Interaction of a Microwave and a Low-Pressure Plasma under Electron Cyclotron Resonance

The microwave propagation through a layer of low-pressure magnetoactive plasma under electron cyclotron resonance is studied theoretically. Emphasis is placed on assessing the role of electron-gas viscosity in the wave motion. It is found by computer simulation that the viscosity significantly affects microwave transmission and absorption if the electron concentration is high enough, especially in the case of intense wave–plasma interaction under electron cyclotron resonance. The viscosity effect dominates at low pressures.     

Improvement of Linear Model of Plasma Filled Dielectric Cerenkov Maser

The plasma filled dielectric Cerenkov maser considering the effect of the plasma grating has been studied. The plasma grating is formed by the modulation of the strong fields. According to the plasma-grating model, An equivalent model is constructed. The modified dispersion relation has been derived .The numerical results show that when the modulation over the background plasma increases, the operation frequency also increases, however, the growth rate varies slightly. Compared with the calculation results obtained by treating the plasma as uniform fluids, the calculation results with the equivalent model describe the bounded bandwidth of the dielectric oscillator more precisely.     

ICP刻蚀中等离子体分布的模拟

采用直接蒙特卡罗方法对反应器中的气体分布进行粒子模拟，从而得到在不同条件下的一组结果，给出了粒子浓度和温度与腔体尺寸的关系图。并对结果作出分析比较，得出不同的条件对粒子浓度以及温度等产生影响，结果对ICP刻蚀的工艺控制有参考价值。     

空间等离子体鞘层的时域特性研究

空间等离子体环境,是计算机及各类电子设备所面临的新型恶劣环境。通过将设备表面简化为平面,给出了一维粒子层模型。根据静电场理论给出了描述鞘层电位的Poisson方程、等离子体理论和Boltzmann方程,给出了粒子数密度守恒方程。通过牛顿运动定律建立了等离子体的动量方程。基于Poisson方程、粒子数密度守恒方程和等离子体动量方程建立了等离子体鞘层动力学模型。该模型可以给出航天器表面附近等离子体鞘层形成过程的时域特性,如电荷通量、充电电位随时间的变化规律,为电子设备抗空间等离子体防护技术的研究提供理论基础。     

硅基固态等离子体通道的电磁波传输特性研究

基于PIN 二极管形成的硅基固态等离子体通道天线由于具有多功能、超宽带、隐身等优良特性,而成 为国内外研究的热点。简要阐述了此种通道的形成机理,通过理论推导获得了通道中的自由载流子浓度与通道等 效折射率、自由载流子浓度与PIN 结构参数和外加激励之间关系的解析解。理论研究发现,在一定条件下通道可以 获得浓度高且均匀的带电粒子分布,并能够有效地传输高频电磁波信号。三维有限元法计算结果表明,当多个这样 的等离子通道以一定的间隔和方式排列后,其可以有效地作为天线来接收和传输电磁波。这些系统的理论研究将 进一步促进人们对硅基固体等离子通道的理解,为此类天线的设计和加工提供理论指导。     

小功率平面螺旋电感耦合微波等离子体源的研究

 本文提出一种基于平面螺旋微带的2.45GHz小功率电感耦合微波等离子体源,根据等效变压器耦合模型分析等离子体源的谐振特性,通过微波等离子体吸收功率与等离子体阻抗之间的关系,研究不同气压条件下的放电规律.研究表明,在低气压条件下,输入功率不超过220mW时,空气开始放电;而在常压条件下,输入功率不超过1.5W时,氩气开始放电;随着微波等离子体的激励,小功率微波等离子体源的谐振频率和S参数都发生变化.这为电感耦合微波等离子体源的小型化研究提供了理论基础.     

