Probing Plasma Instabilities with high performance simluations

托卡马克的聚变性能受到背景磁场在中心等离子体体积内保持粒子和能量并远离托卡马克壁的有效性的强烈影响。由大量小尺度等离子体不稳定性引起的电磁势波动会限制这些托卡马克等离子体中可以实现的约束。因此，研究这些不稳定性和相关的湍流波动是至关重要的，以便更好地了解物理过程，导致增加的损失，从而融合性能退化。波动的小尺度和湍流性质可能对不稳定性的实验测量和数据解释构成挑战。因此，不稳定性的理论和数值研究都是非常有用的方法，可以帮助解释实验数据，并允许更灵活地详细探测潜在的物理学。在这个项目中，研究人员将开发使用前沿陀螺动力学模拟的经验，在实验相关的情况下调查的不稳定性的属性。作为这项工作的一部分，一种新的方法来捕捉重要的影响所产生的缓慢的空间变化的背景平衡将被利用来研究的不稳定结构和诊断测量和解释的敲门效应的平衡属性的影响。该项目的一个关键动机，除了提高我们对等离子体不稳定性和相关湍流的基本理解外，还将探索不稳定性特征对实验诊断的影响，如多普勒背散射（DBS）和束发射光谱（BES）系统。这也将有助于通过比较测量和预测的波动信号来验证gyrokinetic工具，并鼓励研究人员利用他们的gyrokinetic模拟技能，为实验数据的诊断提供解释性支持。该项目与涉及约克和牛津大学以及卡勒姆聚变能中心（CCFE）的更广泛的合作项目的目标密切相关，为研究人员提供了与实验重点博士生以及国际聚变社区内的实验和理论专家密切合作的机会。

The fusion performance of tokamaks is strongly influenced by the effectiveness of the background magnetic field in holding particles and energy inside the central plasma volume and away from the tokamak's walls. Fluctuations in the electromagnetic potentials, resulting from a multitude of small scale plasma instabilities, can limit the confinement that can be achieved in these tokamak plasmas. The study of these instabilities and the associated turbulent fluctuations is therefore vital in order to better understand the physics processes leading to enhanced losses and hence fusion performance degradation. The small scale and turbulent nature of the fluctuations can pose a challenge to experimental measurements of instability properties and data interpretation. Both theoretical and numerical studies of instabilities are therefore extremely useful approaches which can aid interpretation of the experimental data as well as allowing more flexibility in probing the underlying physics in detail. In this project the researcher will develop experience with using leading edge gyrokinetic simulations to investigate the properties of instabilities in experimentally relevant scenarios. As a part of this work, a novel approach to capturing important effects arising from the slow spatial variation of the background equilibrium will be exploited to study the impact of equilibrium properties on the instability structure and the knock on effect for diagnostic measurements and interpretation. A key motivation of this project, alongside improving our fundamental understanding of plasma instabilities and associated turbulence, will be to explore the consequences of instability character for experimental diagnostics such as the Doppler Back Scattering (DBS) and Beam Emission Spectroscopy (BES) system. This will also aid efforts to validate the gyrokinetic tools through comparison of measured and predicted fluctuation signals and the researcher will be encouraged to exploit their gyrokinetic simulation skills to provide interpretive support in the diagnosis of experimental data. This project aligns closely with the goals of a wider collaborative project involving the universities of York and Oxford and the Culham Centre for Fusion Energy (CCFE), providing the researcher with the opportunity to work closely with experimentally focussed PhD students as well as with experimental and theoretical experts within the international fusion community on these areas.