SiTi1—xSbxO3透明导电薄膜的光电子能谱研究

我们用XPS和同步辐射技术研究了钙钛矿型氧化物SrTi1-xSbxO3(x=0,0.05,0.10,0.15,0.20）薄膜的电子结构。该薄膜系列在可见光波段透明,其透过率均超过90％。所有掺杂薄膜均导电。同步辐射电子能谱研究结果表明该薄膜中来自Sb杂质的退局域化电子在母化合物的禁带中引入了杂质能级。这是导电性的根源,价带中很小的电子态密度限制了跃迁几率。大的禁带宽度和小的跃迁几率是光学透明性的原因。     

高质量类金刚石薄膜的制备与性能分析

采用直流/射频耦合磁控溅射法在Si(100)衬底上成功制备出类金刚石(DLC)薄膜。利用Raman光谱仪、X射线光电子能谱仪表征不同射频功率下所制备薄膜的化学结构,讨论射频功率对薄膜化学结构的影响。采用X射线小角反射法表征薄膜的质量密度,利用曲率弯曲法表征薄膜的残余内应力,采用扫描电镜和原子力显微镜表征所制备薄膜的表面形貌与粗糙度。研究表明:薄膜中sp3键的含量随着射频功率的增加而呈现出先增大后减小的趋势,且在射频功率为40 W时达到最大值45.6%。随着射频功率的增加,薄膜的表面粗糙度呈现出先减小后增大的趋势,当射频功率为40 W时薄膜的表面粗糙度最小,为1.6 nm。直流/射频耦合磁控溅射法在不同射频功率下制备出的薄膜,其内应力均低于1.0 GPa,薄膜质量密度的变化范围为2.26~2.44 g/cm~3,有望成功制备出内应力低、密度高的高质量DLC薄膜。     

氟盐冷却球床高温堆燃料管理程序的开发与分析

基于确定论的中子学分析程序在计算氟盐冷却球床高温堆（PB-FHR）时需解决双重非均匀性的燃料球均匀化、燃料球均匀化时出现的泄漏效应及燃料球在堆芯内连续移动与多次通过堆芯的燃料循环模式问题。本文基于DRAGON5与DONJON5程序开发了PB-FHR的燃料管理程序PBMSR,并进行了验证。使用PBMSR对PB-FHR在不同燃料循环模式下进行计算与初步分析,结果显示在多次通过的燃料管理模式下,燃料球的通过次数对最深卸料燃耗影响较小,但对轴向功率分布影响较大。     

基于修改后RELAP5/MOD3.2的氟盐高温堆实验回路分析

大型热工流体整体效应系统实验(CIET)台架是为模拟氟盐冷却高温堆(FHR)热工水力响应而设计的实验回路,采用DOWTHERM A模拟氟盐作为冷却剂。通过在RELAP5/MOD3.2程序中加入DOWTHERM A物性参数以及传热关系式,计算FHR实验回路CIET在两种工况下的热工水力行为,并与实验结果进行对比,计算工况包括强迫循环条件与自然循环条件。计算结果表明:在强迫循环条件下,堆芯热量主要靠盘管式空气换热器(CTAH)排出,堆芯进出口冷却剂温度及CTAH出口冷却剂温度与实验值符合良好,CTAH进口冷却剂温度与实验值有些微偏差;在自然循环工况中,堆芯热量主要通过DHX与堆芯辅助冷却系统(DRACS)回路的换热带走,DHX及DRACS的流量与实验值接近,相对误差在10%左右,验证了修正后RELAP5/MOD3.2的正确性。     

物性参数对氟盐球床堆传热模型不确定性和敏感性的影响分析

为了确保氟盐球床堆堆芯传热模型的预测能力满足安全限制,研究了氟盐冷却剂的物性参数对堆芯传热模型不确定度和敏感性的影响。采用统计学不确定性评估方法,将氟盐冷却剂物性参数(包括动力粘度、密度、比热容、导热系数)作为输入参数,选取经典传热关联式作为计算模型,分析了努赛尔数(Nu)的不确定性及其对物性参数的敏感性程度。结果表明,无论氟盐物性参数的概率分布为正态分布或均匀分布,计算得到的Nu的平均值非常接近,其分布形式都接近正态分布;同时发现,动力粘度是物性参数中对Nu影响最大的参数,并且呈负相关;导热系数对Nu的影响为负相关,密度和比热容对Nu的影响较小且均为正相关。     

球床型氟盐冷却高温堆的初步中子学分析

为分析球床型氟盐冷却高温堆(PB-FHR)堆芯的关键中子学参数,建立了显式随机模型,基于随机填充方法计算了燃料球石墨基质内所有三层各向同性包覆颗粒(TRISO)颗粒的空间坐标,并采用离散元方法计算出堆芯活性区内全部燃料球的空间坐标。最后采用蒙特卡罗程序开展中子输运计算,分析燃料颗粒随机分布对堆芯中子学参数的影响。研究结果表明,TRISO颗粒的随机分布对栅元增殖系数、栅元群截面、活性区燃料球功率的影响较小,本文研究可为简化PB-FHR设计提供理论依据。     