批量式等离子清洗机与在线式等离子清洗机的对比

等离子清洗机的主要原理是利用清洗时高能电子碰撞反应气体分子,使之离解或电离,利用产生的多种粒子轰击被清洗表面或与清洗表面发生化学反应,从而有效地清除各种污染物。针对此,主要使用ANSYS有限元分析软件对批量式等离子清洗机与在线式等离子清洗机反应仓的气流和电磁场进行了仿真分析。实验结果表明,在线式等离子清洗机具有清洗效果好,清洗后不会产生有害污染物、效率高、节省劳动力和安全可靠等优点,具有更广泛的市场前景。     

等离子体隐身技术分析

等离子体雷达隐身理论和技术在军事领域具有十分重要的意义,受到国内外的广泛关注和高度重视。文章介绍了等离子体及其特点,讨论了等离子体的隐身原理和对电磁波的吸收原理,分析了等离子体隐身技术的特点、发展现状,以及等离子体技术在军事等领域的发展前景。     

Model of shear viscosity for underfill flows

To analyze the flow of an underfill encapsulant between the chip and substrate, a shear viscosity model is needed. This paper presents a model of the viscosity for the flow of slurry between two parallel walls, which is a typical situation found in electronic packaging applications. It is postulated that the flow behavior of a dense slurry is governed by the particle-particle and particle-wall interactions. Fluid film lubrication theory is used to find the unit solutions of interaction between two particles. The unit solutions are applied to the simple case of slurry flow densely packed with neutrally buoyant particles. The dependence of the effective viscosity of the slurry on packing parameters is revealed.     

Excitation of Plasma Waves in an Unbounded Homogeneous Plasma by a Line Source

The radiation characteristics of a line source of magnetic current embedded in a homogeneous electron plasma of infinite extent are investigated for the case in which a uniform magnetic field is impressed externally throughout the medium in the direction of the source. The single-fluid theory of magnetohydrodynamics is employed. A very simple model is assumed for the plasma. Under this assumption, it is found that there are two modes of propagation of waves of small amplitude. By examining the behavior of these modes in the limiting cases of vanishing external magnetic field or infinite source frequency, they are identifiable as the modified forms of the usual plasma and optical modes which exist in an isotropic electron plasma. The dispersion relations for these two modes are discussed. The power radiated in each of the two modes is also evaluated. It is found that the power radiated in the optical mode is always lower than that due to the line source in free space, whereas the power radiated in the plasma mode is higher than that value for certain ranges of the source frequency.     

激光等离子体流场的数值模拟

本文采用二阶精度迎风ＴＶＤ格式对轴对称的激光等离子体流进行了数值计算，模拟研究了Ｎｄ：ＹＡＧ高功率脉冲激光与铝靶作用时等离子体场的形成过程，获得与实验结果一致的时间相关解。     

Plasma simulation with an artificial dielectric in a horn geometry

The simulation of a plasma sheath using an artificial dielectric is studied in this investigation and is applied to an antenna geometry which is similar to some configurations encountered in aerospace applications. The antenna configuration is equivalent to a horn in an infinite ground plane with an unbounded plasma layer in front of the horn. The plasma layer is simulated by a rodded medium, and the radiation patterns of the antenna system are studied experimentally at 9, 10, and 11 Gc/s. Two constructions of rodded media are utilized in the pattern measurements. The experimentally determined radiation patterns have a secondary maximum associated with the properties of the plasma sheath. More energy is radiated in the OFF-axis region when the plasma sheath is present.     

等离子体隐身的极化损耗机理

通过等离子体对电磁波的折射效应和吸收衰减实现隐身是等离子体隐身技术的基本机理，但同时，磁化等离子体还可以通过改变电磁波的极化方式造成雷达波的极化损耗。文中研究了极化雷达波在磁化等离子体中传播时的法拉第旋转、双折射等现象，分析了这些效应使雷达波产生极化损耗的机理。结果表明磁化等离子体对雷达波的极化损耗在理论上是完全成立的，其效果也相当显著。     

瞬变等离子体中电磁波频率漂移特性研究

推导一维瞬变磁化等离子体的时域有限差分(FDTD)递推式,并以一维金属谐振腔作为计算模型,分析了瞬变等离子体中电磁波频率漂移特性。从理论分析出发,得到了一维瞬变等离子体对电磁波作用的解析解。通过选取相同的模型和参数,将FDTD数值解与解析解进行对比, 验证了所用FDTD方法的准确性,在此基础上研究了瞬变等离子体中电磁波的频率漂移规律。     

