Two-Dimensional Hybrid Particle-in-Cell Simulations of Magnetosonic Waves in the Dipole Magnetic Field: On a Constant L-Shell

Min，Kyungguk1; Liu，Kaijun2; Denton，Richard E.3; Němec，František4; Boardsen，Scott A.5,6; Miyoshi，Yoshizumi7

2020-10-01

10.1029/2020JA028414

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS   影响因子和分区

2169-9380

2169-9402

Two-dimensional hybrid particle-in-cell (PIC) simulations are carried out on a constant L-shell (or drift shell) surface of the dipole magnetic field to investigate the generation process of near-equatorial fast magnetosonic waves (a.k.a equatorial noise; MSWs hereafter) in the inner magnetosphere. The simulation domain on a constant L-shell surface adopted here allows wave propagation and growth in the azimuthal direction (as well as along the field line) and is motivated by the observations that MSWs propagate preferentially in the azimuthal direction in the source region. Furthermore, the equatorial ring-like proton distribution used to drive MSWs in the present study is (realistically) weakly anisotropic. Consequently, the ring-like velocity distribution projected along the field line by Liouville's theorem extends to rather high latitude, and linear instability analysis using the local plasma conditions predicts substantial MSW growth up to ±27° latitude. In the simulations, however, the MSW intensity maximizes near the equator and decreases quasi-exponentially with latitude. Further analysis reveals that the stronger equatorward refraction at higher latitude due to the larger gradient of the dipole magnetic field strength prevents off-equatorial MSWs from growing continuously, whereas MSWs of equatorial origin experience little refraction and can fully grow. Furthermore, the simulated MSWs exhibit a rather complex wave field structure varying with latitude, and the scattering of energetic ring-like protons in response to MSW excitation occurs faster than the bounce period of those protons so that they do not necessarily follow Liouville's theorem during MSW excitation.

equatorial noise magnetosonic waves PIC simulation in dipole geometry

SCI

英语

其他

National Research Foundation of Korea (NRF) - Korea government (MSIT)[2020R1C1C1009996] ; National Natural Science Foundation of China (NSFC)[41974168] ; NSF[AGS-1602469] ; NASA["80NSSC19K0270","NAS5-01072"] ; GACR[18-00844S] ; JSPS[20H01959] ; National Supercomputing Center[KSC-2019-CRE-0003]

Astronomy & Astrophysics

Astronomy & Astrophysics

WOS:000600990300071

AMER GEOPHYSICAL UNION

SPACE SCIENCE

2-s2.0-85093936386

Scopus

1.Department of Astronomy and Space Science,Chungnam National University,Daejeon,South Korea
2.Department of Earth and Space Sciences,Southern University of Science and Technology,Shenzhen,China
3.Department of Physics and Astronomy,Dartmouth College,Hanover,United States
4.Faculty of Mathematics and Physics,Charles University,Prague,Czech Republic
5.NASA/GSFC,Greenbelt,United States
6.Goddard Planetary Heliophysics Institute,University of Maryland,Baltimore,United States
7.ISEE,Nagoya University,Nagoya,Japan

Min，Kyungguk,Liu，Kaijun,Denton，Richard E.,et al. Two-Dimensional Hybrid Particle-in-Cell Simulations of Magnetosonic Waves in the Dipole Magnetic Field: On a Constant L-Shell[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS,2020,125(10).

Min，Kyungguk,Liu，Kaijun,Denton，Richard E.,Němec，František,Boardsen，Scott A.,&Miyoshi，Yoshizumi.(2020).Two-Dimensional Hybrid Particle-in-Cell Simulations of Magnetosonic Waves in the Dipole Magnetic Field: On a Constant L-Shell.JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS,125(10).

Min，Kyungguk,et al."Two-Dimensional Hybrid Particle-in-Cell Simulations of Magnetosonic Waves in the Dipole Magnetic Field: On a Constant L-Shell".JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 125.10(2020).