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

磁化等离子体中的输运特性、模式动力学和自组织态

• 批准号: RGPIN-2019-05234
• 负责人: Sydora, Richard
• 金额: $ 2.48万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=762592
• 关键词: Transport; Properties; Pattern; Dynamics; Self

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.

磁化等离子体存在于各种空间和天体物理环境中，在聚变磁约束装置以及其他技术上重要的装置中发挥着重要作用。等离子体通常远离平衡状态，密度、温度和电流的空间不均匀性可以驱动小规模的不稳定波，这些波将非线性饱和，并导致涉及多个自由度的准稳态湍流状态。这些湍流波动可以引起粒子、能量和动量传输，这通常被称为“反常传输”，以将其与等离子体带电粒子种类之间的经典库仑碰撞产生的碰撞传输区分开来。 在异常传输中，传输过程涉及不同的机制，从扩散到平流，再到湍流或混沌运动情况下的混合。最近，G. Haller 在研究复杂流体流动的输运过程中引入了一个新概念，称为拉格朗日相干结构（LCS），自然地形成了输运动力学的骨架。 LCS 可以将流域分成宏观区域，在宏观区域内将发生快速混合现象。在濒海海域的有限时间跨度内，宏观区域不交换流体元素，因此可能充当运输障碍。 LCS概念具有广泛的适用性，已开发的分析技术可用于海洋表面污染物输送、浮游生物繁殖、血流、太阳光球流和大气数据集分析。它最近才被引入等离子体物理学，该提案的主要目标之一是充分表征磁化等离子体中的 LCS，其中传输是由带电粒子在交叉电场和磁场中以及沿着约束磁场的漂移的组合产生的，这些漂移是规则或随机。在这项工作中，我们建议研究 3D 圆柱几何形状的两个磁化等离子体系统中的拉格朗日相干结构。第一个由多个相互作用的磁通绳组成，第二个是具有多个紧密靠近的磁化热丝的配置。这些系统将首先使用具有适当边界条件的回旋粒子内细胞模拟进行建模，以便可以将它们与线性等离子体装置中的测量进行比较。 LCS 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。该项目的主要成果将是磁化等离子体中 LCS 的首次详细表征，其中传输由 ExB 漂移和磁场随机化产生。