Formation of Coulomb lattice in a dusty plasma

研究了尘埃粒子在过程和空间等离子体中的结构形成，并进行了数值模拟建模，编制了模拟程序，其中假设尘埃粒子与汤川型相互作用力相互作用。利用此模拟程序，我们证实了库仑晶格的形成，并与以前的模拟工作进行了比较。此外，我们还开发了一个模拟程序，其中介绍了尘埃粒子，正离子和电子的动力学，正离子和电子的尘埃粒子的附件。利用该模拟程序，我们观察到尘埃粒子随时间带负电，库仑晶格随着尘埃粒子负电荷的增加而形成。这对应于实验室等离子体中的库仑晶格形成。然而，这种模拟模型是相当昂贵的，因为粒子，离子和电子之间的相互作用力是直接计算的。因此，我们开发了高性能的尘埃等离子体模拟程序与PPPM（粒子-网格）方法。该方法直接求解了相邻粒子间的相互作用，而远距离粒子间的相互作用则通过空间网格来求解。另一方面，我们还对无碰撞等离子体中重负离子局域产生的等离子体结构进行了PIC（Particle-in-Cell）模拟。我们已经表明，一个负电位结构，这是在负离子产生区域创建，间歇地传播到下游区域的等离子体流。

We have researched structure formation of dust particles in process and space plasmas and made numerical simulation modeling.We made simulation code in which dust particles are assumed to interact with Yukawa type interaction force. Using this simulation code, we have confirmed that the formation of Coulomb lattice and have compared with previous simulation works. Furthermore, we have developed a simulation code in which the dynamics of dust particles, positive ions, and electrons, the attachment of positive ions and electrons to dust particles are introduced. Using this simulation code, we have observed that the dust particles are negatively charged with time and the Coulomb lattice is formed with the increase in negative charge of dust particles. This corresponds to the Coulomb lattice formation in laboratory plasmas. However, this simulation model is quite expensive because the interaction force among particles, ions and electrons are directly calculated. Thus, we have developed high-performance dust plasma simulation code with PPPM (Particle-Particle-Particle-Mesh) method. In this method, the interaction between neighboring particles are directly solved while the interaction between far away particles are solved by using spatial meshes.On the other hand, we have also performed the PIC (Particle-in-Cell) simulation on the formation of plasma structure due to localized generation of heavy negative ions in a collisionless plasma. We have shown that a negative potential structure, which is created in the negative ion production region, propagates intermittently to the downstream region of the plasma flow.