Probing Plasma Instabilities with high performance simluations

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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.