电弧离子镀的旋转横向磁场弧源设计

电弧离子镀工艺中电弧蒸发产生的大颗粒污染严重影响了所沉积涂层的性能.为了从源头上解决大颗粒难题,本文提出了一种新的旋转横向磁场的设计思路,通过频率和强度可调且覆盖整个靶面的旋转横向磁场控制弧斑的运动.通过有限元模拟磁场的分布,对旋转横向磁场控制的电弧离子镀弧源进行了优化设计.并根据方案制作了旋转磁场发生装置及其电源,使该弧源的旋转磁场具有多模式可调频调幅的功能,用以改善弧斑的放电形式,提高靶材刻蚀均匀性和靶材利用率,减少靶材大颗粒的发射,用以制备高质量的薄膜以及功能薄膜,以拓展电弧离子镀的应用范围.     

应用于工具镀膜的磁场辅助离子镀弧源及其放电特性分析

针对几种应用于工具镀膜的磁场控制的电弧离子镀弧源,分析了其结构、工作原理以及弧斑运动、放电特性;比较了不同磁场辅助受控弧源的靶结构及磁场位形,并讨论了对弧斑运动、放电及镀膜工艺的影响;对磁场控制的电弧离子镀弧源的发展进行了展望。     

电弧离子镀弧斑运动对膜层质量影响分析

随着薄膜材料在现代工业中的广泛应用,电弧离子镀技术已成为制备功能性膜层的重要方法,在航空航天方面主要面向于功能表面改性、复合材料表面金属化等领域。本文采用磁场控制电弧离子镀靶材表面的弧斑运动,在Ti靶上验证了弧斑在不同磁场下的运动状态,分析了弧斑的运动速度及运动范围。在五种磁场情况下制备Ti N膜层,通过扫描电镜、能谱分析仪、台阶仪、X射线衍射仪等对Ti N膜层的表面形貌、微观结构、成分元素、膜层厚度等进行了分析。结果发现,当磁场控制弧斑均匀地分布在整个Ti靶面,且弧斑运动速度加快时,膜层表面大颗粒数最少,膜层最厚,晶体择优生长方向为（111）晶面。     

电磁场对电弧离子镀沉积AlTiN涂层的影响

主要研究电磁场对电弧离子镀沉积AlTiN涂层的影响。通过改变电磁场的电压,研究阴极弧斑在不同电磁场下的运动现象以及AlTiN涂层的微观结构和力学性能。结果表明阴极弧斑的运动受磁场电压的影响。增加磁场电压,弧斑更多的在电弧靶中心区域聚集。AlTiN涂层的大颗粒分布、沉积速率、微观结构和硬度相应地受电磁场电压的影响。文章对相关机理进行了研究。     

旋转横向磁场对电弧离子镀弧斑运动的影响

研究了旋转横向磁场对电弧离子镀弧斑运动的影响规律,采用有限元分析软件FEMM对旋转横向磁场的分布进行了模拟,考察了不同频率(80~210 Hz)及电磁线圈励磁电流对弧斑运动的影响。从电弧斑点放电的物理机制出发,探讨了不同频率和磁场线圈电流对电弧离子镀弧斑运动的影响机制。结果表明,随着旋转横向磁场强度和频率的提高,使弧斑逐渐从聚集的斑点态(或者弱分散的团絮态)转变为大面积分布在靶面较强的分散弧斑絮线,最后转变为完全分布在整个靶面的强分散弧斑线,弧斑分裂强烈,产生的弧光等离子体更加均匀细腻。随着瞬态弧斑线在靶面分布面积的增加,弧压增加,弧电流密度急剧下降,靶材利用率达到85%以上。旋转横向磁场的应用,带来了弧斑大面积稳定放电、等离子离化率、密度及靶材利用率大幅度提高的多重效应。     

多模式交变耦合磁场辅助电弧离子镀弧源设计

采用有限元模拟对多模式交变耦合磁场进行了优化设计,介绍了多波形电磁线圈控制电源的原理,并对按此原理制作的电源进行了测试,分析讨论了不同波形励磁电流条件下磁场对于弧斑运动的影响,提出了一种多模式交变耦合磁场辅助电弧离子镀弧源设计原理及方案。研究表明:轴对称发散磁场有推动弧斑向外扩展的趋势,轴对称拱形磁场将弧斑约束在固定的轨道,反极性聚焦导引磁场有约束弧斑在靶材中心的趋势,多模式反极性动态聚焦导引磁场与轴对称发散磁场或者拱形磁场叠加,可形成动态的拱形耦合磁场,动态的控制弧斑运动,改善弧斑放电状态,减少颗粒发射;在聚焦磁场引导下,等离子体稳定的传输,同时可以增强等离子体的粒子碰撞机率,提高离化率和离子密度。反极性动态聚焦导引磁场线圈由多波形电磁线圈控制电源驱动,可输出频率、幅值单独可调的直流及直流偏置的三角波、矩形波、馒头波、正弦波及其他形式的交变电流,实现对弧斑的多种模式控制。     

