Speaker
Description
Alfvén waves are known to be efficient carriers of magnetic energy from the Sun. Although they are linked to coronal heating and solar wind acceleration, the energy dissipation processes remain poorly constrained, particularly in open-field regions. For example, it is unclear whether a turbulent cascade of energy to the dissipation length scales is triggered in coronal conditions. Density enhancements in the background plasma can reflect a fraction of the incident Alfvén wave energy, potentially leading to wave trapping and more efficient dissipation in the lower corona. Using a series of 1.5-D magnetohydrodynamic simulations, we calculate the amount of trapped wave energy for different background density profiles. By varying the different length scales involved, namely the Alfvén wave wavelength and the spatial scale of the density inhomogeneity, we identify the conditions required for maximum wave energy reflection – which happens at a specific ratio between these two length scales. We further investigate the cause of this scale selectivity using a semi-empirical model that accounts for wave reflection and interference. Using both these models, we provide energy estimates for the optimal scenario for Alfvén wave trapping.
