V波段圆波导TE01模式激励器

V波段圆波导TE01模式激励器由矩形TE10模式到矩形TE20模式变换器和矩形TE20模式到圆波导TE01模式变换器组成。采用H面（磁面）转弯激励的方式实现矩形TE10模式到矩形TE20模式的变换;根据圆波导TE01模式的场分布特性,引入过模波导实现了矩形TE20到圆波导TE01的变换。计算结果表明设计的激励器转换效率在95%以上;模式纯度在98%以上的相对带宽可达4.2 GHz;其中在43.4 GHz处的最大转换效率为99.08%,纯度为99.20%。     

Ka波段TE01模回旋速调管输出腔

利用模式展开和场匹配理论,建立了具有突变结构谐振腔的散射矩阵。在此基础上编制了FORTRAN计算程序,并对Ka波段TE01模回旋速调管的具有突变结构的开放式输出腔进行了数值计算。分析了回旋速调管输出腔的腔体长度和半径变化,以及输出耦合孔的半径和厚度变化对输出腔的品质因数和频率的影响。结果表明：由程序模拟输出腔所得到的计算结果与HFSS软件的结果一致;与冷测实验结果相比,品质因数的相对偏差为1.65%,谐振频率的偏差为10 MHz。     

圆波导TM01-矩形波导TE10模式转换器

设计了一种高功率圆波导TM01-矩形波导TM10模式转换器,可以实现圆波导TM01模式与矩形波导TM10模式之间的相互转换。仿真结果表明：中心频率为9.7 GHz时该模式转换器转换效率大于99.99%,回波损耗小于-40 dB,转换效率大于90%时的带宽大于0.4 GHz。调节底面短路圆波导长度可以实现模式转换器在9.2~10.1 GHz范围内调谐(模式转换效率大于99%)。在圆波导和耦合段连接处引入倒角可有效降低场强,提高功率容量,注入功率0.7 GW,其表面场强小于1 MV/cm。     

Numerical Simulation of Waveguide TM01-TE11 Mode Converter Using FDTD Method

We study a transmission problem of an electromagnetic pulse with given transversal structure passing through a waveguide converter from TM₀₁ to TE₁₁ mode of circular waveguide. Using FDTD numerical simulation method we have investigated mode structure of the pulse at the output of the converter and its dependence on pulse length at the input. Also we have obtained frequency characteristic by calculating Fourier response for a pulse with wide spectrum.     

A High Efficiency Launcher and Mirror System for Use in a 110 GHZ TE22,6 Mode Gyrotron

A four-mirror internal quasi-optical mode converter designed for a CPI gyrotron is discussed. Many improved methods were used in designing the mode converter. The launcher was designed and analyzed using the TOL and Surf3d codes developed by CCR. Mirrors 1 and 2 were designed using analytic surfaces to shape the general wavefront curvature of the beam radiated from the launcher. Mirrors 3 and 4 were iteratively designed using improved techniques that produced smooth mirror surfaces. Good agreement was found between theory and low-power cold-test measurements. The fraction of power coupled between the target Gaussian beam and the output of mirror 4, inferred from measurements, was 0.990. The stray radiation from the internal quasi-optical mode converter, inferred from measurements, was only 1.9% of the total power radiated from the launcher. This resulted in a high overall system efficiency of 97.0%, which is greater than previous designs.     

TE03 to TE01 mode converters for use with a 150 GHz gyrotron

Two-step high-power TE03-to-TE01 mode transducers (TE02 is the intermediate mode) were designed to transform the TE03 output mode of the 150 GHz KfK gyrotron into the fundamental circular symmetric TE01 mode for low-loss propagation and further conversion into the linearly polarized quasioptical HE11 mode. The advanced perturbation structures of the ruppled-wall mode converters (with input- and output-diameter D=27.8 mm) were optimized by numerically solving the proper coupled-wave differential equations. The overall TE03-to-TE01 conversion efficiency at 150 GHz was calculated to be ₀=99.1% for a long converter (total length L=2.67 m) and ₀=97.8% for a short converter (L=1.07 m); ohmic attenuation is included. The corresponding theoretical bandwidth (for 95%) is ±1.4 GHz and ±2 GHz, respectively. Low-power experimental data are in excellent agreement with these computed values.     

