“神龙-I”直线感应加速器束流输运系统设计

系统分析了强流相对论电子束在输运过程中影响束流品质的几种因素,针对束流不同能区凸现的主要矛盾,采取对应性措施以抑制空间电荷效应、束包络振荡和束心横向运动。所有措施归结到束流输运系统设计上表现为合适的束输运半径和匹配磁场的选取,提出了束流输运磁场配置的一般策略,初步设计了“神龙 I”直线感应加速器束流输运系统的总体布局。     

直线感应加速器模拟软件多功能发射模块开发

在模拟直线感应加速器电子束输运过程中,为了正确设置注入器电子束参数,以注发射模型为基础,研发了可设置发射度、能散和电子束倾斜的多功能发射模型。理论研究了发射度、能散以及电子束倾斜角度,并将这些理论实现到发射模块上。建模对多功能发射模块进行测试,比较设定的电子束参数与模拟测定的电子束参数。通过比较,观测到设定电子束参数与模拟测定值一致,验证了多功能模块开发的正确性。     

振幅型复合计算全息模式波前传感理论及验证

全息模式波前传感器是利用复合全息元件对待测波前中像差模式进行直接测量的一种新型波前传感器,其中的复合全息元件可编码设计多阶Zernike像差模式。提出一种有效方案以编码设计振幅型复合计算全息元件,该方案通过将多个编码有某阶Zernike像差模式的透过率调制扭曲光栅叠加产生振幅型计算全息元件。在小像差近似条件下推导了传感器输出信号与Zernike像差模式系数的解析关系。编码设计了振幅型复合全息图,并研究了其对单阶和多阶Zernike像差模式的探测性能。利用液晶光阀加载复合全息图进行了验证实验。所得实验结果与数值模拟结果基本一致。     

气流加热对气动光学效应的影响

以光束穿过三维高速流场为物理模型,研究了由于辐射加热气流对流场的干扰及激光束穿过流场后光束远场的分布。应用二维哈特曼波前测量系统,对高功率光束在风洞高速气流传输中的气动光学效应进行了测量。结果表明,气流未电离情况下,激光与高速气流相互作用对气流的温度、密度等参数影响很小,通过该区域流场的光束波前基本没有变化。     

SOME EXTENDED RESULTS OF “SUBHARMONIC RESONANCE BIFURCATION THEORY OF NONLINEAR MATHIEU EQUATION”

The authors of [1] discussed the subharmonic resonance bifurcation theory of nonlinear Mathieu equation and obtained six bifurcation diagrams in (α,β )-plane. In this paper, we extended the results of[1] and pointed out that there may exist as many as fourteen bifurcation diagrams which are not topologically equivalent to each other.     

自适应光学系统对大气湍流补偿的有效性分析

从伺服控制系统的角度分析了自适应光学系统的闭环噪声、大气湍流引起的误差以及系统的总体误码差,并在此基础上对自适应光学系统的有效性、系统的最佳带宽选取及系统的极限工作能力进行了分析,对已经建立的2.16米望远镜红外自适应光学系统给出了分析结果曲线。     

A detailed study of hydrogen bonded ferroelectric mesogens formed between alkyl and alkyloxy benzoic acids with carbamyl glutamic acid

A new ferroelectric homologous series of hydrogen-bonded ferroelectric liquid crystals is designed and synthesised with 14 compounds comprising two homologous series. The hydrogen bond is formed between dicarboxylic acid, viz. Carbamyl glutamic acid (CGA) with p-n-alkyl/alkyloxy benzoic acids (BA/BAO) and is confirmed by Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR) studies. These two series referred as the CGA+nBAO and the CGA+nBA yields 14 mesogenic homologues and the mesogenic nature is detected by optical textures through polarising microscope which is confirmed through Differential Scanning Calorimetry (DSC). CGA+nBAO series exhibit cholesteric, smectic X*, smectic C* and smectic G* phases while CGA+nBA exhibits cholesteric and smectic G*phases. The enthalpy values of the corresponding temperatures are elucidated. Odd–even effect is evinced at smectic C* to smectic G* phase transition temperatures of CGA+nBAO series. The order of the individual phase transition and thermal stability factor of the phases is also calculated. Optical tilt angle in smectic C* phase is obtained by optical extinction method. Dielectric relaxation and their corresponding frequency shift observed in different ferroelectric phases are measured and a dielectric molecular modelling is presented. Crystallisation kinetic study of smectic G* phase in CGA+nBAO is computed. An interesting phenomenon – ‘Parachromatism’ – is elaborated.     

A modified Langevin-Debye model for investigating the electro-optic behaviour of de Vries smectic liquid crystals

An external electric field applied across a planar-aligned cell in Smectic A* phase of de Vries smectic liquid crystal induces director redistribution over a cone, resulting in a substantial increase in the birefringence and the apparent optical tilt angle. Such an electro-optic response is modelled by Shen et al. [Y. Shen et al., Phys. Rev. E 88, 062504 (2013)], who modified their previous hollow cone with a diffuse cone model by introducing the molecular distribution function limited over a range of tilt angles, that lie in between θ_min and θ_max. The limits in these two tilt angles are assumed to be temperature independent though the tilt angle in between the two values can be temperature dependent. However, the high resolution measurements of birefringence and the layer thickness indicate the presence of temperature dependent diffuse cone angle in SmA* phase.. In the proposed model, we replace θ_min by θ_T, a temperature dependent fitting parameter and the change shows that a better fit of the experimental data to the model is obtained. We determine the temperature dependence of θ_min and show that this angle increases as SmA* to SmC* phase transition temperature is approached.     

The coupling dynamical modeling theory of flexible multibody system

Based on the deformation theory of elastic beams, the coupling effect between the coupling displacements of a point on the middle line of beam and large overall motion is presented. The “coupling matrix library” and Jourdain's variation principle and single direction recursive formulation method are used to establish the general coupling dynamical equations of flexible multibody system. Two typical examples show the coupling effect between coupling displacements and large overall motion on the dynamics of flexible multibody system consisting of beams. The project supported by the National Natural Science Foundation of China (No. 19832040).