Extremely intense whistler mode waves near the bow
Extremely intense whistler mode waves near the bow
复制标题
船头附近极其强烈的哨声波
DOI：
10.1029/1998ja900049
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发表时间：
1999
影响因子：
2.3
通讯作者：
Y. Omura
中科院分区：
文献类型：
--
作者：
Yongliang Zhang;H. Matsumoto;H. Kojima;Y. Omura
在弓形激波中，Geotail卫星上的波形捕获器经常记录到振幅高达101 nT的非常强烈的哨声模式波。强哨声波的频率范围为0.02 ~ 0.56Ωe（10 ~ 400 Hz），持续时间为几十~几百毫秒。这些强烈的哨声波以准平行于环境磁场的方向传播，平均角度为22°。大部分（约80%）的强烈哨声波向下游方向传播，只有20%的哨声波向太阳风方向传播。激波法线角在66° ~ 86°之间的准垂直激波与强哨声波有关。准平行传播表明电子回旋共振是激发强哨声波的主要机制。结果表明，在准垂直弓形激波底部具有温度各向异性的损失锥电子是强哨声波的主要来源。由弓形激波内的电场形成的电子束很可能是那些向上游方向传播的哨声的来源。这些强烈的哨声波的电子陷阱可以部分解释平顶电子分布在下游边缘的弓形激波。
Very intense whistler mode waves with amplitudes up to ∼1 nT were frequently recorded by the Waveform Capture on board the Geotail satellite in the bow shock. The intense whistler waves cover a frequency range from 0.02 to 0.56Ωe (10 ∼ 400 Hz) with durations from tens to hundreds of milliseconds. These intense whistler waves propagate in a direction quasi-parallel to the ambient magnetic field with an average angle of 22°. Most (∼80%) of the intense whistler waves propagate in a downstream direction, while only 20% of them propagate toward solar wind. Quasi-perpendicular shocks with shock normal angles from 66° to 86° are associated with the intense whistler waves. The quasi-parallel propagation indicates that the electron cyclotron resonance is the dominant mechanism for the excitation of the intense whistler waves. It is found that loss cone electrons with temperature anisotropy at the foot of quasi-perpendicular bow shocks are the major source of the intense whistler waves. The electron beams, formed by an electric field within the bow shock, are very likely the source of those whistlers propagating in an upstream direction. Trapping of electrons by these intense whistler waves may partially explain the flat-topped electron distribution at the downstream edge of the bow shock.