氟盐冷却球床堆与HTR-10和MSRE的定量相似性分析

氟盐冷却球床堆是当前国际上一种新的研究堆型,尚无已经建造完成的反应堆,因此,选择相似且具有运行经验的反应堆作为基准题有助于堆芯核设计软件适用性分析。利用国际上常采用的相似性分析软件,可对熔盐实验堆(Molten Salt Reactor Experiment,MSRE)及10 MW高温气冷堆(10 MW high-temperature gas-cooled test reactor,HTR-10)与氟盐冷却球床堆的相似性进行分析,定量判断它们作为基准题的合理性。分析结果表明,MSRE和氟盐冷却球床堆的能谱峰位能量接近且堆内元素种类相近,二者相似程度较高;常温临界HTR-10和氟盐冷却球床堆冷却剂不同,且能谱峰位能量差异较大,二者相似程度较低。因此,MSRE是氟盐冷却球床堆中子物理设计软件较理想的基准题。     

随机球床模拟方法对氟盐冷却高温堆中子学参数的影响分析

氟盐冷却高温堆（FHR）采用氟盐冷却球形燃料元件,其中子物理计算面临双重不均匀性问题：燃料球在堆芯内的随机排布和包覆燃料颗粒在燃料球中的随机排布。此问题是该堆型设计中面临的主要挑战之一。本文基于MCNP程序和固态燃料钍基熔盐堆（TMSR-SF1）模型完成了不同燃料球床与燃料球描述对关键中子学参数（如k_eff、堆芯能谱、控制棒价值和温度系数等）的影响分析。燃料球床描述使用随机序列添加（RSA）方法建立了随机球床模型与体心立方（BCC）结构的等效规则模型。包覆燃料颗粒描述则基于简立方（SC）等效模型利用MCNP程序中的URAN卡实现随机扰动。结果表明,包覆燃料颗粒随机分布的影响远小于燃料球随机分布的影响;尽管具有相同的总堆积密度,等效规则模型相比于随机球床模型会增加堆芯中子的泄漏,低估冷态满装载反应性约0.5%,高估控制棒价值约5%。     

多普勒展宽舍弃修正对氟盐冷却球床高温堆中子学的影响分析

超热区中子的弹性散射易受靶核热运动影响,传统的蒙特卡罗程序采用常数散射截面自由气体模型来描述超热区中子的散射过程。研究表明,忽略共振弹性散射效应所引入的误差随温度的升高而增加,而氟盐冷却球床高温堆工作在高温条件下,为减小共振区弹性散射计算误差,有必要在中子学计算中使用多普勒展宽舍弃修正方法以考虑其共振弹性散射效应。本文使用修改源码后的蒙特卡罗程序MCNP5对氟盐冷却球床高温堆栅元开展中子学计算,发现经多普勒展宽舍弃修正后的²³⁸U的中子俘获率增加,无限增殖因数减小123～1182 pcm,且无限增殖因数偏差随燃料球栅元填充率及温度的升高而增大。     

Determination of sulphur and copper depth distribution in patina layers using nuclear reaction techniques

A method for Cu and S profiling in patina layers was developed by applying a combination of nuclear reaction analysis (NRA) and Rutherford backscattering spectroscopy (RBS). The copper profiling was performed by using the 1327 keV γ-ray deexciting the third excited state to the ground state of ⁶³Cu produced by the reaction ⁶³Cu(p,p^′γ)⁶³Cu. For the determination of sulphur the 2230 keV γ-ray was used deexciting the first excited state to the ground state of ³²S formed through the reaction ³²S(p,p^′γ)³²S, which exhibits three sharp resonances at projectile energies 3.094, 3.195 and 3.379 MeV. The relevant cross-sections were measured in the energy range between 3.0 and 3.7 MeV in steps of 20 keV at 125° to the incident proton beam direction. The technique was tested using artificially produced and natural copper patina layers. Supporting information on the depth distribution of the constituent elements of the patina samples was obtained by p-RBS (E_p: 1.5 MeV, θ: 160°).     

用内转换电子穆斯堡尔谱法研究掺锑气敏材料SnO2

用CEMS方法对掺锑的SnO_2气敏薄膜作了研究。该材料对H_2、CO的气敏响应取决于掺锑浓度(x％)和退火温度。实验发现:样品的CEMS参量同质异能移和四极分裂分布宽度在x=1％时为最小值,正好与气敏响应灵敏度达最大值相一致。由此进一步讨论了气敏薄膜的敏感机理。     

核分析技术在大气环境研究中的重要作用

核分析技术（尤其是中子活化分析）以其检测限低、精密度高、不破坏样品等优点成为气溶胶元素分析的最有效手段之一。核分析方法所产生的大量可靠数据对气溶胶领域研究近一二十年来的重大发现起到了不可取代的作用。以中国气溶胶对太平洋生产力乃至全球环境变化的影响为例,评述了近20看来气溶胶研究的重大成果和发展,并阐明了该分析技术在大气环境研究中的重要作用。     

