High Efficiency Multi-kW Diode-Side-Pumped Nd：YAG Laser with Reduced Thermal Effect

We demonstrate a high efficiency multi-kW diode-side-pumped Nd：YAG laser. High cooling efficiency of the diode-side-pumped module in the laser is achieved. The middle portion of the Nd：YAG rod in the module is cooled by a coolant jet with screwed side surface, and the end-caps of the rod without screwed side surface are cooled by Au coated on the surface. The thermal effect of the laser rod is reduced, which leads to high output power with high optical-optical conversion efficiency. By using three identical Nd：YAG laser modules, an output power of 4.2 kW and beam quality of 58 mm＆#12539;mrad with an optical-optical efficiency of 35% at 1064 nm is obtained in a laser oscillator. By using four identical Nd：YAG laser modules, an output power of 3.1 kW and beam quality of 17 mm＆#12539;mrad with an optical-optical efficiency of 25.8% is demonstrated in a master oscillator power-amplifier system.     

Phase Transition Behavior of LiCr 0.35 Mn0.65O2 under High Pressure by Electrical Conductivity Measurement

The electrical conductivity of powdered LiCr 0.35 Mn0.65O2 is measured under high pressure up to 26.22 GPa in the temperature range 300-413 K by using a diamond anvil cell. It is found that both conductivity and activation enthalpy change discontinuously at 5.36 GPa and 21.66 GPa. In the pressure range 1.10-5.36 GPa, pressure increases the activation enthalpy and reduces the carrier scattering, which finally leads to the conductivity increase. In the pressure ranges 6.32-21.66 GPa and 22.60-26.22 GPa, the activation enthalpy decreases with pressure increasing, which has a positive contribution to electrical conductivity increase. Two pressure-induced structural phase transitions are found by in-situ x-ray diffraction under high pressure, which results in the discontinuous changes of conductivity and activation enthalpy.     

窄带吸收光谱扫描技术在气体定量检测中的应用

提出一种基于窄带气体吸收光谱扫描技术的气体定量测量系统。利用可调谐光纤滤波器(TOF)输出的窄带光作为探测光,结合波长调制技术,克服不同气体间的交叉敏感,提高了对环境中待测气体测量的选择性。为克服TOF非线性特性对测量结果的影响,提高系统运行稳定性,系统以光纤光栅反射光谱作为参考波长,实现了TOF透射光波长调制范围以及调制中心的稳定控制。为提高系统测试灵敏度,开发了以同步累积器为核心的微弱信号检测电路,实现了系统微弱响应信号的高灵敏度提取。以乙炔气体为实验气体,通过实验证明系统响应与输入乙炔气体浓度之间具有良好的线性关系。当信噪比为3时,系统最低检测限为5×10-6。     

空间调制干涉光谱成像仪的星上定标系统稳定性研究

空间调制干涉光谱成像仪对地物光谱辐射信息以目标像元干涉图的形式进行采集,系统定标后,复原的光谱图能定量地反映地物目标实际对太阳光的漫反射特性。分析了空间调制干涉光谱成像仪的定标原理,经计算推导和实验,介绍了空间调制干涉光谱仪的星上定标系统,并进行了实验室光谱测试和航天元件的多种环境测试,解决了空间调制干涉光谱仪星上定标技术的关键组件定标光源、光谱滤光片、积分球组件的技术难点,对定标卤钨灯进行了辐射稳定性测试,光谱滤光片进行了光学性能测试和粒子辐照试验,星上积分球组件进行了环境力学试验和热真空实验,均得到了较好的结果。通过全孔径、部分视场的相对光谱定标,能够得到星上定标光谱和干涉图,在经过不同条件下复原光谱比较后,证明此星上定标系统是稳定可靠的。     

Excitation Transfer for K2 in High-Lying States by N2

A K-N2 mixture is irradiated in a glass fluorescence cell with pulses of 710hm radiation from an OPO laser, populated K2 （^1∧g） state by two-photon absorption. The cross section for ^1∧g →^3∧g transfer in K2 is determined using molecular fluorescence spectrometry. The cell temperature is kept constant at 553K. The N2 pressure is varied between 40 Pa and 400 Pa. The effects of K2-K collisions could not be neglected. These effects are subtracted out by using the results of the pure K experiment. The cross sections are （3.8 ± 1.5） ×10^-15 cm^2 for K2 （^1∧g） ＋ N2 → K2（^3∧g） ＋N2 and （8.9 ± 3.5） × 10^-15 cm^2 for K2 （^3∧g） collisions with N2.     

沿均匀无限介质中固体杆传播的导波特性研究

针对均匀无限固体介质包围的无限长固体杆,研究了沿固体杆传播的导波的频散和激发特性。在理论分析的基础上,用二分法快速求取了导波所有模式的频散曲线,在4种介质参数下,对斯东利模式和简正模式进行了深入的分析和总结;研究了固体杆中导波的激发强度特性,分别在对称点源、轴向力源和径向力源激励下,研究了导波诸模式的激发机理及频谱特性,分析了不同频段导波的主导模式,研究了主导模式的频响特性及位移径向分布关系。     

一种用于数字助听器的WOLA滤波器组的设计准则

针对WOLA(weighted overlap-add)滤波器组在数字助听器多通道处理中的应用,本文提出了一个满足该领域要求的具体的设计准则。根据这一准则,可用窗函数法进行滤波器设计,并把问题简化为对窗长度的选取。对线性扫频信号和语音信号多通道放大两种情况进行了仿真,结果表明,适当选取窗长度,滤波器组输出信号将符合要求并且无混迭。     

Design and construction progress of BRIF

A new RIB project, the Beijing Radioactive Ion-beam Facility (BRIF), has been running at CIAE since 2004. In this project, a 100 MeV H-cyclotron, CYCIAE-100, is selected as the driving accelerator providing a 75-100 MeV, 200-500 μA proton beam. An ISOL system employs two stage separators to reach the mass resolution of 20000. Its RIB beam will be injected into the existing Tandem and a superconducting booster installed down stream of the Tandem will increase the energy by 2 MeV/q. The progress of BRIF, giving special emphasis to CYCIAE-100, will be introduced in this paper.     

CCl自由基A 2Δ←X 2Ⅱ跃迁REMPI光谱研究

在271～279 nm波长范围内采用REMPI技术研究CCl自由基的A 2Δ光谱.实验观察到12C35Cl以及同位素分子12C37Cl 的A 2Δ←X 2Ⅱ1/2,0-0,1-0和2-1跃迁谱带,其中2-1的跃迁为新观察到谱带.获得了A 2Δ←X 2Ⅱ1/2电子跃迁0-0,1-0,2-1谱带的同位素位移.