Design of the H10□ to H01° Sector-Type Mode Converter at Ka-Band

A design procedure for the H₁₀^□ to H₀₁^° sector-type mode converter at Ka-band is described in detail. As an example, an H₁₀^□ to H₀₁^° sector-type mode converter with an input rectangular port size as 7.112×3.556 mm² and another output circular port diameter as 17.2 mm is designed and measured for insertion losses and wanted mode pattern. The mode converting efficiency from H₁₀^□ mode to H₀₁^° mode is about 91.2%. The insertion losses of the converter are lower than 0.1525 dB with 2GHz band.     

用八孔耦合器识别TM0_(1)/TE_(11)混模中TE_(11)模式的方法北大核心CSCD

在高功率微波传输系统中,为了提高功率容量和效率,往往采用过模波导,因此圆波导中往往出现TM_(01)和TE_(11)混合模式的情况。采用角向均匀分布的8孔圆波导耦合器,对提取TE_(11)模式的混合比和极化角度的方法进行了分析和研究。分析了圆波导中TM_(01)和TE_(11)模式在耦合孔处的电场分布,并采用CST对各耦合孔的输出功率进行了模拟计算,得出相互正对的耦合孔的平均功率与8个孔的平均功率之比与模式之间的相位差无关的结论。同时,发现该比值与TE_(11)模式的混合比成线性关系,线性关系中的比例系数是极化角度线性函数。通过线性拟合获得了计算TE_(11)模式混合比和极化方向的表达式。与仿真设定的参数相比,用该表达式计算的结果表明,在TE_(11)模式混合比小于30%时,用其计算TE_(11)模式的混合比和极化角度是可行的,误差不超过10%。在此基础上,给出了实际情况下TE_(11)模式信息的具体判断方法。     

高功率速调管TE_(11)-HE_(11)模式变换器的设计及实验验证

基于模式匹配法编制了分析内壁刻槽TE11-HE11圆波导模式变换器数值计算程序;采用该程序为工作频率为30.5GHz的高功率速调管设计了一半径为16mm的TE11-HE11模式变换器。计算表明该变换器在2.6%的带宽内转换效率在98.8%以上,实验结果表明该变换器性能良好。     

Calculation of Mutual Coupling between Two RLTs in Millimeter Wave VCO Waveguide Cavities with Mode Matching Methods

In the design of millimeter wave voltage control oscillators (VCOs), mutual coupling effect is of great importance for it influences the tuning and power characteristics of VCOs significantly. In this paper, mutual coupling between two in-line radial line transformers (RLTs) in rectangular waveguide cavities of millimeter wave VCOs has been evaluated with mode matching methods. Mutual coupling characteristics varying with various parameters of resonate cavity such as the distance between two diodes, the position of sliding short, the radii of bias pins, the radii of RLTs, and the height of diodes are presented. Some useful conclusions concerning two RLTs configuration have been derived, which is helpful to design millimeter wave VCO of this structure.     

