共查询到20条相似文献,搜索用时 203 毫秒
1.
为了在无箔二极管电磁PIC模拟中采用与电磁场自洽的空间电荷限制发射模型,对查尔特定律模型、高斯定律模型和一维二极管模型进行了理论分析和实例模拟比较。模拟结果表明,三种模型都能与电磁场自洽并反映外加磁场对发射电流的影响,但高斯定律模型受网格剖分粗细程度的影响较大且容易产生振荡,一维二极管模型在网格参数合理的情况下结果与查尔特定律模型基本接近,但需要求解超越方程,花费时间多。通过对模拟结果进行分析和比较,认为外加磁场对电子发射模型本身的影响很小,在电磁PIC数值模拟中可以不考虑,因此,查尔特定律模型更适合用于无箔二极管的电磁PIC模拟。 相似文献
2.
Dynamics of late-stage phase separation in crystalline solids 总被引:2,自引:0,他引:2
The dynamics of Ostwald ripening in elastically stressed crystalline solids is determined through large-scale numerical simulations. Using the insight provided by the simulations, a theory for the dynamics of late-stage phase separation in elastically anisotropic homogeneous solids is developed. Both the theory and simulations show that for the systems considered elastic stress does not alter the exponent of the temporal power law for the average particle size but does affect the amplitude of the power law in a manner that is only a function of the symmetry of the particle morphology. 相似文献
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D. Kikola W. Peryt Y. M. Sinyukov M. Slodkowski M. Szuba 《Acta Physica Hungarica A》2006,27(2-3):373-378
An effective computer program for three-dimensional relativistic hydrodynamical model has been developed. It implements a new approach to the early hot phase of relativistic heavy-ion collisions. The computer program simulates time-space evolution of nuclear matter in terms of ideal-fluid dynamics. Equations of motions of hydrodynamics are solved making use of finite difference methods. Commonly-used algorithms of numerical relativistic hydrodynamics RHLLE and MUSTA-FORCE have been applied in simulations. To speed-up calculations, parallel processing has been made available for solving hydrodynamical equations. The test results of simulations for 3D, 2D and Bjorken expansion are reported in this paper. As a next step we plan to implement the hadronization algorithm by implementing the continuous particle emission for freeze-out and comparing it with Cooper-Frye formula. 相似文献
5.
D. A. Kulikov N. V. Agudov B. Spagnolo 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,83(2):263-269
We present two Gaussian approximations for the
time-dependent probability density function (PDF) of an overdamped
Brownian particle moving in a tilted periodic potential. We assume
high potential barriers in comparison with the noise intensity. The
accuracy of the proposed approximated expressions for the
time-dependent PDF is checked with numerical simulations of the
Langevin dynamics. We found a quite good agreement between
theoretical and numerical results at all times. 相似文献
6.
Molecular dynamics simulations of mobile particles confined in disordered immobile particles are carried out. Slow dynamics
in random media are characterized by two types of dynamics: Type B dynamics for large mobile particle density and Type A dynamics for small mobile particle density. The crossover from Type A to B dynamics is studied by the mean square displacement and the density correlation function. Our results are qualitatively consistent
with the results of recent numerical and theoretical studies on relevant spatially heterogeneous systems. We also investigate
the effect of random matrix generation on the dynamics of mobile particles in order to examine the reentrant transition predicted
by the recent mode-coupling theory. Our simulations demonstrate that the diffusion of the mobile particles largely depends
on the protocol of the random matrix generation and that the reentrant transition is observed for a particular protocol. 相似文献
7.
P. Vrba 《Czechoslovak Journal of Physics》1995,45(1):65-77
Theoretical analysis and numerical simulations of the Relativistic Electron Beam (REB) generation in a high current diode immersed in an external magnetic field has been done. The calculations have confirmed that the generated beam is homogeneous and monoenergetic in a broad central region. In the case of cylindrical diode the mixing of electron trajectories has been observed only in a narrow periphery beam region. The angle between particle trajectories and external longitudinal magnetic field varies chaotically from 0° to –25°. This phenomenon suppresses the excitation of two stream instability excited by the REB in the plasma column. 相似文献
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Ilyin A. A. Shmirko K. A. Golik S. S. Proschenko D. Yu. 《Russian Physics Journal》2022,64(9):1629-1636
Russian Physics Journal - A numerical model describing the dynamics of plasma particle density upon filamentation of femtosecond emission in air is presented. The simulation results are in good... 相似文献
10.
The dynamics of a compound vesicle (a lipid bilayer membrane enclosing a fluid with a suspended particle) in shear flow is investigated by using both numerical simulations and theoretical analysis. We find that the nonlinear hydrodynamic interaction between the inclusion and the confining membrane gives rise to new features of the vesicle dynamics: The transition from tank treading to tumbling can occur in the absence of any viscosity mismatch, and a vesicle can swing if the enclosed particle is nonspherical. Our results highlight the complex effects of internal cellular structures have on cell dynamics in microcirculatory flows. For example, parasites in malaria-infected erythrocytes increase cytoplasmic viscosity, which leads to increase in blood viscosity. 相似文献
11.
Pisarchik AN Jaimes-Reátegui R Sevilla-Escoboza R Huerta-Cuellar G Taki M 《Physical review letters》2011,107(27):274101
Clear evidence of rogue waves in a multistable system is revealed by experiments with an erbium-doped fiber laser driven by harmonic pump modulation. The mechanism for the rogue wave formation lies in the interplay of stochastic processes with multistable deterministic dynamics. Low-frequency noise applied to a diode pump current induces rare jumps to coexisting subharmonic states with high-amplitude pulses perceived as rogue waves. The probability of these events depends on the noise filtered frequency and grows up when the noise amplitude increases. The probability distribution of spike amplitudes confirms the rogue wave character of the observed phenomenon. The results of numerical simulations are in good agreement with experiments. 相似文献
12.
