用于HIRFL-CSRm纵向压缩高频腔的磁合金环测试

在HIRFL-CSRm上进行高能量密度物理和等离子体物理的研究需要一个能提供高电压的高频腔来对束团进行纵向压缩, 而磁合金加载腔获得较高的加速场梯度可以满足这一要求, 且腔体不需要调谐, 从而简化了高频控制系统。为了选择磁导率和阻抗较大、Q值(品质因数)小于1的磁合金材料来加载压缩高频腔, 对型号为V和A的两种磁合金材料进行了测试。测试结果表明: 型号为V的材料具有较大的磁导率、 阻抗和小于1的Q值, 将被用来加载腔体以获得足够高的加速电场梯度。A high voltage RF cavity is required to compress the beam bunch in the longitudinal for high energy density physics and plasma physics research at HIRFL CSRm. A magnetic alloy (MA) loaded cavity which has high acceleration gradient and without tuning loop (can simplify the RF control system), can meet the requirement. In order to select a proper MA material with higher permeability and shunt impe dance, Q< 1 value to load the RF compression cavity, two different MA materials V and A have been tes ted. The results indicate that the material V will be better for the construction of the RF cavity than material A because of its higher permeability and shunt impedance, Q< 1 value.     

国产磁合金环性能的测试

通过搭建谐振电路的方法对国产磁合金环性能进行了测试。测试的主要参数包括磁合金环的磁导率、Q值及其并联阻抗值等。测试结果表明：该磁合金环的Q值很低,随频率的变化不明显;磁导率很大,随频率的增加而减小;并联阻抗值随频率增加而变大。在100 ℃温度以内,其性能参数变化很小。     

Bi2223带材的临界电流及交流损耗研究

测量了77K温度下不同基体材料和不同芯数带材的临界电流和交流损耗.分析了弯曲应变对它们的影响.结果表明单芯样品的不可逆应变小于0.15%,而多芯样品的不可逆应变在01%到03%之间,多芯导体的机械性能比单芯导体的好,增加芯数可以提高机械性能,金属包套材料对超导芯起到了增强的作用,它防止了超导芯中裂纹的进一步传播.自场损耗随外加应变的增加而增加,这种大幅度的增加与应变使带材的临界电流急剧减小直接相关 关键词： 高温超导体 临界电流 交流损耗     

低温辐射计黑体腔吸收率分析

低温辐射计是目前国际上光辐射功率计量中准确度最高的测量系统,其光辐射测量不确定度可达10-5量级,目前国内仅有少数研究机构从国外引进低温辐射计开展计量研究,亟待发展国产低温辐射计替代进口产品。由于低温辐射计采用低温超导状态下的电替代测量原理进行光辐射功率测量,发展低温辐射计的难点之一在于研制黑体吸收腔这一核心光辐射接收器件,并要求黑体腔在各波长下的吸收率都要达到0.999 9以上。为研制超高光谱吸收率的黑体吸收腔,系统性分析了各影响黑体腔光谱吸收率因素,在此基础上利用蒙特卡罗光线追迹方法重点研究了光谱波长、腔体长度、黑材料漫反射系数、黑材料吸收率和入射光空间位置等对斜底黑体腔光谱吸收率的影响。研究结果表明：在300～1 100 nm波长范围内黑体腔吸收率与其内壁涂黑材料的吸收率呈正相关,且在300～1 000 nm范围内的吸收率都达到了0.999 9以上,其中在700 nm处的吸收率取得最大值0.999 941 5,表明采用该类型黑材料的黑体腔只在300～1 000 nm范围内满足低温辐射计设计要求,后续需要根据仿真和测试结果对低温辐射计在不同波长下的光电不等效性进行修正;在黑体腔结构和口径确定的情况下,黑体腔吸收率将随腔长增加而逐渐升高,在40 mm后变化趋缓,并在65 mm后逐渐趋于平衡,考虑到低温辐射计低温舱对腔体尺寸的限制,认为腔体长度与口径之比为6.5时较为合适;黑体腔吸收率还受黑材料的漫反射系数影响,随着黑材料漫反射系数的提高,腔体吸收率呈现近似线性下降,所以在选择黑体腔涂黑材料时,在吸收率等指标相同的情况下应尽量选择镜面吸收黑;黑材料吸收率从0.8到1的变化过程中,腔体吸收率提升了0.05个百分点,且黑材料吸收率为0.92时腔体吸收率可达到0.999 9以上,表明黑材料在其有效工作波长范围内任一点的光谱吸收率都要大于0.92;腔体吸收率还受入射光投射的空间位置影响,光线位置越靠近斜底腔顶点处,腔体吸收率越高,但整体吸收率变化不明显,光线位置对腔体吸收率影响只有不到0.004个百分点,几乎可以忽略,认为斜底腔不同位置处的吸收率是均匀的。研究结果对低温辐射计黑体腔研制有一定参考价值。     

