The use of titanium metal in vacuum devices

The excellent gettering and gas retention properties of titanium metal make it highly suitable for use in vacuum devices. Tiny receiving tubes made with titanium parts are described which are capable of operating at high cathode emission densities. These high densities reduce the electron transit times and give better high-frequency performance. They permit the use of small electrodes and reduced heater and plate input powers. Vacuum devices made with titanium and ceramic parts can be operated for long periods of time at temperatures up to 700°C.     

真空及大气下激光对复合材料的烧蚀试验对比

激光与物质相互作用受到环境因素的影响。为了研究真空及大气环境下激光对复合材料的烧蚀模式和烧蚀规律,开展了激光辐照碳纤维复合材料对比试验。在不同辐照能量水平下,研究了两种环境中激光对复合材料的烧蚀特征,获得了复合材料瞬态温度响应数据,并对烧蚀样品进行了显微观测。试验结果表明,环境因素的影响与入射激光能量水平紧密相关。在低辐照能量水平下,复合材料表面烧蚀形貌具有差异,但瞬态热响应非常接近。在较高辐照能量水平下,复合材料烧蚀形貌差异较大:在真空环境下复合材料的环氧树脂发生热解和挥发,碳纤维束发生脱层;在大气环境下复合材料的环氧树脂发生明显的氧化反应,碳纤维束轻微脱层。最后,结合样品显微观测结果,分析了真空及大气环境下激光对复合材料烧蚀模式差异的原因,为建立激光烧蚀理论模型提供了参考。     

Laser interaction with solids--A bibliographical review

This paper provides a review of papers published on laser interaction with solids, from the point of view of plasma production. The material is divided into one section dealing with theoretical work and one dealing with experiments. In addition, an extensive bibliography of papers published on the subject up to the end of 1968 is presented.     

双光子Jaynes-Cummings模型与压缩真空态辐射场的一般相互作用

本文考虑到失谐量及初始原子相干性。讨论了双光子Jaynes-Cummings模型与由SU(1,1)相干态所描述的压缩真空态辐射场的一般相互作用。得到了任意分布的二能级原子与任意单模场相互作用中场的密度算符的一般表达式。计算了平均光子数及场的正交分量的方差。详细研究了各种条件下系统的压缩行为。     

Laser energy limitation for buried metal cuts

Redundancy by laser cutting of polysilicon fuses has been used by the memory industry for many years. As the levels of metallization increase, it becomes more difficult and expensive to delete deeply buried polysilicon lines. Ideally, metal fuses will be cut exclusively. However, to achieve reliable metal line cutting, a wide process window has to be found that can cut buried metal lines. The upper energy limit has previously been thought to result from excess laser energy absorbed by the substrate. We show that another failure mode exists at energies below the threshold to cause substrate damage directly. The same laser pulse which ejects the passivation and removes the metal is also likely to crack the dielectric material below the metal. Molten metal then fills the crack and maintains an electrical short circuit, preventing the line from being disconnected     

RF激励全金属CO2激光器

本文描述了一个紧凑的封离型,ＲＦ激励全金属ＣＯ２激光器的构造和基本特性,这种激光器有着一系列优点,例如：低成本,冷却好,易装配,稳定性好,长寿命和轻便等,用这个小型设备,在３７５ｍｍ放电长度上,得到了１５Ｗ ＴＥＭ００模激光输出。     

Electron transmission through a metal target from vacuum to air

An investigation, in connection with work on a direct electron printing tube, has been made on electron beam transmission through a thin nickel target into atmosphere. Comparison with vacuum-to-vacuum transmission measurements indicates that electron multiplication occurs and that such a system can provide a tool for studying ionization processes, as well as act as an ion source.     

