Turbulent crossfield transport of nonthermal electrons in coronal loops: theory and observations 

Eduard Kontar Submitted: 20120201 15:17
Context. A fundamental problem in astrophysics is the interactionbetween magnetic turbulence and charged particles. It is now possibleto use Ramaty High Energy Solar Spectroscopic Imager (RHESSI)observations of hard Xrays (HXR) emitted by electrons to identify thepresence of turbulence and to estimate the magnitude of the magneticfield line diffusion coefficient at least in dense coronal flaringloops. Aims: We discuss the various possible regimes of crossfield transportof nonthermal electrons resulting from broadband magnetic turbulencein coronal loops. The importance of the Kubo number K as a governingparameter is emphasized and results applicable in both the large andsmall Kubo number limits are collected. Methods: Generic models, based on concepts and insights developed inthe statistical theory of transport, are applied to the coronal loopsand to the interpretation of hard Xray imaging data in solar flares.The role of trapping effects, which become important in the nonlinearregime of transport, is taken into account in the interpretation ofthe data. Results: For this flaring solar loop, we constrain the ranges ofparallel and perpendicular correlation lengths of turbulent magneticfields and possible Kubo numbers. We show that a substantial amount ofmagnetic fluctuations with energy ~1% (or more) of the backgroundfield can be inferred from the measurements of the magnetic diffusioncoefficient inside thicktarget coronal loops.
Authors: Bian, N. H.; Kontar, E. P.; MacKinnon, A. L.
Projects: RHESSI

Publication Status: published in Astronomy and Astrophysics
Last Modified: 20120203 12:03


