采用改进尾流振子模型的柔性海洋立管的涡激振动响应分析

建立了柔性杆件在非均匀流作用下的涡激振动响应预测模型, 考虑了涡激振动锁频阶段流体附加质量的变化, 以及振动响应和来流简缩速度的非线性关系. 该模型通过经验公式结合迭代求解的方式, 计算方便、速度快, 避免了数值计算(CFD)的繁琐, 较为适合于海洋工程实际应用. 与试验和数值结果的比较表明采用该文提出的计算模型, 可以更合理、准确地给出结构涡激振动响应. 最后, 结合实际平台参数, 进行了柔性立管在非均匀流场的作用下的涡激振动响应分析, 并研究了立管的预张力、流场分布等参数的影响. 分析结果表明: 随着立管张力和流场分布的改变, 各阶模态锁频区域发生了变化, 从而改变了结构的总体响应

Design of the IMP microbeam irradiation system for 100 MeV/u heavy ions

Abstract A state-of-the-art high energy heavy ion microbeam irradiation system is constructed at the Institute of Modern Physics of the Chinese Academy of Sciences. This microbeam system operates in both full current intensity mode and single ion mode. It delivers a predefined number of ions to preselected targets for research in biology and material science. The characteristic of this microbeam system is high energy and vertical irradiation. A quadrupole focusing system, in combination with a series of slits, has been designed to optimize the spatial resolution. A symmetrically achromatic system leads the beam downwards and serves simultaneously as an energy analyzer. A high gradient quadrupole triplet finally focuses a C6+ ion beam to 1 µm in the vacuum chamber within the energy range from 10 MeV/u to 100 MeV/u. In this paper, the IMP microbeam system is described in detail. A systematic investigation of the ion beam optics of this microbeam system is presented together with the associated aberrations. Comparison is made between the IMP microbeam system and the other existing systems to further discuss the performance of this microbeam. Then the optimized initial beam parameters are given for high resolution and high hitting efficiency. At last, the experiment platform is briefly introduced.

离子束生物技术及其在玉米育种中的应用

离子束作为一种新兴诱变源,已广泛应用于各种农作物的诱变育种。离子束生物技术为玉米品种的改良和种质资源的创新开辟了一条新的途径,推动了玉米育种事业的长足发展。本文阐述了离子束的特点、诱变机理以及在玉米育种中的应用。

利用α关联衰变链鉴别新同位素_(107)~(265)Bh

主要介绍了合成和鉴别107号元素的新同位素265Bh的实验装置、实验方法以及实验结果.目标核265Bh是由能量为135MeV的26Mg离子轰击243Am靶,通过融合蒸发反应而产生.反应产物首先由He jet系统传输到装有数个探测器对的转轮收集测量系统,然后依靠母子核遗传关系通过观察新同位素和它们已知子核261Db和257Lr之间的α衰变的关联,来实现对新核素的鉴别.实验测得265Bh的α衰变能量为(9.24±0.05)MeV, 半衰期为0.94+0.70-0.31s.从该实验得出的265Bh的α衰变能量和半寿命能够与理论预言一致.

新同位素~(265)Bh(Z=107)的合成证据

利用兰州重离子加速器提供的26Mg离子束轰击243Am靶, 产生了新同位素265Bh. 实验中用氦喷技术对产物进行传输, 并用一套具有数对探测器组的转轮收集探测系统对产物进行收集和测量. 通过观测265Bh与它的衰变子核261Db及257Lr之间的α衰变的关联, 实现了对新核素的鉴别. 实验测得265Bh的α衰变能量为(9. 24±0. 05)MeV, 半衰期为 0. 94+0. 70 0. 31 s.

