6—30keVB^＋,C^＋,N^＋,O^＋与H2碰撞单电子剥离的实验研究

用增长率方法首次测量６－３０ｋｅＶＢ＾＋、Ｃ＾＋、Ｎ＾＋、Ｏ＾＋与Ｈ２碰撞的单了截面，给出的Ｂ＾＋和Ｃ＾＋和６－３０ｋｅＶ能区截面随离子能量的趋势与已有的１００－２５００ｋｅＶ能区截面的变化趋势衔接很好。根据截面随入射离子能量和核电荷数的变化，对碰撞机理作了分析，Ｂ＾＋、Ｎ＾＋、Ｏ＾＋与Ｈ２碰撞的单电子剥离截面的变化规律由分子轨道模型得到很好的解释。     

keV量级的N+注入引起的氨基酸分子损伤

利用电子顺磁共振和红外光谱研究了ｋｅＶ级Ｎ＾＋注入到几种固态氨基酸样品中引起的分子结构损伤。结果表明，这一注入导致了分子的严重损伤：分子结构解体，红外吸收普遍降低；产生了大量的碎片，其中自由基碎片的类型和数量随注入离子的剂量发生显著变化；损伤碎片重组，形成了新的化学组合，表现出新的红外吸收峰。     

注入低能重离子在模拟细胞中的能量沉积

用Ｍｏｎｔｅ Ｃａｒｌｏ法模拟计算了３０ｋｅＶ和２００ｋｅＶ的Ｎ＾＋与１１０ｋｅＶ的Ｆｅ＾＋模拟细胞中本身及级联离子非弹性散射产生的电子，分子振动的能量沉积；讨论了电子分子振动的总能量沉积的深度分布。     

离子辐照聚合物薄膜引起的降解和能量传输过程

用１２０ｋｅＶＮ＾＋，Ａｒ＾＋，Ｆｅ＾＋辐照聚酰亚胺薄膜，辐照剂量为５×１０＾１４－１×１０＾１７ｉｏｎｓ／ｃｍ＾２，对辐照样品做了表面电阻和光学吸收数量，结果表明：辐照后样品的表面电阻有明显变化，且随辐照剂量变化呈现阈值，在高剂理下达到饱和值。     

离子束混合形成氮化钛膜的摩擦和光学性能

用载能氮离子束轰击纯铁镀钛膜样品，成功地形成了金黄色氮化钛薄膜。结果表明：注入剂量为０．５×１０＾１７ Ｎ＾＋／ｃｍ＾２的混合样品表面颜色与纯金类似；氮离子束混合样品表面显微硬度及耐磨性都远优于纯铁基体，且随离子剂量的增加，混合样品的表面硬度和耐磨性也提高。     

蒙特卡罗模拟Si^＋注入Si3N4／GaAs的射程分布和损伤分布

用蒙特卡罗方法模拟Ｓｉ＾＋注入Ｓｉ３Ｎ４／ＧａＡｓ的力学运动，以考察沉积在ＧａＡｓ材料表面的无定形Ｓｉ３Ｎ４阻挡层对Ｓｉ＾＋射程分布的影响。模拟计算和实验结果都表明，Ｓｉ３Ｎ４阻挡层能够有效地削减Ｓｉ＾＋在ＧａＡｓ衬底中的射程，避免沟道效应，得到浅结。但是阻挡层中也有相当数量的Ｓｉ、Ｎ原子由于与入射的Ｓｉ＾＋相互碰撞反冲进入ＧａＡｓ衬底。     

AMS系统中电离室计数望远镜对^14C粒子的探测与鉴别

为探测和鉴别来自加速器质谱计考古样品中的＾１４Ｃ粒子，建造了一台分裂式阳极屏栅电离室计数望远镜。它可以清楚地将＾１４Ｃ＾３＋离子与干扰离子＾１２Ｃ＾３＋、＾１３Ｃ＾３＋和＾１４Ｎ＾３＋区分开，并实现对＾１４Ｃ３＋离子的稳定计数。     

低能氮离子注入固态甘氨酸剩余产物的研究

采用２０ｋｅＶ Ｎ＾＋注入固态甘氨酸（Ｇｌｙ）薄膜。对注入样品的α粒子透射能谱以及样品溶于水后溶液的电导率和氨基含量的测量，揭示了低能离子注入的损伤作用具有饱和性。ＸＰＳ测量表明低能Ｎ＾＋注入Ｇｌｙ后形成了多种损伤产物，其中Ｃ、Ｎ元素的结合能变化较大，而Ｏ元素所处的化学环境变化很小。     

离子注入α—Al2O3陶瓷材料的表面改性研究

研究了α－Ａｌ２Ｏ３单晶注入Ｎ＾＋后的力学性能变化。结果表明，注入剂量为１×１０＾１７Ｎ＾＋／ｃｍ＾２时，Ａｌ２Ｏ３的显微硬度提高了９２％，注入剂量为３×１０＾１７Ｎ＾＋／ｃｍ＾２时，在Ａｌ２Ｏ３表面形成晶层，导致表面软化，显微硬度只是其５０％左右。离子注入在样品表面产生了高达－１１５０ＭＰａ的压应力，材料的断裂韧性的改善与此有关，实验亦发现Ｎ＾＋离子注入后Ａｌ２Ｏ３的断裂韧性提高了９５％左右。     

