共查询到20条相似文献,搜索用时 125 毫秒
1.
2.
《原子与分子物理学报》2017,(2)
我们测量了激光尾波场加速实验的透射光谱.与之前实验所不同的是,我们所采用的等离子体密度偏高.透射光谱同样呈现出低密度等离子体中光子加速现象的的两个明显特征,光谱加宽和频谱分裂.为了解释该现象,我们利用粒子模拟程序作了模拟计算,计算结果同样证实了高密度等离子体中只要有尾波场激发,同样能产生光子加速现象.利用该现象,为我们优化激光尾波场加速提供了一种新的方法. 相似文献
3.
16.1光电探测中呈现的现象 16.1.1原理和分类为探测光线,我们原则上可以利用光对物质产生的某种效应。本章主要讨论固体因吸收辐射而激发出电子的一些现象,只在最后一节才讨论探测光线时所使用的热辐射效应。在前一卷犷(第4.8.2节)中已经谈到,固体中电子分布在由禁带隔开的能带之中,我们感兴趣的现象系发生在价带、导带以及半无限“带”之间。电子在价带中几乎不动,在导带中非常常活跃,而在半无限“带”中不再被束缚在原固体中。我们称半 相似文献
4.
物质在固态、液态和气态之间的互相变化,是我们在日常生活中时常接触到的一些现象;即使是初中学生,对于这些现象也是此较熟悉的。这在我们的教学上显然就是一个有利的条件。因此,在“物态的变化”这一课题中,如果我们能够结合学生已有的经验,多从演示实验出发来介绍其中的一些基本概念,例如熔 相似文献
5.
6.
7.
本文报道Ti扩散LiNbO_3光波导中四种直角配置的喇曼散射光谱。实验中,我们观测到了在这些配置下异常的喇曼光谱现象。这一现象可归结为光波导中入射光TE/TM模式的变换行为。 相似文献
8.
网球拍效应(TRE)指刚体绕第二惯量主轴旋转时的不稳定现象,它作为生活中常见的现象,在物理教学中常被提及,但有关的定量实验较为缺乏.本文中,我们在约化相空间中给出了TRE的直观解释,并利用COMSOL软件对该现象进行了研究,研究了不同初始条件参数和刚体设置对翻转周期的影响.我们发现“翻转耗时”对初始扰动不敏感,用它代替整个翻转周期可以减少测量和仿真模拟中误差的影响,从而在COMSOL仿真中实现了0.14%的测量误差.此外我们利用手机进行实验,观察到了TRE且定量结果与理论预期一致.本工作有助于学生形成关于TRE的物理图像,有助于TRE的物理教学定量实验设计. 相似文献
9.
10.
11.
Squeezing of the electromagnetic field is investigated in fundamental mode in fourth harmonic generation under a short time approximation based on quantum mechanical approach. The occurrence of squeezing in field amplitude and in higher power amplitude (up to fourth-order) in fundamental mode has been studied. It is found to be dependent on phase of field amplitude of the fundamental mode. The dependence of squeezing on the photon number has also been investigated. It is found that squeezing increases non-linearly. It has also been found that the photon statistics of the field in fundamental mode is sub-Poissonian. The signal to noise ratio has been studied in different order. It is found that signal to noise ratio is higher in lower order. 相似文献
12.
Lead carbonate whiskers were grown by diffusion of ammonium carbonate in the silica gel charged with lead nitrate. It is found that low pH is preferred to the whisker growth. In addition to straight whiskers gently curved whiskers are also found. Curving of whiskers is found to be maximum at high concentration of carbonate ions. Growth kinetics of whiskers are studied by changing the parameters of gel growth. It is found that the parabolic relationship between dimension and growth period is obeyed in this. 相似文献
13.
14.
D.U. Matrasulov U.R. SalomovG.M. Milibaeva N.E. Iskandarov 《Physica D: Nonlinear Phenomena》2011,240(6):470-476
We study nonlinear dynamics of the kicked particle whose motion is confined by square billiard. The kick source is considered as localized at the center of a square with central symmetric spatial distribution. It is found that ensemble averaged energy of the particle diffusively grows as a function of time. This growth is much more extensive than that of kicked rotor energy. It is shown that momentum transfer distribution in a kicked billiard is considerably different than that for kicked free particle. Time-dependence of the ensemble averaged energy for different localizations of the kick source is also explored. It is found that changing of localization does not lead to crucial changes in the time-dependence of the energy. Also, escape and transport of particles are studied by considering a kicked open billiard with one and three holes, respectively. It is found that for the open billiard with one hole the number of (non-interacting) billiard particles decreases according to exponential law. 相似文献
15.
《Journal of magnetism and magnetic materials》2002,241(1):110-117
The propagation of damage in magnetic materials in confined geometries is studied by means of Monte Carlo simulations. It is found that the presence of interfaces between magnetic domains considerably enhances the spatio-temporal spreading of damage. It is found that damage propagation in the direction parallel to an interface is faster than in the perpendicular direction. 相似文献
16.
17.
A nonlinear quintic Schrödinger equation (NLQSE) is developed and studied in detail. It is found that the NLQSE has soliton solutions, the stability of which is analysed using variational method. It is also found that the soliton pulse width in the materials supporting NLQSE is small compared to soliton pulse width of the commonly studied nonlinear cubic Schrödinger equation (NLCSE). 相似文献
18.
19.
本文用非平衡分子动力学方法计算了超晶格材料内部热流的组成和分布,发现在固体中,热能主要是通过分子间作用力做功的方式传递,此方式在固体中的热流传递中占的比率比液体或气体情况下要大,因此可以忽略动能和势能传递项的贡献。超晶格材料的分于动力学模拟显示,它的界面对切向热流有阻碍作用,热流分布比普通的复合材料不均匀。由此导致超晶格材料平面热导率的降低。本文对于探讨和解释超晶格材料的热特性具有指导意义。 相似文献
20.
Role of Ga vacancies in enhancing the leakage current of GaN Schottky barrier ultraviolet photodetectors 下载免费PDF全文
The leakage current of GaN Schottky barrier ultraviolet
photodetectors is investigated. It is found that the photodetectors
adopting undoped GaN instead of lightly Si-doped GaN as an active
layer show a much lower leakage current even when they have a higher
dislocation density. It is also found that the density of Ga
vacancies in undoped GaN is much lower than in Si-doped GaN. The Ga
vacancies may enhance tunneling and reduce effective Schottky
barrier height, leading to an increase of leakage current. It
suggests that when undoped GaN is used as the active layer, it is
necessary to reduce the leakage current of GaN Schottky barrier
ultraviolet photodetector. 相似文献