Investigation of the Dielectric-Loaded, Ridged Helical Groove Slow-Wave System for the Millimeter Wave TWT

A dielectric-loaded, ridged helical groove slow-wave structure for the millimeter wave traveling wave tube is presented in this paper. The effects of the groove depth, ridge dimensions and the dielectric permitivety on the wave propagating properties and the interaction impedance are investigated in detail. From the analysis, it is indicated that for broader band amplification in a helical groove travelling wave tube, a ridged helical structure with shallow groove and loaded by dielectric with proper relative permitivety may be applied.     

Wave Propagation Along a Helical Step-Loaded Groove Waveguide

A new kind of helical groove structure, step-loaded groove waveguide is presented and analyzed in this paper. The dispersion equation of this structure is derived by means of a field-matching method. This equation may be reduced to the dispersion equation of helical ridge-loaded structure and rectangular one. In order to demonstrate the influence of the step on the dispersion properties, the comparison of the dispersion characteristics is made in these helical rectangular and modified rectangular groove structures. Form the analysis, it is shown that the step loading tends to reduce the dispersion of the helical groove circuit and the step-loaded structure has the weaker dispersion compared with the rectangular one or the ridge-loaded one. The effect of the step shape on the wave properties is also discussed under the deep groove case. The theoretical results explicitly indicate that the V-like step-loaded structure has the weakest dispersion in all step-loaded structures.     

Study of Novel Slow Wave Circuit for Miniaturized Millimeter Wave Helical Traveling Wave Tube

Two kinds of novel helical slow wave circuit, supported by Chemical Vapor Deposition (CVD) diamond, are presented. They are applying in miniaturized millimeter wave helical traveling wave tube. Cold test characteristic of these circuits are simulated by MAFIA code. Higher performances are achieved with smaller size, compared with conventional circuit supported by BeO rods. The nonlinear analysis is implemented by Beam and Wave Interaction (BWI) module, which is a part of TWTCAD Integrated Framework. Results have been found to be consistent with the expectation. It should be wider apply in microwave and millimeter wave vacuum electronic devices.     

Linear Theory of the Coaxial Ridge-Loaded Helical Groove Waveguide

The coaxial ridge-loaded helical groove waveguide, an all-metal slow-wave circuit, has advantages of good heat dissipation and great size, and thus is suitable for use of millimeter TWTs. In this paper, the dispersion equation of the circuit with an annular electron beam is obtained according to self-consistent field theory. The influence of various electron beam parameters on the small signal gain is investigated and discussed by the numerical computation.     

Dielectric effect on the rf characteristics of a helical groove travelling wave tube

A new type of partial-dielectric-loaded helical groove slow-wave structure (SWS) for millimetre wave travelling wave tube (TWT） is presented in this paper.The radio-frequency characteristics including the dispersion properties,the longitudinal electric field distribution and the beam-wave coupling impedance of this structure are analysed.The results show that the dispersion of the helical groove circuit is weakened,the phase velocity is reduced and the position of the maximum Ez is moved from the mouth to the inside of the groove after partially filling the dielectric materials in the helical groove SWS.Therefore,the dielectric-loaded helical groove SWS is suitable for a multi-beam TWT with broad band and high gain.     

Theoretical Analysis of the Gain in FEL with Helical and Tapered Axial Magnetic Fields

Efficiency enhancement in the free-electron laser is described with a taPered axial guide field. A 3-dimensional analytical decription of this process in the strong-pump regime is given by means of the energy theory based on the dynamic equations. With its clear physical meaning and simple calculation, this theoretical analysis method can also be appropriate to other kinds of FELs.     

