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Laboratory for Atmospheric and Space Physics

Acceleration mechanisms of energetic electrons in the Earth’s radiation belts

September 24, 2012

We have examined signatures of two types of waves that may be involved in the acceleration of energetic electrons in the Earth’s radiation belts. First, ULF wave power from SAMNET and IMAGE ground magnetic observatories was compiled into a database. Second, VLF wave activity was obtained from low-altitude SAMPEX observations of electron microbursts, since these microbursts are thought to be caused by interactions between VLF chorus and trapped electrons. We then compared the ULF and microburst observations to in situ trapped electrons observed by high altitude satellites. The comparison showed that electron acceleration at low L shells is probably closely associated with VLF activity. We suggest that electron flux and possible phase-space density peaks observed at L ~ 4.5 are likely caused by local VLF wave acceleration. However, ULF activity is probably responsible for electron acceleration and transport at higher L shells.

Contributed by T. Paul O’Brien and Bern Blake, Aerospace Corp.

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