Based on the beam–plasma system model established in this paper, the trajectory of the electron beam in the ion channel is studied quantitatively through the envelope equation. Under different initial system parameters, the focusing transmission conditions of the beam in the ion channel are discussed. Then, a series of particle-in-cell simulations are performed, which generally versifies the theoretical results and shows some further details of the focusing behavior of the beam. It is found that the deceleration of some electrons around the focusing point or the beam–plasma interaction at the ion channel boundary will result in the generation of the residual electrons, which forms the electron return current that leads to the new instabilities influencing the focusing characteristics of the beam.

中文翻译：

---

相对论电子束在离子通道中传输的聚焦特性

基于本文建立的束-等离子体系统模型，通过包络方程定量研究了离子通道中电子束的运动轨迹。在不同的初始系统参数下，讨论了离子在离子通道中的聚焦传输条件。然后，执行一系列的单元内粒子模拟，通常可以验证理论结果，并显示光束聚焦行为的更多详细信息。已经发现，一些电子在聚焦点附近的减速或离子通道边界处的束流-等离子体相互作用将导致残留电子的产生，从而形成电子返回电流，从而导致影响聚焦特性的新的不稳定性。光束