Non-equilibrium plasma physics near criticality: phase-space cascades, wave-flow interactions, edge-of-chaos structures and turbulent transport

接近临界的非平衡等离子体物理：相空间级联、波流相互作用、混沌边缘结构和湍流传输

• 批准号: 2117056
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2117056
• 关键词: Non; equilibrium; plasma; physics; near

The question of how large a temperature difference can be maintained between the core and the edge of the plasma in a fusion machine opens a window onto some of the most fundamental theoretical questions about the structure of nonlinear, non-equilibrium states in magnetised plasma. These questions revolve around the ways in which free energy extracted from macroscopic inhomogeneities of the system (in the case of a fusion plasma, from the background temperature gradient) in the form of electromagnetic fluctuations is distributed in phase space (particles' positions and momenta) so as to give rise to a chaotic, multiscale (=turbulent) state that accommodates a steady flow of energy from macro to micro scales and its return to its inevitable resting place in the form of the thermal motion of the particles. This distribution of energy is then what determines how the turbulent plasma transports heat and momentum. This project's aim is to follow up on a number of recent developments in our understanding of these phenomena and investigate: the implications of the nonlinear suppression of energy flows into phase space [1,2] for transport models; the delicate balance between a chaotic field of plasma excitations ("drift waves") and self-generated regular "zonal" flows [3] that maintains the nonlinear state of a plasma near the critical threshold separating the turbulent and quiescent phases; the emergence of persistent coherent structures at this so-called "edge of chaos" [4] --- and how all this fits together and conspires to set limits on the background gradients. The project will have analytical, numerical and possibly experimental [5] components, depending on rate of progress and student's inclinations.1. A. A. Schekochihin et al., J. Plasma Phys. 82, 905820212 (2016)2. T. Adkins & A. A. Schekochihin, J. Plasma Phys. 84, 905840107 (2018)3. G. J. Colyer et al., Plasma Phys. Control. Fusion 59, 055002 (2017)4. F. van Wyk et al., J. Plasma Phys. 82, 905820609 (2016)5. M. F. J. Fox et al., Plasma Phys. Control. Fusion 59, 034002 (2017)

聚变机中等离子体的核心和边缘之间可以维持多大的温差的问题为了解有关磁化等离子体中非线性、非平衡态结构的一些最基本的理论问题打开了一个窗口。这些问题围绕着从系统的宏观不均匀性（在聚变等离子体的情况下，从背景温度梯度）中以电磁波动的形式提取的自由能在相空间（粒子的位置和动量）中的分布方式从而产生混乱的多尺度（=湍流）状态，容纳从宏观到微观尺度的稳定能量流，并以粒子热运动的形式返回到其不可避免的静止位置。这种能量分布决定了湍流等离子体如何传输热量和动量。该项目的目的是跟进我们对这些现象的理解的一些最新进展，并研究： 能量流进入相空间 [1,2] 的非线性抑制对输运模型的影响；等离子体激发的混沌场（“漂移波”）和自生规则“带状”流之间的微妙平衡[3]，使等离子体的非线性状态保持在分离湍流和静止相的临界阈值附近；在这个所谓的“混乱边缘”[4] 处出现了持久的相干结构——以及所有这些如何组合在一起并共同对背景梯度设置限制。该项目将具有分析、数值和可能的实验 [5] 组成部分，具体取决于进度和学生的倾向。1。 A. A. Schekochihin 等人，J. Plasma Phys。 82、905820212（2016）2。 T. Adkins 和 A. A. Schekochihin，J. 等离子体物理学。 84、905840107（2018）3。 G. J. Colyer 等人，等离子体物理学。控制。融合 59, 055002 (2017)4。 F. van Wyk 等人，J. Plasma Phys。 82、905820609（2016）5。 M. F. J. Fox 等人，等离子体物理学。控制。融合 59, 034002 (2017)