On the Lifetime of Hot Coronal Plasmas Arising from Nanoflares

摘要

The cooling of plasmas in closed coronal loops by thermal conduction is important when considering their detectability at X-ray and EUV wavelengths. A non-local formalism of thermal conduction originating in laboratory plasmas is used and it is shown that while the effect is unlikely to be important for loops that are in a steady state, it does play a significant role in loops that are impulsively heated (e.g., by nanoflares). Such loops are “under-dense”, and so hot electrons have a relatively long mean free path. Analytic and numerical models are presented, and it is shown that conduction cooling times are lengthened quite considerably. A comparison of various cooling times with ionisation times is also presented, and it is noted that this conductive physics may enhance the chances of observing hot nanoflare-heated plasma.