Details

Autor(en) / Beteiligte

• Ma, Q.
• Li, W.
• Yue, C.
• Thorne, R. M.
• Bortnik, J.
• Kletzing, C. A.
• Kurth, W. S.
• Hospodarsky, G. B.
• Reeves, G. D.
• Spence, H. E.

Titel

Ion Heating by Electromagnetic Ion Cyclotron Waves and Magnetosonic Waves in the Earth's Inner Magnetosphere

Ist Teil von

• Geophysical research letters, 2019-06, Vol.46 (12), p.6258-6267

Ort / Verlag

Washington: John Wiley & Sons, Inc

Erscheinungsjahr

2019

Link zum Volltext

Quelle

Wiley Online Library All Journals

Beschreibungen/Notizen

• 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