Fast electrons relaxing

James Clerk Maxwell

James Clerk Maxwell first wrote down the distribution of velocities in a gas of fixed temperature, a contribution to theoretical physics that most of us now use routinely, without reflection, on a daily basis. The Maxwell-Boltzmann distribution represents a state of maximum entropy, the overwhelmingly most likely state given that the temperature of the gas has been fixed. It is such a standard ingredient of our thinking about gases and plasmas that "non-maxwellian" is one of the trendiest words you can use. A non-maxwellian distribution is of course what we would expect to find in a coronal hard X-ray source, like the one Säm Krucker has described. How would it relax to Maxwellian form? Might we recognise this in observations? How efficient is it as a source of hard X-rays? Ross Galloway, Per Helander, John Brown and I have been thinking about this here and I'll describe some of what we've been doing and why it might be interesting for solar hard X-rays. First some more non-maxwellian words.