宽带相对论速调管放大器输出腔模拟设计

为了展宽相对论速调管放大器的输出段带宽，设计了一种用于S 波段、10%带宽、相对论速调管放大器输出腔结构。该结构采用重叠模双间隙腔，该腔有两个工作模式（0 模和π 模）。采用三维程序模拟分析发现：两个腔间的圆盘半径增大时，0 模的谐频率几乎不变，π 模的谐振频率升高即模式间隔增大；当间隙长度增大时，模式间隔减小；当输出耦合孔的角度在一定范围内由小变大时，模式间隔增大；输出腔半径增大时, 模式间隔减小。本文通过调节以上腔体尺寸使两个工作模式的频率部分重合增加了输出腔的工作带宽。在束压850kV、束流7.6kA、基波调制深度为90%时、调制微波频率为2.85GHz 时，采用三维PIC 程序模拟得到2GW 的输出微波功率，3dB 相对带宽约10%。

Simulation Design of Output Cavity for Broadband RelativisticKlystron Amplifier

With 3D full electromagnetic code, an S-band overlapped mode two-gap output cavity for broadband relativisticklystron amplifier has been designed and calculated, and there is two modes in the two-gap output cavity. It is found that the twomodes will be overlapped partially by adjusting the structure of output caviy and it is beneficial to expand the bandwidth of outputstructure. A 2.0GW averaged power over the oscillator period is generated by simulation, with 850kV electron beam voltage,7.6kA current and 90% depth of the modulated current using the two-gap output cavity. The centric frequency is 2.85GHz. The3dB bandwidth is about 10%.