The breakdown problem in the relativistic backward wave oscillator (RBWO) limits the microwave pulse energy and should be solved. The slow wave structure (SWS) is the most key component of the RBWO. The breakdown of SWS may be triggered by field-induced electron emission and electron bombardment on the wall. This paper demonstrates that the space charge field of the relativistic electron beam (REB) can enhance the electric field forbidding field-induced electron emission and decrease the electric field igniting the RF breakdown, and therefore, the RF breakdown can be significantly suppressed. However, the enhanced electric field will enlarge the radial displacements of electrons, especially the high-energy electrons. When the RBWO operates with a low guiding magnetic field or a long-pulse REB, this situation will worsen and some electrons may possess large enough radial displacements and bombard on the SWS surface with the help of radial oscillation of REB and radial expansion of cathode plasmas. This may aggravate the breakdown of SWS.

中文翻译：

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空间电荷场对相对论后向波振荡器的影响研究

相对论反向波振荡器（RBWO）中的击穿问题限制了微波脉冲能量，应该解决。慢波结构 (SWS) 是 RBWO 最关键的组成部分。SWS 的击穿可能是由场致电子发射和壁上的电子轰击触发的。本文论证了相对论电子束（REB）的空间电荷场可以增强电场，阻止场致电子发射，并降低引发射频击穿的电场，因此可以显着抑制射频击穿。然而，增强的电场会扩大电子的径向位移，尤其是高能电子。当 RBWO 在低引导磁场或长脉冲 REB 下工作时，这种情况会变得更糟，一些电子可能拥有足够大的径向位移，并在 REB 的径向振荡和阴极等离子体的径向膨胀的帮助下轰击 SWS 表面。这可能会加剧 SWS 的崩溃。