Measurement and modelling of magnetic properties of soft magnetic composite material under 2D vector magnetisations

This paper reports the measurement and modelling of magnetic properties of SOMALOY^TM 500, a soft magnetic composite (SMC) material, under different 2D vector magnetisations, such as alternating along one direction, circularly and elliptically rotating in a 2D plane. By using a 2D magnetic property tester, the B–H curves and core losses of the SMC material have been measured with different flux density patterns on a single sheet square sample. The measurements can provide useful information for modelling of the magnetic properties, such as core losses. The core loss models have been successfully applied in the design of rotating electrical machines with SMC core.     

HOMs simulation and measurement results of IHEP02 cavity

In accelerator RF cavities, there exists not only the fundamental mode which is used to accelerate the beam, but also higher order modes(HOMs). The higher order modes excited by the beam can seriously affect beam quality, especially for the higher R/Q modes. 1.3 GHz low-loss 9-cell superconducting cavity as a candidate for ILC high gradient cavity, the properties of higher order mode has not been studied carefully. IHEP based on existing low loss cavity, designed and developed a large grain size 1.3 GHz low-loss 9-cell superconducting cavity(IHEP02cavity). The higher order mode coupler of IHEP02 used TESLA coupler's design. As a result of the limitation of the mechanical design, the distance between higher order mode coupler and end cell is larger than TESLA cavity.This paper reports on measured results of higher order modes in the IHEP02 1.3 GHz low-loss 9-cell superconducting cavity. Using different methods, Q e of the dangerous modes passbands have been obtained. The results are compared with TESLA cavity results. R/Q of the first three passbands have also been obtained by simulation and compared with the results of the TESLA cavity.     

旋转盘腔流场速度与压力的实验研究

本文描述一个旋转盘腔流场的实验研究。该盘腔由一个旋转盘，一个静止盘及静止的外围屏组成．实验表明在盘腔的两个盘面上都有边界层形成，在边界层中，流体除有切向速度外，还有沿径向的二次流存在。在边界层外的核心区中径向速度为零。一般来说，静盘边界层比转盘边界层向紊流转捩地要早。另外，压力的测量表明，在半径较大的区域中压力分布可由“流体以恒角速度旋转”的假设所得的结果近似。     

基于有源Fabry-Perot腔的激光脉冲延时自外差研究

对注入有源Fabry-Perot腔内的单纵模脉冲进行了延时理论分析, 计算了Fabry-Perot腔内增益, 并对脉冲输出进行了数值模拟, 结果表明当脉冲能量衰减到一定值时, 新增抽运粒子数提供的增益可以补偿腔内损耗, 延时脉冲的输出可以达到稳态. 然后利用激光二极管侧面抽运Nd: YAG激光器做为Fabry-Perot腔, 对外部入射的单纵模脉冲光进行了延时, 得到了延时时间2 μups、脉冲数量140个的实验结果. 最后利用有源Fabry-Perot腔对参考光进行延时, 声光移频器对信号光产生频移, 进行了外差实验, 实验结果与移频器的设置值相符, 误差在4%以内.     

MA量级螺线圈型爆磁压缩发生器

采用多分支螺线圈型爆磁压缩发生器数值模拟程序MFCG8-7进行理论模拟及参数优化,设计了EMG-125型螺线圈型发生器,并开展了实验研究。电感负载实验结果表明：EMG-125型发生器可以在25 nH电感负载上输出大于3 MA脉冲电流,负载能量大于100 kJ,电磁能量放大50倍。     

A guided wave technique for the characterization of highly attenuative viscoelastic materials

The measurement of the acoustic properties of highly attenuative materials such as bitumen is very difficult. One possibility is to use measurements of the extent to which filling a cylindrical waveguide with the material affects the dispersion relationship of the cylinder. Torsional modes have been excited using piezoelectric transducers placed at one end of the cylinder, while the phase velocity and attenuation spectra have been measured by means of laser scanning. At each frequency, under the hypothesis of linear viscoelasticity, the phase velocity and attenuation of the fundamental torsional mode have been calculated as a function of the bulk shear velocity and the bulk shear attenuation of the inner core at that frequency. The resulting phase velocity and guided wave attenuation contour plots have been employed for deriving the unknown shear properties from the measured velocity and attenuation of the guided wave. The monochromaticity of the approach has not required a particular frequency dependence of the material properties to be assumed. Results for bitumen are given.     