Characteristics and genesis of maghemite in Chinese loess and paleosols: Mechanism for magnetic susceptibility enhancement in paleosols

IEECAS SKLLQG

准∧型四能级系统中的量子干涉现象

研究了原子与分子混合共振相互作用过程中准∧型四能级系统的量子干涉效应 ,特别对在驱动激光场作用下钠原子、钠分子和氩气组成的混合系统中出现量子干涉现象的机理作了分析 ,提出缀饰态能级有交叠区 ,并依据相应的理论计算 ,解释了原子光谱中的量子干涉增强效应。

一台300kV电子帘加速器辐照箱屏蔽物理设计

介绍一台电子能量为 30 0keV、束流强度为 6 0mA的电子帘加速器辐照箱的屏蔽物理设计。箱体厚度为 1.5cm的铅。

Magnets for HIRFL-CSR rings

The magnet design, fabrication, and measurement of HIRFL-CSR (Heavy Ion Research Facility in Lanzhou Cooling Storage Ring) are presented. All magnets will be laminated And welded with an armor-coated surface between two big endplates made of sticking glue 0.5 mm-thick sheets. The dipole of CSRm was chosen an H type with an air circle on the pole to improve the field uniformity. The dipole of CSRe was chosen the C type with an air circle and two air slots on the pole to improve the field homogeneity. Its reproducibility of magnet to magnet was adjusted with inserting small laminating pieces before demountable pole ends to reach less than +/- 2 x 10(-4) at optimized field level. CSRm quadrupoles diameter is 170 mm and has two different lengths, and its endplates were made with punching pieces after coating with epoxy glue, there is chamfered directly on the pole ends to reduce 12th-order contribution of field and without the demountable pole ends. CSRe main quadrupoles diameter is 240 mm and has two different lengths, and its endplates were also made with punching pieces coated with epoxy glue, there is also chamfered directly on the pole ends to reduce 12th-order contribution of field like CSRm.

The stripper design and test at HIRFL-CSR

Charge stripping is employed to produce multi-charged ions for injecting the cooling storage ring After penetrating through the carbon foil, the widened distribution of ion charge states poses a limit to the ion injection Therefore, the carbon foil plays a key role in the charge snipping injection In this paper, foul strippers for Heavy Ion Research Facility at Lanzhou (HIRFL) and Cooling Sun age Ring (CSR) are introduced The charge state distribution of the stripped ions is measured and the stripping efficiency of the foils is investigated The experimental results are consistent with the theoretical values

非晶态合金的表面辐照效应研究

本工作用120Kev的He~+离子对非晶态Ni_(60)Nb_(40)、Fe_(40)Ni_(38)Mo_4B_(18)、Fe-Ni-B合金样品进行了辐照，辐照剂量为1.6、2.0、2.5，3.0 * 10~(18)/cm~2四种。借助X射线衍射扫描电子显微镜（SEM），内转换电子穆斯堡文谱（CEMS）等方法对辐照前后的样品进行了分析。X射线衍射结果表明在冷却靶的辐照条件下，样品辐照前后的非晶状态来改变，但辐照产生了原子的重排。SEM研究发现：表面发论的形成须一定的临界剂量对于Ni_(60)N_(240)，所需临界剂量最高；随剂量的增加，在所研究的剂量范围内，发论大小增大且来观察到表面发论的破裂与剥学；对不同组织的非晶合金，其发论程度稍有不同；辗压减药不影响材料的发论性质；表面结构的粗糙有助于降低发论程度；晶化样品，发论程度的显加剂。CEMS分析指出；辐照使结构的天度增加，有效的平均原子间距减小；因辐照导致原子的重新溶合使CSRO降低；随辐照首先的缺陷周围自旋取向及急进的应力源的变化。磁各向异性发生了变化

CAPRICE源磁场改进和冷阴极电子枪的应用及激光离子源的初步实验

在本文第一部分主要描述了ECR离子源的现状、发展和重要物理机制，着重介绍了CAPRICE 10GHz ECR源磁场构形的改进，使其Ar~(8+)离子束流增强了约20%且注入级和引出级线包的电功率消耗分别降低10%和20%。当把冷阴极电子松应用于CAPRICE源中时，Ar~(8+)离子束流入140μA增加到240μA微波功率也有明显降低。所有这些结果都表明ECR源对于气体或已产生的固体蒸气是一个很好的离化装置，为了将激光技术应用于ECR源中来产生固态元素离子，我们又开展了激光离子源的研究.在第二部分则介绍了激光源的现状、发展和激光产生等离子体的物理过程，并详细研究了激光参数及掺气对激光等离子体的影响，在实验中，当用磁镜场或磁Cusp场约束激光等离子体时，离子总束流峰值增加了约5倍；而在激光产生等离子体后附加上高频再游离装置时，同样也使总束流峰值从460μA增至1.4mA，这些低电荷态离子数量足以使ECR源产生需要的高电荷态离子输出