高功率脉冲离子束的产生

 分析了高功率二极管中的双向流以及提高离子流产生效率的反射三极管、磁绝缘二极管和箍缩二极管工作原理,概述了高功率脉冲离子束研究进展及发展方向。     

“闪光二号”加速器HPIB的产生及应用初步结果

主要给出了“闪光二号”加速器高功率离子束(HPIB)产生及应用研究的初步结果.介绍了强箍缩反射离子束二极管的结构及工作原理，给出了考虑阴阳极产生的等离子体运动对二极管间隙影响的饱和顺位流修正公式.实验得到的离子束峰值能量约500keV，峰值电流约160kA.介绍了利用高功率离子束(质子束)轰击¹⁹F靶产生6—7MeV准单能脉冲γ射线的初步实验结果，给出了利用高功率脉冲离子束模拟1keV黑体辐射x射线对材料的热-力学效应初步研究结果. 关键词： 高功率离子束 箍缩二极管 准单能脉冲γ射线 热-力学效应     

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。     

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。     

真空中聚乙烯膜在纳秒脉冲电压下的沿面闪络特性

 在高功率离子束二极管中，当利用阳极膜沿面闪络产生的等离子体作为离子束引出源时，其特性对产生离子束的大小和品质有着很大的影响，因此要深入研究阳极膜的沿面闪络特性。主要介绍了所研制的一套适用于沿面闪络特性研究的实验装置和测量诊断系统。对离子束二极管中使用的三种厚度聚乙烯薄膜在脉冲电压下的沿面闪络特性进行了实验研究，并对沿面闪络过程中薄膜表面的发光现象作了初步的诊断。     

阴阳极等离子体运动对强箍缩离子束二极管束流特性的影响

 主要研究了阴阳极等离子体运动对“闪光二号”加速器强箍缩离子束二极管束流特性的影响。给出了考虑阴阳极产生的等离子体运动对二极管间隙影响的Child-langmuir流、弱聚焦流、强聚焦流和饱和顺位流4个阶段的离子流和二极管总束流修正公式，利用这些修正公式计算的二极管总束流和离子束流强度与实测结果符合很好，在此基础上分析了提高离子束流强度和效率的方法，通过调整加速器参数，实验得到了峰值能量约500 keV，峰值电流约160 kA的高功率离子束。     

叠片法测量“闪光二号”加速器的高功率离子束能谱

给出了利用叠片法测量“闪光二号”加速器高功率离子束能谱的基本原理及初步实验结果. 采用Ziegler的拟合公式编制程序计算了不同能量质子和碳离子穿过不同厚度Mylar膜后的能 量损失情况.在偏压法拉第筒阵列各个法拉第筒的准直孔前分别覆盖0—6μm厚的Mylar膜， 根据不同膜厚对应的信号衰减情况(叠片法)，得到了高功率离子束的离子能谱，离子的最高 能量>440keV，平均能量约为270keV，能量为200—300keV之间的离子数目最多，碳离子数和 90keV以下的质子所占总离子数的组分不多于32％.所测量离子能谱和离子数目随时间的分布 关系与二极管的电压和电流符合也较好.还将叠片法的测量结果与利用磁谱仪和采用飞行时 间法等的测量结果进行了比较，三种方法所得的测量结果基本一致. 关键词： 高功率离子束 离子能谱 法拉第筒 叠片法 能量损失     

二极管泵浦高能激光研究进展和展望

高能激光广泛应用于材料加工、科学研究、空间碎片清除、军事应用等领域。二极管泵浦高能激光具有结构紧凑,系统简单、全电驱无限弹仓的特点,近年来,各类二极管泵浦高能激光围绕着同时实现高功率、高效率、高光束质量这一总目标发展迅速。详细综述了国内外高平均功率块状固体激光、高功率可见光波段激光、高峰值功率激光、高功率光纤激光、碱金属蒸气激光等二极管泵浦高能激光的研究进展,并对其发展趋势进行了展望。     

强流电子束无箔二极管结构设计与特性研究

 主要叙述高功率二极管的理论模型和结构设计，采用基于引导磁场和相对论近似情况下的空间电荷限制流模型，对磁浸没无箔二极管产生的空心相对论电子束进行了动态数值模拟，研究了二极管几何结构及引导磁场对二极管束流特性的影响。     

高功率二极管激光器失效特性研究

利用统计分析手段,对高功率二极管激光器封装中各工艺环节引起器件失效的原因进行了分析和归类.根据几种失效模式的分析结果,焊接空隙、结短路、腔面退化是引起高功率DL失效的主要模式,针对高功率二极管激光器失效的主要模式,对焊料沉积夹具及焊接工艺参数进行了改进和优化,大大提高了封装工艺水平,使封装的器件成品率由原来的77%提高到了85%以上.     

Characteristics of the distributed Bragg reflector fiber laser sensor for lateral force measurement

Characteristics of the distributed Bragg reflector fiber laser sensor for lateral force measurement are investigated. The distributed Bragg reflector fiber laser operates in dual-polarization modes and converts the lateral force into a corresponding shift in the beat frequency generated by the fiber laser. The sensitivity dependence on the angle between the force direction and the polarization axis orientation of the fiber is investigated theoretically and experimentally. The impact of the force action location and force length on the sensor response is also discussed. Good agreement between the theoretical data and the experimental results was obtained. A maximal sensitivity magnitude of ∼10 GHz/(N/mm) is recorded.     

