Modulation of plasmaspheric hiss intensity by thermal plasma density structure
Modulation of plasmaspheric hiss intensity by thermal plasma density structure
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DOI：
10.1029/2012gl052308
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发表时间：
2012-07
影响因子：
5.2
通讯作者：
Lunjin Chen;R. Thorne;Wen Li;J. Bortnik;D. Turner;V. Angelopoulos
中科院分区：
文献类型：
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作者：
Lunjin Chen;R. Thorne;Wen Li;J. Bortnik;D. Turner;V. Angelopoulos
等离子体层嘶嘶声是一种电磁哨声模式发射，仅限于高密度区域，例如等离子体层和等离子体层羽流。我们提出了日间 THEMIS 事件，表明嘶嘶声发射强度受到热等离子体密度变化的强烈调节。计算出的局部增长率很小（小于 5 dB/RE），并且随着等离子体密度的增加而增加，这部分解释了调制。射线追踪表明，最终演变成等离子层嘶嘶声的合唱射线聚焦于较高密度的场线，并远离较低密度的场线散焦。我们认为观察到的调制是由局部回旋加速器谐振放大与传播过程中射线聚焦的综合效应引起的。
Plasmaspheric hiss is an electromagnetic whistler‐mode emission confined to high density regions such as the plasmasphere and plasmaspheric plumes. We present a dayside THEMIS event showing that the hiss emission intensity is strongly modulated by thermal plasma density variations. The calculated local growth rate is small (less than 5 dB/RE) and increases as the plasma density increases, which partly accounts for the modulation. Ray tracing shows that chorus rays, which eventually evolve into plasmaspheric hiss, are focused towards field lines of higher density and defocused away from field lines of lower density. We suggest that the observed modulation is caused by a combined effect of local cyclotron resonant amplification together with ray focusing during propagation.