Radio frequency (RF) breakdown can result in pulse shortening and seriously degrade the stability and reliability of relativistic backward wave oscillators (RBWOs). This paper discusses the energy range of electrons causing breakdown traces in slow-wave structures (SWSs) through particle-in-cell (PIC) simulation, numerical calculation, and experimental verification. The PIC simulation and numerical calculation results reveal that the energy of the majority of the field-induced electrons bombarding the SWS surfaces after being accelerated is less than 120 keV. Furthermore, the micro appearances of the breakdown traces in SWSs and the witness targets bombarded directly by electrons of various energy levels have been analyzed. Scanning electron microscope (SEM) shows that the breakdown traces are featured with corrugated morphologies with a wide range and a shallow depth. A mass of craters emerge in the vicinity of the corrugated morphologies. These appearances are quite similar to destructive traces impacted directly by low-energy electrons (around 160 keV). Thus, it is confirmed that the breakdown traces result from the bombardment of low-energy electrons. Therefore, the breakdown mechanism of field-emitted electrons impacting on the structure surfaces in RBWOs has been further improved.

中文翻译：

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慢波结构中电子轰击破坏效应分析

射频 (RF) 击穿会导致脉冲缩短并严重降低相对论反向波振荡器 (RBWO) 的稳定性和可靠性。本文通过细胞内粒子（PIC）模拟、数值计算和实验验证，讨论了在慢波结构（SWS）中引起击穿痕迹的电子的能量范围。PIC模拟和数值计算结果表明，大部分场致电子在加速后轰击SWS表面的能量小于120 keV。此外，还分析了SWS中击穿痕迹的微观外观以及被各种能级电子直接轰击的目击目标。扫描电镜（SEM）显示，击穿痕迹呈波纹状，范围宽，深度较浅。在波纹形态附近出现大量陨石坑。这些外观与低能电子（约 160 keV）直接影响的破坏性痕迹非常相似。因此，可以确认击穿痕迹是由低能电子轰击造成的。因此，场发射电子撞击RBWOs结构表面的击穿机制得到了进一步的改进。确认击穿痕迹是低能电子轰击造成的。因此，场发射电子撞击RBWOs结构表面的击穿机制得到了进一步的改进。确认击穿痕迹是低能电子轰击造成的。因此，场发射电子撞击RBWOs结构表面的击穿机制得到了进一步的改进。