Linear kinetic instability analysis based on in situ observations for one typical oxygen ion cyclotron harmonic (OCH) wave event is performed to investigate the wave excitation mechanism. The observed partial-shell velocity distribution of energetic O⁺s is fitted by the superposition of multiple ring-beam distributions. The calculated linear growth rate shows that the observed OCH waves can be excited by energetic O⁺s with the partial-shell velocity distribution, and the maximum growth rate occurs at the third harmonic, coinciding with the frequency associated with the maximum peak of the wave electric field power spectral density measured. In addition, it is found that cool heavy ions have a damping effect on the OCH waves near the corresponding heavy ion cyclotron frequency.

中文翻译：

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内磁层氧离子回旋谐波的产生机理——基于观测的线性不稳定性分析


基于对一个典型氧离子回旋加速器谐波 （OCH） 波事件的原位观测进行线性动力学不稳定性分析，以研究波的激发机制。观察到的高能 O ⁺ s 的部分壳层速度分布是由多个环梁分布的叠加拟合的。计算的线性增长率表明，观察到的 OCH 波可以被具有部分壳层速度分布的高能 O ⁺ s 激发，最大增长率发生在三次谐波处，与测得的波电场功率谱密度的最大峰值相关的频率一致。此外，研究发现，冷重离子对相应重离子回旋加速器频率附近的 OCH 波具有阻尼作用。