Understanding the role of chemical interactions on detached divertors in MAST-Upgrade

位于Culham的MAST升级托卡马克将是一个世界领先的设施，用于研究导流器分离的物理特性，这是一种高密度、低温（Te < 5eV）的状态，被设想为减缓ITER及以后的导流器热流的主要手段。分离分流器中的等离子体条件导致等离子体离子、燃料原子和分子（以及分子离子）之间产生过多的化学反应，这些化学反应可以增强等离子体的功率和动量的耗散，但在计算模型中捕捉这些相互作用提出了严峻的挑战。例如，化学反应物质的传输，如分子离子，被认为在核聚变界的最新代码中是不存在的，需要解决。该项目旨在对MAST-U进行计算和实验研究，以表征发生的化学相互作用和化学反应物质在导流剂中的传输，包括导流剂固有的H， D和C，以及外部杂质，如N2。光谱诊断和模型的结合将用于识别在转向器中发生的主要化学反应，并使用合成诊断来辅助数据解释。该项目的目的是测试并在必要时升级模型代码中使用的等离子体化学模型，以提高与实验观察的一致性及其预测能力。希望对球形托卡马克的排气区提供更多的了解，以便在未来的原型装置中使用。在这个博士学位的过程中，我将学习如何使用现有的代码来模拟复杂的等离子体化学，了解如何解释实验数据。我还将获得科学写作、公开演讲和网络方面的技能。

The MAST Upgrade tokamak in Culham will be a world-leading facility to study the physics of divertor detachment, a high density, low temperature (Te < 5eV) regime which is envisaged to be the primary means of moderating divertor heat fluxes in ITER and beyond. The plasma conditions in detached divertors give rise to a plethora of chemical reactions between plasma ions, fuel atoms and molecules (and molecular ions) that can enhance the dissipation of power and momentum from the plasma but presents a serious challenge to capture these interactions in computational models. For example, the transport of chemically reactive species, such as molecular ions, is assumed to be non-existent in state-of-the-art codes in the fusion community, and needs to be addressed.This project aims to perform computational and experimental research on MAST-U to characterise the chemical interactions that take place and the transport of chemically reactive species in the divertor, including H, D & C intrinsic to the divertor, and extrinsic impurities such as N2. A combination of spectroscopic diagnostics and models will be applied to identify the dominant chemical reactions taking place in the divertor, with synthetic diagnostics to aid data interpretation. The aim of this project is to test, and if necessary upgrade, the plasma chemistry models used in modelling codes to improve agreement with experimental observations and their predictive capability. In hopes of providing additional understanding of the exhaust region of spherical tokamaks for use in future prototype devices.During the course of this PhD I will learn how to model complex plasma chemistries using existing codes, understand how to interpret experimental data. I will also gain skills in scientific writing, public speaking and networking.