Investigation of G-band High Power and Broad Bandwidth Extended Interaction Klystron with Rectangular Electron Beam

A G-band ladder-type Extended Interaction Klystron (EIK) with rectangular electron beam is designed. The bi-periodic structure with long-slots and short-slots alternatively distributed is adopted to form the multi-gap resonance cavity. The dominant advantage of the bi-periodic structure is the broader operation bandwidth compared with the periodic structure. The another significance of the proposed structure is that the rectangular electron beam with small aspect ratio is used, which will be helpful in decreasing the focusing difficulty of bunched beam compared with the sheet beam, and in increasing the beam current compared with the cylindrical beam. Through the theoretical analysis and optimization, the structure parameters of the resonance cavity operating at π mode along with the good high-frequency properties are obtained. With the 16.5 kV operating voltage and 0.30 A beam current, the output power of 270 W, efficiency of 5.5% and 3dB bandwidth of 670 MHz is achieved. As the beam current increases to 0.50 A, the output power, efficiency and 3dB bandwidth will improve to 1378 W, 16.7% and over 1 GHz, respectively.