采用超连续谱激光的双光束光纤光阱实验

以超连续谱激光器作为捕获光源,首次提出并搭建了超连续谱双光束光纤光阱实验系统,实现了聚苯乙烯微球的捕获和操控。通过改变光纤端面间隔和调整捕获光功率的方式精确控制微球的位置,采用CCD图像分析方法实现了微球位置的精确测量。对微球受限布朗运动下的位置变化进行傅里叶变换,计算得到功率谱,与理论功率谱函数拟合后求出了其光阱刚度。结果表明,捕获光束的功率为28 mW时,光阱刚度达到1.3×10-6N/m,高于相同实验条件下单波长光纤光阱的刚度。与传统采用单色光作为捕获光源的光镊系统不同,超连续谱双光束光阱系统利用其宽谱优势,通过研究被捕获微粒的散射光谱信息可获取其尺寸、折射率等物理特征参数。     

X射线背光成像的实现

为了实现对惯性约束聚变的诊断,获取聚爆过程中高温等离子体X射线能谱信息和内爆靶丸的二维空间分辨信息,利用晶体的布拉格衍射特性设计制作了球面晶体分析器,晶体弯曲半径为125 mm。为了验证球面晶体的空间分辨能力,搭建了背光成像平台进行了背光成像实验,石英球面晶体为衍射核心元件,接收装置IP板得到了Cu靶的二维空间分辨信息,基于石英球面晶体的成像平台得到的空间分辨率约为100 μm。     

Structural evolution study of additions of Sb_2S_3 and CdS into GeS_2 chalcogenide glass by Raman spectroscopy

The structures of pseudo-binary GeS_2–Sb_2S_3, GeS_2–CdS, Sb_2S_3–CdS, and pseudo-ternary GeS_2–Sb_2S_3–CdS chalcogenide systems are systematically investigated by Raman spectroscopy. It is shown that a small number of [S_3Ge–GeS_3]structural units(SUs) and-S-S-/S8 groups exist simultaneously in GeS_2 glass which has a three-dimensional continuous network backbone consisting of cross-linked corner-sharing and edge-sharing [GeS_4] tetrahedra. When Sb_2S_3 is added into GeS_2 glass, the network backbone becomes interconnected [GeS_4] tetrahedra and [SbS_3] pyramids. Moreover, Ge atoms in[S_3Ge–GeS_3] SUs tend to capture S atoms from Sb_2S_3, leading to the formation of [S_2Sb–SbS_2] SUs. When CdS is added into GeS_2 glass, [Cd_4GeS_6] polyhedra are formed, resulting in a strong crystallization tendency. In addition, Ge atoms in[S_3Ge–GeS_3] SUs tend to capture S atoms from CdS, resulting in the dissolution of Ge–Ge bond. Co-melting of Sb_2S_3 or CdS with GeS_2 reduces the viscosity of the melt and improves the homogeneity of the glass. The GeS_2 glass can only dissolve up to 10-mol% CdS without crystallization. In comparison, GeS_2–Sb_2S_3 glasses can dissolve up to 20-mol% CdS,implying that Sb_2S_3 could delay the construction of [Cd_4GeS_6] polyhedron and increase the dissolving amount of CdS in the glass.     

非磁杂质对高Tc超导电性的影响

本文证明了在氧化物高T_c超导体的Anderson晶格模型中,由于序参量是能量的函数,非磁掺杂也具有拆对效应,在稀掺杂情况下,求出了T_c随杂质浓度增加而线性下降的规律,与实验结果相符,文中还计算了掺杂对超导态密度中能隙的影响,结果表明,当非磁掺杂浓度增加时,零温能隙的减小比T_c的下降慢得多,从而在转变为正常态之前可能不出现类似通常BCS超导体磁性掺杂的无能隙区。 关键词：     

声化学的崛起与建议

声学对化学的渗透与影响从八十年代中期起开始有了新的转折,表征声学这一外在特性的边缘学科——声化学或曰超声波化学业已形成。从我们跟踪众多国家的研究工作来看,声化学的迅速发展正从学术上给化学研究开拓新的领域;将从应用上对化学工业产生重大影响;声化学与热化学、光化学等具有等同地位的论点日逐扩大。下面列出声化学崛起的一些重要标志:     

Linewidth of electromagnetically induced transparency under motional averaging in a coated vapor cell

The linewidth of electromagnetically induced transparency(EIT) in a coated Rb vapor cell was studied under a magnetic field gradient.The nonlinear broadening of the EIT linewidth with the magnetic field gradient was observed.It was found that the motional averaging of the field gradient was more pronounced at higher laser intensities and larger beam sizes.In the same regime,there was a small linewidth decrease with the increasing magnetic field gradient.We have established a Monte-Carlo model,which gave results in good qualitative agreement with our experiment.Physics pictures for the above phenomena were also suggested.These results provide an understanding of the EIT linewidth behavior under motional averaging,and should be useful for applications in quantum optics and metrology based on coated vapor cells.     

三氯化氮气体喷射自发分解实验研究

 在气体流动管中对三氯化氮气体喷射自发分解的现象进行了初步实验研究。在一根长80 cm，直径4 cm的圆柱形石英玻璃管中，用喷嘴向气体流动管内喷射NCl₃/He混合气体，观察到了NCl₃喷射分解时的红色火焰。测量了火焰光谱并进行了归属，认为该光谱是Cl₂(B→X)辐射跃迁。NCl­₃的喷射自发分解本质上是激波诱导发生的，即分子的动能转化为分子内能而引起的，生成的Cl原子及NCl₂自由基与NCl₃分子反应，从而得到持续燃烧火焰。实验结果表明了NCl₃自发分解反应可代替放电或燃烧作为Cl原子的来源。     

Monte Carlo studies on the burnup measurement for the high temperature gas cooling reactor

Online fuel pebble burnup measurement in a future high temperature gas cooling reactor is proposed for implementation through a high purity germanium (HPGe) gamma spectrometer. By using KORIGEN software and MCNP Monte Carlo simulations,the single pebble gamma radiations to be recorded in the detector are simulated under different irradiation histories. A specially developed algorithm is applied to analyze the generated spectra to reconstruct the gamma activity of the ¹³⁷Cs monitoring nuclide. It is demonstrated that by taking into account the intense interfering peaks,the ¹³⁷Cs activity in the spent pebbles can be derived with a standard deviation of 3.0%(1σ). The results support the feasibility of utilizing the HPGe spectrometry in the online determination of the pebble burnup in future modular pebble bed reactors.     

智能化掺铒光纤放大器

介绍一种智能化的掺铒光纤放大器(EDFA)技术.基于掺铒光纤的光放大特性与EDFA内外部工作参量(如构成EDFA的元器件参量、泵浦激光参量、输入/输出光信号参量等)的关系,采用智能化处理技术使EDFA能按照外界条件,自动地调整自身工作状态,使之符合应用系统的需要.智能化掺铒光纤放大技术可以使EDFA的应用更灵活,既可用作前置放大,也可用作功率放大或线路放大,同时还带来一些新的特点和优越性能.实验制作的智能化EDFA可以在输入信号小到-40dBm或大到+10dBm即约50dB的宽动态范围内正常工作.     

自发喇曼成像法在线测量流场组分浓度(II)

 介绍了利用自发Raman散射光谱测量低压气流组分绝对浓度的方法，在流动状态下得到了不同压力下的自发喇曼散射光谱，检测最低压力为133帕；对于含N₂氧气流在已知N₂浓度时实时标定检测了O₂的绝对浓度，测量误差小于8%。