Plasma Turbulence and Turbulent Transport

The research group investigates fundamental mechanisms of turbulence and quasi-coherent modes and their influence on particle and energy transport.

Raw signals (left) and frequency spectrum (right) of data from the thermal helium beam diagnostic. The comb-like pattern around the last closed flux surface (LCFS, white line, left) is a signature of the so called quasi-coherent mode (QCM), that plays a crucial role for the edge transport in reactor relevant plasma regimes. This mode appears in the frequency spectrum (right) as a peak at a frequency of 29 kHz.

Raw signals (left) and frequency spectrum (right) of data from the thermal helium beam diagnostic. The comb-like pattern around the last closed flux surface (LCFS, white line, left) is a signature of the so called quasi-coherent mode (QCM), that plays a crucial role for the edge transport in reactor relevant plasma regimes. This mode appears in the frequency spectrum (right) as a peak at a frequency of 29 kHz.

Turbulent processes are the main cause of the particle and energy transport observed in fusion plasmas. The group investigates the fundamental turbulent mechanisms and their influence on plasma parameters and parameter dependencies of energy confinement. Microwave reflectometers, Langmuir probes and neutral beam diagnostics are used to diagnose turbulent fluctuations, profiles and flow velocities from the edge of the plasma to its centre. Modern gyrofluid and gyrokinetic turbulence codes play an important role in the interpretation of the measurement data.

The research topics are:

The relationship between the microscopic properties of turbulence and the global confinement behaviour of fusion plasmas.
The comparison of the microstructure of turbulent fluctuations with simulation results from plasma turbulence codes.
The interaction between micro-turbulence and equilibrium as well as turbulent driven shear flows and the significance for plasma regimes with high energy confinement.
The structure of geodetic-acoustic modes (GAM) and edge modes (e.g. the quasi-coherent mode, QCM, see figure) and their influence on the global confinement properties of fusion plasmas.
The development of synthetic diagnostic models for a better interpretation of measurement results in comparison with the simulation.