紧凑型L波段同轴相对论返波振荡器的粒子模拟

 设计了紧凑型L波段同轴相对论返波振荡器，通过粒子模拟研究了L波段同轴相对论返波振荡器相互作用的物理过程，并对器件的电磁结构进行了优化和改进。分析表明，采用同轴慢波结构可以在较低的外加磁场下实现L波段返波振荡器的微波输出，同时可以大大减小微波器件的径向尺寸。这是因为同轴慢波结构的TM01模式有类似于TEM模的性质，没有截止频率，但纵向电场不为零，电子束能够与它发生强相互作用过程。粒子模拟优化结果表明，在器件半径仅为4.0 cm，电子束能量240 keV，电子束流1.8 kA，导引磁场仅为0.75 T时，返波振荡器可以在频率1.60 GHz处获得较大功率的微波输出， 平均峰值功率达140 MW，平均峰值功率效率约为32%。

Particle simulation of compact L-band coaxial relativistic backward wave oscillator

In this paper,a compact L-band coaxial relativistic backward wave oscillator is investigated using the 2.5 D particle simulation code.Detail physical interaction pictures of the oscillator are presented.Simulation results show that the radius of the L-band slow-wave structure can be much smaller in the coaxial BWO case than that in the non-coaxial BWO case,because the TM_(01) mode of the coaxial BWO has no cut-off frequency,which is similar to the TEM mode in the conventional coaxial wave-guide.It is mentioned that the longitudinal component of electric field of the coaxial TM_(01) mode can be strong,differing from the TEM mode in the conventional coaxial waveguide.Therefore,the coaxial TM_(01) mode could have strong interaction with the electron beam.For an electron beam of 240 keV and 1.8 kA,a microwave of TM_(01) mode is generated with an average peak power of 140 MW and frequency of 1.60 GHz when the external guiding magnetic field is only about 0.75 T.The beam to microwave efficiency is about 32%.The radius of the slowwave structure is only 4 cm.