基于波导等效阻抗建模用于钛铁矿微波还原的谐振腔体研究

提出了一种利用等效阻抗的思想来设计微波谐振腔。通过计算传输波导的主模等效阻抗与谐振腔近似等效阻抗匹配来确定谐振腔体的尺寸,从而使多模谐振腔与传输波导具有良好的匹配,微波源能够以最小的反射馈入谐振腔内。以钛铁矿作为加热研究的物料,利用HFSS软件分别对单馈口和多馈口多模腔的反射系数进行了优化仿真,并且给出了腔体内场分布的情况,仿真优化的结果与等效阻抗匹配方法计算值接近,验证了根据波导等效阻抗方法来设计腔体结构的可行性,为设计高温微波冶金多模腔体提供了新的参考依据。     

用于大面积材料表面改性研究的微波等离子体源

介绍了环形狭缝波导天线等离子体源的原理和结构。采用微波单探针测量了无等离子体情况下环形波导狭缝天线内的电场分布，利用Langmuir双探针测量了该源的氩等离子体的特性，结果表明在微波功率为200～600W，运行气压为40～600Pa范围内，电子温度可达0.5～3eV，离子密度最高达6×1010cm-3在气压为100Pa，等离子体的直径为16cm范围内，其不均匀性不超过25％。     

环形波导等离子体源阻抗特性的研究

采用微波三探针研究了环形波导等离子体源阻抗特性随运行参数的变化。分析了微波等离子体源的阻抗特性。该方法有助于微波等离子体特性的研究和实现快速阻抗调配。     

气压对氩等离子体特性的影响

研制了一种新的大面积微波等离子体源。由环形波导腔环绕直径３０ｃｍ、高５０ｃｍ耐热玻璃圆筒真空室构成。环形波导内侧开有多个狭缝用来激励产生等离子体。利用该源研究了气压对等离子体参数、击穿功率和熄灭功率的影响。     

高Q值环形波导微谐振腔研究进展

基于高Q值环形波导微谐振腔和微加工工艺的微光机电器件及系统是当前微纳制造科学和量子光学技术领域的研究热点。主要分析了环形波导微谐振腔的物理作用及应用价值,系统综述了环形波导微谐振腔Q值的测量方法,重点讨论了硅基环形波导微谐振腔Q值的影响因素,从材料、结构设计、加工工艺方面分析了提高环形波导微谐振腔Q值的技术途径,指出了当前高Q值环形波导微谐振腔研究存在的技术瓶颈问题,并展望了未来的发展趋势。     

W波段共焦波导回旋行波管色散特性和衍射损耗研究

从共焦波导的电磁场分布出发,得到共焦波导的色散方程和衍射损耗方程。使用数值分析软件MATLAB对W波段共焦波导回旋行波管高频结构的色散特性和衍射损耗进行理论计算,并且绘制了色散曲线和衍射损耗曲线。利用HFSS电磁仿真软件,采用本征模的求解方法,把主从边界条件应用在共焦波导结构上,对其色散特性进行仿真计算,使用场求解器,仿真计算其衍射损耗率。理论计算和仿真结果相互吻合。     

新型微波ECR-PECVD装置的研制

介绍一台新型的ECR-PECVD装置.这一装置设计和采用了一种由单个电磁线圈和永磁体单元组合的新型磁场,使整个装置结构明显简化.为提高装置的微波转换效率,通过计算机仿真微波场在等离子体室的分布,选择和采用了一种新型的矩形耦合波导.应用这一装置分解H2稀释的SiH4气体以沉积a-Si:H薄膜,获得了2 nm/s以上的高沉积速率.     

铯喷泉钟C场的测量与计算

在铯原子喷泉钟实验中，C场均匀度决定了二阶塞曼频移的不确定度评定。使用微波激励法可以测量C场各个高度经时间加权的磁感应强度的平均值。为了得到C场的实际磁场分布，需要对微波激励法的测量结果进行去时间加权计算。介绍了两种去时间加权的算法，并利用仿真数据对算法进行了验证。最后使用微波激励法和两种去时间加权算法，结合蒙特卡洛不确定度评定方法对NIM6铯喷泉钟C场进行了测量与计算。     

金刚石膜气相沉淀技术中微波等离子体反应腔的数值模拟

采用有限积分法(FIT算法) ,并利用一种简单的等离子体模型模拟了具有轴对称的微波等离子体反应腔中微波场与等离子体的行为。计算出了给定等离子体的空间分布时电场的分布情况 ,以及给定电场的空间分布时等离子体的分布情况 ,从而得到微波———等离子体反应腔中电磁场稳定分布以及等离子体的放电位置。并依据实验中的一些可变参数 ,寻求影响等离子体放电位置的参数 ,为设计化学气相沉淀(CVD)技术沉积大面积金刚石膜微波反应腔提供依据     

