Turbulent Motions in Magnetically Confined Plasmas

对核聚变的追求是一项世界性的事业，面临着跨越物理、工程、材料科学和许多其他领域的巨大挑战。最终的挑战是通过磁场限制热聚变等离子体，以便聚变反应能够发生，并且这个过程可以自我维持。然而，各种等离子体现象会导致不稳定性和限制损耗。稳定性问题在等离子体边缘最为严重，导致炽热、致密的丝状结构撞击聚变装置的材料表面，从而可能造成损害并缩短装置的寿命。因此，该项目的目标是了解等离子体边缘的输运过程。人们普遍认为，由于压力梯度和磁场曲率，等离子体边缘湍流是由所谓的交换不稳定性驱动的。其基本机制类似于经典的流体动力热对流--即从下面加热的一层流体。因此，该项目将通过使用水动力稳定性理论中的技术来利用这种类比，以在互通不稳定的线性阶段及其随后的非线性演变方面取得进展。

The quest for nuclear fusion is a worldwide enterprise, with tremendous challenges spanning the fields of physics, engineering, material science and many more. The ultimate challenge is to confine hot fusion plasma - by magnetic fields - so that fusion reactions can occur, and the process can become self-sustaining. However, various plasma phenomena cause instabilities and confinement losses. The stability problem is most severe at the plasma edge, causing hot, dense filamentary structures to strike the material surfaces of the fusion device, thus potentially inflicting damage and shortening the lifetime of the device. The goal of this project is therefore to understand the transport processes at the plasma edge. It is widely recognised that plasma-edge turbulence is driven by so- called interchange instability, due to pressure gradients and magnetic field curvature. The underlying mechanism is analogous to that of classical hydrodynamic thermal convection - i.e. a layer of fluid heated from below. The project will therefore exploit this analogy by using techniques from hydrodynamic stability theory to make progress with both the linear phase of the interchange instability and its subsequent nonlinear evolution.