arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2201.00079physics.space-ph
收藏

太阳风电子的动力学膨胀:输运理论和对日球层内部的预测

The Kinetic Expansion of Solar-Wind Electrons: Transport Theory and Predictions for the very Inner Heliosphere

Seong-Yeop Jeong, Daniel Verscharen, Christian Vocks, Joel B. Abraham, Christopher J. Owen, Robert T. Wicks, Andrew N. Fazakerley, David Stansby, Laura Berčič, … 展开作者

Seong-Yeop Jeong, Daniel Verscharen, Christian Vocks, Joel B. Abraham, Christopher J. Owen, Robert T. Wicks, Andrew N. Fazakerley, David Stansby, Laura Berčič, Georgios Nicolaou, Jeffersson A. Agudelo Rueda, Mayur Bakrania

摘要:

我们提出了一个太阳风电子在日光层中动力学演化的输运理论。我们推导出一个陀螺平均动力学输运方程,该方程考虑了太阳风的球形膨胀和帕克螺旋磁场的几何形状。为了解决我们的三维动力学方程,我们开发了一种数学方法,结合曲柄-尼科尔森计划在速度空间和有限差分欧拉计划在配置空间。我们初始化我们的模型与各向同性的电子分布函数和计算的动能膨胀在日心距离从5到20太阳半径。在我们的动力学模型中,电子主要通过弹道粒子流、磁镜力和电场的组合来演化。通过对数值结果的拟合,我们量化了电子速度分布的电子散射和核心部分的参数。strahl拟合参数表明,在20个太阳半径的距离处,电子strahl的密度约为总电子密度的7%,平行于背景磁场的strahl体速度和strahl温度在15个太阳半径的距离之外保持近似恒定,并且$β_{\parallel s}$(即,Strahl平行热压力与磁压力之间的比率)近似恒定,日心距离的值约为0.02。我们将我们的结果与帕克太阳探测器测量的数据进行了比较。此外,我们提供的理论证据表明,电子strahl是不散射的斜快磁声/哨声不稳定性在近太阳环境。

英文摘要:

We propose a transport theory for the kinetic evolution of solar-wind electrons in the heliosphere. We derive a gyro-averaged kinetic transport equation that accounts for the spherical expansion of the solar wind and the geometry of the Parker-spiral magnetic field. To solve our three-dimensional kinetic equation, we develop a mathematical approach that combines the Crank--Nicolson scheme in velocity space and a finite-difference Euler scheme in configuration space. We initialize our model with isotropic electron distribution functions and calculate the kinetic expansion at heliocentric distances from 5 to 20 solar radii. In our kinetic model, the electrons evolve mainly through the combination of the ballistic particle streaming, the magnetic mirror force, and the electric field. By applying fits to our numerical results, we quantify the parameters of the electron strahl and core part of the electron velocity distributions. The strahl fit parameters show that the density of the electron strahl is around 7% of the total electron density at a distance of 20 solar radii, the strahl bulk velocity and strahl temperature parallel to the background magnetic field stay approximately constant beyond a distance of 15 solar radii, and $β_{\parallel s}$ (i.e., the ratio between strahl parallel thermal pressure to the magnetic pressure) is approximately constant with heliocentric distance at a value of about 0.02. We compare our results with data measured by Parker Solar Probe. Furthermore, we provide theoretical evidence that the electron strahl is not scattered by the oblique fast-magnetosonic/whistler instability in the near-Sun environment.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