Role of turbulent transport in the evolution of the κappa distribution functions in the plasma sheet

Abstract:

We studied the evolution of ion and electron distribution functions, approximated by
kappa
distributions, in the plasma sheet with the distance from the Earth using the data of the Time History of
Events and Macroscale Interactions during Substorms spacecraft mission. Five events were used to calculate
the main parameters of the κ distribution. For these events at least four spacecraft were aligned along the
tail between approximately 7 and 30 RE . It was found that for the majority of events the values of κ increase
tailward. The observed radial profiles could be related to the inner magnetosphere sources of particle
acceleration and to the net tailward transport of particles. This net transport is the result of a balance
between the average regular bulk transport toward the Earth and the turbulent transport by eddies in the
tailward direction.