Parametric interaction and spatial collapse of beam-driven Langmuir waves in the solar wind. [upstream of Jupiter bow shock]
Parametric interaction and spatial collapse of beam-driven Langmuir waves in the solar wind. [upstream of Jupiter bow shock]
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DOI：
10.1029/ja086ia10p08833
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发表时间：
1981-09
期刊：
影响因子：
--
通讯作者：
D. Gurnett;J. Maggs;D. Gallagher;W. Kurth;F. Scarf
中科院分区：
文献类型：
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作者：
D. Gurnett;J. Maggs;D. Gallagher;W. Kurth;F. Scarf
本文介绍了观测的参数衰减和空间坍缩的朗缪尔波驱动的电子束流到太阳风从木星弓形冲击。旅行者1号和旅行者2号的高分辨率频率-时间谱图显示，弓形激波上游的长波长朗缪尔波非常有效地转换为短波长朗缪尔波，不再与光束共振。这种转换被证明是一个非线性相互作用的结果，涉及的光束驱动泵，边带发射和低水平的离子声湍流总是出现在太阳风中。的相互作用的发病发生在大约的时间，泵波的振幅饱和，这表明参数过程可能在稳定的电子束中发挥重要作用。对电场波形的详细研究表明，光束驱动的朗缪尔波发射分裂成一个非常复杂的边带结构，具有正和负的多普勒频移。正频移对应于远离太阳传播的波，负频移对应于向太阳传播的波。在某些情况下，边带辐射由持续时间非常短的孤立波包组成，有时仅持续几毫秒。这些短时间的爆发，通常是非常强烈的，被认为是由信封孤子已经崩溃到只有几个德拜长度的空间尺度。«少
This paper presents observations of the parametric decay and spatial collapse of Langmuir waves driven by an electron beam streaming into the solar wind from the Jovian bow shock. High-resolution frequency-time spectrograms from Voyager 1 and 2 show that long wavelength Langmuir waves upstream of the bow shock are very effectively converted into short wavelength Langmuir waves which are no longer in resonance with the beam. This conversion is shown to be the results of a nonlinear interaction involving the beam-driven pump, a sideband emission and a low level of ion-acoustic turbulence which always appears to be present in the solar wind. The onset of the interaction occurs at about the time that the amplitude of the pump wave saturates, which indicates that parametric processes are probably playing an important role in stablizing the electron beam. Detailed examination of the electric field wave-forms shows the beam-driven Langmuir wave emission breaks up into a very complex sideband structure with both positive and negative Doppler shifts.Positive frequency shifts correspond to waves propagating away from the sun and negative frequency shifts correspond to waves propagating toward the sun. In some cases the sideband emissions consist of isolated wave packets with very short durations,more » sometimes lasting only a few msec. These short duration bursts, which are usually very intense, are thought to consist of envelope solitons which have collapsed down to spatial scales of only a few Debye lengths.« less