单根电极或沟槽形成的栅格对声表面波的散射*

该文借鉴汪承灏先生研究栅格声表面波散射的技术路线,提出一种既不限制基片和栅格形状、类型,也不限制声波入射方向,可精确计算栅格对SAW散射的有限元通用模型。作为对《超声学》第六章"声表面波"中栅格对声表面波的反射和体波散射一节部分结论的进一步阐释和说明,计算了YZ-Li Nb O3和128?YX-Li Nb O3单晶上厚度为200 nm、宽度为1μm的单根悬浮铝栅条以及沟槽在不同频率下的反射系数曲线。提出的计算方法今后可推广应用于层状结构基底、应用到非规则指条、沟槽、金属点阵、基片端面、台阶等的反射的精确分析,为优化设计新型声表面波器件奠定理论基础。     

Analysis for a Novel Cocoon-Shaped Groove Guide with Method of Lines

An arbitrarily cross-sectional groove guide is analyzed by using the method of lines and its characteristic equations are gives for TE and TM modes. Some numerical results show that correctness of the method of lines compared with the relevant results in the references is verified, and it is convenient to solve groove guide with arbitrary shape in practical application problems. A novel cocoon-shaped groove guide is firstly presented and its transmission characteristics are analyzed and discussed. The new type of cocoon-shaped groove guide has the good performances. The obtained results are of important application values in theoretical studies and practical applications of groove guides for millimeter waves.     

球面反射镜的放大自发辐射方法测量小信号增益的理论研究

提出了球面反射镜的放大自发辐射（ＡＳＥ）方法测量小信号增益的理论模型，给出了相应的小信号增益系数的计算公式，该公式具有精确，简洁，显函数等特点，该模型有抑制光束横向分布引起的测量误差的机制。     

阶梯槽交错双栅慢波结构高频特性理论和模拟

本文基于一种阶梯槽交错双栅周期慢波结构模型,获得了该结构中的电磁场分布公式.通过场匹配方法,求出了该结构的高频色散方程和耦合阻抗表达式.以W波段行波管用的阶梯槽交错双栅为例,利用本文公式和CST-MWS电磁软件比较计算了色散和耦合阻抗特性,分析了阶梯尺寸参数对高频特性(基模色散、+1次空间谐波归一化相速和耦合阻抗)的影响.结果表明,理论和CST-MWS软件模拟有很好的一致性;相对矩形交错双栅,改善了色散特性,拓展了基模带宽,同时具有足够大的耦合阻抗和适合工程应用的机械强度,在一定程度上可以弥补矩形交错双栅周期慢波结构的不足.     

声表面波梯形谐振滤波器级联结构的研究

本对声表面波梯形谐振滤波器4级级联的5种不同级联结构进行了理论分析，计算出了其频响特性曲线。对5种不同结构的特性进行了比较，得出了不同结构在带宽、矩形系数、带外抑制等方面的特性，以期对以后实际器件的设计提供理论根据。     

太阳能材料CuInS2的晶体结构、电子和光学特性

用全电势线性缀加平面波法加局域轨道方法调查了黄铜矿半导体CuInS2的结构、电子和光学特性。我们计算的带隙0.17 eV是直接的,其它实验和理论也表明这种材料有一个直接带隙。在 In 4d和S 3p轨道之间有相当强的杂化,构成了(InS2)4-阴离子。我们计算的反射率光谱,介电函数的实部和虚部,消光系数和折射率和实验结果取得了很好的一致。     