基于耦合振子模型的摩擦力计算研究

以界面摩擦为研究对象,探讨了基于耦合振子模型(coupled-oscillator model)的滑动摩擦微观机理,分析了滑动过程中的能量耗散问题. 采用Maugis-Dugdal接触模型替代界面摩擦中的Lennard-Jones势能,并将该模型融入耦合振子模型之中,通过计算振子在一个周期内的能量增加值,推导出了界面摩擦力的理论计算公式. 理论分析表明,对于探针-试样接触系统,滑动摩擦力近似随着法向载荷的2/3次方增加,这与纳米摩擦学经典理论是相符的.理论计算结果与超高真空原子力显微镜镀铜探针在Cu(111)晶面扫描实验结果符合良好,表明本文提出的理论和方法可行. 关键词： 耦合振子模型 界面摩擦 摩擦力 法向载荷     

Fluctuation-induced electromagnetic interaction of a moving particle with a plane surface

The most general (nonrelativistic) formulas for the force of attraction to the surface and for the drag of a nonrelativistic atom moving parallel to it, as well as for the lateral and normal forces acting on a moving dipole molecule and on a charged particle (in the case of parallel and perpendicular motion), are derived for the first time in the framework of the fluctuational electromagnetic theory. The dependences of these forces on the velocity, temperature, separation, and dielectric properties of the atom and the surface are derived. The effect of the nondissipative resonance interaction between a moving neutral atom and the field of surface plasmons, as well as the possible emergence of a positive (accelerating) force acting on the atom (nanoprobe), is substantiated theoretically. The role of dynamic fluctuational forces and their possible experimental measurement when using the quartz microbalance technique and an atomic-force microscope (in the dynamic mode), as well as during deceleration of atomic beams in open nanotubes, are considered. The correctness of the obtained results is confirmed by their agreement with most of the available theoretical relations derived by other authors.     

Transverse Vibration and Stability Analysis of Circular Plate Subjected to Follower Force and Thermal Load

Transverse vibration and stability analysis of circular plate subjected to follower force and thermal load are analyzed . B ased on the thin plate theory in involving the variable temperature, the differential equation of transverse vibration for the axisymmetric circular plate subjected to follower force and thermal load is established. Then, the differential equation of vibration and corresponding boundary conditions are discretized by the differential quadrature method. Meanwhile, the generalized eigenvalue under three different boundary conditions are calculated. In this case, the change curve of the first order dimensionless complex frequency of the circular plate subjected to the follower force in the different conditions with the variable temperature coefficient and temperature load is analyzed. The stability and corresponding critical loads of the circular plate subjected to follower force and thermal load with simply supported edge, clamped edge and free edge are discussed. The results provide theoretical basis for improving the dynamic stability of the circular plate.     

Origin of contractile force during cell division of bacteria

When a bacterium divides, its cell wall at the division site grows radially inward like the shutter of a camera and guillotines the cell into two halves. The wall is pulled upon from inside by a polymeric ring, which itself shrinks in radius. The ring is made of an intracellular protein FtsZ (filamenting temperature sensitive Z) and thus is called the Z ring. It is not understood how the Z ring generates the required contractile force. We propose a theoretical model and simulate it to show how the natural curvature of the FtsZ filaments and lateral attraction among them may facilitate force generation.     

Optical levitation by means of two horizontal laser beams: A theoretical and experimental study

Stable optical levitation of transparent solid glass spheres has been demonstrated using two horizontal TEM00 laser beams. The experimental results agree with a theoretical calculation which gives the value of the lateral force pushing the sphere towards the region of maximum light intensity and maintaining it on the axis of the beam.     

变孔径像面散斑平均光强标定随机表面的理论与实验

采用随机表面的高斯相关模型和统计光学原理,推导出弱散射体在4f系统中的像面上光强的表达式.在此基础上提出了均方偏差粗糙度和横向相关长度的标定方法,该方法用理论结果对实验测量的像面散斑平均光强随滤波孔半径的关系曲线进行拟合,同时测量出被测样品表面的两个统计量.实验上制作了高斯相关随机表面样品,对其表面参数进行了测量,与AFM所测结果符合得较好,这表明该方法具有较高的精度. 关键词： 弱散射体 像面散斑 平均光强     

利用光纤光栅在双侧悬臂梁中的啁啾实现对挠度和应力的传感研究

报道一种利用双侧悬臂梁展宽光纤光栅带宽实现对挠度和应力线性传感的新方法,理论研究与实验结果表明,光纤光栅的带宽对挠度及外力均很敏感,并呈线性关系,实验上传感范围超过17nm,传感灵敏度分别达到0．658nm/mm及5．32nm/N。     

Probing quantum-vacuum geometrical effects with cold atoms

The lateral Casimir-Polder force between an atom and a corrugated surface should allow one to study experimentally nontrivial geometrical effects in the electromagnetic quantum vacuum. Here, we derive the theoretical expression of this force in the scattering approach. We show that large corrections to the "proximity force approximation" could be measured using present-day technology with a Bose-Einstein condensate used as a vacuum field sensor.