Study of Statistical Dynamic properties of Strongly Coupled Dusty Plasmas using Molecular Dynamics Simulations

利用分子动力学模拟研究强耦合尘埃等离子体的统计动态特性

• 批准号: 13680556
• 负责人: HAMAGUCHI Satoshi
• 金额: $ 2.62万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13680556/
• 关键词: dust plasma; Yukawa system; strongly coupled plasma; Coulomb crystal; particulate; generalized hydrodynamics; transport coefficient; dynamics correlation

Particulates in plasmas are normally negatively charged in thermal equilibrium since the mobility of electrons is much higher than that of ions. Such charged particulates (I.e., dust particles) are commonly observed in plasmas in both nature and man-made devices. If the dust number density is sufficiently high and the kinetic energy per particle is less than the interparticle potential energy, the system is called to be in strongly coupled state. In this research project, under various coupling conditions, we have investigated dynamical properties (such as waves, diffusion, dissipation, fluctuations, etc.) for collective motions of plasmadust systems, using molecular dynamics (MD) simulations, in order to clarify properties of the system in the light of statistical dynamics. In 2001, we evaluated dynamical stress correlation functions of the Yukawa system, using MD simulations, and calculated shear viscosity of the system in the wide range of coupling parameters, using Green-Kubo formula. Since transport coefficients of the system are generally non-local in space and time under strongly coupled conditions, one may approximately express such coefficients with memory functions. In 2002, using MD simulations, we determined the memory function for shear viscosity. Especially if the dependence of memory function on the wave number can be ignored, the macroscopic behavior of the system can be described by the "generalized hydrodynamics (GH) equations". In the present work, we have determined the dependence of coefficients that appear in the GH equations on the thermodynamical parameters (such as the system temperature and screening length of the interparticle potential function) of the Yukawa system. With these results, we are now able to analyze dynamical properties of the Yukawa system under non-equilibrium conditions in the longwave and lowfrequency limit by solving the macroscopic equations

等离子体中的粒子在热平衡状态下通常是带负电荷的，因为电子的迁移率远高于离子的迁移率。这种带电颗粒(即尘埃颗粒)在自然界和人造设备的等离子体中都能常见地观察到。如果尘埃数密度足够高，且每个粒子的动能小于粒子间的势能，则系统称为强耦合状态。在本研究项目中，我们研究了不同耦合条件下的动力学性质(如波动、扩散、耗散、涨落等)。对于等离子体尘埃系统的集体运动，使用分子动力学(MD)模拟，以便根据统计动力学阐明系统的性质。2001年，我们利用分子动力学模拟计算了Yukawa系统的动应力关联函数，并利用Green-Kubo公式计算了该系统在各种耦合参数范围内的剪切粘度。由于在强耦合条件下，系统的输运系数一般在空间和时间上都是非定域的，因此可以用记忆函数来近似表示这种系数。2002年，利用分子动力学模拟，我们确定了剪切粘度的记忆函数。特别是如果可以忽略记忆函数对波数的依赖关系，则系统的宏观行为可以用“广义流体动力学(GH)方程”来描述。在本工作中，我们确定了GH方程中出现的系数对Yukawa系统的热力学参数(如系统温度和粒子间势函数的屏蔽长度)的依赖关系。有了这些结果，我们现在可以通过求解宏观方程来分析长波和低频非平衡条件下Yukawa系统的动力学性质

项目成果

A.Wierling, T.Saigo, S.Hamaguchi: "Dynamic properties of Yukawa plasmas at moderate coupling"Proceedings of the 11th International Workshop on the Physics of Non-Ideal Plasmas. (印刷中). (2003)

A. Wierling、T. Saigo、S. Hamaguchi：“中等耦合下汤川等离子体的动态特性”第 11 届国际非理想等离子体物理学研讨会论文集（2003 年）。

A.Wierling, T.Saigo, S.Hamaguchi: "Dynamic properties of Yukawa plasmas at moderate coupling"Proceedings of the 11th International Workshop on the Physics of Non-Ideal Plasmas. (発表予定). (2003)

A. Wierling、T. Saigo、S. Hamaguchi：“中等耦合下汤川等离子体的动态特性”第 11 届国际非理想等离子体物理学研讨会论文集（即将发表）。

浜口智志: "強結合ダストプラズマ"日本物理学会誌. (2002年掲載予定). (2002)

Satoshi Hamaguchi：“强耦合尘埃等离子体”日本物理学会杂志（预定于 2002 年出版）。

T.Saigo, S.Hamaguchi: "Shear viscosity of strongly coupled Yukawa systems"Physics of Plasmas. 9. 1210-1216 (2002)

T.Saigo，S.Hamaguchi：“强耦合汤川系统的剪切粘度”等离子体物理学。

浜口智志: "強結合ダストプラズマ"プラズマ・核融合学会誌. 78. 313-319 (2002)

Satoshi Hamaguchi：“强耦合尘埃等离子体”等离子体与聚变学会杂志 78. 313-319 (2002)。