Simulation research on influence of RF breakdown plasma on performance of relative backward wave oscillator
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摘要: 金属高频结构的射频击穿是引起功率下降和脉冲缩短的重要原因，是限制高功率微波(HPM)向更高功率、更长脉冲发展的重要因素。射频击穿的物理过程极其复杂，并且开展射频击穿研究对实验条件等要求高，因此粒子模拟是研究射频击穿的重要手段。通过在慢波结构表面设置爆炸发射电子和离子的方式模拟等离子体对一个X波段的相对论返波振荡器(RBWO)和一个Ka波段的RBWO工作的影响。粒子模拟结果表明，对于分段式慢波结构，后段慢波结构产生等离子体会对电子束的调制造成影响，进而影响器件正常工作，引起微波功率下降。当等离子体由质量较轻的正离子和电子组成时，会对束波作用造成更大的影响，引起较大的输出功率下降。相同密度的射频击穿等离子体对Ka波段RBWO工作的影响大于对X波段RBWO的影响。Abstract: RF breakdown of the metallic high frequency structures is an important reason of power decrease and pulse shortening; it is also an important limitation of the development of high power microwave (HPM) to higher power and longer pulse. The physical process of RF breakdown is pretty complicated, and the experiment research of RF breakdown is hard to conduct, thus simulation research becomes an important method. We simulated the influence of plasma on the performance of an X-band RBWO and a Ka-band RBWO by setting electron and ion emission from the surface of SWSs. The simulation results show that the formation of plasma in back SWSs will influence the performance of RBWO by influencing the electron beam. When the plasma consists of light ions and electrons, it will bring stronger influence on the beam wave interaction, leading to power decrease in a high degree. The breakdown plasma has a bigger influence on the Ka-band RBWO than X-band RBWO.
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Key words:
- high power microwave /
- RBWO /
- RF breakdown /
- PIC simulation
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图 1 D/λ=2.7的X波段过模RBWO结构示意图
Figure 1. Schematic of an X-band overmoded RBWO with D/λ=2.7
图 2 X波段过模器伴的2维PIC模拟中获得的微波功率和输出微波频率
Figure 2. Microwave power and output spectrum of the X-band overmoded RBWO in 2D PIC simulation
图 4 前段慢波结构中段设置不同发射粒子和后段慢波结构中段设置不同发射粒子时器件输出功率对比(X波段)
Figure 4. Output power of the X-band divice different charged particles at SWS1 or SWS2
图 5 29 ns时前半段慢波结构设置爆炸发射氢离子和氧离子情形时的粒子分布图
Figure 5. Distribution of the particles at 29 ns when set explosive emission of hydrogen ions and oxygen ions
图 7 Kα波段过模器件的2维PIC模拟中获得的微波功率和输出微波频谱
Figure 7. Microwave power and output spectrum of the Kα-band overmoded RBWO in 2D PIC simulation
图 9 前段慢波结构中段设置不同发射粒子和后段慢波结构中段设置不同发射粒子时器件输出功率对比(Ka波段)
Figure 9. Output power of the Kα-band device emitting different charged particles at SWS1 or SWS2
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