Yushui Zhong, 雨水 仲, Yang Wang, 洋 汪, Gang Qin and 刚 秦
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引用次数: 0
摘要
Wang 等人最近的一项研究调查了 STEREO-A、STEREO-B 和太阳和日光层观测站航天器观测到的能量大于 10 MeV 的渐变太阳质子事件。针对每个事件,确定了三个航天器中与源区磁连接最好的航天器,并通过拟合分析了航天器观测到的高能质子强度。拟合过程产生了每个事件中四个能量通道(13-16 MeV、20-25 MeV、32-40 MeV 和 40-64 MeV)的两个参数,即 b 和 c。参数 b 和 c 分别控制粒子强度的上升和衰减。统计分析显示,b 和 c 之间存在幂律相关性,用 c ∼ b-γ 表示。在本研究中,为了解释这两个参数之间的关系,我们研究了行星际空间的粒子扩散系数模型。在我们的模拟中,径向平均自由路径被模拟为径向距离的幂函数,成功地再现了 b-c 关系。因此,观测结果表明,径向平均自由路径随径向距离呈幂律变化。在未来的研究中,扩散系数模型有望用于确定高能质子的平均自由路径。
The Mean Free Path of 13–64 MeV Protons Derived from Statistical Results of Solar Energetic Particle Events
A recent study by Wang et al. investigated gradual solar proton events with energies >10 MeV, as observed by STEREO-A, STEREO-B, and the Solar and Heliospheric Observatory spacecraft. For each event, the spacecraft with the best magnetic connection to the source region among the three spacecraft was identified, and energetic proton intensities observed by the spacecraft were analyzed through fitting. The fitting process produced two parameters, b and c, for four energy channels (13–16 MeV, 20–25 MeV, 32–40 MeV, and 40–64 MeV) in each event. Parameters b and c govern the rise and decay of particle intensities, respectively. Statistical analysis revealed a power-law correlation between b and c, expressed as c ∼ b−γ. In this study, in order to explain the relation between the two parameters, we investigate the model of particle diffusion coefficients in the interplanetary space. In our simulations, the radial mean free path is modeled as a power function of radial distance, successfully reproducing the b–c relation. Consequently, the observations demonstrate that the radial mean free path varies with radial distance in a power law. In future research, the model of diffusion coefficients holds promise in determining the mean free path of energetic protons.