Just came across a write-up of a recent PRL in Physics World
http://physicsworld.com/cws/article/news/2013/jan/10/physicist-homes-in-on-universes-earliest-magnetic-fields
The paper by R. Schlickeiser for those with access is at http://prl.aps.org/pdf/PRL/v109/i26/e261101
Not really sure what to make of the maths in the paper, but re-affirms my view that you have to consider non-linear interactions across a vast range of scales in plasmas to get the correct equilibrium balance of the system with regard to the partition of energy between the kinetic energy of the particles and the energy of the fields.
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