Woods, Magnus Morton;
(2019)
Spectroscopic Investigations of Pre-flare Activity using IRIS and Hinode/EIS Observations.
Doctoral thesis (Ph.D), UCL (University College London).
Preview |
Text
Woods_10069239_thesis.pdf Download (104MB) | Preview |
Abstract
Solar flares are the most energetic phenomena observed in the solar system. Lasting on timescale from minutes to hours they release vast amounts of stored magnetic energy in the form of emitted light. However, the initiation processes of these flares are not well understood. This thesis utilises observations taken by the IRIS and Hinode/EIS instruments, which are sensitive to far-ultraviolet and extreme-ultraviolet emission respectively, to investigate the solar atmosphere in the hours prior to flaring. Additionally, this thesis incorporates the results of non-linear force free magnetic field extrapolations to investigate the evolution of the three-dimensional magnetic field prior to and post flaring. The work carried out as part of this thesis has resulted in the identification of fast plasma flows in the solar atmosphere up to an hour prior to flaring. The flows were found to be situated close to a region of magnetic flux cancellation and are thought to be driven by magnetic reconnection at this site. These flows and the accompanying brightenings observed in multiple regions of the solar atmosphere are found to be related to the triggering of the flare itself but also are a signature of the destabilisation of twisted magnetic structures (magnetic flux ropes) in the active region which subsequently erupt away from the sun. Additionally, an investigation into a series of three flares is presented and discussed within the context of the earlier results from observations and modelling presented in this thesis. The study found that the triggering scenario presented earlier in this work was not applicable to the series of flares. This result serves to highlight that the pre-flare environment is highly complex, and that flare triggering is very individual to each event.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Spectroscopic Investigations of Pre-flare Activity using IRIS and Hinode/EIS Observations |
| Event: | UCL (University College London) |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2019. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10069239 |
Archive Staff Only
 |
View Item |