高能离子注入对聚酰亚胺薄膜硬度的影响

报道了聚酰亚胺薄膜在高能（６５０ｋｅＶ－２ＭｅＶ）Ｂ＾＋、Ｃ＾＋和Ｃｕ＾＋离子注入后硬度的变化。对注入样品进行了显微硬度测量和ＸＰＳ及ＲＢＳ分析，观察了硬度与离子种类、能量及注入剂量的依赖关系。结果表明，离子注入之后薄膜样品的显微硬度值明显提高，注入离子在样品中的电子能量损失对聚合物材料改性起着关键作用。ＸＰＳ和ＲＢＳ分析显示，离子注入之后聚酰亚胺薄膜中Ｃ的含量增加，形成了以苯环结构为主的新的交联     

Experimental and empirical study of steam condensation heat transfer with a noncondensable gas in a small-diameter vertical tube

An experimental study was performed to investigate local condensation heat transfer coefficients in the presence of a noncondensable gas inside a vertical tube. The data obtained from pure steam and steam/nitrogen mixture condensation experiments were compared to study the effects of noncondensable nitrogen gas on the annular film condensation phenomena. The condenser tube had a relatively small inner diameter of 13 mm (about 1/2-in.). The experimental results demonstrated that the local heat transfer coefficients increased as the inlet steam flow rate increased and the inlet nitrogen gas mass fraction decreased. The results obtained using pure steam and a steam/nitrogen mixture with a low inlet nitrogen gas mass fraction were similar. Therefore, the effects of noncondensable gas on steam condensation were weak in small-diameter condenser tubes.A new correlation was developed to evaluate the condensation heat transfer coefficient inside a vertical tube with noncondensable gas, irrespective of the condenser tube diameter. The new correlation proposed herein is capable of predicting heat transfer rates for tube diameters between 1/2- and 2-in. because of the unique approach of accounting for the heat transfer enhancement via an interfacial shear stress factor.     

Adjustment of Group Cross Sections by Means of Integral Data, (II)

Adjustment of the ABBN set is performed using various integral data obtained from fast critical experiments; through this adjustment, some practical properties are also examined in detail. The correlation coefficient between group cross sections is numerically obtained by assuming that the compound nucleus formation cross section can be described by a statistical model. The effect brought by this correlation to the adjustment of group cross sections is also studied. When the differential and integral data used in the adjustment contain a systematic error, the normalized sum of squares of residuals has a non-central Chi-square distribution. This is numerically examined by generating artificial differential and integral data with the aid of random numbers. The ABBN set collapsed into 15 energy groups is adjusted, and the principal results are compared with the measurements. The reliability of the adjusted integral data and group cross sections is also studied.     

Quantitative Analysis of Heavy Metals in Water Based on LIBS with an Automatic Device for Sample Preparation

Heavy metals in water can be deposited on graphite flakes,which can be used as an enrichment method for laser-induced breakdown spectroscopy(LIBS) and is studied in this paper.The graphite samples were prepared with an automatic device,which was composed of a loading and unloading module,a quantitatively adding solution module,a rapid heating and drying module and a precise rotating module.The experimental results showed that the sample preparation methods had no significant effect on sample distribution and the LIBS signal accumulated in 20 pulses was stable and repeatable.With an increasing amount of the sample solution on the graphite flake,the peak intensity at Cu Ⅰ 324.75 nm accorded with the exponential function with a correlation coefficient of 0.9963 and the background intensity remained unchanged.The limit of detection(LOD) was calculated through linear fitting of the peak intensity versus the concentration.The LOD decreased rapidly with an increasing amount of sample solution until the amount exceeded 20 mL and the correlation coefficient of exponential function fitting was 0.991.The LOD of Pb,Ni,Cd,Cr and Zn after evaporating different amounts of sample solution on the graphite flakes was measured and the variation tendency of their LOD with sample solution amounts was similar to the tendency for Cu.The experimental data and conclusions could provide a reference for automatic sample preparation and heavy metal in situ detection.     

稳定蒸汽浸没射流冷凝传热系数评价

为分析稳定蒸汽浸没射流的传热特性,对3类典型冷凝传热系数开展评价。结果表明:平均传热系数实验值精度主要受界面面积计算模型影响,由冷凝驱动势和蒸汽质量流速表征的传统半经验关系式在不同孔径下的预测偏差较大,新增排放孔径为独立拟合变量的纯经验关系式适用范围更广且误差在±30%以内;界面传热系数的预测精度主要受汽羽微观参数取值的影响;由压力振荡主频表征的无量纲传热系数在低池水过冷度下与实验值偏差较大,关系式中纳入汽羽贯穿长度后,预测趋势与实验值类似。      

Correlations for subcooled pool film boiling heat transfer from large surfaces with different configurations

Experimental saturated and subcooled-pool film-boiling heat-transfer data from horizontal cylinders in liquid nitrogen for wide ranges of surface superheat, liquid subcooling and system pressure showed little dependence on the diameter for relatively large diameters. A correlation for subcooled pool film boiling heat transfer from horizontal cylinders with relatively large diameters was derived by slightly modifying a theoretical solution based on laminar boundary layer theory to accord better with experimental data. A similar correlation applicable to saturated and subcooled local film-boiling heat-transfer on vertical plates and vertical cylinders was similarly derived using existing data. Local pool film-boiling heat-transfer coefficients at the midpoint of a light water PWR-type active fuel rod of a pulsed reactor agreed within experimental error with the values calculated from the correlation for the subcooling ranging from 10 to 80 K.     

