脉冲磁化条件下非晶磁芯的损耗特性

基于工频或高频磁化条件下磁芯的测试数据不能准确反映磁芯在单次脉冲磁化下的性能,给出了一种脉冲磁化条件下磁芯性能的测试方法和数据处理方法,实验研究了快脉冲磁化条件下非晶态合金磁芯的损耗特性,磁芯最短饱和时间67 ns,最大磁化速率达到40 T/s。通过数据处理,给出了磁芯损耗与磁化速率的关系曲线,获得了不同磁化速率下磁芯的损耗数据。分析了脉冲磁化条件下涡流损耗和磁滞损耗所占的比例。研究结果表明:脉冲磁化条件下非晶态合金磁芯损耗与磁化速率关系符合饱和波模型,磁芯损耗随磁化速率增大而线性增大。     

高功率固体激光器锥形空间滤波孔应用

锥形空间滤波孔是一种应用于高功率固体激光装置空间滤波的新型结构滤波小孔,其内部光滑的锥形结构可以有效滤除光束中的高频成分且避免等离子堵孔现象的发生。根据神光-Ⅲ主机装置结构特点,设计并加工了适用于主机装置的锥形空间滤波小孔,并开展了应用实验研究。通过与传统的平面结构滤波小孔对比可以看出,锥形小孔有效地避免了等离子体度堵孔现象,在与光束波前补偿技术配合使用条件下,保证光束顺利过孔,并成功实现了基频光7988 J的满能量输出。     

2D parameter optimization of Ne-like Cr x-ray laser on slab

A method of studying a non-equilibrium x-ray laser plasma is developed by extending the existing one-dimensional similarity equations to the case of two-dimensional plasma study in the directions perpendicular to the slab and along a focal line. With this method the characteristics of pre-plasma are optimized for transient neon-like Cr x-ray laser. It is found that when the duration and the intensity of 1.053μm pre-pulse are 1.2ns and 6.5 TW/cm² respectively with a delay time of 1.5ns, the temperature and the temperature discrepancy each approach a proper state, which will provide a uniform distribution of properly ionized neon-like Cr ions before the arrival of pumping pulse.     

Electrical, dielectric and surface wetting properties of multi-walled carbon nanotubes/nylon-6 nanocomposites

This paper reports that the multi-walled carbon nanotubes(MWCNT)/nylon-6 (PA6) nanocomposites with different MWCNT loadingshave been prepared by a simple melt-compounding method. Theelectrical, dielectric, and surface wetting properties of theCNT/PA6 composites have been studied. The temperature dependence ofthe conductivity of the CNT/PA6 composite with 10.0 wt{\%} CNTloading ($\sigma _{\rm RT} \sim 10^{-4}$ S/cm) are measured, andafterwards a charge-energy-limited tunnelling model (ln $\sigma (T)\sim T^{-1/2})$ is found. With increasing CNT weight percentage from0.0 to 10.0 wt%, the dielectric constant of the CNT/PA6composites enhances and the dielectric loss tangent increases twoorders of magnitude. In addition, water contact angles of theCNT/PA6 composites increase and the composites with CNT loadinglarger than 2.0 wt%even become hydrophobic. The obtainedresults indicate that the electrical and surface properties of thecomposites have been significantly enhanced by the embedded carbonnanotubes.     

积分球内的铷原子激光冷却

研究了积分球内激光冷却原理,设计积分球时对积分球的反射率、尺寸及球上开孔大小对于激光冷却的影响进行了讨论. 进行了积分球冷却⁸⁷Rb实验,实验结果表明积分球有效的冷却了球腔中的铷原子,获得了积分球内冷原子的吸收信号以及冷原子随冷却光失谐的变化曲线. 关键词： 漫反射光场 积分球 全光冷却     

