在高频振荡器结构设计中价值工程的运用

一、高频振荡器简介高频振荡器为某机发射机的核心部分,由金属陶瓷三极管(发射管)和精密同轴谐振腔组成。其结构复杂,零部件加工精度、光洁度高,部分零件有特殊加工要求。发射机脉冲功率、频率调节范围、频率稳定度直接取决于高频振荡器的设计、制造和调试。其主要技术经济指标:(1)频率f_0±4MHz;(2)输出脉冲功率大于800瓦;(3)平均无故障工作时间MTBF不低于200小时;(4)备份发射管两只,以便更换;(5)每台成本3063元。     

FCVA沉积TiAlN薄膜的工艺研究

采用磁过滤阴极真空弧源(FCVA)沉积技术,在高速钢(HSS)基体上沉积TiAlN薄膜,用显微硬度计测定TiAlN薄膜的硬度和厚度,用X射线衍射(XRD)分析技术进行TiAlN薄膜的相分析并进行了摩擦磨损实验,为在刀具表面沉积TiAlN薄膜打下较好的工艺基础。     

轨行式设备的红外防碰撞装置

红外防碰撞装置主要由发射机和接收机两部分组成，采用红外直射方式发射信号，在一定距离内接收信号，实现防碰撞。为扩大红外线发射距离，选用功率较大的红外发射管，发射信号用高频及低频调制、多管发射和光学透镜聚光。为提高检测精度采用了角度定距离的方法。     

磨床上用的导磁夹具

在装有磁性工作台的平面磨床上,利用各种典型导磁夹具可以扩大平面磨床的加工范围。它可以加工几何形状较复杂的定形零件和一些基面很好,而不能用机械装夹的零件;同时导磁夹具还能保证达到较高的精度,比用机械装夹法节省工时,定位准确,能保证平行度在150毫米长度上为0.005～0.01的偏差。另外导磁夹具的构造简单,制造容易。基本原理导磁夹具如图1所示,磁力线由磁力工作台通过导磁夹具的铁片和铁     

微米束离子聚焦系统的研究

本文介绍了离子探针用微米束离子聚焦系统的设计方法,讨论了冷阴极双等离子体离子源、对称式三膜片静电双聚光镜系统、非对称式静电物镜、无象差双静电偏转式离子束扫描系统及12.6°磁分析器。本装置在加速电压为20千伏时,离子源亮度优于4.2×10~(10)毫安/米~2·立体角,阴极寿命超过1000小时,很易获得直径2～200微米的离子束。     

减少阴极弧金属等离子体源液滴的技术措施

液滴的存在并伴随着金属等离子体输运是阴极弧金属等离子体源的主要特性之一,液滴问题的严重性常常影响着阴极弧金属等离子体源广泛应用的可能性。文中针对如何减少液滴,提出了在阴极弧金属等离子体源物理和结构设计上采取的适当技术措施;然后在金属等离子体输运过程中,用正偏压的45°弯管(短磁导管)进行电磁过渡,使液滴减少到最少,使离子得到高效传输,最大限度地减少了液滴对被沉积薄膜性能的影响。     

微波同轴电缆发展趋势展望

介绍了微波同轴电缆技术发展情况,总结了国内外技术水平差距,指出了其未来的重点发展方向为高频(毫米波、太赫兹)传输、超稳相传输、耐特殊环境及新材料新工艺开发。     

经颅磁声电刺激中感应电场聚焦度优化方法的探究

经颅磁声电刺激是一种利用磁声电耦合效应进行神经调控的无创脑调控技术。其神经调控效果取决于超声换能器与磁场在神经组织中诱发的感应电场的聚焦度。本文对经颅磁声电刺激中的感应电场进行仿真,并对阵列换能器各阵元幅值进行了序列加权以提高焦点处轴向、径向分布的感应电场聚焦度。结果表明:基于三角窗的阵元序列加权能有效提高径向分布的电场梯度横向分辨率。基于布莱克曼窗的阵元序列加权能有效抑制轴向分布的旁瓣伪影,总体优化效果强于其他窗序列。本文分析的基于不同窗函数序列加权对聚焦电场性能的影响,为将来提高感应电场聚焦度、推动神经调控发展提供了参考与帮助。     

