COSMIC RAY TRANSPORT IN HELIOSPHERIC MAGNETIC STRUCTURES. I. MODELING BACKGROUND SOLAR WIND USING THE CRONOS MAGNETOHYDRODYNAMIC CODE
COSMIC RAY TRANSPORT IN HELIOSPHERIC MAGNETIC STRUCTURES. I. MODELING BACKGROUND SOLAR WIND USING THE CRONOS MAGNETOHYDRODYNAMIC CODE
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DOI：
10.1088/0004-637x/788/1/80
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发表时间：
2014-05
期刊：
影响因子：
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通讯作者：
T. Wiengarten;J. Kleimann;H. Fichtner;P. Kühl;A. Kopp;B. Heber;R. Kissmann
中科院分区：
文献类型：
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作者：
T. Wiengarten;J. Kleimann;H. Fichtner;P. Kühl;A. Kopp;B. Heber;R. Kissmann
高能粒子（例如宇宙射线）的传输受所穿过的等离子体的特性控制。虽然由于缺乏原位测量，人们对银河和星际等离子体的这些特性知之甚少，但航天器已经对日光层等离子体环境进行了数十年的探测，并为测试传输理论提供了独特的机会。对于高能粒子的三维 (3D) 日光层输运特别感兴趣的是诸如共旋转相互作用区域之类的结构，由于磁场强度、湍流和相关冲击的强烈增强，这些结构一方面可以充当扩散屏障，另一方面也可以充当低能 CR 的加速器。在一系列的论文中，我们通过使用数值磁流体动力学（MHD）设置对日光层内太阳风条件进行建模（本文）来研究这些影响，该设置将作为采用随机微分方程方法的传输代码的输入（第二篇论文）。在第一篇论文中，我们展示了使用代码 CRONOS 进行 3D MHD 模拟的结果：出于验证目的，我们使用分析边界条件并与 Pizzo 的类似工作进行比较。为了对太阳风条件进行更真实的建模，利用通过 Wang-Sheeley-Arge (WSA) 模型从天气磁图导出的边界条件，其中势场建模是使用有限差分方法执行的，这与 WSA 模型中经常使用的传统球谐函数展开相反。我们的结果通过与黄道 (STEREO-A/B) 和黄道外 (Ulysses) 区域的多航天器数据进行比较得到验证。
The transport of energetic particles such as cosmic rays is governed by the properties of the plasma being traversed. While these properties are rather poorly known for galactic and interstellar plasmas due to the lack of in situ measurements, the heliospheric plasma environment has been probed by spacecraft for decades and provides a unique opportunity for testing transport theories. Of particular interest for the three-dimensional (3D) heliospheric transport of energetic particles are structures such as corotating interaction regions, which, due to strongly enhanced magnetic field strengths, turbulence, and associated shocks, can act as diffusion barriers on the one hand, but also as accelerators of low energy CRs on the other hand as well. In a two-fold series of papers, we investigate these effects by modeling inner-heliospheric solar wind conditions with a numerical magnetohydrodynamic (MHD) setup (this paper), which will serve as an input to a transport code employing a stochastic differential equation approach (second paper). In this first paper, we present results from 3D MHD simulations with our code CRONOS: for validation purposes we use analytic boundary conditions and compare with similar work by Pizzo. For a more realistic modeling of solar wind conditions, boundary conditions derived from synoptic magnetograms via the Wang–Sheeley–Arge (WSA) model are utilized, where the potential field modeling is performed with a finite-difference approach in contrast to the traditional spherical harmonics expansion often utilized in the WSA model. Our results are validated by comparing with multi-spacecraft data for ecliptical (STEREO-A/B) and out-of-ecliptic (Ulysses) regions.