High-power continuous wave green beam generation by use of simple linear cavity with side-pumped module

High-power continuous wave green radiation has been generated by means of type-II phase-matched frequency doubling in a KTP crystal located in a simple linear cavity incorporating a diode side-pumped Nd:YAG laser module. The cavity was designed to make the fundamental beam radius at the KTP crystal smaller than that at the gain medium, as is required for obtaining large mode volume in Nd:YAG crystal and realizing efficient CW intracavity frequency doubling. Output power of 51.2 W is obtained in the experiment with a diode-to-green optical conversion efficiency of 10.3%. The M²-parameters of the laser are measured at different output powers. For the output power of about 47 W, the power fluctuation is measured less than 1%. The experimental results show that the continuous wave green laser system using this simple linear cavity offers good laser performance and output stability.     

A simplified finite element method for studying acoustic characteristics inside a car cavity

A simplified finite element method has been developed for analyzing the acoustic resonances of a prismatic car cavity. Use is made of the non-variant geometric and material properties of such a cavity in one direction (across the width of the car) and the solution of the full three-dimensional problem is related very simply to the solution of a single two-dimensional problem, with a consequent reduction of computing effort. Some experimental results obtained for a half-size model of a car cavity are compared with the finite element results. The accuracy of the finite element solution is assessed by analyzing a rectangular cavity and a cylindrical cavity, for which analytical solutions are already available.     

10 MA多支路汇流装置上钽的强度实验研究

磁驱动准等熵加载技术通过电流产生的磁压力加载材料,加载路径由负载电流波形和负载结构决定。作为应变率介于静高压加载和冲击加载之间的新型实验技术,熵增小、温升低。10 MA装置是典型的多支路汇流装置,包括24个电流支路,可在较大范围内控制负载电流波形,实现mm厚、cm直径样品在不同应变率下的准等熵加载。基于10 MA装置,通过调节负载电流波形实现样品加载路径控制,在一定压力-应变率范围,开展金属钽的强度实验研究,获取了不同厚度金属钽样品的加-卸载波剖面速度历史,分析获得了钽在系列峰值压力下的强度数据,比较了多个加载平台不同加载路径下的强度数据,实验结果与美国圣地亚国家实验室的磁驱动准等熵结果接近（平均应变率都约为10⁵ s⁻¹）,明显高于冲击加载的流动强度,低于准静态加载获取的流动强度,与应变率增高强度会有所下降的理论预测一致。基于多支路汇流装置,未来将可开展更为丰富的材料动力学特性实验研究。

     

Photo-thermal-elastic interaction in an unbounded semiconducting medium with spherical cavity due to pulse heat flux

In this work, the photothermal waves in an unbounded semiconducting medium with spherical cavity are studied. This problem is solved using the theory of coupled plasma, thermal, and elastic wave. An unbounded material, elastic semiconductor containing a spherical cavity with isotropic and homogeneous thermal and elastic properties has been considered. The inner surface of the cavity is taken traction-free and subjected to an exponentially decaying pulse boundary heat flux. Laplace transform techniques and eigenvalue approach were used to obtain the analytical solutions. Numerical computations have been done for silicon-like semiconductor material, and the results are presented graphically to estimate the effect of time and the coupling between the plasma, thermal, and elastic waves.     

‘神光Ⅱ’上冲击波法测量黑腔辐射温度

 在“神光Ⅱ”三倍频装置上,由黑腔产生的辐射驱动铝台阶样品产生冲击波,采用光学条纹相机测量冲击波速度,利用冲击波速度与黑腔辐射温度的定标关系,获得了与软X光能谱仪测量相一致的辐射温度;采用热波关系和能量守恒原理对辐射温度进行了分析,计算结果与实验结果一致。     

