Ring current decay during storm recovery phase may be affected by different loss processes. In this study, we have investigated the lifetimes of ring current ions (H⁺ and O⁺) of energies from 1 keV to several hundred keV at L shell from 3 to 6 during the storm recovery phase through a statistical survey. The observational data of 48 geomagnetic storms from March 2013 to May 2019 are collected based on Van Allen Probe observations. We find that (1) the observed lifetimes of H⁺ and O⁺ in general increase with L shell and (2) the lifetimes of H⁺ is short than that of O⁺ when E < ∼50 keV while the situation is reversed when E > ∼50 keV. In addition, we have made use of the charge exchange theory, combined with previous experimental results on the charge exchange cross section and two distribution models of neutral hydrogen atoms in the exosphere, so as to directly estimate the ring current ions decay caused by charge exchange mechanism only. Through the comparison between the model predictions of charge exchange lifetime and the observed lifetimes, we find that (3) the observed lifetimes are in general consistent with model results, which confirms that charge exchange is a dominant loss mechanism of ring current ions during storm recovery phase.

中文翻译：

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地磁风暴恢复阶段的环流衰减：RBSP观测值与理论模型之间的比较

风暴恢复阶段的环形电流衰减可能会受到不同损耗过程的影响。在这项研究中，我们通过统计调查研究了在风暴恢复阶段L壳从3到6的能量从1 keV到几百keV的环电流离子（H ⁺和O ⁺）的寿命。根据Van Allen Probe的观测资料，收集了2013年3月至2019年5月的48次地磁风暴的观测数据。我们发现，（1）H的所观察到的寿命⁺和O ⁺与L-壳和普遍增加（2）H的寿命⁺短比的O ⁺时Ë  <〜50千电子伏，而情况相反时Ë >〜50 keV。另外，我们利用电荷交换理论，结合以前在电荷交换截面上的实验结果和两个中性氢原子在外层的分布模型，直接估算了由电荷交换引起的环电流离子衰减。仅机制。通过将电荷交换寿命的模型预测值与观察到的寿命进行比较，我们发现（3）观察到的寿命与模型结果基本一致，这表明电荷交换是风暴恢复期间环流离子的主要损耗机制。相。