التفاصيل البيبلوغرافية
| العنوان: |
Ion‐Acoustic Waves in a Quasi‐Perpendicular Earth's Bow Shock. |
| المؤلفون: |
Vasko, I. Y., Mozer, F. S., Bale, S. D., Artemyev, A. V. |
| المصدر: |
Geophysical Research Letters; 6/16/2022, Vol. 49 Issue 11, p1-10, 10p |
| مصطلحات موضوعية: |
ELECTRIC field strength, ION acoustic waves, THERMAL electrons, ELECTRIC potential, DEBYE length, ELECTRIC waves, CORONAL mass ejections, ACOUSTIC wave propagation |
| مستخلص: |
We present analysis of electrostatic waves around the ramp of a quasi‐perpendicular Earth's bow shock observed by the Magnetospheric Multiscale spacecraft. The electrostatic waves have amplitudes up to 800 mV/m, which is the largest value ever reported in the Earth's bow shock. In contrast to previous studies, the electrostatic waves have large amplitudes of the electrostatic potential, up to 20 V or 20% of local electron temperature. The wavelengths are from 150 m to 3 km, that is from 15 to 300 Debye lengths and typically from 0.4 to 1.5 thermal electron gyroradii. Importantly, these waves can propagate not only quasi‐parallel or oblique, but also almost perpendicular to local magnetic field. The electrostatic waves are interpreted in terms of ion‐acoustic waves, although the presence of electron cyclotron harmonic waves cannot be entirely ruled out. These results suggest that electrostatic waves may strongly affect the dynamics of electrons in collisionless shocks. Plain Language Summary: Electrostatic fluctuations are always present around collisionless shocks observed in the heliosphere. However, the effects of these fluctuations on the shock dynamics have not been quantified yet, mostly because experimental studies of their properties are scarce and, moreover, limited to electric field measurements in a spacecraft spin plane. We present analysis of electrostatic waves in a quasi‐perpendicular Earth's bow shock using three‐component electric field measurements aboard the Magnetospheric Multiscale spacecraft. We show that electrostatic waves have rather high amplitudes of the electrostatic potential, wavelengths comparable with thermal electron gyroradius, and can propagate at various angles to local magnetic field, including almost perpendicular propagation. The revealed properties indicate that electrostatic waves may be efficient in pitch‐angle scattering/demagnetization of electrons in collisionless shocks, thereby potentially facilitating electron heating and thermalization. Key Points: Ion‐acoustic waves have electric field amplitudes up to 800 mV/m and electrostatic potential amplitudes up to 20 VThe typical wavelength of ion‐acoustic waves is comparable with thermal electron gyroradiusIon‐acoustic waves can propagate at arbitrary angles to local magnetic field, including almost perpendicular propagation [ABSTRACT FROM AUTHOR] |
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