140GHz大功率交错双栅行波管的设计和模拟研究

采用交错双栅结构,结合带状电子注,研究了一种工作在140 GHz频段的大功率行波管. 本振模数值计算表明该结构具有良好的色散特性和耦合阻抗.针对所采用的慢波结构, 提出了慢波过渡结构、输入输出耦合器和集中衰减器,保证了行波管的良好工作. 利用三维大信号模拟计算的方法得到的结果显示,当电子注直流功率为5.115 kW,输入信号功率为0.1 W时, 所研究的行波管能在132-152 GHz范围内提供大于300 W的峰值功率,其中在138 GHz时得到最大功率546 W, 对应增益为37.37 dB.当在0.027-0.46 W内调节输入信号功率,可以保持该行波管在128-152 GHz 频带内得到大于440 W的峰值功率,对应的电子效率大于8.6%. 结果显示该行波管将在大功率短毫米波领域具有重要意义和潜在应用价值.     

新型碳团簇HI的微波低透射率性能研究

文中主要研究了新型碳团簇ＨＩ在低频率１．５～３．５ＧＨｚ之间的微波透射性能，及其温度对微波透射性能的影响，得到了具有低透射率的新型碳团簇ＨＩ的制备条件。     

2.45GHz下常用有机试剂复介电常数的测量与研究

1986年加拿大的R．Gedye和R．J．Giguere等发现了微波可以显著加快有机合成，他们发现用微波辐射可使反应速率和产率有不同程度的提高。由于微波作用机理的特殊性，微波化学对很多化学领域带来了冲击。但是，微波与化学反应体系之间相互作用的一些重大问题还未得到解决，如微波加热过程中化学反应系统的非线性反射、非均匀加热等。解决这类问题，首先必须了解化学反应过程中混合物的电学性质与磁学性质，而物质的宏观电学和磁学性质都用其介电常数和磁导率来描述。对于大部分是非磁性材料的有机试剂，微波与反应体系相互作用的特性集中体现在体系的等效复介电常数上。了解各种常用试剂的复介电常数，可以进一步了解各种化学试剂对微波的吸收和反射的情况。而很多试剂的复介电常数无法从现有文献中得到。本文利用谐振腔微扰法测定了在2．45GHz室温下各类常用有机试剂的复介电常数，结果显示：醇类试剂复介电常数实部与虚部都较大；酮类试剂复介电常数实部相对较大，而虚部较小；酸类试剂复介电常数实部和虚部都较小；烷烃和苯类试剂实部，虚部更小。同时，随着碳链增加，所有试剂的复介电常数的实部与虚部均有下降趋势。这些测试和分析结果将为微波辅助有机合成提供了有益参考。     

Development of a China test cryomodule for ILC

Research and development of a 1.3 GHz 9-cell cavity test cryomodule were carried out by a collaboration group between IHEP (Institute of High Energy Physics) and TIPC (Technical Institute of Physics and Chemistry) in China. The cryomodule is a "test model" for the ILC cryomodule, and a key component of a superconducting accelerator test unit which will be built in the near future, also can be used as a horizontal test facility for 1.3~GHz 9-cell cavities. This paper presents the development status of the cryomodule, including structure design, cryogenic flow diagram, thermal and mechanical simulations, heat load estimation and etc.     

利用准谐频叉指换能器实现GHz高频SAW滤波器

本文利用准谐频设计方法,在常规光刻工艺水平上,成功地实现了ＧＨＺ级声表面波（ＳＡＷ）器件,准谐频叉指换能器（ＱＨＩＤＴ）的优点为：其指条宽与指间隙可以比一般的单指换能器宽,克服了单指换能器内指间的多次反射,并且又较好地解决了普通谐频叉指换能器基频抑制不好的缺点,本文给出了制作在ＳＴ石英基片上,工作频率１１２８ＭＨＺ的声表面波滤波器的实验结果。     

94 GHz回旋管准光模式变换器设计

基于几何光学理论和矢量绕射理论,研究了将回旋管及其他高功率微波器件的振荡输出模式转换成准光高斯波束的模式变换器,采用伏拉索夫(Vlasov)辐射器和三级准光反射面实现了准高斯模TEM₀₀的横向输出.研究了Vlasov辐射器的工作机理,运用矢量绕射理论计算出波导辐射场,口面电流分布的方法计算反射面辐射场.通过编写程序设计了将94 GHz,模式为TE₆₂的毫米波转化为准光高斯波束的内置式准光模式变换器. 关键词： 94 GHz回旋管 内置式准光模式变换器 Vlasov辐射器 矢量绕射理论     

A review on enzyme and ultrasound: A controversial but fruitful relationship

A critical review on the effect of ultrasound (US) on enzymes and their biocatalytic action is presented here. Discussion on the information users of US acquire before utilizing the different devices, and the importance they give to US frequency is constant along the review. The authors have gone into the different areas in which the US–enzyme binomial has been applied. The lack of enough information on the US–enzyme-working conditions under which each piece of research has been developed, and the necessity to provide complete information on the data and metadata to give enough light on each piece of research (and thus on the potential comparison of results from different studies) are critically exposed. With this aim, the study has been divided into the positive effect of US on enzymes to favor the production of metabolites, polymers or proteins; and the degradation, inhibition or activation of the biocatalyst under US application. Also the effect of US on enzyme production and the main fields of application of the US–enzyme binomial are discussed.     

Development of 1.3GHz high-T-c rf SQUID

A new high-T_c (HT_c) rf SQUID working at around 1.3GHz has been developed to avoid electromagnetic interference such as growing mobile communication jamming. This new system works in a frequency range from 1.23 to 1.42GHz (centred at 1.3GHz), which is not occupied by commercial communication. The sensor used in the 1.3GHz rf SQUID is made of a HT_c coplanar superconducting resonator and a large-area HT_c superconducting film concentrator. We have achieved in the 1.3GHz HT_c rf SQUID system a minimal flux noise of 2.5×10^{-5}Φ_0/\sqrt{Hz} and a magnetic field sensitivity of 38fT/\sqrt{Hz} in white noise range, respectively. The effective area of the concentrator fabricated on a 15×15mm^2 substrate is 1.35mm^2. It is shown that the 1.3GHz rf SQUID system has a high field sensitivity. Design and implementation of 1.3GHz HT_c rf SQUID offers a promising direction of rf SQUID development for higher working frequency ranges.     

Millimeter-Wave over Fiber Systems Using Hybrid OCDM/WDM Transmission

In this paper, we propose and simulate 2 OCDM × 4 WDM transmission system for a millimeter-wave (60 GHz) over fiber system to be used in broadband wireless access networks (BWANs). The general system setup is devised and the necessary building blocks identified. Results gathered (for a 155 Mbit/s per user system) under worst case parameter specifications and settings suggest indicate that system performance is severely limited by optical multiuser interference (OMUI) penalties. Several methods to reduce the OMUI limitations are described. These methods should ensure that this transmission scheme possible wavelength-reuse option for future MMW BWANs.     

平面环状碳团簇的微波吸收特性

此文对平面环状碳团簇提出三类可能的结构和振转运动模型，计算其转动谱线与振转光谱的精细结构，所吸收的微波谱线一般在１－２０ＧＨＺ。