This may be of interest:
SCHOOL OF PHYSICS COLLOQUIUM
Monday 31st May, 2010 at 3:15 pm
refreshments from 3pm
Venue: Slade Lecture Theatre, School of Physics
Title: The multi-scale physics of aurorae
Presenter: Dr C.C. Chaston
University of California at Berkeley
The Earthward acceleration of electrons which powers the emission auroral light is a consequence of large scale processes in the Earth’s magnetosphere. However this acceleration occurs in electromagnetic fields with small scale sizes. In this presentation we explore the physics of how energy is transported across scales in the auroral acceleration region to facilitate particle acceleration, and show how cross-scale energy transport ultimately leads to the formation of the rapidly kinking, curling and folding light displays that make watching the aurora so compelling.
In pursuing this goal we exploit simulations and recent high resolution observations from space borne and ground based cameras along with plasma measurements from a number of polar orbiting spacecraft. Together these methods indicate that the motion and structuring of auroral forms is a manifestation of the action of well known plasma instabilities common in many space and astrophysical plasma environments. These instabilities launch an Alfven wave cascade toward smaller scales through the auroral acceleration region to form finely structured bright auroral forms and drive auroral plasmas toward a turbulent state. The universality of this kind of process in high Reynolds number plasmas means that the auroral acceleration region is a easily accessible laboratory for the study of energy transport and conversion in space with relevance to a wide range of space and astrophysical plasma contexts.