宽带高幅驱动静电探针与湍流扰动的传播途径

在KT—5C装置上用高输出能力的宽频带功率源驱动静电探针调制等离子体湍流振动，研究了等离子体边界湍流扰动的传播特性。在实验中用静电探针和磁探针探测到该功率源驱动的扰动沿磁力线传播，得出湍流扰动既可通过静电涨落形式传播，又可通过电磁落落选径传播。     

HL—1装置边缘扰动谱的初步分析

一、引言目前许多实验都已证实托卡马克边缘扰动对等离子体的反常输运有重要的影响,由于扰动而产生的反常粒子输运流大约在玻(王母)扩散量级,而且,边缘扰动的大小、湍流频谱和波数谱的宽度对约束时间的影响很大。用探针对边缘等离子体进行湍流扰动分析已在许多托卡马克实验中进行过,用静电探针得到的电子密度扰动n和悬浮电位扰动,可以估计出扰动产生的粒子输运通量。本文主要给出了一套静电探针系统及其数据获取和频谱分析方法,     

HL-2Aװ�ñ�Ե�Ŷ����Թ۲�

用中平面往复快速扫描6探针组观测HL-2A装置边缘等离子体的扰动特性。在一次放电中能测量到边缘等离子体参数的时空分布及其涨落量，雷诺胁强与极向流和带状流的关系，以及静电涨落驱动的粒子通量和热通量的径向变化。在多发弹丸注入(MPI)和多脉冲超声分子束注入(SMBI)条件下，研究了边缘参数的涨落和相关特性。实验结果表明：SMBI和MPI等注入手段改变了边缘的扰动特性；雷诺胁强的径向梯度可以驱动带状流，抑制湍流输运。     

HL-1M托卡马克边缘参数和雷诺胁强的径向分布

利用多组马赫/郎缪尔探针测量了HL-1M装置刮离层和边缘静电雷诺胁强，等离子体极向旋转，径向和极向电场的径向分布，在低杂波电流驱动，超声分子束注入，多发弹丸注入和中性束注入实验中，给出了雷诺胁强和极向流的关系。结果表明，由于雷诺胁强的径向变化，托卡马克等离子体可以自发地产生剪切极向流。     

HL-2Aƫ����λ�εı�Ե������������

通过中平面活动10探针组、往复快速扫描4探针和低杂波天线口的固定4探针测量了主等离子体边缘的温度、密度、悬浮电位、径向和极向电场、雷诺协强、径向和极向等离子体流速及其径向分布。用偏滤器靶板上的14组嵌入式静电3探针阵列测量了同一环向截面的内外中性化板上的电子温度、密度、悬浮电位及其分布。比较了在孔栏位形和偏滤器位形下边缘等离子体特性的差异,特别是两种位形下边缘温度和密度衰减长度的变化。分析了在多脉冲超声分子束加料和低杂波注入条件下的边界等离子体特性,以及雷诺协强的径向梯度与极向流和径向电场梯度与湍流损失的相互关系。     

HL—1M装置等离子体中类锯齿电子密度振荡

在欧姆放电和低杂波电流驱动（ＬＨＣＤ）及激光吹气注入杂质的联合实验中,首次在ＨＬ－１Ｍ 装置上观测到了与软Ｘ射线对应得非常好的锯齿型密度振荡。这种类锯齿型的密度振荡存在于低杂波电流驱动与激光吹气等离子体中。分析表明,该锯齿不是通常的ｑ ＝ １ 有理面上的锯齿,而是在低杂波与杂质共同作用下产生的类锯齿型的密度振荡。一种可能的机制是低杂波电流驱动下杂质的中心积累及崩塌引起的扰动磁场导致了快电子的损失,从而使得密度发生振荡     

湍流雷诺协强及密度扰动对极向动量输运影响的实验研究

利用静电探针阵列对HL-2A边缘等离子体径向和极向速度进行了测量,获得了最后闭合磁面附近湍流的雷诺协强 以及 和 间相位差的剖面。实验表明,虽然 、 的幅值对雷诺协强的大小会有影响,但雷诺协强的变化趋势主要取决于二者相位差的变化;另一方面,欧姆放电以及不同电子回旋加热功率L模放电条件下的实验结果显示,密度扰动引起的粒子输运所带来的极向动量输运的贡献与雷诺协强项对极向动量输运的贡献是可比的。这表明在分析湍流引起的动量输运时必须考虑粒子输运的贡献。     

