基于LabVIEW的扫描探针电子能谱仪离线数据处理系统

报道了自行搭建的扫描探针电子能谱仪(SPEES)的离线数据处理系统。该系统是由国家仪器公司(National Instrument,NI)开发的图形化语言LabVIEW(Laboratory Virtual Instrument Engineering Workbench)来实现的,能够根据我们SPEES实验中能谱测量的不同模式(扫描模式和非扫描模式)来选择相应的处理模式。功能包括"文件批处理"、"方位角选择"、"原点校正"、"能量刻度"和"能谱处理及效率修正",同时还能对电子密度分布、角分布、道数分布和能量分布成像。该系统的研制成功为SPEES实验的顺利进行打下了基础。     

一维多道快电子能量损失谱仪的数据获取系统

介绍了用于一维多道快电子能量损失谱仪的数据获取系统。利用简单的与门电路,并配合DAQ2010采集卡的门控信号实现精确定时,利用定时卡PCI8554来同步采集卡和微机的动作,利用微机的RS232接口通讯来控制扫描电源,从而实现了谱仪的扫描测量。利用多线程技术,提高了采集系统的容错能力。该系统目前已经用在电子能量损失谱仪上,效果良好。     

振动扫描极化力显微技术原位研究乙醇在云母表面的吸附行为

用AFM成像技术的振动扫描极化力成像模式(VSPFM),在挥发性有机小分子乙醇的饱和气体氛围条件下,研究了云母表面吸附层对乙醇的吸附行为.通过对扫描探针针尖施加不同的偏压和梯度比较成像质量,探索挥发性两亲分子饱和气体氛围中亲水固体表面吸附层吸附行为的最优成像条件,对比实验发现当扫描探针的针尖施加偏压为AC 4-6V时,...     

基于多模式扫描探针显微镜技术分析碳化硅的辐照损伤

本文在600℃对6H-SiC进行了He~+辐照实验,离子辐照能量为100 keV,剂量为5×10~(15)ions·cm~(-2)、1×10~(16)ions.cm~(-2)、3×10~(16)ions.cm~(-2)和8×10~(16)ions·cm~(-2)。本文采用多模式扫描探针显微镜技术,包括轻敲模式原子力显微镜、纳米压痕/划痕和导电模式原子力显微镜技术对样品辐照前后的表面损伤进行了分析。结果表明,随辐照剂量的增加,样品表面粗糙度逐渐增加,表面硬度逐渐下降。导电模式原子力显微镜能清晰地观测到样品表面氮泡分布形态,进一步说明材料表面的肿胀是由材料内部高压氮泡产生的。     

HT-7托卡马克欧姆放电条件下逃逸电子不稳定性的实验研究

HT-7托卡马克等离子体在低密度逃逸放电条件下,等离子体电流负反馈控制和水平位移振荡成功实现了逃逸电子的反常多普勒共振,分析了共振效应的实现条件.结果显示:反常多普勒共振使逃逸电子的垂直能量增加,平行能量减小,螺旋角增大,从而逃逸电子的同步辐射功率增加,最终逃逸电子的能量降低.可通过此法抑制逃逸电子能量,从而减小逃逸电子对装置造成的损害.     

快电子能量损失谱仪的一种新的多道测量方法

介绍了一维位置灵敏探测器在高分辨快电子能量损失谱仪上的应用。系统地讨论了在定点测量模式和扫描测量模式下的针对此谱仪的数据处理方法,并提出了一种新的数据处理方法,可以在扫描模式下通过离线分析得到更细致的能谱。     

电子束辐射交联电线电缆剂量分布的测量

在电线电缆辐射加工中,测量绝缘介质层中的电子吸收剂量及其分布,从而为实现产品质量控制提供了技术保证。根据电子束辐照电线电缆的工艺特点,利用经硫酸铈化学剂量计校准的带状兰色赛璐芬或三醋酸纤维素薄膜剂量计缠绕在电线电缆的芯线上,模拟电缆的介质层。在自行改装的扫描分光光度计上连续读测薄膜的光密度变化,曲线的每一个波峰代表了每一层剂量分布的极大值,其包络线代表了在射束方向上的介质层中的深度剂量分布。利用碰撞阻止本领比,可以得到绝缘介质中吸收剂量及其分布。实验表明,介质层中的剂量分布是以下三个过程的累积效应:电子能量随深度的变化;从芯线表面的电子反散射贡献;来自邻近线缆和辅助设备的散射线的贡献。     