基于K空间伪谱法的经颅磁声电刺激感应电场聚焦特性仿真研究

经颅磁声电刺激利用超声与静磁场耦合作用产生的感应电场调节相应脑区神经元放电活动,感应电场的聚焦特性直接影响其调控效果的优劣。现有的有限差分法或有限元法在高频波时域模型求解时计算效率有待提升。本文利用基于快速傅里叶变换的K空间伪谱法,将傅里叶级数拟合到网格每一行的数据中,求解经颅磁声电刺激下的感应电场分布,讨论换能器结构参数以及超声频率的改变对感应电场聚焦特性的影响,并依据已有聚焦度评价指标对感应电场聚焦效果进行衡量。仿真结果表明,选用曲率半径25mm、超声频率1.0MHz的自聚焦型换能器时,感应电场具有更加良好的聚焦特性,其中焦域长度、焦域宽度分别为8.50mm、1.44mm。研究结果为经颅磁声电刺激换能器参数设计提供重要的理论依据和参考,有助于推动经颅磁声电刺激在精准神经调控方面的进一步发展。     

磁传动搅拌器气氛控制装置的冷凝回流研究

利用气氛控制装置可以很好地解决磁传动搅拌器在反应釜中频繁出现内磁氢腐蚀等问题。气氛控制装置主要由冷凝回流来实现,而冷凝回流管(简称冷凝管)是实现冷凝回流的关键部件。对气氛控制装置的冷凝回流过程进行热力学计算,给出冷凝管参数的设计过程,进一步完善了磁传动搅拌器气氛控制装置的结构设计。     

Direct coupling of pulsed radio frequency and pulsed high power in novel pulsed power system for plasma immersion ion implantation

A novel power supply system that directly couples pulsed high voltage (HV) pulses and pulsed 13.56 MHz radio frequency (rf) has been developed for plasma processes. In this system, the sample holder is connected to both the rf generator and HV modulator. The coupling circuit in the hybrid system is composed of individual matching units, low pass filters, and voltage clamping units. This ensures the safe operation of the rf system even when the HV is on. The PSPICE software is utilized to optimize the design of circuits. The system can be operated in two modes. The pulsed rf discharge may serve as either the seed plasma source for glow discharge or high-density plasma source for plasma immersion ion implantation (PIII). The pulsed high-voltage glow discharge is induced when a rf pulse with a short duration or a larger time interval between the rf and HV pulses is used. Conventional PIII can also be achieved. Experiments conducted on the new system confirm steady and safe operation.     

Pulsed acousto-optical modulator driver

A gated rf driver for an acousto-optic modulator used to actively mode-lock a laser is described. The modulator is driven in a pulsed mode, so that much higher rf power can be applied to obtain high modulation indices.     

A plasma cathode for a radio-frequency gun

A plasma ferroelectric cathode is used to form electron beams with a high pulse charge and a high charge in an electron bunch in an rf electron gun of a 10-cm wavelength range. The design of the cathode is described, and the results of calculations of the densities of the cathode-emitted and the gun-outputted currents are presented. The operation of the cathode in the rf gun was studied experimentally: the electron energy, the pulse current, and the transverse emittance of the beam were measured. The electron beam obtained at the output of the single-resonator gun had a pulse current of up to 10 A, a pulse duration of 60 ns, and an electron energy of ?500 keV. The normalized beam emittance was 40 mm mrad.     

大尺寸回转体型面点坐标及形心轴线测量系统的研制

针对大型回转体型面测量问题,根据柱坐标机的测量原理,研制了大尺寸回转体型面点坐标及形心轴线测量系统。对影响系统测量精度的不确定度因素进行了量化分析。应用双频激光干涉仪和激光跟踪仪与该系统进行了测量数据比对。该系统不仅能测量回转体工件的任意截面点坐标和形心轴线,还可测量圆柱度、径向跳动、同轴度等,具有高精度、高效率、操作简单等特点。     

High-precision detection of focal position on a curved surface for laser processing

