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Dynamical phenomena in stratified solar coronal plasma

Orza, B. (2013) Dynamical phenomena in stratified solar coronal plasma. PhD thesis, University of Sheffield.

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Abstract

Different dynamical phenomena in the solar corona are investigated in the present Thesis. We aim to investigate using a semi-analytical approach of the effect of the surrounding environment on the period ratio of the fundamental to first harmonic of a thin coronal loop. Investigation of geometrical effects are taken into account, namely asymmetry of the coronal loop, i.e. its deviation from a semi-circular shape. It is found that if we are to obtain more accurate estimates on the effect of the environment on the transversal oscillations of a coronal loop, we have to take into account that in reality a coronal loop depends on more than one coordinate, secondly, isothermal supposition of the loop and its environment also need refinement, as observations show that the loops are not always in hydrostatic equilibrium. The study on the expansion of a coronal loop indicates that in order to have more realistic results one would need to include damping processes, resonant absorption and cooling processes. Further in an expanding loop, the growth of the amplitude due to emergence and decay of amplitude due to resonant damping or cooling will be competing processes. When it expands, a loop can also have accelerated motion upwards in the corona with cross section modification of the ux tube. The final piece of work in this thesis is a numerical investigation into a 2D magnetic reconnection process, where we study reconnection rates and how different parameters such as resistivity and Hall term affect the process of field line reconnection. The Hall effect does speed up the reconnection process, but it depends significantly on the initial conditions of the problem. These initial conditions, i.e. different magnetic field configuration, density stratification, gravity play an important role in the reconnection process.

Item Type: Thesis (PhD)
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > School of Mathematics and Statistics (Sheffield)
Identification Number/EthosID: uk.bl.ethos.589215
Depositing User: Dr B. Orza
Date Deposited: 18 Dec 2013 11:30
Last Modified: 03 Oct 2016 11:03
URI: http://etheses.whiterose.ac.uk/id/eprint/4812

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