MODELLING DUST FORMATION IN A FUSION DEVICE

在聚变反应堆中，燃料（氢同位素）被加热到等离子体状态，必须通过极端磁场进行限制。然而，约束损失使反应堆壁暴露在等离子体载荷下，从而导致损伤和尘埃颗粒。尘埃的形成是聚变反应堆性能和安全的主要问题。灰尘中含有大量的氢，这会影响反应堆的效率，失去燃料，如果它从墙壁上逃逸，会造成潜在的辐射危害。此外，由于其高化学反应性，在冷却剂或水意外损失的情况下，它可能导致爆炸和容器损坏。虽然粉尘形成的几种形成机制是众所周知的，例如1）沉积膜部分的断裂和分层，以及2）熔融金属的固化液滴的再流动由于等离子体破裂，更全面的了解是必要的，未来聚变装置的材料选择。在这个项目中，我们的目标是开发一个有限元模型，能够模拟和预测的断裂和分层的沉积层和分层的再沉积颗粒。该模型将使用从等离子体的热负荷导出的温度分布来计算所产生的诱导应力。利用已知的界面和体积强度和韧性值，我们可以确定沉积膜何时以及如何破裂和界面脱粘发生，从而模拟尘埃的形成。该模型将用于分析和预测尘埃的形成及其在世界上最大的聚变反应堆ITER中的行为。期望具有一般用途，因此将能够处理用于未来反应堆的其他候选材料和材料混合物，如DEMO和STEP。该项目将与另一个博士实验项目一起进行，该项目为JET壁的沉积物和熔滴的界面特性的模拟提供必要的数据，一个原型反应堆之前，国际热核实验堆具有类似的特点。学生承担这一项目将在卡勒姆中心聚变能（CCFE），也将是一个成员的固体力学和材料工程组（SMMEG）在工程科学与联合监督两个组织。该项目属于EPSRC能源研究领域的福尔斯

In fusion reactors, the fuel (hydrogen isotopes) is heated to the plasma state which must be confined through extreme magnetic fields. However, confinement losses expose the reactor walls to plasma loads that cause damages and dust particles.Dust formation is a major concern for fusion reactors performance and safety. Dust retains significant amounts of hydrogen, which affects the efficiency of the reactors losing fuel and being a potential radiation hazard if it escaped from the walls. Furthermore, due to its high chemical reactivity, it may cause explosions and damage to vessels in the case of an accidental loss of coolant or water.Although several formation mechanisms of dust formation are well-known, such as 1) fracture and delamination of parts of deposited films and 2) remobilisation of solidified droplets of molten metal (usually beryllium) due to plasma disruptions, a more complete understanding is necessary for the choice of materials of future fusion devices. In this project, we aim to develop a finite element model capable of simulating and predicting the fracture and delamination of deposition layers and the delamination of redeposited particles. The model will use temperature distributions derived from the thermal loads of the plasma to calculate the resulting stresses induced. The use of known values of interfacial and bulk strength and toughness will allow us to determine when and how deposition films break and interfacial decohesion occurs, and thus simulate how the dust is formed.The model will be used for the analysis and prediction of dust formation and its behaviour in ITER, the world's largest fusion reactor, with the expectation to be of general usage and as such will be able to tackle other candidate materials and material mixes for future reactors as DEMO and STEP. The project will be performed in conjunction with another PhD experimental project which provides data necessary for the simulations from interfacial properties of deposits and melt droplets of the JET walls, a prototype reactor previous to ITER with similar characteristics.The student undertaking this project will be based at the Culham Centre for Fusion Energy (CCFE) and will also be a member of the Solid Mechanics and Materials Engineering Group (SMMEG) in Engineering Science with joint supervision from both organisations.This project falls within the EPSRC Energy research area