Edge-SOL coupling and turbulence in confinement transitions

I completed my undergraduate degree in Physics at the University of Munster during which I spent the final year at the University of York and worked on the detection and analysis of edge localised modes in tokamak plasmas. Being convinced of the importance of fusion research, I am now joining the Fusion CDT to study turbulence in confinement transitions for different divertor configurations. My project will be supervised by Dr Istvan Cziegler (YPI) and by Dr Simon Freethy (CCFE).

After the plasma in a tokamak is heated beyond a critical power threshold, the turbulence located at the edge of the plasma is greatly suppressed and a transition from what is known as low confinement mode (L-mode) into high confinement mode (H-mode) takes place.

While the L-H-transition power threshold dependency on macroscopic plasma parameters such as density and temperature is well understood, the suppression of turbulence also shows to be influenced by different divertor geometries. This coupling is not fully understood and a physical picture is yet missing.

The divertor, which can be thought of as the exhaust of the tokamak, will be subject to especially high heat fluxes in future magnetic confinement fusion devices such as ITER. Different divertor geometries can reduce the heat flux by spreading the magnetic field lines and are hence a promising solution to this problem. I will be conducting research on the MAST-U experimental spherical tokamak that enables the investigation of novel divertor geometries such as 'Super-X' and their influence on the turbulence dynamics.

Identifying a sustainable energy supply is one of the biggest challenges facing humanity. Fusion energy has great potential to make a major contribution to the baseload supply - it produces no greenhouse gases, has abundant fuel and limited waste. Furthermore, the UK is amongst the world leaders in the endeavour to commercialise fusion, with a rapidly growing fusion technology and physics programme undertaken at UKAEA within the Culham Centre for Fusion Energy (CCFE). With the construction of ITER - the 15Bn Euro international fusion energy research facility - expected to be completed in the middle of the 2020's, we are taking a huge step towards fusion power. ITER is designed to address all the science and many of the technology issues required to inform the design of the first demonstration reactors, called DEMO. It is also providing a vehicle to upskill industry through the multi-million pound high-tech contracts it places, including in the UK.
ITER embodies the magnetic confinement approach to fusion (MCF). An alternative approach is inertial fusion energy (IFE), where small pellets of fuel are compressed and heated to fusion conditions by an intense driver, typically high-power lasers. While ignition was anticipated on the world's most advanced laser fusion facility, NIF (US), it did not happen; the research effort is now focused on understanding why not and the consequences for IFE, as well as alternative IFE schemes to that employed on NIF.

Our CDT is designed to ensure that the UK is well positioned to exploit ITER and next generation laser facilities to maximise their benefit to the UK and indeed international fusion effort. There are a number of beneficiaries to our training programme: (1) CCFE and the national fusion programme will benefit by employing our trained students who will be well- equipped to play leading roles in the international exploitation of ITER and DEMO design; (2) industry will be able to recruit our students, providing companies with fusion experience as part of the evolution necessary to prepare to build the first demonstration power plants; (3) Government will benefit from a cadre of fusion experts to advise on its role in the international fusion programme, as well as to deliver that programme; (4) the UK requires laser plasma physicists to understand why NIF has not achieved ignition and identify a pathway to inertial fusion energy.

As well as these core fusion impacts, there are impacts in related disciplines. (1) Some of our students will be trained in low temperature plasmas, which also have technological applications in a wide range of sectors including advanced manufacturing and spacecraft/satellite propulsion; (2) our training in materials science has close synergies with the advances in the fission programme and so has impacts there; (3) AWE require expertise in materials science and high energy density plasma physics as part of the national security and non-proliferation strategy; (4) the students we train in socio-economic aspects of fusion will be in a position to help guide policy across a range of areas that fusion science and technology touches; (5) those students involved in inertial fusion will be equipped to advance basic science understanding across a range of applications involving extreme states of matter, such as laboratory astrophysics and equations of state at extreme pressures, positioning the UK to win time on the emerging next generation of international laser facilities; (6) our training in advanced instrumentation and control impacts many sectors in industry as well as academia (eg astrophysics); (7) finally, high performance computing underpins much of our plasma and materials science, and our students' skills in advanced software are valued by many companies in sectors such as nuclear, fluid dynamics and finance.