前向反冲分析和非卢瑟福背散射

介绍了弹性散射分析中的另外两种分析方法——前向反冲分析和非卢瑟福背散射分析。前向反冲分析适用于材料中H和He同位素分析。高能质子和He离子背散射分析可提高对重基体中C,N和O等轻元素分析的灵敏度。给出了这两种分析方法的应用实例。     

ERD facility for analysis of hydrogen and deuterium in solids

Hydrogen is the lightest element in nature, and so, its detection and quantitative analysis is difficult by the conventional methods utilized for other elements. In the recent years the technique of elastic recoil detection analysis (ERD) using 1–2 MeV He⁺ beam has been developed to quantitatively and simultaneously analyze hydrogen and its isotopes in solids. Such a facility has been set up using the 2 MeV Van-de-Graaff accelerator at IIT Kanpur. It facilitates H and D analysis in a material up to a depth of ∼ 1μm with a detection sensitivity of 0·1 at.% and depth resolution of about 300 ?. The application potential of this setup is illustrated by presenting the results of measurements performed on Al:H:D systems prepared by plasma source ion implantation and highT _c YBCO pellets exposed to humid atmosphere.     

SISAK快速化学分离装置的建立

SISAK(Short-lived Isotopes Studies by the AKUFVE technique)技术是目前使用最广泛的快速化学分离方法之一,主要应用在短寿命核素的分离和鉴别、超重元素的人工合成以及化学性质研究等方面的工作中.本文简单地叙述了SISAK技术的流程、原理和发展现状,介绍了自行建立的国内第一套基于SISAK技术的快速化学分离装置,并通过从裂变产物中分离短寿命核素这一实例验证了SISAK技术在快速化学分离中的优越性.     

动力后坐试验台数据采集系统设计与实现

为满足动力后坐试验台位移、速度数据高速采集的要求,介绍了一种以增量式编码器为位移传感器、以STM32F107VCT6MCU为下位机数据采集模块,采用MicrosoftVc＋＋6．0开发上位机试验软件的动力后坐试验台位移速度采集系统,实现了对试验中位移、速度数据的高速采集,并利用TeeChart控件实现速度位移曲线的绘制。现场试验结果表明该系统达到了设计要求,实现了数据的高速采集和曲线显示。     

Determination of hydrogen concentration in a-Si and a-Ge layers by elastic recoil detection analysis

In this work we have studied the individual a-Si and a-Ge hydrogenated layers prepared by RF sputtering on Si (100) substrates using Ar and H₂ gas mixture. The absolute value of atomic content of the H was determined by Elastic Recoil Detection Analysis (ERDA) with 1.6 MeV 4He⁺ beam. The dynamics of the out diffusion was investigated by annealing in high purity (99.999%) argon atmosphere at 350 °C for several hours. It was clearly shown that hydrogen can diffuse out faster from Ge film than from the Si one during annealing of the samples.     

Characterization of silicon oxynitride films using ion beam analysis techniques

Heavy-ion elastic recoil detection analysis (HIERDA) is the ideal technique for quantitative analysis of silicon oxynitride films on silicon because of its unique ability to measure simultaneously all elements of interest (i.e., H, C, N, O and Si), thereby permitting key parameters such as the O/N-ratio to be determined in a single measurement. However, high-energy accelerators suitable for such HIERDA measurements are becoming much less readily available. Hence, the present paper investigates and calibrates an alternative IBA technique for simultaneous O, N and C analysis – namely, the use of (d,p) and (d,) nuclear reactions. Under optimum analysis conditions (850 keV deuterons and 150° detector angle), the Si background level sets a lower detection limit of 1×10¹⁶ nitrogen atoms/cm² and 3×10¹⁵ oxygen atoms/cm². H analysis is carried out separately, using low-energy ERDA and a 2 MeV ⁴He beam. Absolute cross-sections have been obtained for each of the (d,p) and (d,) groups. Comparison with data in the recent Handbook of Modern Ion Beam Materials Analysis shows reasonable agreement (10–15%) for the (d,p) reactions on oxygen and carbon. However, in the case of nitrogen, the measured cross-section values are 70% larger than the Handbook data. Several silicon oxynitride samples have been analyzed, first at UWO using 850 keV deuterons, and subsequently at ANU using HIERDA and a 200 MeV Au beam. The resulting O/N-ratios agree to within 10%. The relative importance of radiation damage effects is briefly discussed.     

应用磁流变液体制退机的力学模型

磁流变液的流动特性可由外加磁场控制,且具有可逆、响应快、结构简单和易于控制的特点。在火炮制退机中采用磁流变液体,通过改变磁流变液体粘度来调节阻尼,形成液压阻力,也可控制后坐阻力规律。对于采用旁路结构的磁流变制退机,工作时磁流变效应的作用相当于一个磁流变阻尼器,同时液体从两个流液孔流过时仍有节流阻尼产生。从磁流变效应阻尼和液体流动阻尼两个方面进行了分析,通过两种阻尼的耦合建立了磁流变制退机的力学模型。     

Experimental characterization of liquid film behavior during droplets–polyethylene particle collision

Nowadays, the droplet–particle collision characteristics in the gas-phase ethylene polymerization process are still unclear. The high-speed photography and a quasi-circle imaging approach are employed to study the collision interaction characteristics between liquid droplets and polyethylene particles. The liquid film evolution is studied through variations of the film thickness on the particle north pole, the dynamic contact angle, center angle and film thickness at the maximum extension. Results have found that for n-hexane the threshold temperature of the recoil happening increases with increasing initial Weber number, but for 1-hexene it is stable. Over 70°C evaporation and splash occurs immediately. Under low Weber numbers, the water droplet stays for damping oscillations, the reference stable height of which is linearly related to temperatures. Moreover, three regimes of film thickness variation with time are identified and mathematically described, while Regime 3 characteristics are found strongly dependent on the liquid species, Weber number, and particle temperature.     

管后坐式自动机的后坐体质量优化计算方法

对于身管后坐式自动机,后坐体的质量是自动机能否可靠地自动循环运动的重要参数。针对该问题,通过对自动机运动循环和弹药参数进行分析,建立后坐运动微分方程和内弹道方程,运用Matlab编制后坐运动计算模块,对后坐体质量估算值进行了调整和优化,使其运动性能参数能够满足性能指标要求,同时也为管后坐式自动机的后坐体质量优化设计提供一种计算方法。     

基于Herschel-Bulkley模型的火炮磁流变后坐阻尼器设计

针对火炮磁流变(MR)阻尼器的特点,以某25 mm口径试验火炮为研究对象,基于Herschel-Bulkley模型,建立了该25 mm试验炮磁流变后坐阻尼器的平行板一维层流模型,得到不同MR流体行为指数和不同磁场作用下阻尼力随活塞速度的变化规律,确定了磁流变阻尼器的主要技术参数.建立了火炮后坐运动方程,评价了MR流体行为指数对后坐阻尼器性能的影响,此指数越大,阻尼器所产生的阻尼力也越大,火焰的后坐位移和后坐速度也越小.计算结果表明,所设计的火炮MR阻尼器满足设计要求.