基于LabVIEW的高功率微波驱动源监控系统

针对高功率微波源对前级驱动电源的计算机自动控制要求,设计了一套1 200 kV高功率微波驱动电源监控系统。系统采用多功能数据采集卡控制大功率调压器产生连续可调的工频电压,再经过环氧高压变压器和整流硅堆等转换为直流高压,对储能电容进行充电控制;采用高速数据输入输出卡控制触发系统按时序进行工作;监测计算机通过RS-485串口方式对直流高压、闸流管阳极电压、闸流管对地电流等进行实时状态监测;控制主机通过以太网与中央控制计算机实现通讯,可以单独控制电源工作,也可以通过中央计算机统一协调工作;采用LabVIEW作为软件开发平台,利用图形控件完成整个电源系统的控制监测等功能的设计;为了解决因电磁干扰强而引起的地电位抬高、高压采集不正常等问题,系统的软硬件都融入了可靠性设计。实验结果表明,该系统工作可靠稳定,实时性强,界面友好,操作简单,具有良好的可扩展性和移植性。     

卷绕式螺旋形薄膜介质脉冲形成线设计

采用模块化结构,设计了一种卷绕式螺旋形薄膜介质脉冲形成线,并且对绝缘材料、电极材料的选择依据进行了分析。基于模块化卷绕式脉冲形成线,研制的重复频率脉冲方波产生器采用4个开关同步触发四级形成线模块,从而实现多模块的电压串联叠加,以达到产生高压的目的。开关采用气体火花间隙开关,每级开关及充放电采用电感隔离。研制的脉冲产生器输出电压220 kV,脉冲宽度182 ns,前沿50 ns,可10 Hz重复频率稳定运行。     

不同应用条件下最佳绝缘子构型

绝缘子的沿面闪络制约着脉冲功率系统向高电压、大电流方向发展,总结了几种实际应用条件下的最佳绝缘子构型,并对不同角度下绝缘子表面的带电情况进行了分析。结果表明,表面电荷对不同绝缘子构型的性能起着至关重要的作用,需要根据不同的应用条件来开展实验研究以确定最佳的绝缘子构型。     

用于太赫兹光源的准等时性储存环的设计

介绍了一种获得准等时性储存环的方案,即调节Lattice参数,在色散段引入负色散函数从而降低线性滑相因子,获得短束团。根据此方案设计了用于相干太赫兹光源的准等时性储存环,结果给出了线形光学函数曲线以及粒子的动力学孔径,表明了通过调节四极铁参数可以达到降低束团长度获得准等时性储存环的目的。还设计了用于准等时性储存环弯铁处的真空室的3维模型,并对其类腔体部分的本征模进行了计算,得到特性阻抗与品质因数的比值在10-3量级以下,表明类腔体部分对束流的影响很小。     

Design of a small-sized expanded coaxial line antenna at L-band

为了减小常规L波段高功率微波测量接收天线的结构尺寸及增益,设计了一种基于轴向缝隙馈电的小型化同轴扩张型天线.通过理论分析和数值模拟,选择了较优的结构尺寸,得到天线的增益及方向图特性:在1.3～1.6 GHz范围内,增益从-2.0 dBi变化至0.8 dBi;天线最大辐射方向在物理结构轴向.基于矢量网络分析仪E8362B的天线特性测量结果与数值计算结果基本一致:工作频率从1 3～1 6GHz变化时,增益从-2.3 dBi变化至1.2 dBi;E面方向图主瓣宽度大于 60°,轴向轴比大于35dB,结果表明设计的天线能够满足L波段高功率微波渊量天线低增益小型化要求.     

大气条件等离子体针处理Enterococcus faecalis菌

自行研制的等离子体针在大气压下通过介质阻挡放电产生的等离子体,再由喷嘴处安装的漏斗形装置聚焦形成针状等离子体. 然后对针状等离子体的基本特性和杀Enterococcus faecalis（E. faecalis）菌进行了研究,E. faecalis菌是一种引起完善充填根管再感染的主要微生物. 当等离子体针功率为5—28?W时,对等离子体的温度进行了测量,表明它不同于其他热杀菌方式. 通过改变等离子体针内电极末端注入的氧气量,发现适当的氧气量,不仅增加等离子体内含氧粒子的浓度而且对等离子体的长度影响也不明显. 实验表明最佳参数为功率15?W,0.1?m³·h^-1氦和2.5%氧气,间距12?mm,处理时间30 s. 为了找出杀菌的关键粒子,进一步比较了大气压下的等离子体针的发射光谱与agar（琼脂）2?mm下的光谱并找出关键粒子. 关键词： 大气压等离子体 介质阻挡放电 E. faecalis菌')" href="#">E. faecalis菌 光谱     

Improved λ/4 phase-shifted DFB semiconductor laser with spatial hole burning compensation using grating chirp

A λ/4 phase-shifted distributed feedback (DFB) semiconductor laser with a preformed chirped grating used to compensate the spatial hole burning (SHB) induced index change is proposed and analyzed. It shows that compared with the three phase shifted DFB laser which is known for its good performance to eliminate SHB, the proposed SHB compensated laser has better single longitudinal mode property, narrower spectral linewidth and better dynamic characteristics.     

Temperature dependence of the Raman spectra of Bi2Te3 and Bi0.5Sb1.5Te3 thermoelectric films

The temperature dependence of the Raman spectra of Bi₂Te₃ and Bi_0.5Sb_1.5Te₃ thermoelectric films was investigated. The temperature coefficients of the E_g(2) peak positions were determined as –0.0137 cm^–1/°C and –0.0156 cm^–1/°C, respectively. The thermal expansion of the crystal caused a linear shift of the Raman peak induced by the temperature change. Based on the linear relation, a reliable and noninvasive micro‐Raman scattering method was shown to measure the thermal conductivity of the thermoelectric films. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Stereochemical analysis of ferrocene and the uncertainty of fluorescence XAFS data

Methods for the quantification of statistically valid measures of the uncertainties associated with X‐ray absorption fine structure (XAFS) data obtained from dilute solutions using fluorescence measurements are developed. Experimental data obtained from 10 mM solutions of the organometallic compound ferrocene, Fe(C₅H₅)₂, are analysed within this framework and, following correction for various electronic and geometrical factors, give robust estimates of the standard errors of the individual measurements. The reliability of the refinement statistics of standard current XAFS structure approaches that do not include propagation of experimental uncertainties to assess subtle structural distortions is assessed in terms of refinements obtained for the staggered and eclipsed conformations of the C₅H₅ rings of ferrocene. Standard approaches (XFIT, IFEFFIT) give refinement statistics that appear to show strong, but opposite, preferences for the different conformations. Incorporation of experimental uncertainties into an IFEFFIT‐like analysis yield refinement statistics for the staggered and eclipsed forms of ferrocene which show a far more realistic preference for the eclipsed form which accurately reflects the reliability of the analysis. Moreover, the more strongly founded estimates of the refined parameter uncertainties allow more direct comparison with those obtained by other techniques. These XAFS‐based estimates of the bond distances have accuracies comparable with those obtained using single‐crystal diffraction techniques and are superior in terms of their use in comparisons of experimental and computed structures.