Ring Current He Ion Control by Bounce Resonant ULF Waves

Hyomin Kim, Andrew Gerrard, Louis J. Lanzerotti, Angel Soto Chavez, Ross J. Cohen, Jerry W. Manweiler

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)12031-12039
Number of pages9
JournalJournal of Geophysical Research: Space Physics
Issue number12
StatePublished - Dec 2017

All Science Journal Classification (ASJC) codes

  • Space and Planetary Science
  • Geophysics


  • ULF waves
  • bounce resonance
  • helium ion
  • ring current


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