Unusual high frequency EMIC waves: Detailed analysis of EMIC wave excitation and energy coupling between EMIC and magnetosonic waves

Min，Kyungguk1; Kim，Jiwoo1; Ma，Qianli2,5; Jun，Chae Woo3; Liu，Kaijun4

2021

10.1016/j.asr.2021.07.039

ADVANCES IN SPACE RESEARCH   影响因子和分区

0273-1177

1879-1948

A recent event study suggested a coupling process whereby suprathermal protons (10–100 eV), as a result of perpendicular heating by pre-existing magnetosonic waves, can excite electromagnetic ion cyclotron (EMIC) waves with frequency near the local proton cyclotron frequency (f~0.95f). The present study tests this coupling process. First, one-dimensional hybrid (kinetic ions/massless fluid electrons) simulations of parallel-propagating EMIC waves initialized with the plasma conditions derived from the event prove that high frequency EMIC waves can be generated by anisotropic suprathermal protons instead of more energetic (10s of keV) ring current protons. Calculation of the quasilinear pitch-angle diffusion coefficient for electrons using the simulated waves suggests that these high frequency EMIC waves outside the plasmasphere can play a role in the pitch-angle scattering of ~MeV electrons due to the large wavenumber of the excited EMIC waves. Second, the role of the pre-existing magnetosonic waves in the suprathermal proton heating is examined using quasilinear diffusion theory and simple test particle calculation. It is found that the quasilinear diffusion becomes ineffective in energies relevant to the suprathermal protons, indicating that the low-energy (<10 eV) protons cannot be efficiently energized to the observed level through multi-harmonic cyclotron resonances with the magnetosonic waves observed. Rather, some kind of non-resonant process may have been at play, if the magnetosonic waves were actually involved in the heating. This result suggests that more quantitative understanding of the suggested energy coupling process through magnetosonic waves is needed.

EMIC waves Energy coupling Magnetosonic waves Suprathermal protons

SCI ; EI

英语

其他

NASA[80NSSC20K0196] ; National Natural Science Foundation of China (NSFC)[41974168]

Engineering ; Astronomy & Astrophysics ; Geology ; Meteorology & Atmospheric Sciences

Engineering, Aerospace ; Astronomy & Astrophysics ; Geosciences, Multidisciplinary ; Meteorology & Atmospheric Sciences

WOS:000734338000005

ELSEVIER SCI LTD

20213410808803

Cyclotrons ; Diffusion ; Ions

Particle Accelerators:932.1.1

SPACE SCIENCE

2-s2.0-85113237721

Scopus

1.Department of Astronomy and Space Science,Chungnam National University,Daejeon,South Korea
2.Department of Atmospheric and Oceanic Sciences,University of California,Los Angeles,United States
3.Institute for Space-Earth Environmental Research (ISEE),Nagoya University,Nagoya,Japan
4.Department of Earth and Space Sciences,Southern University of Science and Technology,Shenzhen,China
5.Center for Space Physics,Boston University,Boston,United States

Min，Kyungguk,Kim，Jiwoo,Ma，Qianli,et al. Unusual high frequency EMIC waves: Detailed analysis of EMIC wave excitation and energy coupling between EMIC and magnetosonic waves[J]. ADVANCES IN SPACE RESEARCH,2021,69(1):35-47.

Min，Kyungguk,Kim，Jiwoo,Ma，Qianli,Jun，Chae Woo,&Liu，Kaijun.(2021).Unusual high frequency EMIC waves: Detailed analysis of EMIC wave excitation and energy coupling between EMIC and magnetosonic waves.ADVANCES IN SPACE RESEARCH,69(1),35-47.

Min，Kyungguk,et al."Unusual high frequency EMIC waves: Detailed analysis of EMIC wave excitation and energy coupling between EMIC and magnetosonic waves".ADVANCES IN SPACE RESEARCH 69.1(2021):35-47.