过滤电弧抑制薄膜中颗粒机理的实验分析

讨论利用直线型过滤电弧制备TiAlN薄膜中,过滤磁场作用于弧斑、靶中毒现象,电子和离子的回流和叠加偏压等因素影响作用的大小进行了实验分析.结果表明,磁场对弧斑分裂和弧斑运动速度的综合作用最为显著是由于直线型过滤电弧形成的瓶颈磁场造成的电子和离子的回流,以及直流叠加脉冲偏压形成的放电空间的等离子体磁撞,分解和离化的所起的共同作用的结果.这对于控制电弧离子镀沉积薄膜中的颗粒尺寸和颗粒密度,指定合理的工艺参数有一定的指导作用.     

真空阴极电弧离子源磁场分析与设计

真空阴极电弧离子源是多弧离子镀膜设备的核心部件,直接影响镀膜系统的整体性能。真空阴极电弧离子源在工作时,大液滴发射是阻碍电弧离子镀技术广泛深入应用的瓶颈问题。合理设计并利用磁场可以很好地控制弧斑运动,大幅度地减少液滴、减小液滴尺寸、提高膜层质量和使用寿命。对真空阴极电弧离子源的附加磁场进行了理论分析和仿真计算,为附加磁场的优化设计提供了重要的指导依据。     

阴极弧斑放电的机理分析

介绍了阴极弧斑放电的基本特征。参考前人的研究模型和最新的实验结果,系统地分析了阴极弧斑放电的机理和过程：电子的爆裂发射模型;热场致发射理论;阴极电位降区满足的Ｍａｃｋｅｏｗｎ 公式;阴极弧斑在磁场中的运动机理。最后讨论了气压对弧斑运动的影响,解释了阳极弧斑放电特征。     

多弧离子镀中磁场对电弧运动影响的研究

多弧离子镀技术中的关键部件是蒸发源,蒸发源的电弧放电特性受磁场的严格控制。本文对真空电弧等离子体在磁场中的受力进行了分析,研究了磁场对电弧运动的影响规律。     

Grain refinement of horizontal continuous casting of the CuNi10Fe1Mn alloy hollow billets by rotating magnetic field (RMF)

Rotating magnetic field (RMF) is used in horizontal continuous casting of CuNi10Fe1Mn alloy hollow billets. The result shows that the formerly inhomogeneous columnar grain macrostructure turns into homogeneous equiaxed grain with the application of RMF. The microstructure without RMF transforms from coarse and disordered dendrites to dense dendrites which have obvious orientation, while the microstructure with RMF from center to edge displays the evolution from spherical grains to disordered dendrites without orientation. The mechanical properties are improved remarkably.     

Relativistic Quantization of Cooper Pairs and Distributed Electrons in Rotating Superconductors

Relativistic time synchronization along closed integral lines maintains magnetic flux quantization independently from gravitation. All Fermi-volume electrons form time-averaged electromagnetic fields within rotating conductors, while Fermi-surface superelectrons enable flux quantization in SQUID experiments. Inertia is not related to instantaneous self-coherent states of the distributed electric charge and, therefore, the Cooper pair mass cannot be measured in principle from magnetic flux quantization. I dedicate this letter to Irina Boulyjenkova.     

GaAs霍尔元件不等位电势的调制消除

测试了MESFET工艺条件下制作的霍尔片的基本性能。对设计出的GaAs集成霍尔元件进行了不等位电势的测试，采用霍尔元件并联和自旋电流的方法对GaAs方形霍尔元件的不等位电势进行了静态和动态调制消除。实验结果表明GaAs霍尔元件的不等位电势引起的偏差可以控制在可以忽略的范围内。     

Magnetisation loss of BSCCO/Ag superconducting tape exposed to applied field with arbitrary angle

Bi₂Sr₂Ca₂Cu₃O_x/Ag tape superconductors are used in applications like power cables and transformers. In these applications the superconductor is exposed to an alternating magnetic field that has different orientations with respect to the tape surface. In this paper the angle dependency of the magnetisation loss is considered from two points of view. First the measurement technique with pickup coils is analysed theoretically. Measured magnetisation loss in uni-directional magnetic field with various orientations and rotating magnetic field are compared. When the orientation is changed from perpendicular (0°) to parallel (90°) applied magnetic fields, the contribution of the perpendicular field component to the magnetisation loss is dominant up to 60°. A new model to describe the angle dependency of the magnetisation loss, based on the measured loss in perpendicular and parallel magnetic field is developed. Deviations between models and the measured loss are explained with the help of the theoretical analysis of the measurement technique. The new model is not only applicable for the magnetisation loss but also for other AC loss components.     