大气条件等离子体针处理Enterococcus faecalis菌

自行研制的等离子体针在大气压下通过介质阻挡放电产生的等离子体,再由喷嘴处安装的漏斗形装置聚焦形成针状等离子体. 然后对针状等离子体的基本特性和杀Enterococcus faecalis（E. faecalis）菌进行了研究,E. faecalis菌是一种引起完善充填根管再感染的主要微生物. 当等离子体针功率为5—28?W时,对等离子体的温度进行了测量,表明它不同于其他热杀菌方式. 通过改变等离子体针内电极末端注入的氧气量,发现适当的氧气量,不仅增加等离子体内含氧粒子的浓度而且对等离子体的长度影响也不明显. 实验表明最佳参数为功率15?W,0.1?m³·h^-1氦和2.5%氧气,间距12?mm,处理时间30 s. 为了找出杀菌的关键粒子,进一步比较了大气压下的等离子体针的发射光谱与agar（琼脂）2?mm下的光谱并找出关键粒子. 关键词： 大气压等离子体 介质阻挡放电 E. faecalis菌')" href="#">E. faecalis菌 光谱     

Co掺杂MgF2电子结构和光学特性的第一性原理研究

基于密度泛函理论（DFT）的第一性原理平面波超软赝势方法,计算了Co掺杂MgF₂晶体的几何结构、电子结构和光学性质.结果表明,Co掺杂导致MgF₂晶体结构畸变,可能发生一种类四方和斜方型结构相变.由于Co原子的加入,体系的禁带宽度减小,可观察到半导体—金属性转变.计算也表明,Co掺杂对静态介电常数和光吸收系数有重要调制作用,所得结果与最近实验测量很好相符,揭示了Co:MgF₂体系在光学元器件方面的潜在应用. 关键词： 密度泛函理论（DFT） 第一性原理 超软赝势 2')" href="#">Co掺杂MgF₂     

A finite element model using multi-layered shell element in laser forming

Due to its enormously high flexibility laser forming has been gaining importance in recent years. This rapidness and flexibility demand very precise controlling strategies especially when simulating the process of large plates and challenging the limited computation power of the current workstation. A simple, robust and accurate modeling method of laser forming has been demonstrated to solve this problem. The simplified model is meshed by multi-layered shell element, simulated with a more real scanning method and fewer parameters. The intelligent meshing strategies have reduced the number of elements dramatically. Thus the simulation efficiency has been improved significantly. By comparing the simulation results under the simplified model with the results under the traditional model for laser forming, the applicability of proposed method has been proven. The method of these simplified models is also suitable to simulate complex finite element models, which take much time to simulate. It would throw some light on the thermal mechanically coupled-field simulation of large sheet.     

Diode-pumped Q-switched and mode-locked Nd:Gd0.3Lu0.33Y0.37VO4 laser with EO modulator and single-walled carbon nanotube

By using both the single-walled carbon nanotube saturable absorber (SWCNT-SA) and the electro-optic (EO) modulator, the stably doubly Q-switched and mode-locked (QML) operation of Nd:Gd_0.3Lu_0.33Y_0.37VO₄ laser has been demonstrated. The QML laser characteristics such as the pulse width, single-pulse energy, etc., have been measured for different modulation frequencies of the EO modulator (f_e) and reflectivity (R) of output coupler. In comparison with the solely passively QML laser with SWCNT-SA, the experimental results show that the doubly QML laser can generate more stable and shorter pulses with higher pulse energy. At 9.24 W pump power, f_e=1 kHz and R=93.5%, the doubly QML laser has compressed the Q-switched envelope pulse width 88% and improved the mode-locked pulsed energy 55 times.     

Average capacity for non-Kolmogorov turbulent slant optical links with beam wander corrected and pointing errors

The effects of beam wander corrected and pointing errors on the average capacity of a non-Kolmogorov turbulent atmosphere communication channel are studied. The gamma–gamma irradiance probability density function model has been considered to include the effects of non-Kolmogorov turbulence. An expression for the average capacity under beam wander corrected, pointing errors and the spectral index of refractive-index fluctuation. Simulation results for effects of circular detection aperture of radius, atmosphere turbulence strength and wavelength on average capacity are presented. Our results show that the average capacity has an oscillation in the case of short propagation distance, but in the case of long propagation distance, it has gradually reduced curves. And the turbulence strength has a strong influence on average capacity. In general, turbulence reduces the average capacity; it can reduce average capacity by increasing of the power law α. We can ignore the little effects of wavelength increases on the average capacity.