Solar energetic particles, or SEPs, from suprathermal (few keV) up to relativistic (\(\sim \)few GeV) energies are accelerated near the Sun in at least two ways: (1) by magnetic reconnection-driven processes during solar flares resulting in impulsive SEPs, and (2) at fast coronal-mass-ejection-driven shock waves that produce large gradual SEP events. Large gradual SEP events are of particular interest because the accompanying high-energy (\({>}10\)s MeV) protons pose serious radiation threats to human explorers living and working beyond low-Earth orbit and to technological assets such as communications and scientific satellites in space. However, a complete understanding of these large SEP events has eluded us primarily because their properties, as observed in Earth orbit, are smeared due to mixing and contributions from many important physical effects. This paper provides a comprehensive review of the current state of knowledge of these important phenomena, and summarizes some of the key questions that will be addressed by two upcoming missions—NASA’s Solar Probe Plus and ESA’s Solar Orbiter. Both of these missions are designed to directly and repeatedly sample the near-Sun environments where interplanetary scattering and transport effects are significantly reduced, allowing us to discriminate between different acceleration sites and mechanisms and to isolate the contributions of numerous physical processes occurring during large SEP events.

中文翻译：

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大型逐渐的太阳高能粒子事件。

太阳能量粒子或SEP，从超热（很少keV）到相对论（\（\ sim \）很少GeV）能量在太阳附近以至少两种方式被加速：（1）在太阳耀斑期间通过磁重联驱动过程导致冲动性SEP，以及（2）在快速的日冕物质喷射驱动的冲击波产生大的渐进性SEP事件。大型渐进式SEP事件特别令人感兴趣，因为伴随着高能量（\（{>} 10 \）s MeV）质子对生活和工作在低地球轨道以外的人类探索者以及诸如太空中的通信和科学卫星之类的技术资产构成了严重的辐射威胁。然而，对这些大型SEP事件的完整理解使我们难以理解，这主要是因为它们在地球轨道上观察到的特性由于混合和许多重要物理效应的贡献而被抹去了。本文对这些重要现象的当前知识状态进行了全面回顾，并总结了两个即将执行的任务（NASA的Solar Probe Plus和ESA的Solar Orbiter）将解决的一些关键问题。这两个任务都旨在直接和重复地采样近日太阳环境，在这些环境中行星际散射和传输效应大大降低，