Journal article
Ion Heating by Electromagnetic Ion Cyclotron Waves and Magnetosonic Waves in the Earth's Inner Magnetosphere
Geophysical research letters, Vol.46(12), pp.6258-6267
06/28/2019
DOI: 10.1029/2019GL083513
Abstract
Electromagnetic ion cyclotron (EMIC) waves and magnetosonic waves are commonly observed in the Earth's magnetosphere associated with enhanced ring current activity. Using wave and ion measurements from the Van Allen Probes, we identify clear correlations between the hydrogen‐ and helium‐band EMIC waves with the enhancement of trapped helium and oxygen ion fluxes, respectively. We calculate the diffusion coefficients of different ion species using quasi‐linear theory to understand the effects of resonant scattering by EMIC waves. Our calculations indicate that EMIC waves can cause pitch angle scattering loss of several keV to hundreds of keV ions, and heating of tens of eV to several keV helium and oxygen ions by hydrogen‐ and helium‐band EMIC waves, respectively. Moreover, we found that magnetosonic waves can cause the resonant heating of thermal protons. Our study indicates the importance of energy transfer from the EMIC and magnetosonic waves to ions with different species at thermal energies.
Plain Language Summary
Electromagnetic ion cyclotron (EMIC) waves and magnetosonic waves are plasma waves commonly observed in the Earth's magnetosphere. The EMIC waves and magnetosonic waves are associated with the ions drifting around the Earth. We use satellite observations of the plasma waves and ions to study the relation between EMIC or magnetosonic waves with ions at thermal energies. The measurement clearly indicates the correlation between the enhancement of proton, helium, and oxygen fluxes with magnetosonic waves, hydrogen‐band EMIC waves, and helium‐band EMIC waves, respectively. We use the physics‐based model to quantify the possible heating of ions with different species by different wave modes. Our calculation suggests that the protons, helium, and oxygen ions at thermal energies could be effectively heated by magnetosonic waves, hydrogen‐band EMIC waves, and helium‐band EMIC waves, respectively. The model results explain the measured correlation between the ions and waves. Our study suggests that the EMIC and magnetosonic waves which are generated by the ions in ring current could transfer energy to the lower energy ions.
Key Points
EMIC waves in different frequency bands and magnetosonic waves are correlated with the enhancement of ion fluxes of different species
EMIC and magnetosonic waves could heat different ion species at thermal energies through resonant interaction
Field‐aligned thermal ions are accelerated to larger pitch angles and trapped ion fluxes increase due to the EMIC and magnetosonic waves
Details
- Title: Subtitle
- Ion Heating by Electromagnetic Ion Cyclotron Waves and Magnetosonic Waves in the Earth's Inner Magnetosphere
- Creators
- Q. Ma - University of California, Los AngelesW. Li - University of California, Los AngelesC. Yue - University of CaliforniaR. M. Thorne - University of California, Los AngelesJ. Bortnik - University of California, Los AngelesC. A. Kletzing - University of IowaW. S. Kurth - University of IowaG. B. Hospodarsky - University of IowaG. D. Reeves - Los Alamos National LaboratoryH. E. Spence - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Geophysical research letters, Vol.46(12), pp.6258-6267
- DOI
- 10.1029/2019GL083513
- ISSN
- 0094-8276
- eISSN
- 1944-8007
- Number of pages
- 10
- Grant note
- AFOSR (FA9550‐15‐1‐0158) JHU/APL (967399; 921647) NSF (AGS‐1723588) NASA (NAS5‐01072; NNX16AG21G; NNX15AI96G; NNX11AR64G; NNH14AI18G; NNX14AN85G; NNX14AI18G) Alfred P. Sloan (FG‐2018‐10936)
- Language
- English
- Date published
- 06/28/2019
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984428828902771
Metrics
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