Microplasma Technology and Its Applications in Analytical Chemistry

Abstract

This review article describes some existing microplasma sources and their applications in analytical chemistry. These microplasmas mainly include direct current glow discharge (DC), microhollow-cathode discharge (MHCD) or microstructure electrode (MSE), dielectric barrier discharge (DBD), capacitively coupled microplasmas (CCμPs), miniature inductively coupled plasmas (mICPs), and microwave-induced plasmas (MIPs). The historical development and recent advances in these microplasma techniques are presented. Fundamental properties of the microplasmas, the unique features of the reduced size and volume, as well as the advantageous device structures for chemical analysis are discussed in detail, with the emphasis toward detection of gaseous samples. The analytical figures of merit obtained using these microplasmas as molecular/elemental-selective detectors for emission spectrometry and as ionization sources for mass spectrometry are also given in this review article.     

矩阵方程AV＋BW=VF的两种解析通解

本文给出了矩阵方程AV BW=VF的两种解析通解,特别第二种通解还分别为自由参向量和F阵特征值的显式线性表示,本文结果较已有结果简单,适用范围广,且应用方便。     

泛函梯度数值计算的一种新方法—正交试验法

本文研究并揭示了L_(2~a)(2~(2~a-1))型正交表行(列)间的递推规律,提出了一种泛函梯度数值计算的新方法——正交试验法,该方法在计算速度和精度上优于直接梯度法;在通用性及节省内存方面优于伴随算子法。     

表面喷砂对有机玻璃沿面闪络性能影响

绝缘子表面粗糙处理是提升其沿面闪络性能的重要途径,表面粗糙化处理方式不当,极易带来表面结构不均匀,难以获得稳定耐压性能的绝缘材料。为提升绝缘子表面粗糙处理的均匀性,本文利用表面喷砂技术对圆柱形有机玻璃（PMMA）绝缘子进行了粗糙化处理研究,以球形二氧化硅（SiO₂）颗粒为工作介质,研究了不同喷砂粒径、氢氟酸后处理等因素对绝缘材料表面形貌和组分的影响,并利用短脉冲高压测试平台对喷砂处理前后有机玻璃绝缘子样品进行了真空沿面闪络性能测试。研究结果表明,喷砂处理在有机玻璃表面形成了较为均匀的凹坑,HF酸能够有效去除表面残留的SiO₂颗粒,具有表面喷砂粗糙结构的绝缘子沿面闪络电压得到了稳定提升,相较于未处理的绝缘子闪络电压提升了约80%。     

Double Andreev reflections at surface states of the topological insulators with hexagonal warping

We study the Andreev reflection(AR)at the interface of the topological insulator with hexagonal warping and superconductor junction.Due to the hexagonal warping effect,the double ARs are found in a certain range of the incident angle,where for one incident electron beam,two beams of holes are reflected back.Interestingly,both the beams of holes are reflected as retro-AR on the same side of the normal line of the interface but with different reflection angles,different from the previously reported double AR with one retro-AR and one specular-AR.The double reflections owing to the warping effect show the optics-like property of the Dirac fermion and can stimulate the double reflections of light in anisotropic crystals.In addition,we find that the double ARs are dependent on the hexagonal warping parameter nonmonotonically,and in an intermediate strength the double AR phenomenon is prominent,providing a possibility to explore the warping parameter of topological insulators.     

Study of the superconducting transition in YBa2Cu3O7−δ single crystal by thermopower measurements

We have determined the superconducting transition in YBa₂Cu₃O_7−δ single crystal by measurements of thermopower. Two transitions were observed in both the ab-plane and the c-direction. The high temperature transition may have a close relation to the surface shell of the crystal.     

脊加载曲折波导行波管注波互作用的线性理论研究

提出了一类新型毫米波大功率微波器件——脊加载曲折波导行波管,推导出了引入电子注后的"热"色散方程.通过数值求解此方程,研究了加脊尺寸和电子注参数对小信号增益影响.计算结果表明:通过适当的尺寸设计和工作参数的选择,此结构在Kα波段具有18.51%的3 dB增益带宽和1.15 dB/周期的增益;相比于常规曲折波导结构,脊加载结构在保证一定带宽的情况下,具有更高的增益和电子效率;为了进一步提高增益,可以适当增加脊宽度和高度,也可在一定范围内增加电子注电流. 关键词： 毫米波 曲折波导 脊加载 小信号增益     

基于RFM的机载余度计算机软件快速测试平台

现代飞机普遍采用电传飞行控制系统,飞行控制计算机是该系统的核心。为了提升飞控计算机的可靠性,普遍采用余度技术构建余度飞控计算机,该计算机由多个通道构成,每个通道有一个CPU,互相构成备份。但是,这给飞控计算机的软件调试和测试带来的巨大的困难,因为各个通道的机载软件之间相互同步、通信和交叉监控,必须并行调试和测试,这就造成了机载软件调试和测试的滞后,必须等待真实的飞控计算机开发出来之后才能开展工作。本文提出了一种基于RFM(反射内存)的余度计算机快速原型测试平台设计方法。该平台使用商用货架产品构成余度计算机的多个冗余通道,使用RFM模拟多通道间的通信、同步过程,通过对底层驱动封装实现硬件故障模拟和余度功能模拟,方便实现软件调试和从性能、功能测试,大大提高了开发效率,减少了研制周期。     

Orientation dependence of structural transition in fcc Al driven under uniaxial compression by atomistic simulations

By molecular dynamics simulations employing an embedded atom method potential,we have investigated structural transformations in single crystal Al caused by uniaxial strain loading along the [001],[011] and [111] directions. We find that the structural transition is strongly dependent on the crystal orientations. The entire structure phase transition only occurs when loading along the [001] direction,and the increased amplitude of temperature for [001] loading is evidently lower than that for other orientations. The morphology evolutions of the structural transition for [011] and [111] loadings are analysed in detail. The results indicate that only 20% of atoms transit to the hcp phase for [011] and [111] loadings,and the appearance of the hcp phase is due to the partial dislocation moving forward on {111} fcc family. For [011] loading,the hcp phase grows to form laminar morphology in four planes,which belong to the {111} fcc family; while for [111] loading,the hcp phase grows into a laminar structure in three planes,which belong to the {111} fcc family except for the (111) plane. In addition,the phase transition is evaluated by using the radial distribution functions.     

吸收式光纤温度传感器的研究

提出了一种利用半导体光吸收谱随温度变化原理设计的半导体吸收式光纤温度传感器.该传感器用GaAs晶片作为温度敏感元件,以光纤作为传光介质,发光二极管作为光源,光电管作为光电转换器件.利用双光束补偿原理,消除了由于光源不稳定产生的干扰.研制出的光纤传感器具有体积小,结构简单,抗电磁干扰,灵敏度高等优点.实验表明:该传感器在－20℃~85℃温度范围内可以达到0.1℃的准确度,可以实现强电磁干扰下的高空飞行器内环境温度的测量.为进一步实现光传飞控系统中的温度测控奠定了基础.