Intensification of the Electric Convection of Weakly Conducting Liquids by a Pulsed Electric Field

Results of an investigation of the kinematic characteristics of the electric convection of weakly conducting liquids intensified by a pulsed electric field are reported.     

The Renewed KU Leuven Pulsed Field Facility

The KU Leuven pulsed magnet facility was established in the sixties by the late Prof. A. Van Itterbeek (Van Itterbeek et al., Appl. Sci. Res., 18:105, 1967, Van Itterbeek et al., Les Champs Magnétiques Intenses, vol. 379, 1966). During the period 1972–1997 the laboratory was directed by Prof. F. Herlach (Witters and Herlach, J. Phys. D, Appl. Phys., 16:255, 1983, Li and Herlach, Meas. Sci. Technol., 6:1035, 1995, Herlach et al., Physica B, 201:542, 1994) who continuously developed the facility further along two lines: improved pulsed-field-coil design and enhanced capabilities for experimentation. From 1998 on, the facility is lead by Prof. V.V. Moshchalkov, in close collaboration with Prof. E.F. Herlach and Prof. J. Vanacken. Recently, the laboratory has been completely renewed; its present configuration is based on the former installation of the High Field Magnet Laboratory at the Radboud University Nijmegen (the Netherlands) (Rosseel et al., IEEE Trans. Appl. Supercond., 16:1664, 2006), which was originally developed in collaboration with the KU Leuven spin-off company METIS (http://www.metis.be/).     

Field Emission Characteristics of Conducting Polymer Films Conditioned by Electric Discharge

A pure conducting polymer （PANI-CSA） film conditioned by an electric discharge was tentatively utilized as an cathode for emitting electrons under electric fields. The emission of electrons was observed using a phosphor （ZnO：Zn） screen excited by electrons from the conditioned film. The film morphology was investigated using a scanning electron microscope and it was found that undulate whisker-like sites formed on the surface. The emission was presumably due to the undulate whisker-like sites. The field enhancement factor was estimated to be as high as 1150. The electron emitting process of the PANI-CSA film conditioned by electric discharge was also discussed.     

镀锌钢板脉冲电弧钎焊接头界面组织及性能研究

采用脉冲钨极氩弧钎焊使用CuSi3钎料对镀锌钢板进行连接.主要研究脉冲频率变化对接头界面组织和力学性能的影响.实验结果表明,当电弧脉冲频率由100Hz增加到2000Hz时,电弧钎焊熔池的搅拌和冲刷作用效果逐渐增强,促进了界面须状金属间化合物的破碎行为和熔池成分过冷区域的增加,使得钎料区域内部Fe5 Si3(Cu)强化相数量不断增多,弥散宽度变宽,由40μm增加到120μm,接头显微硬度最大值也相应增加,由175MPa增加到204 MPa.     

脉冲磁控溅射制备硼掺杂氧化锌纳米薄膜的光学特性研究

采用脉冲磁控溅射法制备硼掺杂氧化锌（ZnO：B）纳米薄膜,研究了其结构和光学特性,经XRD分析,ZnO：B为多晶纳米薄膜,具有六方钎锌矿结构,薄膜沿着c轴取向择优生长。薄膜在可见光和近红外光谱区的透光性很好,其中在可见光区的平均透光率可达84％以上,而在近红外区的透光率随着波长增加而逐渐降低至45％。在可见光区,ZnO：B纳米薄膜的光学常数随波长的变化很小且数值基本趋于恒定,而在紫外区,光学常数随波长的变化很明显,并且在367nm和397nm附近存在两个紫外发光峰。     

脉冲磁场激励下圆柱导体内瞬态涡流场的快速计算

建立了脉冲磁场激励下圆柱导体内瞬态涡流场的理论模型。实现了瞬态涡流场的快速计算。通过实例表明上述圆柱导体内瞬态涡流场的快速计算方法有效。     

Biomimic Vein-Like Transparent Conducting Electrodes with Low Sheet Resistance and Metal Consumption

In this contribution,inspired by the excellent resource management and material transport function of leaf veins,the electrical transport function of metallized leaf veins is mimicked from the material transport function of the vein networks.By electroless copper plating on real leaf vein networks with copper thickness of only several hundred nanometre up to several micrometre,certain leaf veins can be converted to transparent conductive electrodes with an ultralow sheet resistance 100 times lower than that of state-of-the-art indium tin oxide thin films,combined with a broadband optical transmission of above 80%in the UV–VIS–IR range.Additionally,the resource efficiency of the vein-like electrode is characterized by the small amount of material needed to build up the networks and the low copper consumption during metallization.In particular,the high current density transport capability of the electrode of>6000 A cm^−2 was demonstrated.These superior properties of the vein-like structures inspire the design of high-performance transparent conductive electrodes without using critical materials and may significantly reduce the Ag consumption down to<10%of the current level for mass production of solar cells and will contribute greatly to the electrode for high power density concentrator solar cells,high power density Li-ion batteries,and supercapacitors.     