金属表面形貌对真空击穿阈值的影响

探索提高真空击穿阈值的方法,对脉冲功率技术的发展和应用具有重要意义。在金属表面电子发射理论分析的基础上,采用有限元法计算电极表面电场随二极管电压的变化规律,设计实验系统,并开展实验研究。实验对比钛合金TC4阴极在不同表面粗糙度下真空击穿阈值,实验表明,当阴极表面粗糙度(轮廓最大高度Rz)分别为26.13 m,10.41 m,6.75 m,1.12 m,0.13 m时,击穿阈值分别为306 kV/cm,345 kV/cm,358 kV/cm,392 kV/cm,428 kV/cm。当Rz由26.13 m减小至0.13 m时,击穿阈值提高39%。金属表面击穿阈值随Rz减小而提高,减小金属表面的Rz,是提高真空击穿阈值的有效方法。     

板料三维激光成形研究

在分析影响激光成形的主要因素的基础上,充分考虑了材料性能参数与温度的相关性,建立了与实际情况相吻合的三维热机耦合模型,同时对激光热源进行了适当处理,通过一用户子程序实现了热载荷的自动加载,从而实现了三维激光成形过程的有限元仿真。分析了圆柱形件的成形过程,提出了三维激光成形中合理规划扫描路径和扫描顺序时的基本原则。     

金属粉末选区激光烧结技术研究现状

介绍了选区激光烧结技术的原理、特点,简述了选区激光烧结金属粉末的两种典型成型工艺原理,分析讨论了这两种工艺的特点以及存在的问题,展望了选区激光烧结技术的前景。     

Laser linking of metal interconnects: analysis and designconsiderations

Lateral connections between adjacent lines of metallization have been developed in order to achieve high density linking for customization in programmable gate arrays and for additive redundancy in restructurable integrated circuits. Links were formed by focusing a pulsed laser between two same-level aluminum lines. The mechanism of link formation appears to be the nucleation of a fissure, induced by the thermal expansion mismatch between the metallization and the surrounding dielectric (SiO₂) and passivation layer (Si₃N₄); molten aluminum fills the crack. Numerical simulation by the finite element method was carried out using a plane strain model. The probable path for the link-forming fissure, as predicted by the model on the premise that the local maximum tensile stress determines cracking, is shown to be consistent with experimental observations. Parametric analyses were performed to gain insights into the linking processes. It is found that damage in the passivation can be avoided by increasing the thickness of the dielectric between the aluminum and the passivation. Reducing the spacing between the metal lines increases the chance of successfully forming the link. Under certain conditions, the linking propensity can also be increased by reducing the metal width. In addition, the link is much easier to form when symmetric laser heating between the two metal lines can be achieved. These findings can be directly applied to improving the design of the laser linking processes and devices     

压缩真空场与运动二能级原子相互作用的量子纠缠

用Von Neuman熵研究了压缩真空场与运动二能级原子相互作用的量子体系的量子纠缠特性，讨论了初始压缩真空场的压缩度以及运动原子的场模结构参数对该量子体系纠缠特性的影响。结果表明，原子的运动使系统纠缠度的演化具有严格的周期性；在初始压缩度较大（r〉3）时，除了一些消纠缠点外，系统将长久停留在最大纠缠态，场模结构参数的增大将导致消纠缠次数的增多。     

激光等离子体研究的真空室中背景气体的激光多光子电离

本文报道了在高功率密度激光辐照下,激光等离子体研究用的真空室中背景气体(主要是真空系统中的油蒸气)的多光子电离的实验研究结果。得到的离子按其荷质比决定的飞行时间可以分成四组:H_2~ ,H~ ;C~ ,CH~ ,CH_2~ ,CH_3~ ,N~ ,O~ ;C_2~ ,C_2H~ ,C_2H_2~ ,C_2H_3~ ,C_2H_4~ ,Si~ ,CHO~ ,O_2~ 和C_3~ ,C_3H~ ,C_3H_2~ ,C_3H_3~ 等。此外,还观测到C~( )离子。最后充入一定浓度的氩气,观测到了氩离子。     

带涂层金属板件缺陷的激光超声检测研究

针对带涂层金属板件的缺陷检测存在分辨率低,形状、尺寸难确定等问题,基于热弹激励原理、依托两套不同的检测系统对带涂层金属板件的缺陷进行检测,展开对激光超声检测技术的方法研究。首先通过实验验证这项技术的可行性和有效性、检验涂层对缺陷检验有无影响,其次利用实验产生的数据以及图像分析了涂层影响下缺陷波形并对缺陷波进行理论分析,然后对波形参数进行了实时计算最终得到了50 μm涂层影响下缺陷的形状和尺寸特征 。研究结果表明:激光超声检测技术可以实现对带涂层机械板件缺陷的定性定量检测,可应用于工程领域的实时在线检测,并有良好的发展前景。     

