Pick‐up ions and the 2–3 kHz radio emissions
Pick‐up ions and the 2–3 kHz radio emissions
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拾取离子和 2-3 kHz 无线电发射
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
J. Heerikhuisen
中科院分区：
文献类型：
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作者：
J. Mitchell;I. Cairns;J. Heerikhuisen
旅行者号宇宙飞船观测到的2-3千赫的无线电发射被认为是在拾取离子驱动低混合波的地方开启的。以前的工作集中在通过与内日鞘的中性电荷交换产生的拾取离子上。然而，玻尔兹曼模拟表明，与流体模拟相比，内部日鞘中性粒子在穿过日层顶后的速度要低得多。我们计算了由与各种中性物质的电荷交换所产生的吸收离子分布，发现在超音速太阳风中产生的中性离子具有环束分布，而日鞘内的中性离子则不具有环束分布。以超声速太阳风中性离子作为吸收离子源，发射理论仍然存在。这导致环束和电子尾速度、可用的低混合波能量和无线电通量的增加。较大的环速度增加了所需的磁场到0.2 nT，限制了源的位置，并且预测磁场强度与日球层和星际介质模型一致。
The 2–3 kHz radio emissions observed by the Voyager spacecraft are thought to turn on where pick‐up ions drive lower‐hybrid waves. Previous work focused on pick‐up ions born via charge exchange with neutrals from the inner heliosheath. However, Boltzmann simulations show that inner heliosheath neutrals have significantly lower speeds after crossing the heliopause compared with fluid simulations. We calculate the pick‐up ion distributions resulting from charge exchange with various neutral species, finding that neutrals born in the supersonic solar wind give a ring‐beam distribution, but inner heliosheath neutrals do not. The emission theory survives with supersonic solar wind neutrals as the pick‐up ion source. This leads to increases in the ring‐beam and electron tail speeds, available lower‐hybrid wave energy, and radio flux. Larger ring speeds increase the necessary magnetic field to ≳0.2 nT, constraining the source location, and predicting magnetic field strengths agreeing with heliosphere and interstellar medium models.