Ring Current He Ion Control by Bounce Resonant ULF Waves

Document Type

Article

Publication Date

12-1-2017

Abstract

Ring current energy He ion (∼65 keV to ∼520 keV) differential flux data from the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instrument aboard the Van Allan Probes spacecraft show considerable variability during quiet solar wind and geomagnetic time periods. Such variability is apparent from orbit to orbit (∼9 h) of the spacecraft and is observed to be ∼50–100% of the nominal flux. Using data from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument, also aboard the Van Allen Probes spacecraft, we identify that a dominant source of this variability is from ULF waveforms with periods of tens of seconds. These periods correspond to the bounce resonant timescales of the ring current He ions being measured by RBSPICE. A statistical survey using the particle and field data for one full spacecraft precession period (approximately 2 years) shows that the wave and He ion flux variations are generally anticorrelated, suggesting the bounce resonant pitch angle scattering process as a major component in the scattering of He ions.

Identifier

85040656283 (Scopus)

Publication Title

Journal of Geophysical Research Space Physics

External Full Text Location

https://doi.org/10.1002/2017JA023958

e-ISSN

21699402

ISSN

21699380

First Page

12031

Last Page

12039

Issue

12

Volume

122

Grant

NNN06AA01C

Fund Ref

National Aeronautics and Space Administration

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