等离子体与电磁波相互作用FDTD 数值模拟

围绕等离子体与电磁波相互作用的问题,将气体分子动力学与电磁场理论相结合,基于玻尔兹曼方程和麦克斯韦方程建立了等离子体与电磁波相互作用自洽模型,为了对模型进行验证,将该方法与经典的电流密度卷积时域有限差分法进行对比,以一维情况下电磁波由自由空间向等离子体内传播为例,应用时域有限差分法对二者进行了数值仿真,仿真结果证明了所建立模型的正确性。此外,基于该模型仿真分析了等离子体参数对电磁波在等离子体中传播的影响,为等离子体与电磁波相互作用的研究提供了一种新思路和新方法。     

非均匀等离子体包覆平板模型微波反射功率测量与分析

介绍了等离子体隐身技术的原理性试验。在大气环境中利用已有的微型固体火箭发动机作为等离子体发生器进行试验,控制发动机喷流流场中的电子密度分布,采用微波反射仪测量金属平板在有无以及不同电子密度喷流包覆情况下的微波反射功率。试验结果表明,峰值电子密度为1011 e/cm3的非均匀等离子体对9.5GHz的微波具有明显的吸收作用,并且试验结果和数值计算结果吻合较好。通过试验,验证了等离子体隐身的特性,为下一步开展等离子体隐身研究打下基础。     

一种新型高效率微波等离子体炬

微波等离子体具有无电极、电子密度大、电子温度高和能量效率高等优势,广泛应用于日常生活、能源、化工和材料等领域,但是目前微波等离子体装置作用距离短,效率低,因此等离子体在腔体中停留时间较短,很难发挥出更好的性能,限制了等离子体在工业领域很好的应用.本文提出了一种新型等离子体炬结构,电磁波通过波导馈入圆柱腔体,能量在圆柱腔...     

船用钢板大功率CO2激光深熔焊等离子体研究

焊接过程中产生的等离子体是激光深熔焊的固有现象，它通过对激光能量的吸收、折射、反射等降低到达小孔的激光能量密度，影响激光与工件相互作用。使用微距高速摄影系统，研究了大功率CO2激光焊接不同功率和不同侧吹气体流量下等离子体的形态和尺寸的变化规律。在相同条件下，激光功率越大，等离子体的尺寸越大，而且越不稳定，容易出现激光维持的燃烧(LSC)波，严重影响焊接过程的稳定性。而通过增加侧吹气体的流量，可以有效抑制LSC波的产生，并且减小等离子体的尺寸，增加焊缝熔深。     

Plasma Etching for Sub-45-nm TaN Metal Gates on High-k Dielectrics

Etching of TaN gates on high-k dielectrics (HfO₂ or HfAlO) is investigated using HBr/Cl₂ chemistry in a decoupled plasma source (DPS). The patterning sequence includes 248-nm lithography, plasma photoresist trimming, etching of a SiN-SiO₂ hard mask, and photoresist stripping, followed by TaN etching. TaN etching is studied by design of experiment (DOE) with four variables using a linear model with interactions. It is found that at a fixed substrate temperature and wafer chuck power, etch critical dimensions (CD) gain decreases with decreasing HBr/Cl₂ flow rate ratio and pressure and with increasing source power and total gas flow rate. Based on these DOE findings, subsequent optimization is performed and a three-step etching process is developed; a main feature of the process is progressively increasing HBr/Cl₂ flow rate ratio. The optimized process provides etch CD gain within 2 nm and gate profile close to vertical and reliable etch-stop on high-k dielectric. This process is successfully applied to the fabrication of the 40-nm HfAlO/TaN gate stack p-MOSFETs with good electrical parameters     

等离子体天线原理与设计

等离子体天线因具有隐身、动态重构、超宽带等优点,可广泛应用于多功能雷达、电子对抗等军事技术领域。等离子体天线主要包括等离子体柱形电介质天线和反射面天线2种形式。基于表面波在等离子体中的传播特性,给出了柱形等离子体天线系统设计;基于等离子体反射电磁波特性,给出了反射面等离子体天线系统设计,为等离子体天线技术趋于实用化提供了必要的理论及技术准备。