铅锌矿区居民头发中Pb，As，Cd等有害元素含量、微区分布及元素形态特征研究

头发是人体元素的排泄器官之一,头发中元素含量能反映出一段时间内矿区毒性元素在人体内的吸收和代谢情况。采用电感耦合等离子体质谱(ICP-MS)和电感耦合等离子体原子发射光谱(ICP-OES)对某铅锌矿区居民头发中Pb,As,Cd,Ca,Mg,Fe,Zn,Cu,Mn和Sr进行了定量分析,应用微区X射线荧光(Micro-XRF)和X射线吸收近边结构谱(XANES)测定了头发中的Pb和As等元素微区分布和Pb形态。研究发现(1)当地部分居民已经受到矿区中Pb,Cd,Cu和Mn等重金属污染的危害。(2)不同性别群体的生理特征和生活习惯是决定其分布特征的主要因素,其中女性头发中Pb,Cd,Ca,Mg,Zn,Cu和Sr的平均含量都显著高于男性,男性头发中的Fe显著高于女性;(3)由于各元素性质、来源和吸收机制等原因,矿区居民头发中Ca-Mg-Sr-Zn,Pb-Cd-Cu-Mn,Fe-Mn具有相关性;(4)矿区典型头发样本中Pb和As主要沿头发中轴分布,从发根至发梢含量有逐渐增多的趋势;(5)头发样品中Pb由4.7%Pb₃(PO₄)₂,36.8%Pb-GSH和8.4%PbS组成;(6)头发中不溶性磷酸铅、铅-半胱氨酸巯基结合态是发铅的主要存在形态,揭示了其为人体铅代谢的主要途径之一。     

二维镨-镉异核金属配合物的水热合成、晶体结构及谱学性能研究

利用水热合成法,以柔性的乙二胺四乙酸（H₄EDTA）为配体、氧化镨以及氯化镉为金属源合成了一种镨-镉异金属-有机配合物[Pr₂Cd₃(EDTA)₃(H₂O)₁₁]·14H₂O （1）。通过X射线单晶衍射确定化合物1的结构,该化合物属单斜晶系的C2空间群,a=16.154(3) Å,b=14.863(3) Å,c=14.875(3) Å,β=115.855(3)°,V=3214.2(9) Å3, Z=2,化合物1的结构中存在纳米尺寸大小的“心形”Pr₆Cd₆O₁₂轮簇。其中Cd2+的配位数为7,采取单帽三棱柱的配位构型,而Pr3+采取十配位双帽四方反棱柱的构型。EDTA4-配体的四个羧基全部去质子化,与一个Cd2+和两个Pr3+配位,其中4个羧基氧原子和2个氮原子都与Cd2+配位,两个羧基分别桥连1个Pr3+。Pr3+和Cd2+通过μ₂-O氧原子交替连接形成Pr₆Cd₆O₁₂轮簇,每个Pr₆Cd₆O₁₂轮簇与附近的6个Pr₆Cd₆O₁₂轮簇共边连接,从而形成一个二维（6, 3）层状结构。二维层再通过…AAA…类型的堆积方式形成三维超分子结构。游离水分子填充在二维层空隙中,与羧基以及配位水分子之间形成比较强的O-H…O氢键,这些氢键有利于结构的稳定。通过热重分析、稳态荧光光谱、热微扰二维红外相关光谱（2D-IR COS）、固体紫外-可见漫反射光谱等手段进一步对化合物1的谱学性能进行表征。在红外光谱上,由于存在大量的氢键,化合物的红外光谱在3 680～2 640 cm-1波数范围内出现宽而强的吸收谱带。同时配体H₄EDTA中的羧基脱去了质子氢,并且与金属离子发生配位,因此化合物1中羧基的C=O双键的伸缩振动吸收峰与未配位配体中的C=O双键的伸缩振动吸收峰相比,向低波数移动,在1 527 cm-1波数处出现吸收峰。固体荧光测试显示在325 nm的紫外光照射下,配合物1能发出强的360 nm左右的荧光,主要是由能量在Cd2+和EDTA4-之间发生明显的LMCT跃迁转移引起的,因此化合物1可作为一类潜在的发光材料。热微扰下的二维红外光谱显示,由于水分子与羧基及水分子之间存在氢键,使得O-H的伸缩振动吸收峰对热的微扰响应比较敏感。紫外-可见光谱测试显示化合物1在位于216 nm处出现很强的紫外吸收峰,归属于化合物1中EDTA4-配体的中n→σ*跃迁及π→π*,位于444, 468和484 nm的弱吸收峰,归属为Pr3+的f-f跃迁。     

The ArNe-N2O van der Waals trimer: a high resolution spectroscopic study of its rotational spectrum,structure and dynamics

