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Effects of partial ionisation in the solar atmosphere
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Leake, James Edward (2006) Effects of partial ionisation in the solar atmosphere. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b2157974~S1
Abstract
In this thesis techniques are developed for the simulation of partially ionised
plasmas in the fluid approximation. These techniques are used to model the evolution
of magnetic fields in the partially ionised regions of the solar atmosphere. Single fluid
equations for a partially ionised plasma are derived based on the individual equations for
each species. A Lagrangian Remap MHD code is then adapted to simulate a plasma of
arbitrary degree of ionisation.
The effects of the presence of neutrals on the propagation and damping of Alfv´en
waves in the solar atmosphere are investigated. Ion-neutral collisions are shown to be
an efficient damping mechanism for outwardly propagating Alfv´en waves of frequencies
greater than 0.1 Hz, showing that high frequency waves in the outer solar atmosphere
cannot originate at the surface of the Sun.
Next simulations to show the effects of neutrals on the emergence of magnetic
flux from beneath the solar surface into the outer atmosphere are performed. Results
from 2D and 3D numerical experiments show that the presence of neutrals increases
the amount of magnetic flux that can emerge into the corona. Furthermore, ion-neutral
collisions are strong enough to dissipate currents perpendicular to the magnetic field
as it emerges. This shows that ion-neutral collisions are a viable mechanism for the
formation of force-free (j ∧B = 0) coronal magnetic field from sub-surface field, which
is not the case when the plasma is assumed to be fully ionised.
Item Type: | Thesis (PhD) | ||||
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Subjects: | Q Science > QB Astronomy | ||||
Library of Congress Subject Headings (LCSH): | Solar atmosphere, Ionization | ||||
Official Date: | September 2006 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | Department of Physics | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Arber, T. D. | ||||
Extent: | xvi, 169 pages | ||||
Language: | eng |
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