Premium
A Comparative Study of the Proton Properties of Magnetospheric Substorms at Earth and Mercury in the Near Magnetotail
Author(s) -
Sun W. J.,
Slavin J. A.,
Dewey R. M.,
Raines J. M.,
Fu S. Y.,
Wei Y.,
Karlsson T.,
Poh G. K.,
Jia X.,
Gershman D. J.,
Zong Q. G.,
Wan W. X.,
Shi Q. Q.,
Pu Z. Y.,
Zhao D.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl079181
Subject(s) - physics , proton , mercury (programming language) , particle acceleration , earth radius , betatron , plasma sheet , computational physics , plasma , planet , adiabatic process , geophysics , atomic physics , magnetosphere , astrophysics , nuclear physics , computer science , programming language , thermodynamics , electron
The variations of plasma sheet proton properties during magnetospheric substorms at Earth and Mercury are comparatively studied. This study utilizes kappa distributions to interpret proton properties at both planets. Proton number densities are found to be around an order of magnitude higher, temperatures several times smaller, and κ values broader at Mercury than at Earth. Protons become denser and cooler during the growth phase, and are depleted and heated after the dipolarizations in both magnetospheres. The changes of κ at Earth are generally small (<20%), indicating that spectrum‐preserving processes, like adiabatic betatron acceleration, play an important role there, while variations of κ at Mercury are large (>60%), indicating the importance of spectrum‐altering processes there, such as acceleration due to nonadiabatic cross‐tail particle motions and wave‐particle interactions. This comparative study reveals important intrinsic properties on the energization of protons in both magnetospheres.