Study of the double rectangular waveguide grating slow-wave structure

A slow-wave structure (SWS) with two opposite gratings inside a rectangular waveguide is presented and analysed. As an all-metal slow-wave circuit, this structure is especially suited for use in millimetre-wave travelling wave tubes (TWTs) due to its advantages of large size, high manufacturing precision and good heat dissipation. The first part of this paper concerns the wave properties of this structure in vacuum. The influence of the geometrical dimensions on dispersion characteristics and coupling impedance is investigated. The theoretical results show that this structure has a very strong dispersion and the coupling impedance for the fundamental wave is several tens of ohms, but the coupling impedance for --1 space harmonic wave is much lower than that for the fundamental wave, so the risk of backward wave oscillation is reduced. Besides these, the CST microwave studio is also used to simulate the dispersion property of the SWS. The simulation results from CST and the theoretical results agree well with each other, which supports the theory. In the second part, a small-signal analysis of a double rectangular waveguide grating TWT is presented. The typical small-signal gain per period is about 0.45 dB, and the 3-dB small-signal gain bandwidth is only 4\%.     

浸钴熔铁氨合成催化剂的研究

浸钴熔铁氨合成催化剂的研究王文祥，刘照穹，张元珍，苏运来，秦春玲，关新新，董维阳（郑州大学催化研究室，４５００５２）熔铁催化剂用于合成氨工业已有８０多年的历史。多年来为了提高催化活性，特别是低温活性，对改变组成的研究试验不计其数。由于熔铁催化剂机械强...     

毫米波沟道梯型慢波结构行波管的线性理论

 在电子通道内引入一薄层空心电子注，对沟道梯型慢波结构行波管进行了线性理论研究，推导出了沟道梯型结构行波管的工作色散方程，计算了沟道梯型行波管的小信号增益和工作相速。计算结果表明：沟道梯型结构行波管每周期的增益高，带宽窄；当沟宽度由零增加到环内径的2倍时，增益减小量不足1%，这表明沟宽度对增益的影响不大；当脊高度增大10%时，增益增加62%，当环内径增大10%，增益减小57%，因此增益与脊高度正相关，与环内径负相关，且相关性十分明显。     

Radio-Frequency Characteristics of a Printed Rectangular Helix Slow-Wave Structure

A new type of printed rectangular helix slow- wave structure （SWS） is investigated using the field-matching method and the electromagnetic integral equations at the boundaries. The radio-frequency characteristics including the dispersion equation and the coupling impedance for transverse antisymmetric （odd） modes of this structure are analysed. The numerical results agree well with the results obtained by the EM simulation software HFSS. It is shown that the dispersion of the rectangular helix circuit is weakened, the phase velocity is reduced after filling the dielectric materials in the rectangular helix SWS. As a planar slow-wave structure, this structure has potential applications in compact TWTs.     

Wiggler磁场聚焦带状电子注

 带状电子注在螺线管磁场作用下传输时,易形成Diocotron不稳定性,导致电子注崩溃。采用Wiggler磁场聚焦带状电子注能防止Diocotron不稳定性。研究了Wiggler磁场聚焦带状注的作用机理,得出带状电子注在Wiggler场作用下的包络方程。结合理论分析,使用3维粒子模拟程序对带状电子注的Diocotron不稳定性和Wiggler磁场抑制不稳定性分别进行了模拟。研究表明:合适的选择磁场大小和周期能有效抑制Diocotron不稳定性,使得设计带状电子注行波管成为可能。