"The Formation of Kappa Distributions in Solar Flares," by Nicolas Bian and Duncan Stackpole. It turns out that a kappa distribution can arise naturally from Coulomb collisions, as in a coronal thick target.
See
http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/RHESSI_Science_Nuggets
listing the current series, 2008-present, and
http://sprg.ssl.berkeley.edu/~tohban/nuggets/
for the original series, 2005-2008.
We publish these at roughly two-week intervals and welcome contributions,
which should be related, at least loosely, to RHESSI science.