基于紫外光谱成像技术的两相体直流电晕放电

电晕放电是治理环境污染物的一种有效手段,使用光电倍增管作为光谱探测设备,以紫外光谱成像技术作为两相体直流电晕放电的研究方法,分析了常见气固两相体的直流电晕放电特性,得到空气和气固两相体颗粒的直流电晕放电光斑亮度和起晕电压不同,这些结论是与颗粒的介电常数有关.     

空间太阳阵二次放电的模拟实验研究

二次放电是造成空间高压大功率太阳阵功率损失的主要原因.通过地面模拟实验研究，确定 了二次放电阈值电压并监测了二次放电脉冲电流，对高压太阳阵二次放电特性及其击穿机理 进行了讨论.结果表明，高压太阳阵工作电压和电池串间电流的提高增加了高压太阳阵发生 二次放电事件的可能性；通过采用特殊的结构设计和在太阳阵电池串之间涂覆RTV胶，可以 有效抑制二次放电事件的发生. 关键词： 高压太阳阵 空间静电放电 二次放电     

高压耦合高功率脉冲磁控溅射的增强放电效应

等离子体源离子注入与沉积技术作为一种可生产高结合力、高致密度涂层的真空镀膜技术,具有广阔的应用前景,尤其适用于高载荷工况下服役的功能涂层制备.该技术中金属等离子体源是关键,而现有的脉冲阴极弧源结构复杂,且由于伴随"金属液滴"而需要增加过滤装置.本文研究了另一种简单结构的金属等离子体源备选一高功率脉冲磁控溅射源(HPPMS)的放电特性,采用等离子体发射光谱仪探索了不同的耦合高压对HPPMS放电靶电流特性和等离子体特性的作用.发现耦合高压对HPPMS放电有明显的促进作用,相同靶电压下的放电强度大幅增加,相对于金属放电,耦合高压对气体放电的促进作用更加明显,但在自溅射为主的高压放电阶段对金属放电的促进作用明显增强.讨论了耦合高压对HPPMS放电的增强机制,发现耦合高压自辉光放电、耦合高压和HPPMS电压构成双向负压形成的空心阴极效应,以及耦合高压鞘层改善的双极扩散效应都对HPPMS放电的增强有明显作用.     

水中高压放电的二次放电现象

通过测量水中铜丝电爆炸的电流、电压波形发现水中高压放电存在着二次放电现象.利用高速摄影拍摄了二次放电过程的高速阴影和高速扫描照片.直观的图象证实了这一奇特的放电现象的存在.比较了二次放电与一次放电的不同并简要分析了原因 关键词： 高压放电 等离子体 高速摄影     

飞行器GNSS接收机静电放电干扰效应分析

针对飞行器全球卫星导航系统接收机易受静电放电干扰的问题,研究了机体表面电晕放电与机务维修火花放电对接收机的干扰效应。分析了静电放电的时频域特征,使用针球电极与高压源组成的模拟器开展了电晕放电对接收机的前门耦合实验,证明了电晕脉冲产生的辐射场对接收机无明显干扰效应。基于人体金属ESD模型开展了火花放电对接收机的干扰效应实验,发现浪涌电流易导致接收机串口转换芯片电位波动,读写程序主循环卡死,应针对串口端进行静电阻抗器防护。     

液体电极上辉光放电丝的运动特性研究

大气压液体电极放电在生物医疗、化学降解、环境保护等众多方面具有广泛的应用前景,引起了研究者的关注.本文利用直流电压激励棒-水电极装置,在6 mm气隙间产生了大气压辉光放电.研究发现,随着电流的增大,放电由锥状转变成柱状,且此过程中水面上放电环的直径先增大后减小.利用高速照相机对放电进行研究,发现锥状放电是由单个放电丝旋转形成的.通过测量放电的伏安特性,表明放电处于正常辉光机理.利用光谱学方法,研究了不同电流下的振动温度、转动温度和谱线强度比I_(391.4)/I_(337.1),发现它们均随电流的增加而增大.根据气体放电理论,分析和解释了放电丝的运动机理,并对水面上放电环直径随电流的变化关系进行了解释.这些结果对于大气压液体电极放电的理论研究和实际应用均具有一定参考价值.     

微型固态特斯拉线圈尖端放电演示仪

微型固态特斯拉线圈尖端放电演示仪以RLC串联谐振为基本原理实现高压放电.振荡信号由555输出,以Mosfet驱动芯片TC4420构建驱动电路,功率电路采用MOS管IRFP460,音频采用电源调制方式.该仪器可以演示尖端放电现象、音乐电弧、荧光灯隔空点亮以及无线传电现象.演示实验装置采用模块化设计,体积小、功率低,既达到了演示效果,又保障了演示实验的安全性.     

棒-板电极下缩比气隙辉光放电相似性的仿真研究

建立了棒-板电极下氩气直流放电的流体模型,利用有限元法对几何位形相似的两个气隙放电过程进行了数值求解.两放电气隙外加电压相同,气隙线性尺寸的比值为10:1,气压分别为1 Torr和10 Torr.仿真得到了两相似气隙的放电的伏安特性曲线以及放电物理量(如电位、电场、电子密度、离子密度、电子温度等)的空间分布.根据气体放电相似性的基本结论,检验了气隙对应物理量之间的数值关系.结果表明:两相似气隙的放电类型为正常辉光放电,对应放电物理量之间存在相似性理论指出的比例关系,且在相同幅值的直流电压作用下,气隙放电的工作点相同.这将为利用气体放电相似性来外推相似气隙的放电特性提供一定的理论依据.     

