Plasma dynamics in the tokamak edge

托卡马克边缘的等离子体动力学

• 批准号: 2889507
• 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: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2889507
• 关键词: Plasma; dynamics; tokamak; edge

Transport in the tokamak edge and scrape-off layer (SOL) plays a crucial role in determining the performance of a magnetic confinement fusion reactor. Turbulence in the edge likely sets the height of the pedestal that forms in high-confinement-mode discharges, and the associated transport sets the heat load to the vessel walls. Plasma dynamics in the edge and SOL are particularly challenging to model and to simulate due to, e.g., the presence of open field lines, neutral particles, extreme changes in magnetic geometry and large-amplitude fluctuations. As part of the ongoing ExCALIBUR/Neptune project, a group of researchers at Oxford - in collaboration with UKAEA colleagues - have created a novel, moment-based drift kinetic code to study the dynamics in the edge and SOL. The fundamental aim of the code is to solve efficiently a self-consistent version of the drift- and/or gyro-kinetic equation, while enabling a straightforward connection to fluid codes in the far SOL and delta-f gyrokinetic codes in the core. To our knowledge, all current codes are either prohibitively expensive for routine physics studies, use a simplified fluid treatment (possibly with a reduction in the number of dimensions considered) or use an inconsistent kinetic treatment. The moment-kinetic approach that we are pursuing should allow for a self-consistent kinetic treatment where required without undue numerical expense. At the moment the code solves only for either parallel dynamics (with or without the moment kinetic approach) or for a homogeneous, helical magnetic field (with only standard drift kinetics). Both versions of the code assume a simplified response for electrons that corresponds to a Boltzmann statistical equilibrium.Our proposal is for a PhD student based at Oxford to carry forward the code development; to continue with more advanced verification, validation and performance benchmarks; and to ultimately use the code to do fundamental physics studies. Key aspects of code development that could be explored include an extension to treat kinetic electrons, addition of collisions amongst charged particles, extension to 3D (non-helical) geometry, treatment of the separatrix region that ties together open and closed field line regions, addition of more sophisticated wall boundary conditions and a scheme for transitioning from drift kinetic to gyrokinetic or fluid models within a single simulation. There are a lot of avenues to explore, and which ones are addressed by the student will depend on the state of the code once the student gets up to speed, what will be seen as the most novel and timely contribution, which provides the most direct path to physics results and the relevance of the targeted physics to reactor design studies.This project falls within the EPSRC "Plasma and Lasers" and "UK Magnetic Fusion Research Programme" research areas.

在Tokamak边缘和刮擦层（SOL）中的运输在确定磁性局限融合反应器的性能中起着至关重要的作用。边缘的湍流可能会设置在高分子模式放电中形成的基座的高度，相关的运输将热负荷设置为容器壁。边缘和SOL中的等离子体动力学对于模型和模拟，例如，由于存在开放线，中性颗粒，磁性几何形状的极端变化和大振幅波动，因此特别具有挑战性。作为正在进行的Excalibur/Neptune项目的一部分，牛津大学的一组研究人员与Ukaea同事合作创建了一种基于瞬间的新型漂移动力学代码，以研究边缘和SOL的动态。该代码的基本目的是有效地解决漂移和/或陀螺仪方程的自洽版本，同时可以直接连接到核心中的远处和delta-f陀螺仪中的流体代码。据我们所知，所有当前的代码要么在常规物理研究中都非常昂贵，要么使用简化的液体处理（可能会减少所考虑的尺寸），要么使用不一致的动力学处理。我们追求的瞬间运动方法应允许在没有过度数值费用的情况下进行自洽动力处理。目前，该代码仅解决平行动力学（有或没有动力动力学方法）或均匀的螺旋磁场（仅具有标准漂移动力学）。该代码的两个版本都假设对电子的简化响应与玻尔兹曼的统计平衡相对应。继续进行更高级的验证，验证和性能基准；并最终使用代码进行基本物理研究。可以探索的代码开发的关键方面包括用于处理动力学电子的扩展，在电荷颗粒之间增加碰撞，扩展到3D（非螺旋）几何形状，处理分隔区域，该区域将开放和封闭的野外线区域连接在一起，添加了更为复杂的墙壁边界条件以及从Kinetic of Grokinetic模型过渡到单个或流动模型中的更精致的墙壁边界条件以及一个单身模型。一旦学生提高速度，学生可以探索很多途径，学生将依赖于代码的状态，这将被视为最新颖，最及时的贡献，这为物理结果提供了最直接的途径，以及针对性物理学的相关性以及反应堆设计与EPSRC“ plasma and LaStma and Laste Fouse”的相关性。