1.3 GHz超导腔磁通排出效应研究

设计并搭建了一套高精度的磁场测量和补偿系统,并结合中国科学院高能物理研究所（IHEP）的2K超导腔垂直测试平台对1.3 GHz 单加速间隙超导腔的磁通排出效应开展了实验研究：利用研制的磁场测量和补偿系统能够精密地测量超导腔赤道位置磁场,并能够将磁场补偿至小于5.0×10⁻⁸ T;并对超导腔不同表面温度梯度下的磁通排出效应进行了测量分析;对钉扎了磁场的超导腔进行了射频性能测试,研究了超导腔电阻对磁通钉扎的敏感度,以及在不同电场梯度下超导腔的表面电阻变化情况。结果表明,研制的高精度磁场测量和补偿系统能够满足超导腔磁通排出研究的需求;高的超导腔表面温度梯度有利于磁通的排出;磁通钉扎电阻的敏感度随着加速电场梯度的增加而增大,导致超导腔的性能下降。此实验研究也为后续超导腔的研制奠定了一定基础。     

Sound absorption characteristics of a double-leaf structure with an MPP and a permeable membrane

As for the sound absorbing system using an MPP (microperforated panel), a double-leaf MPP sound absorber has been studied so far. However, this structure uses two MPPs, which are still expensive, and is disadvantageous when its cost is concerned. Therefore, it is considered that it can be advantageous if one of the leaves can be replaced with a less expensive material keeping high sound absorption performance. In this study, the possibility of producing a useful sound absorbing structure with an MPP and a permeable membrane as an alternative less expensive material is examined. The acoustic properties of this MPP and permeable membrane combination absorber are analysed theoretically with a Helmholtz integral formulation. The absorption performance and mechanism are discussed through the numerical examples. Also, the effect of a honeycomb in the air cavity, which is to be used for reinforcing the structure, is also discussed through a theoretical analysis.     

Composites reinforced by Al—Cu—Fe quasicrystalline particles with a copper matrix and their tribological properties

Copper-based composite coatings with addition of 34 wt % of Al—Cu—Fe quasicrystalline powder of dispersity less than 20 fum, as well as 70 wt % of quasicrystalline powder of dispersity less than 40fum and less than 3 fum, were produced by the cold spray process. The phase composition during annealing of samples at various temperatures was studied by X-ray phase analysis. Tribological properties of each composite coating and pure copper were investigated. The experimental results showed a considerable improvement of the tribological properties of the material at the addition of quasicrystals. The least wear was observed in the composite sample containing quasicrystalline inclusions of less than 3 fum subjected to thermal treatment. In this case the counterbody wear was practically absent.     

Engineered inorganic core/shell nanoparticles

It has been for a long time recognized that nanoparticles are of great scientific interest as they are effectively a bridge between bulk materials and atomic structures. At first, size effects occurring in single elements have been studied. More recently, progress in chemical and physical synthesis routes permitted the preparation of more complex structures. Such structures take advantages of new adjustable parameters including stoichiometry, chemical ordering, shape and segregation opening new fields with tailored materials for biology, mechanics, optics magnetism, chemistry catalysis, solar cells and microelectronics. Among them, core/shell structures are a particular class of nanoparticles made with an inorganic core and one or several inorganic shell layer(s). In earlier work, the shell was merely used as a protective coating for the core. More recently, it has been shown that it is possible to tune the physical properties in a larger range than that of each material taken separately. The goal of the present review is to discuss the basic properties of the different types of core/shell nanoparticles including a large variety of heterostructures. We restrict ourselves on all inorganic (on inorganic/inorganic) core/shell structures. In the light of recent developments, the applications of inorganic core/shell particles are found in many fields including biology, chemistry, physics and engineering. In addition to a representative overview of the properties, general concepts based on solid state physics are considered for material selection and for identifying criteria linking the core/shell structure and its resulting properties. Chemical and physical routes for the synthesis and specific methods for the study of core/shell nanoparticle are briefly discussed.     

Theoretical study on nanoindentation hardness measurement of a particle embedded in a matrix

The finite element method was used to simulate indentation tests on a particle embedded in a matrix, to investigate the influence of the properties of the particle and the matrix, and the indentation depth on the measured hardness. The particle’s work-hardening exponent and the mismatch in particle and matrix yield strength have a significant influence on the measured hardness. A particle-dominated indentation depth was identified, within which the measured nanoindentation hardness agrees very well with the true hardness of the particle material. Numerical results from the simulations of a wide range of material properties determined that the measured hardness is within 5% difference of the particle’s true hardness when the indentation depth is less than 13.5% of the particle’s radius. The results can be used in practice as a guideline to measure the hardness of a particle embedded in a matrix and provides the theoretical basis to develop a particle-embedded method to measure the hardness of individual particles.