阵列波导光栅解复用器光谱响应特性分析

基于单模光波导本征模场及其端面衍射场分布的高斯近似表达,推导出两个端面非接触光波导耦合的耦合系数的函数表达式,并基于此推导出阵列波导光栅解复用器的简单光谱响应效率的函数表达式。建立了分析阵列波导光栅解复用器光谱响应特性的简洁数学模型,阐明了阵列波导光栅解复用器对通道中心频率的响应度和相邻信号通道间的串扰与基本参数的关系,为设计和分析阵列波导光栅解复用器提供了理论基础。     

Near- and far-field properties of annular CO(2) waveguide lasers

The theoretical and experimental investigation of field properties of annular waveguide lasers with a Fabry-Perot resonator is presented. Oscillation with high azimuthal mode order leads to an annular intensity distribution in the far field with almost linear dependence of the annular diameter on the mode order. Low-order fields form a distinct focal spot in the far field. A laser device with a discharge area of 6-cm diameter and 53-cm length yields an output power of 600 W.     

Dual-broadband multistandard printed slot antenna with a composite back-patch

A square slot antenna fed by a coplanar waveguide for dual-band multistandard applications is presented. Printed on the back of the square slot is a composite patch formed by an annular metal ring inscribed by a circular patch. Appropriate design of the composite back-patch resulted in five resonant bands, the first (last) two of which were combined to form a lower (upper) operating band. The ratio of the two operating band centre frequencies can be tuned larger than 2.5. A pair of notches was embedded in the annular metal ring to further broaden the lower (upper) operating band up to a fractional bandwidth of 37% (20%). The measured results indicate that the proposed antenna can cover the frequency bands of the following wireless communication standards: digital communication system, personal communication services, universal mobile telecommunications system and 2.4/5-GHz wireless local-area networks.     

Schrödinger wave equation for confinement of photon in a waveguide

In the present work, electromagnetic field confinement in a subwavelength waveguide structure is obtained using concepts of quantum mechanics and uncertainty principle. Semi-macroscopic considerations of field interaction at the dielectric interfaces are used in this work. The modal field profile in the subwavelength waveguide is obtained by considering the photon as a particle in the waveguide having finite probability of tunneling. Thus, uncertainty of position is assigned to it. The momentum uncertainty is calculated from position uncertainty. Schrödinger wave equation for the photon is written by incorporating position-momentum uncertainty. The equation is solved and the field distribution in the waveguide is obtained. The field distribution and power confinement is compared with conventional waveguide theory. They were found in good agreement with each other.     

环形孔径高斯光束的远场特性

讨论环形孔径高斯光束的远场光斑能量分布，并给出拟合表达式。首先推导光束没有抖动时远场光斑的光能分布表达式，然后研究各种不同中心遮拦和不同光束截断比，在有以及没有激光束抖动的情况下，对高斯光束的远场环围能量分布变化的影响。     

Transfer of orbital angular momentum from a stressed fiber-optic waveguide to a light beam

A stressed fiber-optic waveguide is used to impart orbital angular momentum to a Hermite-Gaussian (HG(10)) laser mode. The transmitted beam has an annular intensity profile and a well-defined azimuthal phase dependence. We confirm the phase structure of the beam by observing the interference pattern produced between it and a plane wave. The transfer of the angular momentum to the light occurs because of a difference in phase velocity within the fiber for two orthogonal modes that comprise the input beam. This represents a mechanism for the transfer of orbital angular momentum to a light beam that has not hitherto been identified.     

双金属复合管固-液铸轧复合工艺环形布流器设计及其流场模拟

为解决双金属复合管固-液铸轧复合（SLCRB）工艺覆层熔体金属的环形均匀稳定布流问题,提出并设计了一种带有三级环形阶梯分流和锥形缓冲的环形布流器,并且基于商用软件Fluent建立了稳态布流过程的流体动力学模型,分析了布流器结构和铸轧速度对系统流场的影响,给出了获得均匀、稳定出口流场的布流器内部结构和布流条件,并用水模实验进行验证。结果表明:布流器内通道高宽比不小于1有利于均匀分流,并且锥形缓冲区的均流缓冲作用至关重要。以1.2 m/min的铸轧速度成功制备了外径为38 mm、内径为26 mm的铅-铝双金属复合管,覆层金属厚度均匀、界面结合效果良好。      

The acoustic modes of superfluid helium in a waveguide partially packed with superleak

We have measured the velocities of the two acoustic modes of superfluid helium contained in an annular waveguide packed to a fraction of its depth with superleak material. The depth of the superleak was varied and the dependence of the velocities on the depth was determined. The results are compared with theory and good agreement is found. Explanations for some observed departures are discussed.Supported in part by the Office of Naval Research, Contract No. N00014-69-A-0200-4014, and in part by the National Science Foundation, Contract DMR 7500761-000.