Coronal energy release by MHD avalanches: EUV diagnostics of a multi-threaded coronal loop

Possible key-element for large-scale energy release is MHD kink instability in a single twisted magnetic flux strand. The initial helical current sheet progressively fragments in a turbulent way into smaller scale sheets. Dissipation of these sheets is similar to a nanoflare storm. Since during the relaxation process the loop expands in the radial direction, an unstable loop could disrupt nearby stable loops and trigger an MHD avalanche. As coronal loops are heated to millions of kelvin degrees, the dense chromospheric plasma expands in their inside and reveals a filamentary structure. The reconfiguration of the magnetic structure and the resulting plasma dynamics are expected to occur on timescales of order 10 s and over spatial scales smaller than 1.0’’. Moreover, loop footpoints response is expected across the transition region. Using full MHD simulations we show that avalanches are an available mechanism for the storing and release of magnetic energy in the solar corona, as a result of photospheric motions. Moreover, we provide a synthetic perspective for AIA and MUSE observables. Many fine scale features as well as rapid changes in emissivity and Doppler shifts seem to be accessible to the MUSE instrument which will reveal details otherwise limited to AIA capabilities.