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.

托卡马克边缘和刮削层（SOL）中的输运对磁约束聚变反应堆的性能起着至关重要的作用。在边缘的湍流可能设置的高度的基座，形成在高约束模式放电，和相关的传输设置的热负荷的容器壁。边缘和SOL中的等离子体动力学对于建模和模拟是特别具有挑战性的，这是由于例如，开放磁力线、中性粒子、磁几何形状的极端变化和大幅度波动的存在。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的同事合作，创建了一个新颖的基于力矩的漂移动力学代码，以研究边缘和SOL的动态。该代码的基本目的是有效地解决自洽版本的漂移和/或陀螺动力学方程，同时使一个简单的连接到流体代码的远SOL和delta-f陀螺动力学代码的核心。据我们所知，所有目前的代码都是昂贵的常规物理研究，使用简化的流体处理（可能减少考虑的维度数）或使用不一致的动力学处理。我们所追求的力矩-动力学方法应允许在必要时进行自洽的动力学处理，而不需要过多的数值费用。目前，代码只解决了平行动力学（有或没有矩动力学方法）或均匀，螺旋磁场（只有标准的漂移动力学）。这两个版本的代码都假设了一个简化的电子响应，对应于玻尔兹曼统计平衡。我们的建议是由牛津大学的一名博士生继续开发代码;继续进行更先进的验证，验证和性能基准测试;并最终使用代码进行基础物理研究。可以探索的代码开发的关键方面包括扩展到处理动力学电子，增加带电粒子之间的碰撞，扩展到3D（非螺旋）几何形状，处理将开放和闭合场线区域联系在一起的分界线区域，添加更复杂的壁边界条件以及在单个模拟中从漂移动力学过渡到陀螺动力学或流体模型的方案。有很多途径可以探索，哪些途径由学生解决将取决于代码的状态，一旦学生开始加速，什么将被视为最新颖和最及时的贡献，该项目为物理结果提供了最直接的途径，并为反应堆设计研究提供了目标物理的相关性。该项目福尔斯EPSRC“等离子体和激光”和“英国磁聚变研究计划”的研究领域。