Complex Systems:
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Project leader: Alexander Kendl
Institute for Ion Physics and Applied Physics - Complex Systems Group
We are investigating complex nonlinear dynamical systems with an emphasis on multi-scale electromagnetic many-particle systems and continua. The major focus is on waves, instabilities and turbulence in magnetized plasmas.
Recent research topics of the Complex Systems Group are: nonlinear dynamics, turbulence and structure formation; physics of fusion plasmas, ultracold quantum plasmas and astrophysical plasma; theoretical biophysics; computational physics and high-performance computing.
In addition to the magnetic confinement fusion related research of the group, the two interdisciplinary projects within the Doctoral School are applying computational methods and models from fusion plasma simulations to current topics in astrophysics and quantum systems:
- Gyrokinetic turbulence in clusters of galaxies
- Waves and instabilities in ultracold and quantum plasmas
Complex Systems:
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In order to explain the astronomically observed plasma temperatures and entropy excess in the intra-cluster medium (ICM) between galaxies in clusters, some form of non-gravitational heating has to be evoked in astrophysical simulations of cluster dynamics. A possible explanation is heating of the ICM plasma by small-scale turbulent dissipation, transferring energy from kinetic large-scale motion into the thermal bath. In principle, the codes used in the group by faculty member S. Schindler for simulations of cluster dynamics are able to use sub-grid models for turbulent dissipation. However, theoretical or computational foundations for the choice of specific (simplified) models have not been studied for parameters and conditions of the ICM, which might necessitate inclusion of kinetic phase-space dissipation mechanisms.
For this purpose the PhD student will, in collaboration with code developers from fusion research institutions, adapt gyrokinetic turbulence codes developed for fusion plasmas to astrophysical problems. The student will conduct detailed numerical studies on the properties of ICM turbulence and use the results to develop (simplified, e.g. parametrised) thermalisation models for galaxy cluster simulations, which can be applied in the DK+ project by faculty member S. Schindler. The results can be compared with ESO telescope observations.
Complex Systems:
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Ultracold quasi-neutral plasmas merge the physics of strongly coupled plasmas and of ultracold quantum gases. Recent experiments report first observations of ultracold plasma waves and instabilities, which are counterparts of classical drift instabilities in hot plasmas (where they are e.g. responsible for turbulent transport in fusion experiments; studied in the Complex Systems Group). However, not much attention has yet been devoted on the theory of ultracold plasma instabilities.
The PhD student will analyse first theoretical approaches to ultracold plasmas and other possible modifications of existing classical approaches by considering strong Coulomb coupling and quantum effects. In particular, implications for the instability of high-frequency drift waves in magnetised ultracold plasmas should be studied by means of analysis and numerical simulation. It is envisaged that the PhD student should develop an electromagnetic hybrid molecular dynamics TREE code (kinetic ions, fluid electrons), which employs similar methods as the astrophysical code (GADGET-2) used by the group of faculty member S. Schindler for the simulation of galaxy cluster evolution (with foreseen collaboration in particular on aspects of computation and visualisation).