电子在无限平行板空腔中的能量沉积

电子源在物质空腔中的能量沉积是核辐射探测和剂量学研究中经常涉及的问题。本文应用了非均匀介质中电子迁移理论计算了电子在无限平行板空腔中沉积的能量份额,给出了电子在石墨铝,铜,铅壁的空腔中沉积能量份额的计算结果     

能量为15keV——1MeV的电子在物质中的慢化谱

本文利用了在电子非弹性碰撞中小能量交换占优这一特点,将电子慢化谱方程中的碰撞积分项按交换能量展开到二级,从而得到一个 Fokker-Planck 型的微分方程,此方程便于数值计算。计算了电子能量为15keV—1MeV 的单能电子在石墨,铅,铜和金中的慢化谱。     

扫描探针显微镜在锆合金氧化膜显微组织研究中的应用

Zr-4合金在高压釜中经360 ℃高温水腐蚀后,用扫描探针显微镜(SPM)研究了氧化膜中的显微组织和晶粒形貌.由于SPM具有很高的水平和垂直分辨率,适合于观察表面只有微小起伏的显微组织,所以能够清晰地观察到氧化膜中的裂纹、空洞和晶粒等显微组织.测试样品的制备方法简便.     

利用杠杆原理制备用于扫描隧道显微镜的钨针尖

利用杠杆平衡原理,设计了一套扫描隧道显微镜(STM)钨针尖的制备装置.它可以使针尖瞬间脱离液面,避免针尖继续腐蚀而影响针尖质量.同时它以简单的力学结构替代了传统复杂的控制电路.扫描电子显微镜使用结果表明,利用此法制备的钨针尖最小半径为50 nm.利用所制备的针尖对高序石墨进行STM扫描,效果良好,可用于原子级图像的扫描.     

Influence of heating on the discharge characteristics of a hollow cathode

Hollow cathodes are widely used as electron sources and neutralizers in ion and Hall electric propulsion. Special applications such as commercial aerospace and gravitational wave detection require hollow cathodes with a very wide discharge current range. In this paper, a heater is used to compensate for the temperature drop of the emitter at low current. The self-sustained current can be extended from 0.6 to 0.1 A with a small discharge oscillation and ion energy when the flow rate is constant. This is also beneficial for long-life operation. However, when the discharge current is high(1 A), heating can cause discharge oscillation, discharge voltage and ion energy to increase. Further, combined with a rapid decline of pressure inside the cathode and an increase in the temperature in the cathode orifice plate, electron emission in the orifice and outside the orifice increases and the plasma density in the orifice decreases. This leads to a change in the cathode discharge mode.     

The formula for the secondary electron yield at high incident electron energy from silver and copper

Based on main physical processes of secondary electron emission from metals, the relation that the multiplication of the real efficient secondary electron yield at high incident electron energy from metals, energy exponent and incident energy of primary electron is equal to constant C was deduced; based on the relation between the real efficient secondary electron yield at high incident electron energy from metals and secondary electron yield, the relation that the multiplication of the secondary electron yield at high incident electron energy, energy exponent and incident energy of primary electron is equal to constant D was deduced. The energy exponent n of primary electron in the energy range 10-100 keV hitting on silver and copper and the constant D are computed with the ESTAR program and experimental results in scanning electron microscope (SEM), respectively, therefore, the formulae for the incident energy dependence of secondary electron yield in the energy range 10-100 keV from gold and aluminum were deduced, the formulae were proved to be true by experimental results in SEM, the results were discussed and a conclusion was drawn that the formulae from silver and copper were successfully deduced.     