TE10矩形波导中填充金属线阵和铁氧体合成的新型左手媒质

在TE₁₀矩形波导中填充金属线阵和铁氧体合成了一种新型的左手媒质结构.分别使用了转移函数矩阵方法以及全波仿真工具Ansoft HFSS对所提出的结构进行了分析.结果表明,在横向磁化铁氧体等效磁导率实部为负的频段范围内,该合成结构呈现左手通带特性并伴随着后向波的传播现象.由于横向磁化铁氧体的等效磁导率为负的频段范围可调,故所提出的结构具有左手通带范围可调的特性. 关键词： 左手媒质 10矩形波导')" href="#">TE₁₀矩形波导 金属线阵 铁氧体     

Design of a TE10-TE30 Rectangular Mode Converter for 4.6GHz LHCD Launcher in the Experimental Advanced Superconducting Tokamak

A compact rectangular TE10-TE30 mode converter is developed for the lower hybrid current drive （LHCD） launcher on the Experimental Advanced Superconducting Tokamak （EAST） at 4.6 GHz. The converter with periodic width perturbation aims to divide the microwave power into three sub-waveguides in the poloidal direction. We present the design and numerical calculation of the mode converter. Calculations are performed on the ripple wall converter by codes based on numerical solving the coupled-mode differential equations and on the simulation of the High Frequency Structure Simulator （HFSS） package. The resulting conversion efficiency from TE10 mode to TE30 mode exceeds 95% within the bandwidth from 4.56 GHz to 4.64 GHz, and the return loss of the oversized transducer can be considerably decreased to 0.068% by means of a capacitive button embedded in the E-plane of the waveguide.     

The cold quality Qcold for magnicon on resonator in the rotating TMn10 mode

Cold quality Q_cold is an important parameter in microwave electronic tube design. Magnicon works in a rotrating TM_n10 mode in the cylindracl cavity, its field distribution is different from the static state. But up to now researchers simply assume its cold quality to be two times of the static one, which usually results in big errors. Here in this paper, based on the rotating field distribution, and using the integrated Bessel function, we deduced the cavity’s storage and the rotating field dissipated power expressions, and obtained a modified cold quality formula for rotating TM_n10 mode in the magnicon, which shows a good agreement with the experimental data. This work supported sci. & Tech. Funds of CAEP. Associate professor.     

The cold quality Qcold for magnicon on resonator in the rotating TMn10 mode

Cold quality Q_cold is an important parameter in microwave electronic tube design. Magnicon works in a rotrating TM_n10 mode in the cylindracl cavity, its field distribution is different from the static state. But up to now researchers simply assume its cold quality to be two times of the static one, which usually results in big errors. Here in this paper, based on the rotating field distribution, and using the integrated Bessel function, we deduced the cavity’s storage and the rotating field dissipated power expressions, and obtained a modified cold quality formula for rotating TM_n10 mode in the magnicon, which shows a good agreement with the experimental data. This work supported sci. & Tech. Funds of CAEP.     

超短脉冲光参量振荡器中TEM_(01)模经典增益的实现

用中心波长为850nm,重复频率为76MHz,脉宽为130fs的飞秒脉冲光产生二次谐波,泵浦TEM01模的同步光学参量振荡器,实验上获得了TEM01模大约4倍的经典增益,并给出了理论分析。这是产生高阶模飞秒脉冲光非经典频率梳的重要步骤,理论预计该增益下可以得到-2.20dB的TEM01模脉冲压缩光。     

A Novel Parallel-Series Feeding Network of Microstrip Patch Arrays with Composite Right/Left-Handed Transmission Line for Millimeter Wave Applications*

A novel parallel-series feeding network of microstrip patch arrays with composite right/left-handed transmission line (CRLH-TL) for millimeter wave applications is proposed. Since there is no inserting phase shift in the patch elements with CRLH-TL feeding structure, the inherent pattern shift resulting from the traditional parallel-series feeding network is removed. Besides, because of the simpler structure and the shorter length of the CRLH-TL feeding network, the antenna array is of higher gain than that with the conventional parallel feeding network.* Supported by the National Natural Science Foundation of China (No. 60371010) and (No. 60471037)     

Searching for the dopant ion in Eu-activated BaMgAl10O17 phosphor with synchrotron diffraction

Searching for the multiple sites predicted in the literature for the europium activator in the BaMgAl₁₀O₁₇:Eu²⁺ phosphor, we undertook a detailed structural study using synchrotron powder diffraction. Three different positions were found for Eu²⁺ in the Beevers-Ross site, near the mid-oxygen position and in substitution for the interblocks Al-O-Al bridge. By favoring the migration of the activator ion, the resulting vacancies in the Beevers-Ross sites may be a major cause of the degradation of the phosphor.     

