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Title: Spectroscopic investigations of pre-flare activity using IRIS and Hinode/EIS observations
Author: Woods, Magnus Morton
ISNI:       0000 0004 7661 1377
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2019
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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.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available