Hydrazine and Hydrogen Co-injection to Mitigate Stress Corrosion Cracking of Structural Materials in Boiling Water Reactors, (III)

The effects of hydrazine on the corrosion of Zircaloy-2 were examined in supercritical water. Hydrazine could be used as a reducing agent to control the corrosive environment for the coolant of boiling water reactors (BWRs). Before the corrosion test, the applicability of supercritical water for corrosion testing of zirconium alloys was studied. Supercritical water was found to be a useful solvent for testing corrosion based on the following facts: (1) the weight gain of Zircaloy-2 in supercritical water followed the same cubic law with the activation energy of 133 kJ/mol as that in water and steam did, and (2) the weight gain in supercritical water at 723 K and 24.5 MPa was more than 8 times greater than that in water at 561 K and 7.8 MPa depending on immersion time. The corrosion tests in supercritical water at 723 K and 24.5 MPa under γ-irradiation for 1,000 h were conducted to study the effects of adding nitrogen and ammonia on the corrosion of Zircaloy-2. Nitrogen and ammonia are decomposed products of hydrazine. The measured weight gain, oxide film thickness, and amount of hydrogen pick-up had slight differences between cases with and without the additives. Based on these data, it was concluded adding hydrazine to the coolant has little influence on the corrosion of Zircaloy-2 used in BWR cores.     

Isotope shifts in beryllium-, boron-, carbon-, and nitrogen-like ions from relativistic configuration interaction calculations

Energy levels, normal and specific mass shift parameters as well as electronic densities at the nucleus are reported for numerous states along the beryllium, boron, carbon, and nitrogen isoelectronic sequences. Combined with nuclear data, these electronic parameters can be used to determine values of level and transition isotope shifts. The calculation of the electronic parameters is done using first-order perturbation theory with relativistic configuration interaction wavefunctions that account for valence, core–valence, and core–core correlation effects as zero-order functions. Results are compared with experimental and other theoretical values, when available.     

An investigation into the nature and significance of a new critical heat flux correlation

An empirical critical heat flux correlation, which is based upon dimensionless groups, and which was developed from a wide range of experimental data for vertical upflow in uniformly heated tubes, has been further examined to determine if, because of its accuracy and generality, it might provide an insight into the mechanisms of boiling crisis. A parameter survey using the correlation showed that it was well able to predict the so-called ‘crisis of the second kind’ without needing to define any separate or distinct flow regimes.Comparison of the empirical correlation with a general form of theoretical correlation, developed from a combination of several simple physical models which occur during the crisis phenomenon, shows a strong similarity in the form of the dimensionless groups. It also indicates that a further dimensionless group may need to be incorporated in the empirical correlation to achieve complete generality.Rearrangement of the dimensionless groups and the form of the empirical correlation, together with some minor approximations, indicate that boiling crisis is influenced by local hydrodynamic and thermal phenomena and can be related to pre- and post-crisis coolant conditions.     

基于扩散界面法的液态铅铋合金中气泡上升行为模拟

基于扩散界面法,对单个氮气气泡在液态铅铋合金内从静止到充分发展整个过程中的动力学行为进行数值模拟,得到气泡形变特性和气泡上升速度随时间的变化关系,将模拟结果与Grace经验关系图对比,发现模拟得到的气泡形变结果在Grace经验关系图中均可找到且很好地吻合,从而验证了扩散界面法在模拟液态铅铋合金中气泡上升行为的可行性和准确性。同时基于界面扩散法的模拟,对比了5种不同初始直径的氮气泡在液态铅铋合金中的上升行为,发现初始直径较小的气泡在上升过程中扰动会更剧烈,初始直径较大的气泡在上升过程中易发生分裂现象。     

Electronic stopping power for proton in amino acids and protein in 0.05-10 MeV range

The stopping powers for 0.05-10 MeV protons in a group of 15 amino acids and a protein have been systematically calculated. The calculations are based on Ashley’s dielectric model. An approach of evaluating the optical energy loss function is incorporated into the Ashley’s model because no experimental optical data are available for these bioorganic compounds. The Barkas-effect correction and Bloch correction are included and an empirical minimum impact parameter a is used for the Barkas-effect correction. The proton stopping powers for the 15 amino acids and the protein in the energy range from 0.05 to 10 MeV are presented here for the first time and might be useful for studies of various radiation effects in these materials.