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arXiv 1903.09072physics.space-ph
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在高速太阳风流附近太阳高能质子的行星际传播

Interplanetary spread of solar energetic protons near a high-speed solar wind stream

Nicolas Wijsen, Angels Aran, Jens Pomoell, Stefaan Poedts

摘要:

我们研究了嵌入在慢速太阳风中的高速太阳风流如何影响太阳高能质子在行星际空间的传播。为了模拟高能质子,我们使用了最近开发的粒子输运代码,该代码通过以随机方式求解聚焦输运方程来计算日光层中的粒子分布。粒子在含有CIR的太阳风中传播,CIR由日光层磁流体动力学模型EUHFORIA产生。我们研究了四种情况下,我们假设一个4兆电子伏的质子均匀分布在不同的区域在模型的内边界的三角洲注入。这些源区域具有相同的大小和形状,但在经度上彼此偏移,因此磁性地连接到不同的太阳风条件。沿选定的IMF线的强度和各向异性的配置文件变化强烈,根据不同的太阳风沿场线遇到的条件。穿过冲击边界CIR的IMF线显示了加速粒子群的形成,反向冲击波是比正向冲击波更有效的加速器。此外,我们表明,粒子强度分布的纵向宽度可以增加,减少,或保持不变的日射径向距离,反映了潜在的IMF结构。最后,我们展示了如何在冲击波和压缩的国际货币基金组织在CIR变形的三维形状的颗粒分布在这样一种方式,注射轮廓的原始形状丢失的IMF的偏转。

英文摘要:

We study how a high-speed solar wind stream embedded in a slow solar wind influences the spread of solar energetic protons in interplanetary space. To model the energetic protons, we used a recently developed particle transport code that computes particle distributions in the heliosphere by solving the focused transport equation in a stochastic manner. The particles are propagated in a solar wind containing a CIR, which was generated by the heliospheric magnetohydrodynamic model, EUHFORIA. We study four cases in which we assume a delta injection of 4 MeV protons spread uniformly over different regions at the inner boundary of the model. These source regions have the same size and shape, yet are shifted in longitude from each other, and are therefore magnetically connected to different solar wind conditions. The intensity and anisotropy profiles along selected IMF lines vary strongly according to the different solar wind conditions encountered along the field line. The IMF lines crossing the shocks bounding the CIR show the formation of accelerated particle populations, with the reverse shock wave being a more efficient accelerator than the forward shock wave. Moreover, we demonstrate that the longitudinal width of the particle intensity distribution can increase, decrease, or remain constant with heliographic radial distance, reflecting the underlying IMF structure. Finally, we show how the deflection of the IMF at the shock waves and the compression of the IMF in the CIR deforms the three-dimensional shape of the particle distribution in such a way that the original shape of the injection profile is lost.

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