Characterisation of ion and electron scale electromagnetic turbulent transport in MAST Upgrade and STEP pedestals (Plasma Strand Project)

Supervisor: Dr David Dickinson (University of York)

External Supervisor: Dr Benjamin Chapman-Oplopoiou (UKAEA)

Plasma turbulence acts to degrade the confinement of particles and energy in magnetic confinement devices, such as tokamaks. Worse confinement leads to the need for larger, more expensive, reactors reducing the efficiency and economic viability of fusion produced electricity. Plasma turbulence is also a fascinating area of physics, rich in interesting and complex behaviour. As such, there is significant research activity around the theoretical, computational and experimental study of plasma turbulence.

In experiments, a transition to a regime of improved confinement can be observed in certain modes of operation and is associated with a narrow region near the edge of the plasma known as the pedestal where the nature of the turbulence is thought to change. Understanding the mechanisms behind particle and heat turbulent transport in the pedestal is crucial for the operation of a future spherical tokamak (ST) pilot plant, such as STEP [1]. Due to the high plasma beta of STs, the microinstabilities responsible for this transport are predominantly electromagnetic in nature, including microtearing modes (MTMs) and kinetic ballooning modes (KBMs). These instabilities have previously been observed in MAST pedestals [2], which were predominantly in a ballooning regime with respect to ideal linear MHD instability. Recent data from MAST-U comprises pedestals that are peeling limited at low collisionality, allowing for an interesting comparison of turbulent transport mechanisms in each device. To this end, this project will apply the GENE gyrokinetic code in both its local and global modes of operation to MAST-U pedestals. This will compliment the STEP pedestal analysis already carried out by B. Chapman-Oplopoiou, core MTM analysis underway by others at UKAEA, and the expertise in ST gyrokinetics present at UoY. After a careful analysis of microinstability and turbulent transport in MAST-U pedestals, it is envisaged that the student will be able to offer transport predictions for STEP pedestals. The student would be based at the Culham Science centre.

The student will gain experience in high performance computing and tools for data analysis, as well as opportunities to develop skills in scientific communication.

The project will be mainly based in Culham Science Centre but may also involve travel to support collaborations. There are also opportunities for travel to conferences.

[2] D. Dickinson et. al. PRL 108, 135002 (2012)

The project is offered by the University of York. For further information please contact Dr David Dickinson: Dr Benjamin Chapman-Oplopoiou:

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