by triggering the release of stored internal energy.     

Bonding tungsten,W–Cu-alloy and copper with amorphous Fe–W alloy transition

W/Cu graded materials are the leading candidate materials used as the plasma facing components in a fusion reactor. However, tungsten and copper can hardly be jointed together due to their great differences in physical properties such as coefficient of thermal expansion and melting point, and the lack of solid solubility between them. To overcome those difficulties, a new amorphous Fe–W alloy transitional coating and vacuum hot pressing (VHP) method were proposed and introduced in this paper. The morphology, composition and structure of the amorphous Fe–W alloy coating and the sintering interface of the specimens were analyzed by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The thermal shock resistance of the bonded composite was also tested. The results demonstrated that amorphous structure underwent change from amorphous to nano grains during joining process, and the joined W/Cu composite can endued plasma thermal shock resistance with energy density more than 5.33 MW/m². It provides a new feasible technical to join refractory tungsten to immiscible copper with amorphous Fe–W alloy coating.     

考虑撞击区非线性和土-结构相互作用的飞机撞击核电厂振动效应分析

给出一种简化的飞机撞击核电厂振动效应的评估方法，首先给出了2种飞机撞击荷载模拟方法（力-时程法和飞射物-标靶相互作用法）所产生的核电厂振动响应特性及其传播规律；随后重点分析了核电厂撞击区材料非线性和土-结构的相互作用对核岛内部振动响应的影响；最后结合核电厂抗震裕度评价工作，给出了振动响应对核电厂核岛内部安全相关系统、设备和部件影响的评估实例。结果表明:2种飞机撞击荷载模拟方法所得核电厂撞击区最大变形及其变化规律基本一致，但飞射物-标靶相互作用法将包含更多的高频分量；随振动传播距离的增加，振动响应（特别是高频分量）衰减显著，且2种撞击荷载模拟方法所得响应将逐渐趋于一致。当考虑撞击区材料非线性后，飞机撞击核电厂所产生的振动响应将明显低于线性分析的结果；当进一步考虑土-结构相互作用后，其振动响应还将进一步减小；裕度地震反应谱可作为振动响应评估的参考准则。      

基于白光中子源的核石墨硼当量测量

核材料中热中子吸收截面高的杂质会引起堆芯反应性的变化，一般用硼当量表示这些杂质对热中子的吸收，硼当量是衡量核材料纯度的重要指标之一。热中子宏观吸收截面法是硼当量测量的方法之一，测量时采用同位素中子源则精度低，而白光中子源产生的中子强度高、方向性好，且可慢化为热谱，能有效提高硼当量测量精度。本文基于15 MeV电子加速器驱动的白光中子源开展核石墨硼当量测量的研究，利用蒙特卡罗模拟并优化实验方案，对实验数据进行检验与修正，建立核石墨硼当量测量定量分析方法。该方法能快速、准确检测核材料的硼当量，对反应堆的物理设计、安全性评估等具有重要意义。     

Boron Equivalent Measurement of Nuclear Graphite with Photoneutron Source

Impurities in nuclear materials with high thermal neutron absorption cross section will change the reactivity. The absorption of thermal neutrons by these impurities is represented by boron equivalent, which is one of the important factors to measure the purity of nuclear materials. Boron equivalent can be determined directly via the measurement of macroscopic thermal neutron absorption cross section based on an isotopic neutron source, but with lower accuracy. The photoneutron source, which can generate neutrons with higher intensity, better direction and lower energy, can effectively improve the accuracy of boron equivalence measurement. Therefore, the boron equivalent measurement of nuclear graphite was carried out with the photoneutron source driven by 15 MeV electron LINAC. Monte Carlo simulation method was used to optimize the experimental scheme, and the experimental data were tested and modified. Finally, the quantitative analysis method was established for the measurement of graphite boron equivalent. This method can quickly and accurately measure the boron equivalent of nuclear materials, which is of great significance for the physical design and safety assessment of the reactor.     

Studies of multilayer structure in depth direction by soft X-ray spectroscopy

1 Introduction Over the recent several decades, artificial layered structures have been extensively developed as useful functional structures for semiconductor devices [1], magnetic devices [2], X-ray high-reflectance mirrors [3], and so on. They are initially designed as multilayers consisting of uniform layers with the same properties as those of bulk materials and having clear-cut inter- faces (boundaries). However, in real cases, some lay- ers have structures different from those of bulk m…     

Laser induced fast ignition made realistic by relativistic velocities-dream or reality?

Due to the recent developments in high power lasers it is suggested to accelerate a micro-foil by the laser pressure to relativistic velocities. The time dependent velocity of this micro-foil is calculated analytically for pulsed constant laser intensity. The accelerated foil collides with a target creating a shock wave on impact. The shock wave parameters are calculated within the context of relativistic fluid dynamics.It is suggested to use the energy of the relativistic micro-foil to ignite a pre-compressed target with a density relevant for fusion ignition. The equations are written and solved for the collision between the micro-foil and the very dense target. The criteria for shock wave ignition and heat wave ignition are used to show that one needs significantly less laser energy for heat wave ignition.The present scheme shows that nuclear fast ignition by micro-foil impact could be attained in the near future with lasers that are currently under construction.     

CrAlN/TiAlN纳米多层膜界面结构的中子与X射线反射研究

采用反应磁控溅射技术在单晶硅基片上制备了CrN纳米单层膜和CrAlN/TiAlN纳米周期膜,利用非极化中子和X射线反射对膜层厚度、膜层界面粗糙度、界面扩散等表面、界面结构和性质进行了系统研究。中子反射测得的CrN纳米单层膜和CrAlN/TiAlN纳米周期膜的厚度与设计厚度的差别为3.8%～4.2%。散射长度密度（SLD）分析结果表明,膜层间和膜层与基底间界面较为清晰,扩散较少。X射线反射测得的膜层厚度较中子反射测得的膜层厚度偏高,对于较小调制周期的多层膜,界面弥散会对X射线反射结果产生较大误差。     

承压热冲击下DVI接管动态应力特性研究

压力容器直接注入（DVI）接管在热冲击下的动态应力特性对于反应堆压力容器（RPV）结构完整性评估具有重要意义。建立了含DVI接管的RPV压力壳热流固耦合数值计算模型,并进行了验证分析;然后研究了蓄压安注箱（ACC）和堆芯补水箱（CMT）安注时RPV筒体和DVI接管热工水力特性;最后分析了热冲击下RPV筒体和DVI接管连接高应力区的温度分布、等效应力和等效塑性应变分布特性。研究结果表明,ACC安注阶段RPV筒体和DVI接管连接区存在较大的温度梯度和等效应力,且发生了局部塑性变形。若发生承压热冲击事件,应控制好DVI接管连接区温差,确保反应堆压力容器的结构完整性。本文开发的热冲击下热流固耦合数值计算模型和计算方法可用于核岛内DVI接管与RPV筒体的安全性评价,也可用于类似承压结构在热冲击下的动态应力特性分析。