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An MHD eigenspectrum approach to thermal instabilities

Book - Dissertation

Solar prominences are large, cool and dense loops, stretching out from the solar surface into the hot corona. Observations indicate that many arcades and loops throughout the solar atmosphere show omnipresent coronal rain and prominence fine structure. The local plasma conditions as realised in solar prominences and coronal rain showers are mediated by thermal instabilities, with runaway cooling effects characterising their rapid nonlinear behaviour. The goal of this PhD is therefore to systematically investigate, using a combination of advanced analytic and numerical approaches, the evolution of thermal modes and overstable magnetothermal modes for solar coronal conditions. We will adopt a stepwise approach, starting from uniform media and progress to more advanced slab and flux tube configurations. Combinations of magnetic shear, pressure gradients and gravitational stratification will gradually reveal the complex MHD spectrum of linear perturbations. Modern linear codes will be developed to perform eigenspectrum studies of inhomogeneous plasmas for both Cartesian and cylindrical equilibria. These codes will in turn be used for parametric explorations of linear non-adiabatic MHD spectra in both slabs and flux tubes, providing a fresh look at various wave modes at play in fluids or plasmas and allows us to study their unstable behaviour.
Publication year:2022