部分相干光在大气湍流中的到达角起伏

研究了部分相干高斯谢尔光束在大气湍流中的到达角起伏.主要采用湍流内外尺度的修正Von Karmon谱模型及广义惠更斯-菲涅尔原理和交叉谱密度函数推导出了部分相干光在大气湍流中的到达角起伏表达式.对比分析了湍流内外尺度、湍流强度、传输距离、源相干参数以及波长等参数对部分相干光在大气湍流水平路径上传输时的到达角起伏的影响.结果表明:随着传输距离的增加,到达角起伏越来越小;随着大气湍流内外尺度和源相干参数的增加,到达角起伏也越来越大;与部分相干光相比,完全相干光的到达角起伏受湍流影响很小;随着波长和湍流强度的减小,到达角起伏越来越小.     

含有AlGaAs插入层的InAs/GaAs三色量子点红外探测器

本文报道了采用分子束外延技术制备的三色InAs/GaAs量子点红外探测器. 器件采用nin型结构, 吸收区结构是在InGaAs量子阱中生长含有AlGaAs插入层的InAs量子点, 器件在77 K下的红外光电流谱有三个峰值: 6.3, 10.2和11 μm. 文中分析了它们的跃迁机制, 并且分别进行了指认. 因为有源区采用了不对称结构, 所以器件在外加偏压正负方向不同时, 光电流谱峰值的强度存在一些差异. 不论在正偏压或者负偏压下, 当偏压达到较高值, 再进一步增大偏压时, 都出现了对应于连续态的跃迁峰强度明显下降的现象, 这是由量子点基态与阱外连续态的波函数交叠随着偏压进一步增大而迅速减小导致的.     

Laser R2PI spectroscopic and mass spectrometric studies of chiral neurotransmitters

One color, mass selected resonant two-photon ionization (1cR2PI) spectra of supersonically expanded bare neurotransmitter, (1S,2S)-(+)-N-methyl pseudoephedrine (MPE), and its complexes with chiral and achiral molecules have been investigated. The excitation spectrum of bare MPE has been analyzed and discussed on the basis of theoretical predictions at the B3LYP/6-31G** level of theory. The results allowed to get information on the possible conformers of MPE molecule and on the intermolecular forces on its cluster formed with a variety of solvent molecules, including chiral alcohols, lactates and water. Further information on intermolecular interactions have been obtained with ESI-CID-MS² technique, applied to chiral biomolecules linked through a metal ion to the neurotransmitter. The experimental results are compared with theoretical predictions.     

Study of the temperature rise induced by a focusing transducer with a wide aperture angle on biological tissue containing ribs

We used the spheroidal beam equation to calculate the sound field created by focusing a transducer with a wide aperture angle to obtain the heat deposition, and then we used the Pennes bioheat equation to calculate the temperature field in biological tissue with ribs and to ascertain the effects of rib parameters on the temperature field. The results show that the location and the gap width between the ribs have a great influence on the axial and radial temperature rise of multilayer biological tissue. With a decreasing gap width, the location of the maximum temperature rise moves forward; as the ribs are closer to the transducer surface, the sound energy that passes through the gap between the ribs at the focus decreases,the maximum temperature rise decreases, and the location of the maximum temperature rise moves forward with the ribs.     

高功率离子束在漂移管中的中性化传输

 介绍了“闪光二号”加速器产生的高功率离子束在漂移管中的传输实验。对比了采用中性化措施前后的传输情况，分析了中性化措施对离子束束斑半径、束流均匀性的影响。根据实测的二极管电压模拟得到了传输一定距离后的束流波形，与实测结果符合较好。采取适当的中性化措施后，高功率离子束可以有效传输80 cm以上，束流发散得到抑制，束流均匀性得到改善。     

应用数据挖掘的束流状态描述建模

聚类分析是描述数据群体特征的有效方法.然而,随着挖掘数据库规模的增大,评分函数极值搜索是计算复杂度很高的问题.文中提出了一种新的算法,并将其运用到束流状态描述建模中.试验结果表明,该算法快速有效.同时,重复性是电子储存环的重要指标,聚类模型可作为机器研究和决策的依据,具有指导意义.     

TiO2纳米晶的等离子体改性及光电转换性能的研究

用反应射频溅射法和涂敷法在导电玻璃上制备TiO2薄膜，并用Ar射频等离子体对TiO2薄膜进行处理。按“三明治”结构将TiO2工作电极、Pt／C对电极、0．5MKI 0．05M I2电解液组装成光电池，测量其开路电压和短路电流。结果表明经过Ar射频等离子处理后，溅射法和涂敷法制备的TiO2薄膜组装的光电池的光电流分别提高了约80％和60％。     

BPM-FSRM混合法分析SOI脊形波导与光纤耦合

用束传播-自由空间辐射模（BPM-FSRM）混合法计算了SOI脊形波导和光纤耦合时的透射率, 提出计算反射率的积分公式. 将该混合法和一般FSRM、菲涅尔公式-重叠积分法的计算结果相比较, 提出只有在弱导条件下, 传统的菲涅尔公式法和重叠积分法才可以同时使用.     

诊断中性束加速电源打火检测与保护电路的研究与设计

通过检测打火短路过程中产生较大的di/dt 和du/dt 来实现高压电源的打火短路保护。在研究了中性束加速电源控制和保护特点的基础上, 设计了诊断中性束加速电源在打火短路过程中的di/dt 和du/dt 的检测电路和相应的保护电路, 实现提前对加速器高压电源打火短路的保护。     

Beam-based calibrations of the BPM offset at C-ADS Injector Ⅱ

Beam-based BPM offset calibration was carried out for Injector II at the C-ADS demonstration facility at the Institute of Modern Physics(IMP), Chinese Academy of Science(CAS). By using the steering coils integrated in the quadrupoles, the beam orbit can be effectively adjusted and BPM positions recorded at the Medium Energy Beam Transport of the Injector II Linac. The studies were done with a 2 m A, 2.1 Me V proton beam in pulsed mode.During the studies, the "null comparison method" was applied for the calibration. This method is less sensitive to errors compared with the traditional transmission matrix method. In addition, the quadrupole magnet's center can also be calibrated with this method.