Influence of N2 flow rate on structure and properties of TiBCN films prepared by multi-cathodic arc ion plating and studied with ion beam scattering spectroscopy

TiBCN films were deposited on Si(100) and cemented carbide substrates by using multi-cathodic arc ion plating in C_2H_2 and N_2atmosp~here. Their structure and mechanical properties were studied systematically under different N_2 flow rates. The results showed that the Ti BCN films were adhered well to the substrates. Rutherford backscattering sp~ectroscopy was employed to determine the relative concentration of Ti, B, C and N in the films.The chemical bonding states of the films were explored by X-ray photoelectron sp~ectroscopy, revealing the presence of bonds of Ti N, Ti(C,N), BN, pure B, sp~2C–C and sp~3C–C, which changed with the N_2 flow rate. Ti BCN films contain nanocrystals of Ti N/Ti CN and Ti B_2/Ti(B,C)embedded in an amorphous matrix consisting of amorphous BN and carbon at N_2 flow rate of up to 250 sccm.     

IBAD MoS2-Ta膜的电子显微与能谱分析

用透射电子显微镜与能谱技术对离子辅助沉积的ＭｏＳ２－Ｔａ膜的形态,结构,组成以及元素的化学态等进行了观察和分析。发现膜在沉积过程中已产生部分晶化,膜体出现衬底鲜明的白色”团簇”点缀的两相特殊形态。ＴＥＭ与ＸＰＳ分析确定白鬼“团簇”属析出的第二相ＴａＳ２。两区都具有（００２）,（１００）和（１１０）取向,面间距与晶格常数都比ＭｏＳ２单晶增大,“白区”的参数又比膜基本略大。     

A study on nuclear analysis of the divertor region of the CFETR

This paper presents the nuclear analysis performance of the Chinese Fusion Engineering Test Reactor(CFETR)divertor region using the MCNP-5 Monte Carlo N-particles code in a 3D geometry model.We assessed the nuclear responses of the divertor region component systems and evaluated their shielding capability,which can support the development strategy of the physical and engineering design of the CFETR.Model specification based on the latest CAD model of the CFETR divertor has been integrated into the CFETR MCNP reference model with a major/minor radius R=7.2 m/a=2.2 m in the 22.5° model,and a fusion-power range of around 1-1.5 GW.The nuclear heating and radiation damage of the divertor system are enhanced compared to that of the ITER and the earlier CFETR design.The initial nuclear responses of the toroidal field coil and vacuum vessel systems showed that the shielding of the current divertor design is not sufficient and optimization work has been carried out.We also carried out calculations and analysis using a hypothetical operating scenario of over 14 years.An excellent improvement in the nuclear performance has been obtained by the improved additional shielding block in the divertor region when referring to the ITER design limit,which can support the design of the future update of the divertor region systems of the CFETR.     

放射性核素45Ca2+示踪技术测定核Ca2+摄取和释放功能

介绍细胞核＾４５Ｃａ＾２＋摄取、释放功能测定,＾４５Ｃａ＾２＋向内核膜囊泡转运测定等技术,从而为研究核Ｃａ＾２＋摄取和释放系统在生理及病理条件下的作用提供有力的技术手段。     

Study of the deuterated titanium Ti2Hx sample by using nuclear reaction analysis and material analysis methods

Titanium is one of the best hydrogen loading material.The predicted maximum loading ratio of hydrogen in titanium may reach to 2.0.In this work.a titanium layer on molydbenum substrate was deuterated with the atomic ratio X=^2H/Ti≥1.6,The change of the surface topography and microstructure of the sample before and after lading was observed by using Scan Electron Microscopy (SEM),The surface segregation of the samples after deuteron bombardment was also observed.A fluctuatingly-incrcasing trend of the deuterium density in titanium target was detected in the deuteron implantation experiments.which indicated a suddenly explosion(segregation)or fast diffusion of deuterium in the titanium.Significant amount of nitrogen contamination was found in the Ti^2Hx sample by nuclear reaction analysis(NRA),which indicated that the Ti^2Hx structure might have the feature to trap nitrogen from air.The nitrogen contamination in Ti^2Hx significantly affects the increase of the atomic ration X=^2H/Ti.     

氢化锆表面CO2反应层XPS分析

通过X射线光电子能谱分析了经过700℃加热前后的用CO2反应法制备的氢化锆表面反应层中一定深度(100nm、200nm和300nm)的C、O和Zr的化学态,并用相对灵敏度因子法对X射线光电子能谱分析结果进行了计算分析.结果表明:700℃加热前的膜层中含有C、O和Zr以及C-H键和-OH键;经过700℃加热以后,氢化锆表面氢渗透阻挡层中不仅有C-H键和-OH键,而且还出现了-COOH,与H结合的C、O量增大.