Large Scale Simulations of Fusion Plasmas

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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.