蒙特卡罗碰撞算法在CHIPIC软件中的数值实现

分析离子源中电子所参与的碰撞,利用电子与其它粒子间的空碰撞模型,研究电子之间的库仑碰撞,采用不同的存储和调用机制研制了两种碰撞模型的蒙特卡罗碰撞处理模块,将数值模块添加到粒子模拟软件CHIPIC中,对离子源JAERI 10A进行模拟验证,通过对模拟结果的分析,表明所设计的三维MCC算法正确.     

碰撞转动传能的量子干涉效应中微分干涉角的研究

转动传能的量子干涉效应在静态池实验中发现,并且已测得积分干涉角．为了得到更多关于穿能的准确信息,应利用分之束进行实验．本文基于一阶含时波恩近似,模拟了利用分子束实验进行量子干涉效应研究的理论模型．此模型采用了Lennard-Jones 相互作用势和直线轨道近似．通过本文建立的模型,研究了影响干涉效应的微分干涉角的因素,并且得到了微分干涉角和碰撞速度、碰撞参数及碰撞伴间的关系．此理论模型对于对于指导分子束实验具有重要的意义．     

跟踪碰撞的图形描述

借碰撞的图形描述法,澄清了碰撞分类中的一些相关问题。     

非对心碰撞与旋转问题

讨论了两小球的非对心碰撞,对碰撞后两小球的旋转问题做了详细的讨论,并给出了计算结果,引入了碰撞角和碰撞临界角的概念。     

颗粒碰撞率的实验研究

本文采用一种新的研究思路,以高速摄像作为手段,结合各种新颖的PTV算法,在毫秒级时间尺度和毫米级空间尺度上(颗粒尺寸)来对颗粒碰撞率做实验研究,对长期以来一直沿用的描述颗粒碰撞率的关系进行检验与修正。通过对实际颗粒碰撞率与颗粒浓度、平均相对速度的关系进行测量研究,发现理论关系与实验存在较大的差别,理论关系较大地高估了碰撞率。指出了需要进一步深入和完善描述颗粒碰撞率的实验规律,这些规律可直接应用于气固两相流动的数值计算与理论分析中。     

电子与H2+离子碰撞中的巴耳末α,β发射

对电子与H₂⁺离子碰撞过程中所产生的激发态进行了实验研究,测得巴耳末α,β发射光谱,研究了激发截面随能量变化的依赖关系,并定性讨论了分解复合机制。 关键词：     

电子与H3^＋离子碰撞中的Balmer α,β,γ发射

最近，我们利用光学多道分析器对电子与Ｈ３＾＋郭子交叉束碰撞诱发的激发态进行了实验研究，观察到了碰撞中的发射光谱和激发通道，测量了激发截面随能量变化的依赖关系，定性讨论了复合分解激发机制问题。     

Ar+17和 Ar+16谱线的电子碰撞展宽

利用修改后伦敦理工大学的UCL扭曲波程序, 本文计算了自由电子与原子或离子的碰撞反应矩阵, 以此得到它的散射矩阵和碰撞强度.利用碰撞强度, 研究电子碰撞对辐射谱线影响.具体地, 以Ar⁺¹⁷和Ar⁺¹⁶的α线和β线为例, 计算了不同电子温度和密度下谱线的展宽和位移.     

也谈完全非弹性碰撞和恢复系数

突破了关于完全非弹性碰撞的一种思维定势,引入了两种赝恢复系数。     

C60+的碰撞解离研究

在复旦大学加速器实验室的30keV同位素分离器上,利用911A离子源对C₆₀⁺与电子碰撞引起解离进行了研究。测量了解离碎片的质量分布,发现碎片以偶数个碳原子形式存在,同时碎片强度呈指数分布。实验结果表明,由电子引起的解离与较高能量(～300keV)的原子碰撞解离有相似之处。 关键词：     

Franck-Hertz实验曲线的统计解释

用电子数按能量的分布解释Ｆ－Ｈ实验曲线极大值和极小值的形成原因     

悬线式二维碰撞实验

提出用长摆线单摆实现在准水平面内的无摩擦运动,用摄像头记录二维碰撞过程,设计了检验二维碰撞中动量守恒和机械能守恒的教学实验.     