A new technique for detecting the focal position of a curved surface provides several advantages both in research and industrial applications. The quality of patterns lasered on a roll surface is determined by the precision of the focus detection, and surfaces of the massive rolls used in laser fabrication can be difficult to adjust properly using conventional technologies. Here, a unique method for detecting the focal position of a curved surface based on the reflected profile of a laser beam is presented. The versatility of the proposed technique results from being able to adjust the laser beam based on changes in the shape and diameter of the beam spot when the specimen surface deviates from the focal plane. A theoretical model based on three-axis movement is proposed, and experimental setups are developed based on the model. Analysis of the obtained results enables high precision positioning of the specimen and identification of the focal point. Furthermore, the presented technique can be used to locate the focal point on any curved surface. Therefore, the theoretical model, analysis results, and focal detection method can be combined in an algorithm for a novel auto-focusing system that can be applied to laser processing of curved surfaces, such as fabricating microgrooves, or engraving roll surfaces in printed electronics.     

宝钢连轧管机组机架的加工工艺

介绍了宝钢 140mm连轧管机组机架的加工工艺和加工过程中的注意事项。该加工工艺适用于对串孔同心度与同轴度精度要求高的工件的加工。     

船舶舵系中舵叶两锥孔的加工制造工艺研究

船舶舵系中舵叶两锥孔的加工制造工艺,其包括以下步骤:先将一平板用水平仪校平,在镗床的主轴上以平板平面为基准将主轴校平行,再以平板上的T型槽内壁直线度为基准将主轴校直;定好舵叶放置位置后,将若干等高托架放好,并用该等高托架的定位块在平板上嵌入定位;将镗床主轴伸出,按距离该镗床主轴最近的等高托架内孔校圆,使主轴中心与等高托架孔中心线重合;将镗排连接后放入等高托架内孔,并与镗床主轴连接;主轴带镗排在等高托架内孔内旋转,按舵叶的两锥孔的大端圆线校圆,然后加工舵叶的两锥孔,保证两锥孔有较高的同心度。本方法能够应用于船舶业造船、修船舵叶的加工制造,且能保证舵叶二锥孔同心度在0.10 mm以内。     

基于激光准直的直线度误差自动测量系统

文中介绍了基于激光准直原理的直线度误差自动检测方法,详细分析了激光器.传感器信号处理电路和数据采集处理系统的设计,软件设计时结合了直线度误差的两类测量方法和两种评定方法进行了开发,具有运算速度快、适合直线度误差测量仪器多等特点.     

往复压缩机大缸径安装时找正及测量改进

对现有激光对中仪基本结构和原理分析、研究,自行设计一套中心调整装置,将其与现有激光对中仪巧妙结合,实现大型往复压缩机气缸与机身滑道同轴度的精密测量与实时调整,以满足对气缸工件的同心度的找正及测量精度的要求(误差范围不超过0.001mm)。     

Ionization gauge by carbon nanotube field emission

A newly developed ionization gauge using carbon nanotube (CNT) field emission effect has been designed and manufactured. The fabricated ionization gauge is of a triode type, consisting of a cathode (carbon nanotube field emitter arrays), a grid and a collector. The principle involved here is that for a constant number of electrons available for ionization emitted from carbon nanotube arrays by the grid potential, a constant fraction of gas will be ionized and the number of ions collected in the collector will be proportional to the number of gas molecules in the chamber traversed by the electrons. Due to the excellent field emission characteristics of CNT, it is possible to make a cost effective cold cathode ionization gauge. A screen-printing method has been used to make the CNT cathode. The glass grid with Cr deposited by E-beam has been put on the cathode with a gap of 200 μm between the two electrodes. Using the voltage applied to the grid, the electrons emitted from the carbon nanotube ionize gas molecules in the chamber and the ionized molecules are gathered in the collector. At this time, the collector voltage is maintained at a lower level than that of the grid voltage to obtain a large ionization ratio. The current detected in the collector is proportional to the pressure in the chamber. The ionization characteristics are dependent on the gas and the voltage applied to the grid and collector. In this paper we have shown the various metrological characteristics of the simple pressure sensor utilizing carbon nanotube.