毫米波空间谐波磁控管效率探析

采用非π模空间谐波工作是磁控管往毫米波和太赫兹方向发展的有效实现手段,与同频率π模基波工作磁控管相比,空间谐波磁控管的谐振腔尺寸更大,磁场更低,但效率偏低。本文从单电子模型出发,分析了空间谐波磁控管注波互作用,得到单电子瞬时功率影响因素的公式,电子效率主要受到高频场旋转角速度Ω_m和高频电场m次空间谐波的角向分量E_φm影响。然后从角速度和空间谐波场方面分析了空间谐波磁控管低效率的原因。最后,基于理论分析从耦合阻抗、径向电场和角向电场三个方面开展提高效率的试验研究,成功研制了W波段空间谐波磁控管样管,在脉冲宽度400 ns,工作比为0.42%,工作电压13.6 kV条件下,电子与高频场的π/2模负一次空间谐波同步互作用,输出峰值功率11.2 kW,工作效率达到8.2%。

Analysis on the Efficiency of Millimeter-Band Spatial-Harmonic Magnetron

Space harmonic magnetron(SHM), whose electrons synchronize with high order space harmonic of non-π mode, could realize the development of magnetron towards millimeter wave and terahertz effectively. Compared with the traditional magnetrons synchronized with the fundamental of π mode, the SHM has a larger resonator size and lower magnetic field. But this kind of magnetron has the disadvantage of lower efficiency. In this paper,firstly, using the single electron model, the electron power formula is obtained by analyzing that the wave interacts with the space harmonic in SHM. The electronic efficiency is mainly affected by the angular rotation velocity Ω_m and the angular component E_φm of the m-th electric field. Then, the reason for the low efficiency of SHM is analyzed from angle velocity and space harmonic field. Finally, based on the theoretical analysis, the experimental study is held to improve the efficiency of the SHM on the coupling impedance, radial electric field, and angular electric field. Using these experiment results, a W-band SHM is manufactured successfully, and its electrons interact with the first backward harmonic of π/2 mode. When the anode voltage is 13.6 kV, the prototype is able to deliver an output power of 11.2 kW and an efficiency of 8.2% with a pulse width of 400 ns and a duty factor of 0.42%.