Magneto-optical visualization of three spatial components of inhomogeneous stray fields

The article deals with the physical principles of magneto-optical visualization (MO) of three spatial components of inhomogeneous stray fields with the help of FeCo metal indicator films in the longitudinal Kerr effect geometry. The inhomogeneous field is created by permanent magnets. Both p- and s-polarization light is used for obtaining MO images with their subsequent summing, subtracting and digitizing. As a result, the MO images and corresponding intensity coordinate dependences reflecting the distributions of the horizontal and vertical magnetization components in pure form have been obtained. Modeling of both the magnetization distribution in the indicator film and the corresponding MO images shows that corresponding to polar sensitivity the intensity is proportional to the normal field component, which permits normal field component mapping. Corresponding to longitudinal sensitivity, the intensity of the MO images reflects the angular distribution of the planar field component. MO images have singular points in which the planar component is zero and their movement under an externally homogeneous planar field permits obtaining of additional information on the two planar components of the field under study. The intensity distribution character in the vicinity of sources and sinks (singular points) remains the same under different orientations of the light incidence plane. The change of incident plane orientation by π/2 alters the distribution pattern in the vicinity of the saddle points.     

Preparation and characterization of carbonyl iron/glass composite absorber as matched load for isolator

Composite absorbers made from 66 wt% carbonyl iron and 34 wt% low melting point glass powder were prepared by a pressureless sintering technique in a nitrogen atmosphere. Apparent porosity and bending strength of the as-prepared composites were investigated. The microstructure, heat resisting properties and electromagnetic properties were characterized by scanning electron microscopy, thermal gravimetric analysis–differential scanning calorimetry and vector network analyzer. The results show that the carbonyl iron/glass composite absorbers were difficult to densify. As the sintering temperature and soaking time increased, the apparent porosity first decreased and then increased, whereas the bending strength showed the opposite change. The composite absorber sintered at 520 °C for 40 min achieved the minimum apparent porosity of 13.08% and the highest bending strength of 52 MPa. Compared to the carbonyl iron/silicone rubber absorber, the carbonyl iron/glass composite absorber exhibited better heat resisting properties, and the initial oxidation temperature was increased about 200 °C. The composite absorber with a thickness of 1.25 mm showed a good microwave absorbing property in 8–12 GHz.     

Symmetry Groups and Exact Solutions of New （4＋1）-Dimensional Fokas Equation

In this paper, we investigate symmetries of the new （4＋1）-dimensional Fokas equation, including point symmetries and the potential symmetries. We firstly employ the algorithmic procedure of computing the point symmetries. And then we transform the Fokas equation into a potential system and gain the potential symmetries of Fokas equation. Finally, we use the obtained point symmetries wave solutions and other solutions of the Fokas equation. and some constructive methods to get some doubly periodic In particular, some solitary wave solutions are also given.     

镶嵌正方晶格上具有次近邻耦合作用Ising模型的临界性质

采用部分格点自旋消约变换,将镶嵌正方晶格上具有最近邻耦合作用K1和次近邻耦合作用K2的Ising模型变换成等效的具有最近邻、次近邻和四体耦合作用的正方Ising晶格.发现系统的临界点在(K1C,K2C)=(0.5125,0.2134),由此决定系统的临界温度,幷讨论了系统的普适性.     

The beam-based calibration of an X-ray pinhole camera at SSRF

A pinhole camera for imaging X-ray synchrotron radiation from a dipole magnet is now in operation at the Shanghai Synchrotron Radiation Facility (SSRF) storage ring. The electron beam size is derived by unfolding the radiation image and the point spread function (PSF) with deconvolution techniques. The performance of the pinhole is determined by the accuracy of the PSF measurement. This article will focus on a beam-based calibration scheme to measure the PSF system by varying the beam images with different quadrupole settings and fitting them with the corresponding theoretical beam sizes. Applying this method at SSRF, the PSF value of the pinhole is revised from 37 to 44 μm. The deviation in beam size between the theoretical value and the measured value is minimized to 4% after calibration. This optimization allows us to observe the horizontal disturbance due to injection down to as small as 0.5 μm.     

磁绝缘传输线阻抗变化对空间电子流的影响

介绍了磁绝缘传输线的阻抗大小、传输电压及电流大小对其产生的空间电子流大小及阴极电子鞘层厚度的影响。运用CHIPIC软件建立四层圆盘锥形磁绝缘传输线A层的近似化三维模型进行模拟,对比理论计算值与模拟值,并与相关文献的二维模拟结果进行对照,验证三维模拟的正确性。最后,模拟研究了圆盘锥形磁绝缘传输线阴阳极之间的间距变化对传输效率的影响。     

高功率固体激光器锥形空间滤波孔应用

锥形空间滤波孔是一种应用于高功率固体激光装置空间滤波的新型结构滤波小孔,其内部光滑的锥形结构可以有效滤除光束中的高频成分且避免等离子堵孔现象的发生。根据神光-Ⅲ主机装置结构特点,设计并加工了适用于主机装置的锥形空间滤波小孔,并开展了应用实验研究。通过与传统的平面结构滤波小孔对比可以看出,锥形小孔有效地避免了等离子体度堵孔现象,在与光束波前补偿技术配合使用条件下,保证光束顺利过孔,并成功实现了基频光7988 J的满能量输出。     

Self‐formed Schottky barrier induced selector‐less RRAM for cross‐point memory applications

We propose a selector‐less Pr_0.7Ca_0.3MnO₃ (PCMO) based resistive‐switching RAM (RRAM) for high‐density cross‐point memory array applications. First, we investigate the inhomogeneous barrier with an effective barrier height (Φ_eff), i.e., self‐formed Schottky barrier. In addition, a scalable 4F² selector‐less cross‐point 1 kb RRAM array has been successfully fabricated, demonstrating set, reset, and read operation for high cell efficiency and high‐density memory applications. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

点缺陷对硼掺杂直拉硅单晶p/p~+外延片中铜沉淀的影响

系统研究了点缺陷对晶体硅中氧沉淀生成的影响,及点缺陷和氧沉淀对重掺硼直拉硅单晶p/p⁺外延片中铜沉淀的影响.样品先在不同的气氛下进行1250℃/60 s快速热处理,随后在750℃/8 h+1050℃/16 h常规热处理过程中引入铜沾污.通过腐蚀结合光学显微镜研究发现,以O₂作为保护气氛时,p⁺衬底中的沉淀密度较小,以Ar和N₂作为保护气氛时,重掺硼p⁺衬底中生成了高密度的沉淀,且在上述所有样品的外延层中均无缺陷生成.研究认为,以O₂作为保护气时引入的自间隙硅原子（Si_I）可以抑制沉淀的形成,而以Ar和N₂作为保护气氛时引入的空位则会促进沉淀的生成,这是导致此差异的主要原因.另外,研究还发现,p/p⁺外延结构能很好地吸除硅片中的铜杂质,从而保持了外延层的洁净.     

耦合界面计算格式的一维流体力学Lagrange有限点方法

为探索高维多介质流体力学散乱点集上的Lagrange有限点方法,首先对相应一维问题进行研究,提出一种Lagrange有限点方法:在计算区域内(包括物质界面)设置任意离散点集,所有力学量都设在该点集上,在内点和界面点上分别建立离散格式.内点算法为基于Taylor展开的差分方法.界面点算法为显式追踪算法,从定解条件出发,利用Rankine-Hugoniot关系和特征差分方法,计算界面点位置及相应的状态量变化.通过追踪界面点的运动得到物质界面是方法的最大特色.典型算例计算结果与精确解符合很好,验证了算法的合理和有效性.