轴向磁场下感应耦合放电模式转换的实验研究

为探究轴向磁场对纯Ar感应耦合等离子体放电模式转换的影响,设计并搭建一整套等离子体产生装置展开实验研究,引入阻抗分析法对放电模式转换进行判断,并得到了朗缪尔探针法的验证。实验发现,当气压为10 Pa时,轴向磁场强度的增加使得E-H和H-E模式转换的阈值功率增大;同时,随着轴向磁场的增强,放电中心区域的电子密度不断降低。初步分析认为,这是由于带电粒子在洛伦兹力作用下做回旋运动,导致高能电子在垂直磁场方向上的碰撞减少,降低了电子密度以及感应耦合效率。进一步分析电子能量概率函数(EEPF)发现,在E模式下,轴向磁场对电子运动的约束作用更加明显,高能电子(>27 eV)所占比例增多,电子能量分布更加均匀。     

棱镜非线性波导耦合光学双稳器件

通过K/Na离子交换方法在掺CdS_xSe_1-x玻璃表面制成单模光波导,采用三种不同的光束耦合方式观测到了棱镜非线性波导耦合本征光学双稳态。     

模拟朗缪尔探针伏安特性的非线性电子负载的设计与样机研制

研发了一套模拟朗缪尔探针伏安特性的非线性电子负载,由载波相移正弦脉宽调制(CPS-SPWM)技术的级联型H桥变流器与双向DC/DC变换器两部分组成.通过对电子负载设计方案开展建模仿真验证及样机初步测试表明,该系统基本达到了预期要求,可用于探针电源相关参数的测试及探针后端电子学系统的联合调试.     

银颗粒对Lu2O3:Eu薄膜光学性质影响

采用溶胶凝胶和提拉法制备了含有银颗粒的Lu2O3:Eu薄膜,利用X射线衍射,吸收光谱,光致发光光谱(PL)及荧光衰减光谱对其进行了表征,结果表明:所得材料在800℃下结晶完好,在发射光谱中观察到了银颗粒导致的Eu3 的发光增强效应,讨论了银颗粒对LU2O3:Eu薄膜发光性质的影响.     

Influence of fluorescence time characteristics on the spatial resolution of CW-stimulated emission depletion microscopy

As one of the most important realizations of stimulated emission depletion(STED) microscopy, the continuouswave(CW) STED system, constructed by using CW lasers as the excitation and STED beams, has been investigated and developed for nearly a decade. However, a theoretical model of the suppression factors in CW STED has not been well established. In this investigation, the factors that affect the spatial resolution of a CW STED system are theoretically and numerically studied. The full-width-at-half-maximum(FWHM) of a CW STED with a doughnut-shaped STED beam is also reanalyzed. It is found that the suppression function is dominated by the ratio of the local STED and excitation beam intensities. In addition, the FWHM is highly sensitive to both the fluorescence rate(inverse of fluoresce lifetime) and the quenching rate, but insensitive to the rate of vibrational relaxation. For comparison, the suppression function in picosecond STED is only determined by the distribution of the STED beam intensity scaled with the saturation intensity. Our model is highly consistent with published experimental data for evaluating the spatial resolution. This investigation is important in guiding the development of new CW STED systems.     

超宽谱透射式的太赫兹波正交偏振转换器

利用CST电磁场仿真软件模拟设计了基于开口谐振环-介质-光栅3层结构的超宽谱透射式的太赫兹波正交偏振转换器件,研究了各层透射系数谱以及结构参量对偏振转换的影响,通过计算结构电场和电流分布分析了器件的工作原理.模拟结果表明:设计的器件实现在0.5~2.7THz频谱内,将入射的y偏振太赫兹光转换成x偏振光,转换效率高达99%.由结构电场分布以及表面电流分布推出,入射的y偏振太赫兹光耦合到开口环上,形成振荡的电偶极子,并辐射出太赫兹波x偏振分量.底部光栅层的作用是透过x偏振分量,并将剩余的y偏振光反射回开口环层,并在开口环层和光栅层间形成法布里-珀罗反射进一步提高偏振转换效率.可通过优化介质层厚度、光栅宽度和阵列周期关键参量来优化器件的转换性能.     

半导体硅的Seebeck系数和电阻率测量

本文介绍了半导体硅的Seebeck系数和电阻率的测量，与Hall系数和电阻率测量实验相对应，从另一个方面了解半导体导电性能的一些特征．由Seebeck系数的正负号确定载流子的类型是P型还是N型．半导体内有两种导电机制：杂质导电和本征导电．在杂质导电区，可以确定晶格散射因子；在本征导电区，可以确定硅的禁带宽度．     

TiN对Co基合金激光熔覆层组织与性能的影响

采用5 kW CO2激光器在低碳钢表面熔覆Co基合金涂层及TiN/Co基合金复合涂层,研究了两种涂层的组织、显微硬度以及滑动磨损性能。结果表明,Co基合金涂层主要组成相为-γCo,-εCo,Cr23C6等,TiN/Co基合金复合涂层组成相为-γCo,-εCo,Cr23C6,TiN和TiC等。Co基合金涂层由发达的-γCo枝晶和其间共晶组织所组成,TiN/Co基合金涂层典型组织为等轴固溶体以及细小的共晶组织。TiN对熔覆层的组织有显著的改善作用,促使其组织细化,树枝晶向等轴晶转化,同时可显著提高Co基合金涂层的显微硬度及耐磨性能。     

Piezoelectric effects and electronic structures of InAs/GaAs quantum dots grown along (111) and (011) directions

Piezoelectric effects and electronic structures of InAs/GaAs quantum dots grown along (111) and (011) directions are investigated in this paper. The finite element method is used. Electronic energy levels are calculated by solving the three-dimensional effective mass Schr?dinger equation including a strain modified confinement potential and piezoelectric effects. The difference in electronic structure between quantum dots grown along the (111) direction and the (011) direction are compared. The cubic and truncated pyramidal shaped quantum dots are adopted.     

Y2(Fe1-x-y,Coy,Crx)17化合 物的结构及居里温度

通过x射线衍射及磁测量手段研究了Y₂(Fe_1-y-x,Co_y,C r_x)₁₇化合物的结 构及居里温度.研究结果表明Y₂(Fe_1-y-x,Co_y,Crx)₁₇化合物具有六 角相的Th₂Ni₁₇型结构.随着x的增加，Y₂(Fe 关键词： 2(Fe_1-y-x')" href="#">Y₂(Fe_1-y-x y')" href="#">Co_y x)_{1 7}化合物')" href="#">Cr_x)_{1 7}化合物 x射线衍射 居里温度