The Solar Wind Electron Halo as Produced by Electron Beams Originating in the Lower Corona: Beam Density Dependence
The Solar Wind Electron Halo as Produced by Electron Beams Originating in the Lower Corona: Beam Density Dependence
复制标题
由源自日冕下部的电子束产生的太阳风电子晕：束密度依赖性
作者：
H. Che;M. Goldstein;C. Salem;A. Viñas
有人认为，在太阳风电子速度分布函数中观察到的各向同性电子晕可能源于来自太阳表面的1.1 R以下的纳米级加速电子束通过非线性电子双流不稳定性（ETSI）。该模型统一了动力波、电子晕和日冕弱III型爆发的起源，并在太阳风观测值和纳米耀斑中的电子动力学之间建立了联系。该模型的一个重要预测是晕核温度比与密度比呈负相关，最小值为0.44，这是ETSI加热的遗迹，与太阳风观测结果一致。然而，电子束的密度和相对漂移如何决定太阳风电子的热性质还不清楚。在本文中，使用一组粒子在细胞模拟和动力学理论，我们表明，一个各向同性晕发展的必要条件是，束流密度nb和背景n 0的比例低于临界值Nc <$0.3。随着束流密度的减小，芯电子的加热减弱，而晕电子的加热增强。结果表明，随着束流密度的减小，晕电子与芯电子的温度比增大，从而解释了所预言的晕电子与芯电子的温度关系的物理意义。我们将这些结果应用到当前的观测中，并讨论了纳米片中可能产生的电子束密度。
It has been suggested that the isotropic electron halo observed in the solar wind electron velocity distribution function may originate from nanoflare-accelerated electron beams below 1.1 R⊙ from the solar surface through the nonlinear electron two-stream instability (ETSI). This model unifies the origins of kinetic waves, the electron halo, and the coronal weak Type III bursts, and establishes a link between the solar wind observables and the electron dynamics in nanoflares. One of the important predictions of this model is that the halo-core temperature ratio is anticorrelated with the density ratio, and the minimum ratio is ∼4, a relic of the ETSI heating and has been found to be consistent with solar wind observations. However, how the density and relative drift of the electron beams determine the thermal properties of solar wind electrons is unclear. In this paper, using a set of particle-in-cell simulations and kinetic theory, we show that a necessary condition for an isotropic halo to develop is that the ratio of beam density nb and the background n0 be lower than a critical value Nc ∼ 0.3. Heating of the core electrons becomes weaker with decreasing beam density, while the heating of halo electrons becomes stronger. As a result, the temperature ratio of the halo and core electrons increases with the decrease of the beam density, explaining the physical meaning of the predicted anticorrelated relation. We apply these results to the current observations and discuss the possible electron beam density produced in the nanoflares.
影响因子：
1.9
作者：
A. Macneil;C. Owen;R. Wicks
通讯作者：
A. Macneil;C. Owen;R. Wicks
DOI：
10.1088/1742-6596/1100/1/012025
发表时间：
2018-07
期刊：
Journal of Physics: Conference Series
影响因子：
--
作者：
B. Tang;G. Zank;V. Kolobov
通讯作者：
B. Tang;G. Zank;V. Kolobov
研究 IMF 路径长度对 1 au 内 Strahl 俯仰角散射的影响
DOI：
10.3847/1538-4357/aaaf1b
发表时间：
2018
期刊：
The Astrophysical Journal
影响因子：
--
作者：
Graham G
通讯作者：
Graham G