Talk abstract

Total volume of non-ideal regions in cascading magnetic reconnection and particle acceleration in solar flares
M. Barta, J. Buechner, and M. Karlicky


The 'canonical' solar flare model sketched frequently in textbooks and papers as a X-point type reconnection below erupting filament is challenged by the huge number of energetic electrons as it is inferred from HXR flare observations because of the relatively small volume where particles can be accelerated. Therefore, the 'chaotic current-sheet' class of flare models based (e.g.) on braiding of magnetic flux-tubes whose footpoints are advected by turbulent photospheric motions has been developed. These models provide
sufficient acceleration volumes but, at the same time, they lack natural explanation of large-scale organisation observed in solar flares (e.g. loop arcades). In the presented contribution we investigate the possibility that so called cascading reconnection suggested by Shibata and Tanuma (2001) as a concept
overcoming the scale gap between the global CS width and dissipative region size is capable to reconcile the canonical model with observed flux of energetic electrons as well. We analyse the results of our AMR (Adaptive Mesh Refinement) MHD numerical simulations of reconnection in vertical coronal CS in order to find scaling laws for sizes and peak electric field of non-ideal (dissipative) regions. Based on the obtained spectra we estimate the total volume of dissipative regions, average DC electric field in them and we try to roughly infer the flux of accelerated electrons.