3.0MeV高频高压电子加速器计算机监控系统的研制

描述了基于PLC的高频高压电子加速器的计算机监控系统。在满足加速器正常操作的基础上,增加了能量反馈控制回路,提高了输出能量的稳定度(1％);保证了扫描电流的大小随输出能量变化的自动跟踪调节：在故障诊断方面也提供了有效的手段帮助排除故障或分析故障原因。     

Dynamic characteristics of charging effects on the dielectric constant due to E-beam irradiation: a numerical simulation

A series of synthetic variations of material intrinsic properties always come with charging phenomena due to electron beam irradiation.The effects of charging on the dielectric constant will influence the charging dynamic in return.In this paper,we propose a numerical simulation for investigating the dynamic characteristics of charging effects on the dielectric constant due to electron beam irradiation.The scattering process between electrons and atoms is calculated considering elastic and inelastic collisions via the Rutherford model and the fast secondary electron model,respectively.Internal charge drift due to E-field,density gradient caused diffusion,charges trap by material defect,free electron and hole neutralization,and variation in the internal dielectric constant are considered when simulating the transport process.The dynamics of electron and hole distributions and charging states are demonstrated during E-beam irradiation.As a function of material nonlinear susceptibility and primary energy,the dynamics of charging states and dielectric constants are then presented in the charging process.It is found that the variation in the internal dielectric constant is more with respect to the depth and irradiation time.Material with a larger nonlinear susceptibility corresponds a faster charging enhancement.In addition,the effective dielectric constant and the surface potential have a linear relationship in the charging balance.Nevertheless,with shrinking charging affect range,the situation with a higher energy primary electron comes with less dielectric constant variation.The proposed numerical simulation mode of the charging process and the results presented in this study offer a comprehensive insight into the complicated charging phenomena in electron irradiation related fields.     

K-shell excitation dielectronic recombination resonance strengths of highly charged He-like to O-like Xe ions

Dielectronic recombination is an important process in high temperature plasmas.In the present work,the KLn (n =L,M,N and O) DR resonance strengths of He-like to O-like xenon ions are measured at the Shanghai electron beam ion trap using a fast electron beam energy scanning method.The experiment uncertainty reaches about 6％ with significant improvement of statistics.A relativistic configuration interaction calculation is also made.Theoretical results agree with the experiment results within 15％ in most cases.     

Information depth and spatial resolution in BSE microtomography in SEM

Various methods of visualizing subsurface structures using the scanning electron microscope (SEM) in the backscattered electrons (BSE) mode are analyzed. The problems of image contrast and “in-depth” resolution of layered microstructures are discussed. The potentials of BSE microtomography, i.e. layer-by-layer formation of images of undersurface inhomogeneities are demonstrated by experiment.     

高能电子单粒子效应模拟实验研究

本文基于2 MeV自屏蔽电子加速器和10 MeV电子直线加速器,开展了电子单粒子效应实验研究,并分析了其机理。在保持入射电子能量不变的情况下,在±20%范围内改变器件的工作电压进行了单粒子翻转实验。实验结果表明：45 nm SRAM（额定工作电压1.5 V）芯片在电子直线加速器产生的高能电子照射下能产生明显的单粒子翻转,单粒子翻转截面随入射电子能量的变化趋势与文献数据相符合;电子引起的单粒子翻转截面随器件工作电压的变化趋势与理论预期一致,即工作电压越小,单粒子翻转临界电荷越小,翻转截面也越高。     

大功率脉冲磁场电源系统

描述了中国环流器2号A(HL-2A)装置磁场电源系统,介绍了电源的控制系统和实验结果。磁场电源总脉冲容量近250 MVA,一次放电脉冲释能1 300 MJ,其中单套电源的最高直流电压为3510 V,最大电流为45 kA,均以脉冲方式运行,脉冲时间5 s,重复周期10 min。电源主回路主要由飞轮脉冲发电机、晶闸管变流设备、硅整流器等组成。采用了硅整流器直接并联、电流平衡、恒角移相控制、整流器全关断检测、先进的监控和脉冲高压强流检测等技术措施。实验表明,磁场电源的性能指标能够满足装置实验的要求。