线型脉冲调制器放电噪声的分析

合肥光源速调管走廊内存在着强电磁辐射噪声,这些噪声来源于氢闸流管的脉冲放电.本文阐述了合肥光源高压脉冲调制器放电电路的组成结构,在此基础上,对速调管调制器的放电噪声的产生进行了分析,并提出了抑制调制器放电噪声的方法.     

基于垂直引线和调制电流的三线环形磁导引

提出了一种在单层原子芯片上实现闭合且导引中心无磁场零点的环形磁导引的新方案. 芯片表面刻蚀的导线结构由同心等距三环线构成, 三环线的电流引线垂直于芯片表面. 加载直流电流后, 这种构型即可在芯片表面附近产生闭合的环形磁导引. 交流调制三环线电流后, 环形磁导引的势能极小值附近不再存在磁场零点且其磁场起伏小. 这种方案可用于基于物质波干涉的原子芯片陀螺仪研究.     

Self-organization of five species in a cyclic competition game

Cyclic competition game models, particularly the “rock–paper–scissors” model, play important roles in exploring the problem of multi-species coexistence in spatially ecological systems. We propose an extended “rock–paper–scissors” game to model cyclic interactions among five species, and find that two of the five can coexistent when biodiversity disappears, which is different from the “rock–paper–scissors” game. As the number of fingers is five, we named the new model the “fingers” game, where the thumb, forefinger, middle finger, ring finger, and little finger cyclically dominate their subsequent species and are dominated by their former species. We investigate the “fingers” model in two ways: direct simulations and nonlinear partial differential equations. An important finding is that the number of species in a cyclic competition game has an influence on the emergence of biodiversity. To be specific, the “rock–paper–scissors” model is in favor of maintaining biodiversity in comparison with the “fingers” model when the variables (population size, reproduction rate, selection rate, and migration rate) are the same. It is also shown that the mobility and reproduction rate can promote or jeopardize biodiversity.     

Contrastive analysis on tone between Putonghua and Taiwan Mandarin

The differences of the pitch and duration of Chinese syllables between Putonghua （PTH） and Taiwan Mandarin （TM） were studied. The speech materials to be used are not only isolated syllables, but also sentences. The results reveal that： For the isolated syllables, T1 and T2 in TM are influenced by Minnan dialect, therefore their pitch are lower than those in PTH. T3 is fall-rise in PTH, while it is fall in TM. Moreover, the syllable duration sequence for different tone is T3〉T2〉T1〉T4 in PTH, while it is T1〉T2〉T3〉T4 in TM. For the syllables in sentences, T2 is mid-rise in PTH, while it is mid-level in TM. And the T3 is longer than T4 but shorter than T1 or T2 in PTH, while it is the shortest in TM. Furthermore the effects of prosodic phrase boundary on duration for different tones are almost the same in PTH, but the lengthening part of T1 or T2 is longer than that of T3 or T4 in TM.     

Experimental study on downstep in Chinese intonation

Downstep in pitch contour of Chinese Putonghua is examined using subtly designed sentences by controlling tone combinations. The results show both automatic and nonautomatic downstep phenomena exist in Chinese. In non-automatic downstep, low tones compress downwards the pitch range of the following syllables. and the main influence of downstep is on topline. Low tone not only lower the topline behind it, but also raise the high tones before it, the effects are compatible with each other. In automatic downstep, the topline of pitch contour in intonational phrase is presented as a linear downtrend, but it differs among speakers due to the effect of personal stress practice. In comparison with downstep phenomenon in other tone or non-tone languages, the downstep ratio in Chinese is not constant, and the domain of downstep is not limited within the adjacent tones.     

Abelian-Higgs phase of SU(2) QCD and glueball energy

It is shown that SU(2) QCD admits an dual Abelian-Higgs phase, with a Higgs vacuum of a type-Ⅱ superconductor. This is done by using a connection decomposition for the gluon field and the random-direction approximation. Using a bag picture with soft wall, we presented a calculational procedure for the glueball energy based on the recent proof for wall-vortices [Nucl. Phys. B 741(2006)1].     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Signal generation in an isotropic medium in scanning electron acoustic microscope

Based on the research in Ref. [5][Materials Science and Engineering, 1989; A122： 57 63], an improved model of heat source is set up, the different modes of Lamb wave in an isotropic sample generated by a chopped electron beam at frequency f are obtained with integral transform and normal function expansion method, and the output signal of PZT coupled at the back surface of the sample is found out. The generation mechanism of SEAM （Scanning Electron Acoustic Microscopy） signal is discussed. It shows that the SEAM is a near field imaging technique with high spatial resolution and its best lateral spatial resolution is about 2√2α （α is the radius of the focused electron beam）. Some of experimental results of SEAM images are presented in the paper and it shows that the spatial resolution of SEAM is better than 0.5 μm and smaller than the thermal diffusion length of the sample. Therefore the character of near field imaging in SEAM is also proved experimentally.     

High efficiency filtering using two-dimensional photonic crystal coupled cavity structures

Transmission spectra of coupled cavity structures (CCSs) in two-dimensional (2D) photonic crystals (PCs) are investigated using a coupled mode theory, and an optical filter based on CCS is proposed. The performance of the filter is investigated using finite-difference time-domain (FDTD) method, and the results show that within a very short coupling distance of about 3λ, where λ is the wavelength of signal in vacuum, the incident signals with different frequencies are separated into different channels with a contrast ratio of 20 dB. The advantages of this kind of filter are small size and easily tunable operation frequencies.