Intermittent fluctuation statistics in spherical tori – plasma strand project

Supervisors: Istvan Cziegler (lead academic, University of York), Alsu Sladkomedova (Tokamak Energy scientist, technical).

Heat and mass transport in a tokamak plasma is dominated by turbulence. Although significant progress has been made in understanding this phenomenon, there is no comprehensive model that can robustly predict confinement in tokamaks yet. Experimental analysis of turbulent fluctuations is necessary to address outstanding questions in plasma confinement and investigate the nature of turbulence. The properties of the plasma just inside the separatrix impact core conditions and the scrape-off-layer (SOL) of the plasma. The edge plasma region in tokamaks features structure formation that leads to intermittency in plasma fluctuations. Turbulence spreading can lead to non-local origin of transport both in the confined and in the open-field line region. Addressing the source and properties of turbulent transport is crucial for predicting confinement in tokamaks.

This project is aimed at analysing the dynamics and properties of edge plasma fluctuations in the spherical tokamaks MAST-U and ST40. MAST-U is equipped with a set of turbulence diagnostics allowing exploration of the underlying nature of fluctuations. The Beam Emission Spectroscopy diagnostic on MAST-U allows for investigation of edge ion-scale turbulence and plasma flows. The successful student will perform statistical analyses of edge plasma fluctuations, investigate the intermittent nature of fluctuations, connection to modulation or avalanche-type physics, marginality, and the generation mechanisms involved. Additionally, available fluctuation diagnostics on ST40 will be used for cross-machine comparison of fluctuation dynamics. Dimensionless matching studies will allow investigation into the relationship between confinement and the turbulence properties in MAST-U and link it to that in ST40.

The project will be mainly based in Culham (UKAEA, MAST-U site) and Didcot (Tokamak Energy, ST40 site), Oxfordshire and we expect the student to participate in international conferences.

This project may be compatible with part time study, please contact the project supervisors if you are interested in exploring this.

This project is offered by University of York. For further information please contact Istvan Cziegler: