| Autor: |
Zhou, Yaxiong1,2 (AUTHOR), Gao, Yang1,2 (AUTHOR), Gao, Zhonglei1,2 (AUTHOR) gaozhl@outlook.com, Liu, Si1,2 (AUTHOR) liu.si@hotmail.com, Yang, Hongming3 (AUTHOR), Shi, Chen1,2 (AUTHOR), Yang, Qiwu1,2 (AUTHOR), Tang, Jiawen1,2 (AUTHOR), Wang, Bowen1,2 (AUTHOR), Xiao, Fuliang1,2 (AUTHOR) |
| Předmět: |
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| Zdroj: |
Journal of Geophysical Research. Space Physics. Oct2024, Vol. 129 Issue 10, p1-10. 10p. |
| Abstrakt: |
Magnetosonic (MS) waves usually manifest as electromagnetic fluctuations, while quasi‐electrostatic magnetosonic (QEMS) waves have been recently reported. Here we present an intriguing coexistence of low harmonic electromagnetic magnetosonic (EMMS) waves and QEMS waves within the same band. Ion Bernstein instabilities are calculated based on the observed proton distribution. Effective growth rates >10−5 $\left(> 1{0}^{-5}\right)$ can occur in the first‐fourth harmonic bands with a broad wave number k $k$ range when the wave normal angle is sufficiently large. In each harmonic band, the MS waves would transform from electromagnetic to electrostatic as the wave number increases. This study reveals that the simultaneous occurrence of EMMS and QEMS arises from the expansive excitation range of MS waves in k $k$‐space, thereby implying the potential resonant interactions between MS and particles in a broad energy spectrum. Plain Language Summary: Magnetosonic (MS) waves are a type of space plasma wave that usually have both electric and magnetic components (EMMS). Recently, another kind of MS wave that only the electric component can be observed, called quasi‐electrostatic magnetosonic (QEMS), was discovered. In this study, we find an interesting event that EMMS and QEMS occurred in the same frequency range. We examine whether the proton distribution can be responsible for the coexistence of EMMS and QEMS waves. Our calculations show that when the angle between the waves and the ambient magnetic field is large enough, these waves can grow pretty quickly in the first four harmonic bands, even with a wide variety of wavelengths. As the wavelength gets shorter within each band, the EMMS waves can change into the QEMS ones. Our findings demonstrate that both EMMS and QEMS waves can indeed be excited at the same time because MS waves can be generated across a large range of wavelengths. This also means that MS waves might interact with particles over a wide energy range. Key Points: Observations show an interesting coexistence of electromagnetic and quasi‐electrostatic magnetosonic waves in low harmonic bandsMS waves can be generated across a wide range of wave numbers within the same harmonic bandAs the wave number increases, a transition from electromagnetic to quasi‐electrostatic magnetosonic waves would occur [ABSTRACT FROM AUTHOR] |
| Databáze: |
GreenFILE |
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