The field of magnetically confined fusion physics changes rapidly in these years. From the laboratory size experiments we move towards reactor size machines. ITER is being built now in France, which will be the first fusion reactor size experiment. It was designed to produce more fusion power, than it uses for heating and confinement. Parallel to the government funded research programs a boom of private fusion start-up companies are seen, which collected a few billion Euro fund in the last 3 years. Although fusion research globally focuses increasingly on technology development, the plasma physics is still key to the design of the new devices. A key question towards the fusion reactors is to understand and experimentally study the particle and heat transport in fusion plasmas.
The H-mode is a good confinement mode of the fusion plasmas, where a transport barrier is formed in the edge of the plasma. The H-mode is characterized by suppressed edge plasma turbulence, but disruptive edge-localized mode (ELM) instability occurs in this operation mode. The type I ELMy H-mode is the baseline operating scenario for ITER. However, the energy predicted to be released by a type I ELM in ITER is unacceptably high. In these years plasma scenarios are being developed in tokamaks, where the advantages the H-mode could be kept, without the harm of large ELMs.
In recent years several alkali diagnostic beam and two dimensional turbulence imaging Beam Emission Spectroscopy (BES) diagnostics have been installed to large fusion experiments by the Fusion Plasma Physics Laboratory of the Centre for Energy Research. Nearly all major European and Asian fusion experiments are equipped with a BES diagnostic. Our group in the Fusion Plasma Physics Laboratory partly operates these diagnostics and is also responsible for the data evaluation. This gives a unique opportunity to participate in the physics program of leading fusion experiments and also to compare results from different experiments. Wendelstein 7-X stellarator just starts the new operation campaign in 2022 autumn, where the H-mode transition might also be observed.
To characterize ELMs and edge plasma turbulence via the analysis of the experimental data is the primary aim of this study. A python program package was developed in CER for fluctuation analysis. A part of the work is to develop numerical methods and implement codes to improve the analysis. These codes are then to be tested in simulated data sets and then used in real measurement results. In case of interest the candidate can participate in the operation the diagnostic in remote experiments as well technical development of the experimental setup. As the experiments are in Europe and/or in Asia strong collaboration is necessary with foreign laboratories.