Synthesis and ion conductivity of (Bi2O3)0.75(Dy2O3)0.25 ceramics with grain sizes from the nano to the micro scale

Using (Bi₂O₃)_0.75(Dy₂O₃)_0.25 nano-powder synthesized by reverse titration co-precipitation method as raw material, dense ceramics were sintered by both Spark Plasma Sintering (SPS) and pressureless sintering. According to the predominance area diagram of Bi-O binary system, the sintering conditions under SPS were optimized. (Bi₂O₃)_0.75(Dy₂O₃)_0.25 ceramics with relative density higher than 95% and an average grain size of 20 nm were sintered in only 10 min up to 500 °C. During the pressureless sintering process, the grain growth behavior of (Bi₂O₃)_0.75(Dy₂O₃)_0.25 followed a parabolic trend, expressed as D² − D₀² = Kt, and the apparent activation energy of grain growth was found to be 284 kJ mol^− 1. Dense (Bi₂O₃)_0.75(Dy₂O₃)_0.25 ceramics with different grain sizes were obtained, and the effect of grain size on ion conductivity was investigated by impedance spectroscopy. It was shown that the total ion conductivity was not affected by the grain size down to 100 nm, however lower conductivity was measured for the sample with the smallest grain size (20 nm). But, although only the δ phase was evidenced by X-ray diffraction for this sample, a closer inspection by Raman spectroscopy revealed traces of α-Bi₂O₃.     

Polarizer with Nonrectangular Grooves in the HE11 Mode Transmission Line

This paper presents experimental results on polarizers with nonrectangular grooves to be used in high power millimeter wave transmission lines for electron cyclotron heating (ECH) of fusion plasmas. A low-power test at a frequency of 106.4 GHz has been carried out for several polarizers with different groove depths. The polarization characteristics experimentally measured are in good agreement with numerical results in which the actual groove shape functions are taken into account. This confirms the design optimization for future polarizer. Favorable results have also been obtained in a 400 kW-level high-power test for the polarizer installed in an ECH transmission line of the Heliotron-E plasma device.     

The heat capacity of the layer compound tetrachlorobis (methylammonium) manganese—II (CH3NH3)2MnCl4, from 10 to 300k

The heat capacity of the layer compound, tetrachlorobis (methylammonium) manganese II, (CH₃NH₃)₂MnCl₄, has been measured over the range 10K <T<300K. In this region, two structural phase transitions have been observed previously by other techniques: one transition is from a monoclinic low temperature (MLT) phase to a tetragonal low temperature (TLT) phase, and the other is from TLT to an orthorhombic room temperature (ORT) phase. The present experiments have shown that the lower transition (MLT→TLT) occurs at T = 94.37±0.05K with ΔH_t = 727±5 J mol^?1 and ΔS_t = 7.76±0.05 J K^?1 mol^?1, and the upper transition (TLT→ORT) takes place at T = 257.02±0.07K with ΔH_t = 116±1J mol^?1 and ΔS_t = 0.451±0.004 J K^?1mol^?1. These results are discussed in the light of recent measurements on (CH₃NH₃)₂CdCl₄, and also with regard to a recent theoretical model of the structural phase transitions in compounds of this type.In addition to the structural phase transitions, (CH₃NH₃)₂MnCl₄ also undergoes magnetic ordering at T < 150K. The magnetic component to the heat capacity, as deduced from a corresponding states comparison of the heat capacity of the present compound with that of the Cd compound, is shown to be consistent with the behaviour expected for a quasi 2-dimensional Heisenberg antiferromagnet.