The Effect of Magnetic Field on Optical Conductivity of Hexagonal Boron-Nitride Sheet

Journal of Superconductivity and Novel Magnetism - The main purpose of this work is to investigate the effect of external magnetic field on the optical absorption of single-layer hexagonal boron...     

脉冲强磁体导体材料研究

在脉冲强磁体设计中,磁应力是我们面临的最大挑战,当磁场强度达到100T时,磁体绕组中的磁应力高达4GPa,这是目前任何实用导体材料都无法承受的,因此,脉冲强磁体的发展在很大程度上取决于磁应力的解决情况.文章从提高导体材料机械强度的角度出发,介绍了目前各种导体材料的加工过程和技术参数,包括铜、铜宏复合导体材料、铜微复合导体材料、多层绞线复合导体材料等.     

Small-Sized Hybrid Magnet with Pulsed Field Magnetization

Small-sized hybrid magnet (HM) operated in liquid nitrogen was constructed. It consists of two superconducting Y-Ba-Cu-O annuli, placed on soft magnetic cores made of permenduire. The magnetization of the superconducting annuli was realized by a pulsed method using two copper coils installed near the annuli. The trapped field value of 2.2 T with the radial (r ≈ 5 mm) homogeneity of 0.1 % can be achieved in the gap of 2 mm between magnetic cores. The magnetization procedure and time evolution of the trapped field are also discussed. The magnets of similar type are promising for application in compact electron spin resonance (ESR) spectrometers.     

脉冲磁场传感器的时域标定

针对脉冲磁场测量的要求，对传感器的时域标定问题进行了研究，组建基于高压脉冲源，ＴＥＭ传输室，数字存贮示波器及计算机的时域标定系统，提出了基于输出误差模型的时域定数据处理方法，利用该模型可方便地获得的传感器的灵敏度，转折频率等参数，成功地利用所建立的误差修正模型对传感器造成的测量失真进行了恢复。     

Deformation of the Surface of a Conducting Liquid under the Action of a Pulse of a Strong Field

It has been shown that the development of the process of the so-called Frenkel–Tonks instability occurring in the case of application of an electric field to a plane surface of a conducting liquid is also determined by the size of the initial distortions of the surface.     

Influence of a Thick Stainless Steel Shell on the Field Waveform of a Pulsed Magnet

The coupling between a pulsed magnet coil and a coaxial stainless steel shell has been modelled by means of PMDS and ANSYS. The cylinder increases the equivalent resistance and reduces the equivalent inductance in the circuit, resulting in a decrease of peak field by up to 5%. Experiments have been carried out for a 10 T coil with and without the steel shell at room temperature. The results are in good agreement with the simulations.     

具有高测量重复性的脉冲磁场磁强计

脉冲磁场磁强计是一种新的、高效率、全象限的永磁材料测量仪器.对脉冲磁场磁强计的磁场产生、信号采集和数据处理等原理分别进行了阐述.由于磁体不必与极头构成闭合回路,在采用珀尔帖效应精确控制测试线圈的环境温度以后,脉冲磁场磁强计的测量重复性(重复9次)由原来的0.326%(Br)、1.860%(HCj),提高到了恒温慢速测量模式下的0.0819%(Br)、0.080 8%(HCj).     

铁磁性管道脉冲远场涡流无损检测技术

针对传统正弦激励下的远场涡流技术存在的探头长度较长,无法识别内外壁缺陷的问题,采用脉冲方波作为激励信号,在分析脉冲远场涡流T作原理的基础上,采用ANSYS仿真软件建立了脉冲远场涡流的仿真模型,仿真分析了传感器参数和激励脉冲参数对检测信号的影响以及内外壁缺陷的定量检测能力.最后采用实验的方法对仿真结果进行了验证,实验与仿...     

Method for the Calculation of the Electric Field near a Paraboloidal Metal Tip above a Conducting Plane

A theoretical method for the determination of an electric field near a paraboloidal metal (conducting) tip has been proposed. The accuracy of the proposed numerical solution has been analyzed. The dependence of the electric field strength at the tip vertex on the distance to the plane, which is applicable for predicting fields in various physical problems and engineering calculations, has been considered. The characteristic spatial distributions of the electric potential and field are presented.