Development and stability of heavy ion ring beams created by high speed neutral atom injection in the Earth's ionosphere is analyzed in view of the upcoming space measurement of a rocket-released turbulence (SMART) mission. It is found that due to velocity dispersion of the injected neutral atoms, an ensemble of ion ring beams will be formed at a given location upon photoionization. Associated with the multiple-ion ring beams, various beam and lower-hybrid (LH) waves develop. Wave dispersion analysis indicates that the beam energy is extracted through double resonances with beam and LH modes (i.e., $\omega \sim k{v}_r\sim {\omega }_{lh}$, where ω_lh is the LH frequency, k is the wavenumber, and v_r is the ring mean speed). For the SMART experimental conditions, we find that, far from the release point, the velocity spacing between the ion ring beams $\Delta v$ will be much less than the mean speed of the beams themselves, v_r. Therefore, we show that the system will behave essentially as if represented by a single ring with an effective alpha $(\alpha )$ parameter (a ratio of ring to background plasma density), that is larger by a factor that is equal to N, the total number of rings. A major difference from the traditional single beam analysis is that for the more realistic multiple beam case, the effective instability is more intense because the wave growth rate now scales as $\sim {(N\alpha )}^{2/5}$.

中文翻译：

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SMART实验中由于多个快速重离子环分布而导致的低杂波不稳定

鉴于即将进行的火箭释放湍流（SMART）任务的空间测量，分析了地球电离层中高速中性原子注入产生的重离子环束的发展和稳定性。已经发现，由于注入的中性原子的速度分散，在光电离时将在给定位置形成离子环束的整体。与多离子环形束相关联，产生了各种束波和下混合（LH）波。波色散分析表明，光束能量是通过光束和LH模式的双共振（即，$\omega 〜ķv_{\mathrm{[R}}〜{\omega }_{升H}$其中ω _LH是LH频率，ķ是波数，并且v _[R是环平均速度）。对于SMART实验条件，我们发现离释放点很远，离子环束之间的速度间隔$\Delta v$将远小于光束本身的平均速度v _r。因此，我们证明了该系统的行为本质上就像是一个带有有效alpha的单环所代表$（\alpha ）$参数（环与背景等离子体密度之比）大一个因子，即等于环总数N。与传统的单光束分析的主要区别在于，对于更现实的多光束情况，有效不稳定性更加强烈，因为波的增长率现在随$〜{（ñ\alpha ）}^{2/5}$。