The slow-wave electromagnetic (EM) instability excited by a relativistic electron beam (REB) injecting plasmas has been studied using linear electromagnetic hydrodynamic (EMHD) theory. The features of multiple waves propagation are presented. The results of numerical calculation prove that the EM instability occurs in slow-wave band. The necessary and sufficient condition of the EM instability has been found. Both analytic discussion and physical analysis reveal that the electron betatron motion is one of important factors for the EM instability. The physical mechanism of the instability driven by the electron betatron motion has been discussed.%考虑相对论电子束入射等离子体所产生的离子通道的具体结构,利用线性电磁流体力学理论对离子通道摇摆电子束激发的纵向慢波电磁不稳定性进行研究.通过对导出的系统色散关系的数值分析,给出了系统中电磁波、空间电荷波以及两者在一定条件下互作用形成的电磁-静电混合模式的传播特性.研究发现系统在慢波区域存在电磁不稳定性,并揭示此慢波不稳定性是由电子束的betatron振荡所导致,且系统的不稳定性程度与betatron振动频率密切相关.对betatron振荡激发的慢波电磁不稳定性物理机理进行了分析,并给出了不稳定性存在的条件.在论文的最后通过改变参数,给出了不同电子束能量所对应的不稳定性幅值和不稳定频率区域,对相关的物理问题进行了讨论.
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