Quasilinear Model of Jovian Whistler Mode Emission
Quasilinear Model of Jovian Whistler Mode Emission
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DOI：
10.1029/2021ja029930
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发表时间：
2021-11
期刊：
影响因子：
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通讯作者：
P. Yoon;J. Menietti;W. Kurth;F. Allegrini;S. Bolton
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文献类型：
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作者：
P. Yoon;J. Menietti;W. Kurth;F. Allegrini;S. Bolton
木星磁层环境中的朱诺卫星普遍检测到了口哨模式合唱发射。本文特别关注朱诺号于 2019 年 11 月 3 日进行的样本观测，其中测量了典型的哨声模式合唱波。发射的特点是波频率范围很广，从低于 fce/2 开始，其中 fce 表示局部电子回旋频率，一直到较低的混合频率，并且频率随着时间的推移逐渐下移。激发似乎与“蝴蝶”俯仰角分布的检测以及与高能电子相关的预期损失锥特征相一致。随着波被激发并且电子相空间分布变得各向同性，这些各向异性特征，特别是蝶形俯仰角分布逐渐消失。本文的目的是通过拟线性动力学理论对由具有窄损失锥角的损失锥电子分布函数驱动的哨子不稳定性的特征进行建模，这在木星磁层的低纬度地区是可以预期的。结果表明，理论上构建的动态波谱与 2019 年 11 月 3 日的观测结果一致。目前的发现表明，拟线性理论可以成为解释各种木星等离子体波发射的强大理论工具，其中包括哨声波，但也包括其他波模式。
The whistler mode chorus emissions are pervasively detected by the Juno satellite in Jupiter’s magnetospheric environment. This article pays particular attention to a sample observation made by the Juno on 3 November 2019, where typical whistler mode chorus waves are measured. The emission is characterized by a broad range of wave frequencies from below fce/2, where fce denotes the local electron cyclotron frequency, down to the lower‐hybrid frequency, with a gradually downshifting frequency over time. The excitation appears to coincide with the detection of a “butterfly” pitch‐angle distribution and the expected loss‐cone feature associated with the energetic electrons. These anisotropic features, especially the butterfly pitch‐angle distribution, gradually disappear as the waves are excited and the electron phase space distribution becomes isotropic. The aim of this article is to model the characteristics by means of quasilinear kinetic theory of the whistler instability driven by a loss‐cone electron distribution function with a narrow loss‐cone angle, which is to be expected from low‐latitude regions of the Jovian magnetosphere. It is shown that the theoretically constructed dynamic wave spectrum is consistent with the observation made on 3 November 2019. The present finding demonstrates that the quasilinear theory can be a powerful theoretical tool for interpreting various Jovian plasma wave emissions, which includes the whistler waves, but also other wave modes.