SPRG Seminars
August 24, 2010:
" Particle Acceleration Mechanisms in Planetary Radiation Belts "
Dr. Danny Summers, Memorial University of Newfoundland and Kyung Hee Unversity
A main mechanism for the formation of an electron radiation belt in a planetary magnetosphere is radial (cross-L) transport toward the planet from an external boundary.In this process the first and second adiabatic invariants are conserved and the third is violated.Typical electron energies in the Earth's outer radiation belt are 400keV - 10MeV,while in Jupiter's inner magnetosphere electron energies are in the range 1-100MeV. Radial transport alone cannot explain the observed relativistic electron populations at Earth and Jupiter. Local acceleration due to electron gyroresonance with plasma waves can be effective for energizing radiation belt electrons. Here we discuss special particle energization mechanisms due to nonlinear phase trapping by coherent whister-mode waves. Under appropriate conditions, these mechanisms can be very efficient, e.g., at Jupiter several-hundred keV electrons can be accelerated to tens of MeV in seconds. We expect that these particle acceleration mechanisms can be effective in the wider context of space and cosmic plasmas.