利用相干渡越辐射测量电子束团长度的分析与计算

利用相干渡越辐射(CTR)测量短和超短电子束团长度是国际上束测领域新发展的频域测量技术.文中理论分析和数值计算了北京自由电子激光装置的皮秒级的射频电子束团序列产生的CTR,当辐射波长在长于束长(4ps)时,渡越辐射发生相干增强效应;与非相干渡越辐射相比,当λ≥2πσz时,增强的倍数约等于束团中粒子的数目(10⁸);CTR从亚毫米波到毫米波段呈宽带连续谱特性;渡越辐射能量主要集中在轴线附近,宏脉冲辐射能量高达几毫焦.设计采用偏振型束团长度测量系统,利用CTR自相关技术,实验测量该束团序列的纵向长度,并藉助傅里叶变换光谱法,推求束团电子分布.     

石油套管射孔检测传感器的研制

通过介绍磁通法检测石油井套管射孔质量的基本原理, 研究了磁检测传感器的结构及其环境适应性, 在实验室模拟井中对套管的射孔进行了检测, 给出了具体的检测结果.     

超临界CO_2萃取-气相色谱质谱法测定斑点叉尾鮰肌肉中的脂肪酸

采用超临界CO2萃取工艺、气相色谱-电子电离质谱(GC-EI-MS)法,建立了斑点叉尾鮰肌肉中脂肪酸的定性与定量分析方法。在CO2流速为30 L/h、温度45℃、压力25 MPa、时间100 min条件下进行超临界CO2萃取,所得油脂皂化10 min,采用三氟化硼法进行甲酯化衍生20 min,经HP-Innowax毛细管柱分离,电子电离质谱检测,以全扫描模式定性分析,选择离子扫描模式定量分析,饱和脂肪酸、单不饱和脂肪酸、双不饱和脂肪酸、多不饱和脂肪酸的定量离子分别为m/z74,55,67和79。14种脂肪酸甲酯的检出限和定量限分别在2.2～20μg/L和7.4～60μg/L之间;平均回收率为90.0%～111.2%,相对标准偏差为2.0%～5.9%。本方法灵敏度高、重复性好,可用于测定斑点叉尾鮰肌肉样品的脂肪酸。     

桥梁预应力真空压浆施工技术

在传统压浆施工工艺的基础上,结合现场施工情况,根据真空辅助压浆原理及相关技术要求,通过对原材料、配合比及施工工艺的比选,在箱梁压浆过程中对水泥浆及压力的控制提出了相应的技术措施,并对施工中的常见问题提出了预防处理措施。     

略论邓小平的群众思想

从党的十一届三中全会开始的我国改革开放已进行了二十多年。二十多年来,我国的社会主义现代化建设取得了举世瞩目的成就,祖国大地发生了翻天覆地的历史性变化。这些成就的取得无不得益于邓小平建设有中国特色社会主义理论的指导。本文从三个方面粗浅探讨了邓小平理论中相信群众、依靠群众的观点。     

Design and studies on the traveling wave transverse RF deflecting structure

With the development of free electron laser (FEL) and the international linear collider (ILC), the electron bunch length is getting smaller and smaller. The traveling-wave transverse RF deflecting structure is an important part of the RF deflecting method for bunch length measurement and phase space diagnostics. The operation mode in RF deflector is the ``TM₁₁-like' mode. Since the TM₁₁-like mode in this structure has a pair of degenerate dipole modes, two additional holes are provided on either side of each iris to stabilize the mode. The simulation and optimization have been done. A prototype has been fabricated and tested. The cold test results have been compared with the simulations of the first three modes.     

100 MeV电子直线加速器的物理设计

 能量为100 MeV左右的高性能电子直线加速器是第三代同步辐射光源注入器和自由电子激光注入器的重要组成部分,采用热阴极栅控电子枪、聚束系统和4根SLAC型加速管作为加速器主体结构,一套45 MW的速调管调制器系统和波导系统作为微波功率源系统。设计中,使用了国际通用的模拟软件对加速器的动力学特性进行了数值模拟和参数优化,电子束能量达到100 MeV以上,能散小于1%,归一化发射度小于30 mm·mrad。     

试论高校人文关怀的实施

近年来,高等教育快速发展,但同时也加剧了高校之间及其内部的竞争。广大高校师生置身其中,必然受到很大冲击,各种压力剧增,因此高校实施人文关怀势在必行。全面分析了高校实施人文关怀的对象主要是教师和学生,并针对不同的对象提出了实施人文关怀的具体举措和建设性意见。     

ADSORPTION BEHAVIOR OF AMINO ACIDS ON COPPER SURFACES

The major results of a series of our recent investigations on the adsorption of eight amino acids on Cu(001) and (111) surfaces are reviewed in the present paper. In all studied cases the molecules adsorb onto the surface in their anionic form. With the increase of the coverage three different 2D phases of the adsorbates, that is, the 2D lattice gas, intermediate, and solid phases, appear sequentially, although for few systems one or two of them do not appear. In both the 2D lattice gas and intermediate phases the molecules "stand" with their two oxygen "feet" on the surface and the intermolecular interactions are repulsive, although in the former they can diffuse frequently whereas in the latter they are discommensurate in one direction with the substrate. In the solid phase the molecules "lie" down on the surface to form commensurate superstructures. Adsorption of amino acids may often induce step faceting as well as bunching to form facets. Adsorption of L-lysine on Cu(001) may cause steps bunching to form facets with all the same chirality. Our preliminary results show that it is possible to manipulate individual molecules with the STM tip even at room temperature. These results may have applications in nano-materials, nano-technology, and very likely also in chiral separations or enantioselective heterogeneous catalysis.     

BEPC静电分离器分路阻抗和功率损耗研究

通过测量BEPC静电分离器各主要模式的分路阻抗,分析了BEPC运行过程中静电分离器的高压电缆隔离层不时烧化的原因,同时对BEPC流强进一步提高时静电分离器中的功耗进行了计算.