Laser patterning of metal oxide superconductor films by reactivesolid-state transformation

A planar submicrometer-resolution patterning method has been developed for fabrication of thin-film Ba₂YCu₃O _x devices without photoresist, water, or solvent exposure. The method is based on a rapid transformation from the superconductive to a dielectric phase. The phase change is induced by controlled changes in the oxygen stoichiometry which are induced thermally by local-area laser irradiation of the thin film in a gaseous ambient. Both extended-area pattern projection and scanned-beam direct writing have been demonstrated with a spatial resolution in the submicrometer range and are presently limited by the grain size of available films. Negligible thickness loss is observed in patterning. The method circumvents lithographic techniques which tend to degrade the electronic quality of Ba₂YCu₃O_x superconductors     

Wetting interaction of Pb-free Sn-Zn-Al solders on metal plated substrate

A newly developed Pb-free Sn-9(Zn-5Al) solder was investigated for its wetting behavior on metal plated Cu substrate. The Cu substrate was plated with electroless nickel (EN) or with EN/Cu multilayer plating. The wetting behavior was investigated with a wetting balance which gave rise to a wetting curve. Fluxes including L-glutamic acid and dimethylammonium chloride were applied for enhancing the wetting behavior. The solder was unable to wet the EN plated Cu substrate without the assistance of flux until temperatures of 460°C and above. The material interaction between the solder and the substrate at this high temperature was investigated with scanning electron microscope elemental analysis. The wetting temperature between solder and EN plated copper was lowered to 310°C with the application of the above fluxes. The further incorporation of a layer of Cu plating with the EN layer further lowered the wetting temperature to 250°C.     

激光辅助三维金属微打印（特邀）

当前微纳尺度的三维金属结构,由于其独特的物化性能和空间构型优势,在科学与工程领域的应用需求日益增多。由此应运而生的各种三维金属微尺度打印技术近年来相继被开发,并引起了广泛关注。在众多技术中,基于激光的三维微打印技术有着非接触加工、制造灵活性好等优势。文中综述了当前一些代表性的激光辅助三维金属微打印技术,总结了各种三维金属微打印的基本原理、技术优势及典型应用。针对高表面光滑度、高熔点、高电导率的三维金属微打印存在的挑战,介绍了超快激光制备玻璃微通道模具法辅助实现三维金属微制造的新技术。最后就三维金属微打印的未来方向和应用前景进行了探讨。     

用HCD灯作金属原子蒸气源的激光光谱研究

利用Ne-Cu HCD灯研究了金属原子蒸气源的光电流光谱和激光荧光光谱,发现了Cu 4p~2P_(3/2)能级的表观寿命随灯电流增加而增大。认为这一现象起因于“共振俘获”效应。     

真空断路器真空度在线监测装置

为满足对真空度断路器实时检测的需求,利用电磁波检测法实现了真空断路器真空度在线监测装置.文章首先分析真空灭弧室局部放电机理,局放电磁波信号特征为装置设计提供初始参考依据.其次介绍了信号调理电路,通讯接口电路等主要硬件设计方案.进行了工程实际验证,装置实现在不改动真空开关主体结构及运行状态的前提下的真空度实时在线监测.     

激光预热/流体冷却辅助激光金属沉积AlSi10Mg成形

铝合金导热率高、激光吸收率低、热累积效应显著,难以稳定形成激光金属沉积（LMD）。为实现自动精确预热、消除热累积、分析预热影响并提升AlSi10Mg铝合金LMD成形能力,采用“光内送粉”Ar送气保护式激光金属沉积技术,设计激光预热与流体冷却温控系统并建立预热与冷却温控模型,进行AlSi10Mg 铝合金LMD成形实验研究,系统分析预热对激光吸收率、表面质量、截面形貌、温度场和材料组织性能的影响。结果表明:激光预热与流体冷却温控系统可实现精确预热并消除热累积,获得表面粗糙度Ra为2.6 μm的单熔道,实现AlSi10Mg搭接、块体和薄壁的高精高效稳定LMD成形。预热提高激光吸收率,使熔道扁平化,增大了晶粒尺寸。该辅助系统和方法能够有效解决铝合金LMD成形稳定性差的难题,为成形质量控制与熔池温控提供了新思路新工艺。