The hypothesis of two phases of charged particle acceleration in solar flares is well known, with subrelativistic electrons accelerated in the first phase and relativistic electrons and protons in the second. Both phases are distinguished in the solar proton events and their parent flares of December 26, 2001 (M7.1), November 2, 2003 (X8.3), and August 9, 2011 (X6.9), while in the interplanetary space only electrons were observed from the first phase and electrons and protons from the second. The temporal profiles of the electrons and protons from the second phase are similar; hence, it is concluded that the relativistic electrons and protons observed in the interplanetary space are predominantly accelerated in flares, rather than in the shock front of a coronal mass ejection. Most likely a stochastic acceleration mechanism is realized in flares where protons and electrons gain energy in many elementary events over the entire duration of the flare which lasts much longer than an elementary event. To ensure consistency of a stochastic acceleration process with the existence of two phases in solar flares it is necessary to consider gyrosynchronous radiative electron losses in the second phase which can be neglected in the first phase. The energy of the accelerated protons in the first phase is small for their detection in processes taking place on the sun, but in the second phase it may be sufficient to produce gamma lines, both nuclear and from pion decay.

中文翻译：

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太阳耀斑的两个阶段和电子和质子加速的随机机制

太阳耀斑中带电粒子加速的两个阶段的假设是众所周知的，亚相对论电子在第一阶段加速，相对论电子和质子在第二阶段加速。这两个阶段在 2001 年 12 月 26 日 (M7.1)、2003 年 11 月 2 日 (X8.3) 和 2011 年 8 月 9 日 (X6.9) 的太阳质子事件及其母耀斑中都有区别，而在行星际空间仅从第一相观察到电子，从第二相观察到电子和质子。来自第二相的电子和质子的时间分布相似；因此，可以得出结论，在行星际空间观察到的相对论电子和质子主要在耀斑中加速，而不是在日冕物质抛射的激波前沿。最有可能在耀斑中实现随机加速机制，其中质子和电子在许多基本事件中在整个耀斑持续时间比基本事件持续时间长得多的基本事件中获得能量。为了确保随机加速过程与太阳耀斑中存在两个阶段的一致性，有必要考虑第二阶段中的陀螺同步辐射电子损失，这在第一阶段可以忽略。第一阶段加速质子的能量很小，无法在太阳上发生的过程中检测到，但在第二阶段，它可能足以产生伽马线，包括核衰变和介子衰变。为了确保随机加速过程与太阳耀斑中存在两个阶段的一致性，有必要考虑第二阶段中的陀螺同步辐射电子损失，这在第一阶段可以忽略。第一阶段加速质子的能量很小，无法在太阳上发生的过程中检测到，但在第二阶段，它可能足以产生伽马线，包括核衰变和介子衰变。为了确保随机加速过程与太阳耀斑中存在两个阶段的一致性，有必要考虑第二阶段中的陀螺同步辐射电子损失，这在第一阶段可以忽略。第一阶段加速质子的能量很小，无法在太阳上发生的过程中检测到，但在第二阶段，它可能足以产生伽马线，包括核衰变和介子衰变。