We propose a simple method to determine the local coupling strength Gamma experimentally, by linking the individual particle dynamics with the local density and crystal structure of a 2D plasma crystal. By measuring particle trajectories with high spatial and temporal resolution we obtain the first maps of Gamma and temperature at individual particle resolution. We employ numerical simulations to test this new method, and discuss the implications to characterize strongly coupled systems. 相似文献
13.
We study a one-dimensional totally asymmetric exclusion process with random particle attachments and detachments in the bulk. The resulting dynamics leads to unexpected stationary regimes for large but finite systems. Such regimes are characterized by a phase coexistence of low and high density regions separated by domain walls. We use a mean-field approach to interpret the numerical results obtained by Monte Carlo simulations, and we predict the phase diagram of this nonconserved dynamics in the thermodynamic limit. 相似文献
14.
The intensity-dependent transmission of picosecond ruby laser pulses of different duration through methanolic and ethanolic solutions of rhodamine B and rhodamine 6G is analysed. The transmission is affected by S0-S
n
two-photon absorption, by stimulated emission at the pump-laser frequency, by amplified spontaneous emission and by excited-state absorption. Various parameters involving the two-photon absorption dynamics are determined by comparing experiments with numerical simulations. 相似文献
15.
We present numerical simulations of fully nonlinear drift wave-zonal flow (DW-ZF) turbulence systems in a nonuniform magnetoplasma. In our model, the drift wave (DW) dynamics is pseudo-three-dimensional (pseudo-3D) and accounts for self-interactions among finite amplitude DWs and their coupling to the two-dimensional (2D) large amplitude zonal flows (ZFs). The dynamics of the 2D ZFs in the presence of the Reynolds stress of the pseudo-3D DWs is governed by the driven Euler equation. Numerical simulations of the fully nonlinear coupled DW-ZF equations reveal that short scale DW turbulence leads to nonlinear saturated dipolar vortices, whereas the ZF sets in spontaneously and is dominated by a monopolar vortex structure. The ZFs are found to suppress the cross-field turbulent particle transport. The present results provide a better model for understanding the coexistence of short and large scale coherent structures, as well as associated subdued cross-field particle transport in magnetically confined fusion plasmas. 相似文献
16.
G. Shirkov 《辐射效应与固体损伤》2013,168(10-12):483-493
17.
A. Benyoussef H. Chakib H. Ez-Zahraouy 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,8(2):275-280
The effect of jumping rate probability on the phase diagram of an asymmetric exclusion model is studied by numerical simulations.
Density, current and velocity of particles are calculated for parallel dynamics. In the open boundaries case for one species
of particles (particles 1), a passage from first to second order transition occurs by decreasing the jumping rate. In the
periodic boundaries case, by introducing another species of particle (particle 2) which plays the role of obstacle for particles
1, the average velocity of particles 1 increases with increasing the jumping rate for small density. While the average velocity
of particle 2 decreases for small and intermediate densities.
Received: 21 October 1997 相似文献
18.
本文给出了无箔二极管物理特性的数值模拟研究结果。研究得到了二极管电流与二极管结构参数、二极管电压以及外加磁场强度等参数的变化关系特性,并且应用这些关系特性得到了在外加磁场强度足够大情况下二极管电流的近似表达为Ib=(7.5/x)(x+(0.81-x)/(1+0.7Ld2/δr))(r2/3-1)3/2,其中Ld为阴阳极间距;Rc为阴极发射端面的外半径;Rp为漂移管管壁半径;x=ln(Rp/Rc),δr =Rp-Rc。这一表达式在大量二极管结构参数和二极管电压参数情况下与数值模拟结果在10%误差范围内相一致,能够比较准确的表达无箔二极管的电流电压关系。 相似文献
19.
提出了一种计算超低泄漏电流硅二极管的单粒子位移损伤电流的方法。采用SRIM软件计算了252Cf源的裂变碎片入射二极管产生的初级撞出原子的分布, 并采用Shockley-Read-Hall复合理论探讨了单粒子位移损伤电流值与缺陷参数的关系, 计算了252Cf源辐照引起的单粒子位移损伤电流台阶值, 计算结果与实验结果一致。针对耗尽区电场非均匀的特点, 提出电场分层近似方法来考虑处于耗尽区中不同位置的初级撞出原子产生的缺陷对泄漏电流的影响。结果表明, PN结附近电场增强载流子产生效应最显著, 考虑电场增强效应的情况下单个Frenkel缺陷引起的泄漏电流比未考虑电场增强效应时高约44倍;裂变碎片80 MeV Nd入射比106 MeV Cd入射引起的单粒子位移损伤电流大;252Cf源的裂变碎片在二极管中引起的单粒子位移损伤电流台阶值主要集中于1 fA至1 pA之间。 相似文献
20.
粒子在 Hénon-Heiles势中的逃逸动力学模拟 总被引:1,自引:1,他引:0
利用庞加莱截面和相空间轨迹方法对粒子在Hénon-Heiles势中的逃逸动力学进行了模拟.粒子的动力学性质敏感地依赖于粒子的能量.数值计算表明当能量很小时,粒子的运动是规则的;随着能量的增加,粒子的运动开始出现混沌.当能量增加到鞍点能Es时,几乎所有的相空间轨迹都是混沌的.当粒子的能量E>Es,粒子可以越过势阱发生逃逸.对于给定的大于Es的能量, 我们画出了粒子的逃逸-时间曲线和逃逸轨迹.我们的研究对于研究混沌传输和逃逸动力学具有一定的参考价值. 相似文献