Komplexe Systeme

Possible MSc thesis topics

Please contact Prof. Kendl for more information on possible MSc thesis topics and requirements.

MSc thesis research topics in our group are suitable for the MSc specialisation areas "Many-Body Physics", "Computational Physics", or "Ion Physics and Applied Physics". Usually a thesis work in our group has strong computational elements, so that some basic existing knowledge on numerics, programming (C/C++) and Linux is helpful. Knowledge on plasma physics and/or fluid dynamics (through the courses offered in our MSc programme) is desired.

Topic (1):  Finite Larmor radius effects on the Kelvin-Helmholtz instability in magnetised plasmas

An existing 2D gyro-fluid turbulence code (written in C++) in magnetised plasmas shall be prepared for simulation of
the Kelvin-Helmholtz (shear flow) instability. The gyro-fluid model consistently includes effects of a finite Larmor (gyration) radius (FLR), which gets relevant when plasma fluctuations have spatial extensions in the order of an ion gyration radius.

(1) Review the present status of literature on simulations including FLR effects on the KH instability;
(2) Prepare the code for simulations;
(3) Plan parameter studies for a series of simulations;
(4) Apply or further develop post-processing diagnostics of the simulations;
(5) Characterise the influence of FLR effects on mode numbers, growth rates, and transition to turbulence;
(6) Discuss possible relevance of the effect for applications (fusion, space).

Starting literature:
# Faganello, J. Plasma Phys. 83, 535830601 (2017);
# Kendl, Plasma Physics and Controlled Fusion 60, 025017 (2018).

Topic (2):  Finite Larmor radius effects on reconnection in magnetised plasmas

The reconnection of magnetic field lines in turbulent magnetised plasmas is of high interest both in astrophysical and fusion plasmas. Here we study the influence of different models for finite Larmor radius (FLR) effects on 2D reconnection with delta-f gyrofluid models.

(1) Implement already formulated nonlinear equations in the context of a delta-f model into an existing gyrofluid code.
(2) The model and equations so far implemented in the code have the same structure as those for reconnection, so that some coding but no major new numerical developments will be required.
(3) Devise and run a series of simulation studies in order to compare the reconnection rates and structure formation from simulations of the new code version developed within this thesis, with the delta-f results in the literature.
(4) Investigate the influence of several model approximations and modifications on the reconnection process.

Starting literature:
# Comisso, Phys. Plasmas 20, 092118 (2013)

Topic (3):  Impurity dynamics in large-amplitude plasma turbulence

This thesis should apply a full-f gyrofluid model on self-consistent impurity transport processes in plasma turbulence.  With standard delta-f gyrofluid and gyrokinetic models, the advection, aggregation, clustering and transport of impurities (such as secondary ion species, charged molecules and dust) is only consistently possible for small but homogeneously distributed (“trace impurity”) concentrations. Conventional non-Boussinesq (and “non-gyro”) fluid models on the other hand can only couple multiple inertial species in computationally unhandy and approximate ways.

Full-f models allow for consistent multi-species coupling also of arbitrary numbers of localised non-trace species. This will allow to consistently study the aggregation versus transport mechanisms in vortex centers of fully developed plasma turbulence, including the back-reaction of locally enhanced impurity concentrations on vortex and flow dynamics.

Starting literature:
# Kendl, Phys. Plasmas 19, 112301 (2012)


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