Simulation study of self-organization in plasma

我们与美国、欧洲和澳大利亚的研究人员合作，在不同的空间尺度上研究了“自组织”现象的细节。以下是我们在这个研究项目中取得的一些成功成果。1)为了揭示MHD等离子体中的发电机机制，我们开发了一个新的模拟代码。我们发现旋转等离子体的对流运动通过动能向磁能的转化，形成细胞结构并形成偶极磁场。需要强调的是，磁重联在偶极磁场结构的形成中起着重要的作用。2)我们研究了有限β等离子体在螺旋体系中的结构，发现了以下有趣而重要的自组织过程。即使螺旋等离子体最初是不稳定的，并且由于压力驱动的不稳定性导致结构被破坏，但通过非线性相互作用，有序结构也会重新形成。需要注意的是，当结构形成时，一般会产生熵，即热能。在这种情况下，热能是结构不稳定的原因，同时也导致了有序结构。3)我们开发了一个相当新的开放边界系统的粒子模拟代码。我们发现了“超级”离子声双层，其振幅比普通双层大20倍以上。在本研究中可以指出，当结构被构成时，熵产生率最高，熵排出机制对有序结构的维持起着重要作用。4)我们几乎构建了MHD等离子体自组织过程的一般场景。该情景的一个结论是，结构的形成是间歇性发生的，并根据系统的能量输入方式呈现递归性。除了以上结果，我们还研究了各种自组织过程，如尘埃等离子体中的结构形成，或液体中聚合物的结晶。现在，我们以构建“自组织”的一般理论为目标，继续这一研究。少

We have investigated the detail of "Self-organization" phenomena in various spatial scale in collaboration with the people in U.S., Europe and Australia.The followings are some of the successful results we got in this research project.1) We have developed a new simulation code in order to reveal the dynamo mechanism in MHD plasma.We found that the convection motion of the rotating plasma makes a cell structure and forms a dipole magnetic field through the transformation of the kinetic energy to the magnetic energy.It should be emphasized that the magnetic reconnection plays an important role in the formation of the dipole magnetic field structure.2) We have studied the structure of the finite beta plasma in the helical system and found the following interesting and important self-organization process.Even if the helical plasma is initially unstable and the structure is destroyed due to the pressure driven instability, the ordered structure is formed again through the nonlinear interact … More ion.It should be noticed that when the structure is formed, the entropy, i.e., thermal energy is generally produced.In this case, the thermal energy is the cause of the structure instability, and simultaneously it resulted in the ordered structure.3) We have developed a quite new particle simulation code for an open boundary system.We found the "Super" ion-Acoustic double layr whose amplitude is more than 20 times larger than the regular one.In this study, it can be pointed out that the entropy production rate becomes highest when the structure is made up, and the entropy expulsion mechanism plays an important role in the maintenance of the ordered structure.4) We alomost made up a general scenario of the self-organization process for MHD plasmas.One of the conclusion of this scenario is that the structure formation occurs intermittently and shows the recurrence depending on the way of energy input to the system.Besides above results, we have studied various self-organization processes such as the structure formation in a dusty plasma, or the crystallization of polymer in the liquid.Now, we continue this investigation aiming the construction of the general theory of "Self-organization". Less