Add abstract
Want to add your dissertation abstract to this database? It only takes a minute!
Search abstract
Search for abstracts by subject, author or institution
Want to add your dissertation abstract to this database? It only takes a minute!
Search for abstracts by subject, author or institution
Magnetohydrodynamic Simulation of Reconnection in Turbulent Astrophysical Plasmas
by Fabien Widmer
Institution: | Georg-August-Universität Göttingen |
---|---|
Year: | 2016 |
Posted: | 02/05/2017 |
Record ID: | 2069178 |
Full text PDF: | http://hdl.handle.net/11858/00-1735-0000-0028-8820-4 |
Turbulence is ubiquitous at large-Reynolds-number astrophysical plasmas like in the Solar corona. In such environments, the turbulence is thought to enhance the energy conversion rate by magnetic reconnection above the classical model predictions. Since turbulence cannot be simulated together with the large scale behaviour of the plasma, magnetic reconnection is studied through the average properties of turbulence. A Reynolds-averaged turbulence model is explored in which turbulence is self-sustained and -generated by the large scales (mean-) field inhomogeneities. Employing that model, the influence of turbulence is investigated by large-scale MHD numerical simulations solving evolution equations of the energy and cross-helicity of the turbulence together with the MHD equations. Magnetic reconnection is found to be either rapidly enhanced or suppressed by turbulence depending on the turbulence timescale. If the turbulence timescale is self-consistently calculated, reconnection is always strongly enhanced. Since the solar corona bears strong guide magnetic fields perpendicular to the reconnecting magnetic fields, the influences of a strong guide field on turbulent reconnection is separately investigated. A slow down of reconnection, obtained in the presence of a finite guide field, can be understood by a finite residual helicity working against the enhancement of reconnection by the turbulence. The influence of turbulence on magnetic reconnection is further studied by means of high resolution simulations of plasmoid-unstable current sheets. These simulations revealed the importance of turbulence for reaching fast reconnection. Advisors/Committee Members: Büchner, Jörg (advisor), Büchner, Jörg (referee), Dreizler, Stefan (referee), Peter, Hardi (referee), Schmidt, Wolfram Pd (referee), Tilgner, Andreas (referee), Gizon, Laurent (referee).
Want to add your dissertation abstract to this database? It only takes a minute!
Search for abstracts by subject, author or institution
Beyond the Blur
Construction and Characterization of the First Aut...
|
|
A Search for Pulsation in Young Brown Dwarfs and V...
|
|
Bridging the Gap
Elusive Explosions in the Local Universe
|
|
Reassessing the Fundamentals
On the Evolution, Ages and Masses of Neutron Stars
|
|
Shapes and Spins of Near-Earth Asteroids
|
|
Magnetic Fields Near and Far
Galactic and Extragalactic Single-Dish Radio Obser...
|
|
Recycled Pulsars
|
|
The Many Facets of Cosmic Explosions
|
|