Large Scale Simulations of Fusion Plasmas

1.建立了惯性约束聚变燃料靶内爆过程中强相互作用等离子体的数值模拟方法。对于这样的等离子体，数值模拟在分析它们的各种性质时是必不可少的。对于具有异构性和接口的系统，由于单个CPU速度的限制，需要大规模的模拟，并且只有通过多个CPU的并行计算才能实现。在本项目中，使用了并行PC集群。对于构成大规模等离子体模拟基础的经典离子体系，我们发展了恒温恒压或恒容分子动力学。我们将该方法应用于Yukawa体系和Yukawa混合物--通过电子屏蔽的库仑势相互作用的离子体系，得到了它们在外场中的相图。我们还实现了对大规模库仑系统非常有效的快速多极子方法的代码。因此，我们能够模拟超过100000个粒子。对于包括电子在内的等离子体的量子模拟，我们应用了密度泛函分子动力学。在这种方法中，电子密度是一个动态变量，可以进行大规模的量子模拟。我们已经分析了液态金属领域中的氢等离子体，并表明用1000个电子的量子模拟是负担得起的。当我们从高密度靠近压力电离线时，我们通过可视化电子的分布，清楚地观察到离子的电离度的降低和电子屏蔽性的增加。我们还发展了从头算分子动力学。比较密度泛函分子动力学和密度泛函分子动力学的结果，指导后者的应用。

1. Methods of numerical simulations have been developed for strongly interacting plasmas realized in the process of implosion of fuel targets in the inertial confinement fusion. For such plasmas, numerical simulations are indispensable in analyzing their various properties.2. For systems with inhomogeneity and interfaces, large scale simulations are required and are possible only by the parallel computation with many CPUs due to limitations on the speed of a single CPU.In this project, a parallel PC cluster has been used.3. For the classical ion system which forms the basis of the large scale simulations of plasmas, we have developed the constant temperature and constant-pressure or constant-volume molecular dynamics. We have applied the method to the Yukawa system and the Yukawa mixture, the system of ions interacting via the Coulomb potential screened by electrons, and obtained their phase diagram in external fields. We have also realized the code for the fast multiploe method which is very efficient for large scale Coulomb systems. As a result, we are able to simulate more than 100000 particles.4. For quantum simulations of plasmas including electrons, we have applied the density functional molecular dynamics. In this method, the electron density is regarded as a dynamic variable and one can perform large scale quantum simulations. We have analyzed the hydrogen plasma in the domain of liquid metal and have shown that quantum simulations with 1000 electrons are affordable. When we approach the line of the pressure ionization from high densities, we observe clearly the decrease of the degree of ionization and the increase of the electronic screening of ions by visualizing the distribution of electrons. We have also developed the ab initio molecular dynamics in. order to compare the results with those of the density functional molecular dynamics and guide the application of the latter.