A new ternary van der Waals complex of the type rare gas-rare gas'-linear molecule, ArNe-N₂O, was investigated using a pulsed molecular beam cavity Fourier transform microwave spectrometer. The rotational spectra of six isotopomers of the trimer were studied in detail. These include Ar²⁰Ne-¹⁴N¹⁴NO, Ar²²Ne-¹⁴N¹⁴NO, Ar²⁰Ne-15N¹⁴NO, Ar²²Ne-¹⁵N¹⁴N0, Ar²⁰Ne-¹⁴N¹⁵NO and Ar²²Ne-¹⁴N¹⁵NO. Nuclear quadrupole hyperfine structures of the rotational transitions that are due to the one or two ¹⁴N nuclei were resolved and analysed. The resulting spectroscopic constants were used to provide structural and dynamical information about the trimer. Based on the quartic centrifugal distortion constants, a harmonic force field analysis was performed to estimate the frequencies of the van der Waals vibrational modes. A perturbation of the electronic charge distribution at the site of the central ¹⁴N nucleus of N²0 upon complex formation was detected and discussed. Differences of structural parameters of the trimer as compared to those of the respective dimer units are indicative of the presence of significant three-body non-additive contributions to the interaction energy.     

Infrared spectroscopy of van der Waals modes in the intermolecular potential of Ar-CO: The K a, = 0 combination of stretch and bending

Using our diode laser spectrometer a new subband of Ar^?CO in the 2167 cm^?1 region has been detected. We have assigned 18 rotational transitions to a thus far unobserved K _a = 0 van der Waals mode at 23.927cm^?1 above the ground state. An exact analysis yields a Coriolis coupling of this new observed state to a previously detected van der Waals state at 26.187cm^?1 [10]. The measurements and a complete analysis are presented.     

The crystal structure of Fe2In2Se5, a FeIn2Se4-related polytype

Fe₂In₂Se₅, a polytype of FeIn₂Se₄ (a material belonging to the II □ III₂ VI₄ family of semiconducting compounds) has been synthesized by conventional solid-state reaction of their constituent elements. The product of the reaction was sequentially used as starting material in the crystal growth process carried out by chemical transport using I₂ as transporting agent. The crystal structure of a new polytype of this compound was determined using single crystal techniques with data collected with a CCD-based diffractometer. The successful indexing of the data and refinement of the structure led to an hexagonal unit cell with a=4.0371(4) and c=32.746(4) Å. Although the absorption effect in the data was quite noticeable, because of the layered morphology exhibited by the material, a good agreement was obtained for a structural model similar to the structure reported for a related polytype belonging to the ZnIn₂S₄ system.     

The AΠu state of : Electric properties, fine and hyperfine coupling constants, and magnetic moments (g-factors). A theoretical study

Several properties are calculated for A²Π_u of —the majority for the first time—including electric and magnetic moments, and fine/hyperfine structure (fs/hfs) parameters. The new results are compared with our previous ones for X² and B² of [P.J. Bruna, F. Grein, J. Mol. Spectrosc. 227 (2004) 67–80]. The electric quadrupole Θ and hexadecapole Φ moments, polarizability α, and hfs constants a, b, c, d, eQq₀, eQq₂ are evaluated at the density functional theory (DFT) level [B3LYP/aug-cc-pVQZ]. The fs constants (spin–orbit coupling A_Π, Λ-doubling p, q, spin-rotation γ_Π), and magnetic moments (g-factors) are obtained via 2nd-order sum-over-states expansions, using wavefunctions and matrix elements obtained with a multireference configuration interaction (MRDCI) method, and the Breit–Pauli Hamiltonian. At equilibrium, 2nd-order properties of A²Π_u are dominated by its coupling with B². For the A state, two independent components are reported for traceless tensor properties (multipoles Θ and Φ; hfs parameters c/d and q₀/q₂) and three for traced properties (polarizability α and g-factors), i.e., one more component than for axially symmetric Σ states. The currently available experimental data on — limited to A_Π, p, and q—are well reproduced by our theoretical results.