arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2005.12606physics.plasm-phastro-ph.SR
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太阳风中的准平行哨声波

On quasi-parallel whistler waves in the solar wind

I. Y. Vasko, I. V. Kuzichev, A. V. Artemyev, S. D. Bale, J. W. Bonnell, F. S. Mozer

摘要:

最近的模拟表明,哨声热通量不稳定性,这可能是产生大部分的准平行相干哨声波在太阳风,是不是有效的调节电子热传导。此外,最近的航天器测量表明,太阳风中的相干哨声波的一部分可能传播反平行于电子热通量,是由于超热电子的垂直温度各向异性。我们目前的分析性质的平行和反平行哨声波不稳定的电子热通量和温度各向异性的超热电子典型的原始太阳风。假设电子人口组成的逆流稠密的热核和纤细的超热晕人口,我们进行了线性稳定性分析,以证明反平行哨声波预计有较小的频率,波数和增长率相比,平行哨声波。的稳定性分析进行了广泛的参数范围内的核心和晕电子种群。使用准线性标度关系,我们表明,反平行哨声波饱和的幅度比平行哨声波小一个数量级,这是在原始的太阳风约$10^{-3}\;B_0$。分析表明,在原始的太阳风的反平行哨声波的存在更容易被掩盖的湍流磁场波动,因为较低的频率和较小的振幅相比,平行哨声波。所得结果对太阳风电子热通量调节的数值模拟也有参考价值。

英文摘要:

The recent simulations showed that the whistler heat flux instability, which presumably produces the most of quasi-parallel coherent whistler waves in the solar wind, is not efficient in regulating the electron heat conduction. In addition, recent spacecraft measurements indicated that some fraction of coherent whistler waves in the solar wind may propagate anti-parallel to the electron heat flux, being produced due to a perpendicular temperature anisotropy of suprathermal electrons. We present analysis of properties of parallel and anti-parallel whistler waves unstable at electron heat fluxes and temperature anisotropies of suprathermal electrons typical of the pristine solar wind. Assuming the electron population consisting of counter-streaming dense thermal core and tenuous suprathermal halo populations, we perform a linear stability analysis to demonstrate that anti-parallel whistler waves are expected to have smaller frequencies, wave numbers and growth rates compared to parallel whistler waves. The stability analysis is performed over a wide range of parameters of core and halo electron populations. Using the quasi-linear scaling relation we show that anti-parallel whistler waves saturate at amplitudes of one order of magnitude smaller than parallel whistler waves, which is at about $10^{-3}\;B_0$ in the pristine solar wind. The analysis shows that the presence of anti-parallel whistler waves in the pristine solar wind is more likely to be obscured by turbulent magnetic field fluctuations, because of lower frequencies and smaller amplitudes compared to parallel whistler waves. The presented results will be also valuable for numerical simulations of the electron heat flux regulation in the solar wind.

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