Comparisons between statistics of low energy collision cascades generated by full molecular dynamics and by its binary collision approximation

Abstract

Collision cascades in Cu, Au and Cu₃Au are generated by full molecular dynamics (MD) and by its binary collision approximation (BCA) with the Marlowe program. Cu and Au primaries have 1 keV initial energy.

The same Molière repulsive potential is used in both models for close encounters. In the MD model, this potential is carefully splined to the pair component of the N-body potential developed by Ackland and Vitek. In the BCA, this N-body interaction is roughly modeled by a constant isotropic 4 eV binding energy of the target atoms to their rest positions.

Time distributions of the number of atoms moving with a total energy higher than a threshold value E _d are compared and discussed. Recoil range distributions during the cascade development are discussed as well. The agreement between MD and BCA is fairly good in all cases for E _d larger than about 3 eV. In the case of smaller E _d-values, the BCA may result in an overestimate of the number of moving atoms in the late development of the cascades. This discrepancy is suggested to originate in the lack of attractive forces between the moving particles and the surrounding atoms in the BCA.     

激光感生碰撞能量转移实验

首次观察到Eu(6s6p)^P9/2至Sr(5s10s)^1So、准稳态翼为紫翼的激光感生碰撞能量转移实验现象,其荧光波长为458.42nm,峰值转移激光波长为459.75nm,并对其激发函数谱随温度和随转移激光能量改变进行实验研究,测量了激光感生碰撞能量转移谱的截面,证实了激光感生碰撞能量转移谱为非对称谱。     

A Modeling Study on Particle Dispersion in Wall-Bounded Turbulent Flows

Three physical mechanisms which may affect dispersion of particle's motion in wall-bounded turbulent flows, including the effects of turbulence, wall roughness in particle-wall collisions, and inter-particle collisions, are numerically investigated in this study. Parametric studies with different wall roughness extents and with different mass loading ratios of particles are performed in fully developed channel flows with the Eulerian-Lagrangian approach. A low-Reynolds-number $k-\epsilon$ turbulence model is applied for the solution of the carrier-flow field, while the deterministic Lagrangian method together with binary-collision hard-sphere model is applied for the solution of particle motion. It is shown that the mechanism of inter-particle collisions should be taken into account in the modeling except for the flows laden with sufficiently low mass loading ratios of particles. Influences of wall roughness on particle dispersion due to particle-wall collisions are found to be considerable in the bounded particle-laden flow. Since the investigated particles are associated with large Stokes numbers, i.e., larger than $\mathcal{O}(1)$, in the test problem, the effects of turbulence on particle dispersion are much less considerable, as expected, in comparison with another two physical mechanisms investigated in the study.     

变形核强阻尼碰撞中巨复合体系的形成和衰变

利用改进的量子分子动力学（ImQMD）模型研究了质心系入射能量为980 MeV时变形核238U+238U体系的3种不同碰撞模式（腹对腹、 尖对腹和尖对尖）下强阻尼反应过程中初级超重碎块的产生几率和复合体系的寿命、 形状和拉长取向等性质, 发现尖对腹碰撞模式有利于初级超重碎块的产生, 还发现这种碰撞模式产生的复合体系有最长的寿命。Three different collision modes ( Belly belly, Belly tip and Tip tip) of the deformed uranium nucleus 238U bombarding the deformed 238U in strongly damped reaction at the incident energy 980 MeV has been investigated based on the improved quantum molecular dynamics (ImQMD) model. The formation and properties of the formed composite system during the reaction process were carefully studied including the lifetime, the shape configuration and the angular distribution of primary fragment. It was found that the Belly tip mode is suitable for producing the super heavy fragments, and the composite system has the longest lifetime in this mode.