The fusion performance of tokamaks is strongly influenced by the effectiveness of the magnetic field in holding heat and mass inside the plasma volume and away from solid walls. Turbulent fluctuations in the electromagnetic potentials can limit the confinement that can be achieved in these devices. Plasma flows can interact with these turbulent fluctuations, leading to changes in the confinement.
Zonal flows (ZF) constitute a special case in the field of flow–turbulence interactions, since the mutual effects of turbulence and large-scale flows are of similar magnitude. In most turbulence simulations the plasma is observed to generate its own radially varying flow. Although zonal flows are thus a major component of tokamak turbulence, they are poorly understood, and their detailed measurements (especially in the plasma core) still rare. The University of York is a main stakeholder in a recently funded EPSRC Programme Grant “Turbulence Dynamics of Tokamak Plasmas”, the project fits into this framework and is aimed at exploiting the newly updated, state-of-the art turbulence diagnostic instruments at MAST-U.
The studentship is experimental, using the recently upgraded beam emission spectroscopy system. During an initial training component, the student would be based at the University of York, then spend significant periods at CCFE in Oxfordshire. The primary goals are to refine imaging based ZF detection methods and to develop robust metrics of nonlinear interactions. The researcher will have opportunities to learn fundamental plasma physics, with a focus on flow–turbulence interactions. They will develop a range of experimental skills. They will gain experience in analysing experimental data and in working in an international environment.
This project is offered by University of York and will be supervised by Dr Istvan Cziegler (University of York) and Dr Anthony Field (CCFE). For further information please contact Istvan Cziegler.