Design and Simulation for 100-Watt-Class 340-GHz Extended Interaction Klystron

An extended interaction klystron (EIK) working at the frequency of 340 GHz is designed in this present article. The characteristic impedance, coupling coefficient, and normalized electron conductance of the cold cavities are analyzed and optimized. To improve the output power, the EIK adopts a prebunching (PB)-cavity high-frequency structure (HFS). Compared with the conventional terahertz (THz) EIK, the coherence of PB-cavity EIK is enhanced, and the output power is improved. The 3-D particle-in-cell (PIC) simulation predicts the EIK, driven by a 0.20-A, 22.4-kV electron beam confined in a 0.2-mm-diameter beam tunnel, and generates an output power of 138.3 W at the frequency of 339.7 GHz. The gain, electronic efficiency, and 3-dB bandwidth are 39.6 dB, 3.1%, and 500 MHz, respectively. The proposed EIK can be applied to the THz high-resolution radar.