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October 9, 2012 – “Electron scale structures and dynamics in thin boundary layers”


Speaker:Cecilia Norgren (Uppsala)
Date:Oct. 9, 2012
Time:4:00 PM
Location:LASP Space Science Building, room N248 upstairs. Map

Seminar Abstract:

It is characteristic for many plasma environments in the Universe to form extended thin boundaries, separating regions of different kind of plasmas. Plasma processes at these boundaries are often of multiscale nature, coupling small electron scales and large magnetohydrodynamics scales, and may result in transport of energy and plasma, plasma energization and generation of plasma waves. Understanding these boundaries is thus important in order to know how large plasma regions interact, and how energy is dissipated within a system. We present one event where we observe high amplitude electric fields in the plasma sheet boundary layer, in different forms. By making use of two closely located Cluster spacecraft, we can make detailed cross spacecraft measurements of these structures, which are on electron scale size, determining some of their fundamental properties. We make detailed measurements of lower hybrid drift waves, determining phase velocity, wavelength and the strength of the electrostatic potential. We also observe isolated dipolar electric field pulses interpreted as electron holes, moving with a velocity on the order of the ion velocity.