Design of a 0.23-THz Extended Interaction Klystron With Ridge-Loaded Hughes Structure

Among the various high-frequency structures commonly employed in extended interaction klystrons (EIKs), the Hughes structure is particularly noteworthy due to its broadband properties. To further enhance the performances of EIKs, we devised a novel approach by loading ridges symmetrically on both sides of the grating gap of the Hughes structure. The ridge-loaded Hughes structure (RLHS) facilitates the concentration of electric field energy in the vicinity of the electron beam channel. This configuration effectively increases the characteristic impedance, thereby enhancing the strength of the beam-wave interaction and expanding the operational bandwidth. Through comprehensive numerical analysis, we have thoroughly investigated the high-frequency characteristics and beam-wave interaction properties of the RLHS, comparing with the conventional Hughes structure (CHS). Remarkably, our findings reveal that, when subjected to identical operating conditions-specifically an electron beam voltage of 13.2 kV, a current of 0.3 A, a magnetic field of 0.5 T, and an input signal power of 20 mW, the RLHS demonstrates a notable 62.3% increase in power output and a commendable 20.7% improvement in bandwidth compared to its CHS at 0.23 THz. The simulation results show that RLHS has the capacity to significantly enhance the gain and bandwidth of EIKs.