等离子体中热阴极鞘层的结构

结合热阴极电子发射理论和等离子体鞘层流体方程研究了热阴极附近存在虚阴极结构时的等离子体鞘层问题,采用Sagdeev势的方法讨论了鞘层解和广义Bohm判据.结果表明,不同于普通的Bohm鞘,由于热阴极附近存在大量发射电子,影响整个等离子体鞘层结构,使得进入鞘层的离子临界Mach数不是独立的常数,而是与鞘层电位降等参数有关的物理量.临界Mach数随着鞘层电位降（从鞘边缘到虚阴极）先增大后降低,并且随着热阴极温度的升高单调增大.此外,在平板模型下有相当可观的残余热发射电子越过虚阴极鞘层进入等离子体. 关键词： 鞘层 热阴极发射 Bohm判据     

Na填充型方钴矿化合物CoSb3的高压合成及电输运特性研究

 利用高压合成方法,在压力为2 GPa、温度为900 K的条件下,以NaN₃作为添加剂,成功地合成出了Na填充型的方钴矿化合物CoSb₃。X射线衍射（XRD）研究结果表明,当Na填充量达80%时,合成的Na填充型方钴矿化合物CoSb₃仍为单相方钴矿结构,没有Na和NaN₃等杂质峰。在室温下对不同Na填充量的样品进行了电阻率（ρ）和Seebeck系数（α）的测试,研究了不同Na填充量对样品电阻率、Seebeck系数和功率因子（α²σ）的影响。研究结果表明：室温下,样品的电导率随Na填充量的增加而增大,Seebeck系数的绝对值随Na填充量的增加而减小。当Na填充量为0.4时,样品获得了最高的功率因子（8.72 μW·cm^-1·K^-2）,此值高于He等报道的利用热压法制备的CoSb₃的值。填充量对样品电输运特性的影响规律与Pei等研究的K填充型CoSb₃的研究结果相一致。上述研究结果表明,高压合成技术有利于提高填充型方钴矿化合物的填充量,并有效地提高样品的电输运特性。     

次谐波聚束系统固态放大器相位特性

 为研究BEPCⅡ直线加速器次谐波聚束系统使用的两台固态放大器（20 kW/142.8 MHz,10 kW/571.2 MHz）的相位特性,利用基于现场可编程门阵列(FPGA)的数字测量方法对两台固态放大器的脉内相移和相位稳定度进行了测量。测量系统硬件包括频率综合器、FPGA数字信号处理板和PC;软件部分包括FPGA内部算法、通信及PC端界面程序。该测量系统能真实地反映两台固态放大器的相位特性,为次谐波聚束器的相位补偿提供了参考。     

Investigation on the fabrication of the 3rd harmonic superconducting cavity for the SSRF storage ring

A third harmonic superconducting niobium cavity has been proposed for installation in the Shanghai Synchrotron Radiation Facility （SSRF） storage ring to improve the Touschek lifetime. In order to investigate the feasibility of the superconducting cavity fabrication indigenously and the possibility to master the fabrica tion techniques, cavities were fabricated from copper and niobium sheets by deep drawing and electron-beam welding, and a series of measurements, such as resonant frequency, shape dimensions and wall thickness, were carried out during this process. After analysis of various problems existing in the fabrication process, technique improvements were proposed, and finally the precise shape as designed and resonant frequency within 1.2 MHz were achieved for the new completed cavities. In addition, full annealing was finally proved to be a good cure for niobium sheets＇ tearing up during deep drawing. By fabricating niobium cavities successfully, some problems to the next step were cleared. This paper introduces the process of cavity fabrication and its technique improvements towards forming, and the initial vertical test result of niobium cavity is also presented.     

Octet baryon masses with two-gluon exchange effect

We report our investigation on the octet baryon spectrum in the nonrelativistic quark model by taking into account the two-gluon exchange effect. The calculated octet baryon masses agree better with the experimental data. It is also shown that the two-gluon exchange interactions bring a significant correction to the Gell-Mann-Okubo mass formula.     

A Diode-Side-Pumped Dynamic Fundamental Mode Nd：YAG Laser

A fundamental mode Nd：YAG laser is experimentally demonstrated with a stagger pumped laser module and a special resonator. The rod is pumped symmetrically by staggered bar modules. A dynamic fundamental mode is achieved with the special resonator under different pump levels. A maximal continuous wave output of 61 W （M^2 = 1.4） is achieved with a single rod. An average output of 47 W, pulse width of 54 ns, pulse energy of 4.7 mJ and peak power of 87kW are obtained under the Q-switched operation of 10 kHz.     

小波变换在载频条纹相位分析法中的应用研究

为了克服在非平稳信号分析中傅里叶变换的全局性缺陷,以及窗口傅里叶分析的单一分辨率和伸缩窗口傅里叶分析的尺度不确定性问题,采用伽博解析小波变换技术对空间载频光栅条纹进行相位分析,有效地提取出相对于载频条纹基频的完整相位信息,从本质上解决了上述问题。以三维轮廓术为例,与傅里叶分析进行了对比研究,给出了小波分析应用在空间载频条纹相位分析中详细而完整的理论推导证明、计算机模拟以及实验验证结果。     

含氢添加剂对合成cBN的影响及腔体温度分布

 通过对Li基触媒下立方氮化硼的高温高压合成实验结果的分析,研究了在Li基触媒作为主要触媒及氢化物作为添加剂的环境下,立方氮化硼的生长情况。同时由合成后样品中立方氮化硼的生成区域对V型生长区温度梯度分布进行了分析讨论。     

ICP-AES测定高纯碲中11种杂质元素

电感耦合等离子体原子发射光谱法 (ICP- AES)同时测定高纯碲中 11种杂质元素。用离峰扣背景法消除背景干扰 ,检出限能满足高纯碲中杂质元素的测定要求 ,加标回收率在 94 .0 %— 10 8%之间。     

ICP-AES测定工业用氢氧化钠中Fe、Si、Ca和Mg

电感耦合等离子体-原子发射光谱法(ICP-AES)同时测定了工业用氢氧化钠中Fe、Si、Ca、Mg,探讨了功率对测定结果的影响,用离峰扣背景法消除背景干扰,用基体校正系数消除基体干扰,加标回收率在97.9%—105%之间。