Physics of the Plasma Edge

The edge region of a tokamak plasma is crucial for overcoming two of the biggest challenges encountered in the development of magnetic confinement fusion reactors:

• First, a stable core plasma must be created and maintained, which requires sufficiently good thermal and particle confinement. Only then can net energy be generated through fusion reactions. The plasma edge strongly influences the confinement in the core. Therefore, a comprehensive understanding of the edge properties is required to reliably predict core performance.
   
• Second, the energy and particles that are produced by fusion reactions must be removed from the plasma in a controlled manner (steady-state and transient fluxes). Here, too, the plasma edge plays a decisive role.

To meet these challenges, the E2 division investigates heat and particle transport in all regions of the plasma, but focuses on the edge. In particular, E2 concentrates on the following topics:

• Experiments on heat, particle and momentum transport in the core and edge region of the tokamak plasma, investigating not only the main species of the plasma, hydrogen isotopes, but also the dominant impurities.
   
• Understanding the turbulent and magnetohydrodynamic (MHD) instabilities responsible for this transport. This will allow theoretical models to be tested and behavior in future nuclear fusion devices to be predicted.
   
• Investigation of no-ELM and small ELM scenarios, including the use of magnetic perturbations to modify the edge stability and achieve ELM mitigation. ELMs (Edge Localised Modes) are plasma instabilities that occur in the edge region of a tokamak.