HT-7低杂波电流驱动效率与有效电荷数及电子温度的关系

在HT-7超导托卡马克中进行了低杂波电流驱动的功率扫描实验,功率变化范围为100kW至700kW,频率为2.45GHz。研究了等离子体平均有效电荷数及电子温度与低杂波功率之间的关系。给出了不同功率下低杂波电流驱动效率与有效电荷数及电子温度之间的关系:HT-7装置低杂波驱动效率与电子温度成正比,与有效电荷数成反比。指出了动态杂质控制是改善低杂波电流驱动效率的关键问题。     

激光大气传输湍流扰动仿真技术

为了研究激光大气传输时湍流效应对激光应用技术的影响,对湍流扰动的仿真进行了分析。介绍了在实验室内进行激光大气传输湍流扰动研究的数值仿真技术和仿真系统。阐述了快速傅里叶变换（FFT）和Zernike多项式两种湍流扰动数值仿真方法,并且对比了两种方法的优劣。利用物理相位屏搭建了实物湍流仿真系统,介绍了其理论模型并进行了仿真实验,对激光经湍流系统传输后的光强能量分布进行了研究分析。结果显示,室内湍流仿真系统能够准确地模拟弱起伏条件下湍流对激光传输的影响。     

HT-7װ�õ��Ӳ�ǰ��ϵͳ��΢���������

详细介绍了HT-7装置低杂波前级系统的组成、低杂波系统的采集和功率模式控制。实验中通过前级PIN开关控制不同的低杂波输出模式,满足了HT-7装置相应实验对低杂波的要求。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

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.     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

Retrieval of ultraviolet skylight radiances and O3 slant column densities from balloon-borne limb spectrometer

With a novel light-weight and absolutely calibrated ultraviolet （UV） spectrometer, UV skylight radiances and O3 slant column densities are measured by balloon-borne limb measurements in Xinjiang area, China. UV skylight radiances measured at the height of 31 km are compared with the results from Modtran in the wavelength range from 290 to 420 nm. O3 slant column densities are derived from radiance spectra in the Huggins bands （320 - 335 nm） using differential optical absorption spectroscopy method. And the parameter exhibits a good correlation with the same value simulated by radiative transfer model （Tracy）. The O3 profile simultaneously measured by an O3 sonde is used as input in Tracy calculations. The O3 sonde is launched on the same balloon.     

Design optimization of highly sensitive LSPR enhanced surface plasmon resonance biosensors with nanoholes

For breaking through the sensitivity limitation of conventional surface plasmon resonance (SPR) biosensors, novel highly sensitive SPR biosensors with Au nanoparticles and nanogratings enhancement have been proposed recently.But in practice, these structures have obvious disadvantages.In this study, a nanohole based sensitivity enhancement SPR biosensor is proposed and the influence of different structural parameters on the performance is investigated by using rigorous coupled wave analysis (RCWA).Electromagnetic field distributions around the nanohole are also given out to directly explain the performance difference for various structural parameters.The results indicate that significant sensitivity increase is associated with localized surface plasmons (LSPs) excitation mediated by nanoholes.Except to outcome the weakness of other LSP based biosensors, larger resonance angle shift, reflectance amplitude, and sharper SPR curves' width are obtained simultaneously under optimized structural parameters.     

Polymer gratings based on photopolymerization for low-order distributed feedback polymer lasers

Novel polymer distributed feedback(DFB)gratings are fabricated based on photopolymerization to reduce lasing threshold of polymer lasers.A photopolymer formulation sensitive to 355-nm ultraviolet(UV)light is proposed for the fabrication of polymer gratings and it can be used to form polymer films by spin-coating process.A very low surface-relief depth ranging from 12.5 to about 1.0 nm has been demonstrated with a refractive-index modulation of about 0.012.The experimental results indicate that such polymer gratings have promising potentials for the fabrication of low-order DFB organic semiconductor lasers.