Quantifying, modelling and interpreting edge plasma turbulence in tokamak and stellarator fusion experiments

托卡马克和仿星器聚变实验中边缘等离子体湍流的量化、建模和解释

• 批准号: EP/G02748X/1
• 负责人: Bogdan Hnat
• 金额: $ 56.77万
• 依托单位: University of Warwick
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FG02748X%2F1
• 关键词: Quantifying; modelling; interpreting; edge; plasma

Turbulence in the edge region of magnetically confined plasmas is a central topic in fusion science. Its character helps to determine, and also responds to, the radial profiles of temperature and density which govern the overall confinement properties of the plasma. Together with any magnetohydrodynamic instabilities at the edge, the edge turbulence also determines the outward flux of plasma and energy across the last closed magnetic flux surface, and hence to the divertor or to the first wall. Edge plasma turbulence thus plays an essential role in both the physics of the confined plasma and the associated quasi-engineering constraints such as plasma exhaust and first wall loading. This proposal outlines a systematic study of statistical features of fusion edge plasma turbulence for different plasma regimes and different confinement concepts, namely tokamaks and stellarators. This multi-device study is aligned with the experimental plan to exploit resonant magnetic perturbation mechanisms on the Mega Amp Spherical Tokamak (MAST) at UKAEA, Culham due for commision in 2008. This mechanism generates stochastic magnetic field at the edge region of MAST which is similar to that found in a stellarator. Statistical techniques will allow us to make new direct comparisons between statistical properties of edge plasma in stellarator and a tokamak with, and without, the ergodised magnetic field, building on our existing collaboration with the large Helical Device (LHD) team at National Institute for Fusion Science (NIFS), Japan. This research addresses fundamental issues, such as the extent of universality exhibited by the edge plasma turbulence, quantifying complex turbulent fluctuations with a robust single figures-of-merit and addressing the practical problem of modelling the distribution of radial particle flux in different confinement systems.There are three closely coupled research projects which will address these broad goals. Project 1 will investigate statistical features of transport in the presence of ergodic magnetic field in two different confinement systems, namely MAST spherical tokamak and LHD stellarator. We will address the fundamental role of electromagnetic fluctuations in the evolution of edge plasma turbulence. The project will build on our ongoing collaboration with UKAEA Culham and NIFS, Japan.The second project concerns systematic quantitative characterisation of edge plasma turbulence in MAST. Edge plasma turbulence will be studied under different operating regimes, using the techniques of complex systems science. This high-volume project will require analysis of many datasets in order to build a properly interlinked global picture, which is hitherto lacking. The project will validate the idea that the distribution of large particle flux events can be described with the universal functional form that does not depend on confinement method or plasma parameters. The modelling of the probability density function for the radial fluxes is one of the topical questions in fusion studies. Radial fluxes can be dramatically modified by poloidal zonal flows that interact with edge turbulence. We will use reduced model to quantify the reduction in particle fluxes in reduced turbulence model with zonal flows.The third project is dedicated to the quantitative comparison between the outputs of plasma turbulence simulations and the measurements of plasma turbulence from fusion experiments.This is an underexplored aspect of fusion science; The applicant will use the 2D Hasegawa-Wakatani model and its extension (magnetic field gradient, temperature, zonal flows and magnetic field randomisation will be included), multi-fluid codes and the gyrokinetic code of A. Peeters (CFSA University of Warwick). The reduced model will be extended to 3D drift-Alfven turbulence simulation which will incorporate magnetic effects.

磁约束等离子体边缘区的湍流是聚变科学中的一个中心课题。它的特点有助于确定，也响应，径向分布的温度和密度，管理的整体约束等离子体的属性。与边缘处的任何磁流体动力学不稳定性一起，边缘湍流也决定了穿过最后闭合磁通表面的等离子体和能量的向外通量，并因此决定了到偏滤器或到第一壁的向外通量。因此，边缘等离子体湍流在约束等离子体的物理学和相关的准工程约束，如等离子体排气和第一壁加载中起着至关重要的作用。该建议概述了一个系统的研究统计特性的融合边缘等离子体湍流不同的等离子体制度和不同的约束概念，即托卡马克和仿星器。这多设备的研究是对齐的实验计划，利用共振磁扰动机制的巨型磁球托卡马克（MAST）在英国原子能机构，卡勒姆由于在2008年的委员会。这种机制在MAST的边缘区域产生类似于仿星器的随机磁场。统计技术将使我们能够在仿星器和托卡马克中边缘等离子体的统计特性之间进行新的直接比较，有，没有遍历磁场，建立在我们与日本国家聚变科学研究所（NIFS）的大型螺旋装置（LHD）团队现有的合作基础上。这项研究解决的基本问题，如边缘等离子体湍流所表现出的普遍性的程度，量化复杂的湍流波动与一个强大的单一的数字的优点，并解决实际问题的建模径向粒子通量在不同的约束systems.There的分布密切耦合的研究项目，将解决这些广泛的目标。项目一将研究两种不同约束系统（MAST球形托卡马克和LHD仿星器）中各态历经磁场下输运的统计特征。我们将讨论电磁涨落在边缘等离子体湍流演化中的基本作用。该项目将建立在我们正在进行的合作与英国原子能机构卡勒姆和NIFS，日本。第二个项目涉及系统的定量表征边缘等离子体湍流MAST。将利用复杂系统科学的技术，研究不同工作状态下的边缘等离子体湍流。这一工作量大的项目将需要分析许多数据集，以便建立一个迄今为止缺乏的适当相互关联的全球情况。该项目将验证大粒子通量事件的分布可以用不依赖于约束方法或等离子体参数的通用函数形式来描述的想法。径向通量概率密度函数的建模是聚变研究中的热点问题之一。与边缘湍流相互作用的极向纬向流可以显著地改变径向通量。我们将使用简化模型来量化简化湍流模型中的粒子通量的减少，第三个项目致力于等离子体湍流模拟的输出与聚变实验中等离子体湍流测量结果之间的定量比较，这是聚变科学中一个尚未探索的方面;申请人将使用2D Hasegawa-Wakatani模型及其扩展（将包括磁场梯度、温度、带状流和磁场随机化）、多流体代码和A.彼得斯（CFSA沃里克大学）。简化后的模型将扩展到三维漂移阿尔芬湍流模拟，其中将包括磁效应。