利用均匀磁场提高聚乙烯亚胺-Fe3O4纳米颗粒复合物的磁转染效果

首次研究了不同均匀度磁场对磁转染效果的影响。测定了单边Halbach磁体和商品化96孔磁板的磁场均匀度。以化学共沉淀法制备聚乙烯亚胺(Polyethyleneimine,PEI)修饰的四氧化三铁(Fe_3O_4)纳米颗粒(PEI-Fe_3O_4),并用透射电子显微镜(TEM)、振动样品磁强计(VSM)、原子力显微镜、琼脂糖凝胶电泳等对其形貌、组成、DNA结合能力等进行表征。用倒置荧光显微镜、流式细胞术观察不同均匀度磁场下人肾上皮细胞(HEK293)对带有绿色荧光蛋白报告基因(GFP)的质粒pDNA(pAdTrackOK)的表达效果,并采用TEM观察PEI-Fe_3O_4磁性纳米颗粒进入细胞的过程。结果显示,所选取的两种磁场均匀度相差约100倍。制备的PEI-Fe_3O_4纳米复合物具有超顺磁性,对质粒pDNA(pAdTrack-OK)有较好的复合能力,其最佳结合氮磷比为0.5;流式细胞术显示转染效率为PEI-Fe_3O_4-pDNA+均匀磁场组(77.75%±0.07%)PEI-Fe_3O_4-pDNA+不均匀磁场组(30.65%±0.49%)PEI-Fe_3O_4-pDNA不加磁场组(7.90%±0.56%)(p0.05);PEI-Fe_3O_4磁性纳米颗粒能有效被细胞吞噬,且对细胞形态的影响不大。结果表明,当磁场强度一定时,磁场均匀度越高,磁转染效率越高,单边Halbach磁体与磁转染结合可以作为一种提高转染效率的新手段,也可以进一步应用在基因治疗中。     

Three-dimensional stress analysis of rotating composite beams due to material discontinuities

Material discontinuity could cause in-plane stress gradients that it arises out-of-plane stresses in regions of sudden transition of material properties. A layerwise laminated plate theory is adapted to laminated beams to analyze analytically the three-dimensional stress field at material discontinuities in rotating composite beams. Equations of motion are obtained by using Hamilton’s principle. The beam is divided into two regions with different layups which are joined together to model the region of material discontinuity. The predicted stress distributions at the ply interfaces are shown to be in good agreement with comparative three-dimensional finite element analysis.     

Layered Superconductors in an External Magnetic Field

Presence of localized magnetic moments and inhomogeneites leads to an unconventional behavior of the upper critical field for layered superconductors. In addition, one can observe a large diamagnetic moment at H H _c2 and in the normal resistive state.     

A statistical study of spots in torsional Couette flow

This article presents some results on the statistical behavior of localized structures—called “spots”—that propagate in the flow between a rotating and a stationary disk when those are very close one to the other. Under these conditions the rotating-disk flow belongs to the Couette-flow family and is called the torsional Couette flow. Some visualizations of its transition to turbulence have already revealed the propagation of these spots (Schouveiler et al., J Fluid Mech 443:329–350, 2001) from the rim of the disk towards its center. Using flow visualizations and an original image analysis, the present study aims to better describe the characteristics of the spots whose number continuously increases with the Reynolds number until they invade the whole flow. Moreover, we propose a statistical model that predicts an error-function shape for the probability to observe a spot at a given radial position. This prediction is confirmed by an image analysis of the flow and the stability curve of torsional Couette flow is deduced from these observations.     

强磁环境下的生物大分子结晶研究

近年来,随着超导磁体技术的进步,围绕与强磁场条件相关的应用得到迅速发展.对结构生物学领域的研究人员来说,强磁场有望成为一种可供选择的特殊环境,用于生物大分子结晶研究,并可能成为获取高质量生物大分子晶体的一种手段.就强磁场环境对生物大分子结晶过程的影响研究进行了评述,并对该领域的未来发展方向做了预期.