Transport Properties, Pattern Dynamics and Self-Organized States in Magnetized Plasmas

磁化等离子体存在于各种空间和天体物理环境中，并在用于聚变的磁约束装置以及其他技术上重要的装置中发挥重要作用。等离子体通常远离平衡，并且密度、温度和电流的空间不均匀性可以驱动将非线性饱和的小尺度不稳定波，并导致涉及许多自由度的准稳态湍流状态。这些湍流波动可以诱导粒子、能量和动量传输，其通常被称为“异常传输”，以将其与由等离子体带电粒子物种之间的经典库仑碰撞产生的碰撞传输区分开。 在反常输运中，输运过程涉及不同的机制，从扩散到平流，以及湍流或混沌运动情况下的混合。最近，G。Haller提出的拉格朗日拟序结构（LCS）自然地构成了输运动力学的骨架. LCS可以将流动区域划分为宏观区域，在宏观区域内将发生快速混合现象。在LCS的有限时间跨度内，宏观区域不交换流体元素，因此可以充当传输屏障。LCS概念具有广泛的适用性，已开发的分析技术用于海洋表面的污染物迁移、浮游生物大量繁殖的扩散、血液流动、太阳光球流动和大气数据集分析。它只是最近才被引入到等离子体物理和该建议的主要目标之一是充分表征LCS在磁化等离子体中的运输产生于带电粒子漂移的组合在交叉电场和磁场和沿着限制磁场是规则的或随机的。在这项工作中，我们提出了在两个磁化等离子体系统的三维圆柱几何形状的拉格朗日相干结构的调查。第一种由几个相互作用的磁通绳组成，第二种是具有紧密靠近的多个磁化热灯丝的配置。这些系统将首先被建模使用gyrokinetic粒子在细胞模拟与适当的边界条件，使他们可以与测量在线性等离子体设备进行比较。LCS的分析工具将应用于模拟数据，并与大型线性等离子体装置的实验结果进行比较。该项目的一个主要成果将是第一次详细描述的LCS在磁化等离子体中的运输产生ExB漂移和随机磁场。

Magnetized plasmas are present in a variety of space and astrophysical environments and play an important role in magnetic confinement devices for fusion as well as other technologically important devices. Plasmas are generally far from equilibrium and spatial inhomogeneities in the density, temperature and current can drive small-scale unstable waves that will saturate nonlinearly and lead to a quasi-stationary turbulent state involving many degrees of freedom. These turbulent fluctuations can induce particle, energy and momentum transport which is generally termed "anomalous transport" to distinguish it from collisional transport that arises from classical Coulombic collisions among the plasma charged particle species. In anomalous transport there are different mechanisms involved in the transport processes ranging from diffusion to advection and mixing in the case of turbulent or chaotic motions. Recently a new concept in the study of transport processes in complex fluid flows has been introduced by G. Haller, termed Lagrangian Coherent Structures (LCS) and naturally form a skeleton of the transport dynamics. The LCS can separate the flow domain into macro-regions inside which fast mixing phenomena will take place. Over the finite time span of the LCS macro-regions do not exchange fluid elements and thus may act as transport barriers. The LCS concept has wide applicability and the analysis techniques that have been developed were used in pollutant transport on ocean surfaces, spreading of plankton blooms, blood flow, solar photospheric flows and atmospheric dataset analysis. It has only recently been introduced into plasma physics and one of the main objectives of the proposal is to fully characterize the LCS in magnetized plasmas where transport arises from a combination of charged particle drifts in crossed electric and magnetic fields and along confining magnetic field which are regular or stochastic. In this work we propose to investigate Lagrangian Coherent Structures in two magnetized plasma systems in 3D cylindrical geometry. The first consists of several mutually interacting magnetic flux ropes and the second is a configuration with multiple magnetized thermal filaments in close proximity. These systems will be first be modeled using gyrokinetic particle-in-cell simulations with proper boundary conditions so that they can be compared with measurements in a linear plasma device. The tools for analysis of LCS will be applied to the simulation data and compared to results from experiments in a large linear plasma device. A major outcome of this project will be the first detailed characterization of the LCS in magnetized plasma where transport arises from ExB drifts and stochastization of the magnetic field.