Improvement of Output Performance in G-band Extended Interaction Klystron with Narrow Coupling Cavity

A multi-gap ladder-type resonance cavity with optimized coupling cavity is proposed for G-band extended interaction klystron (EIK). The unequal-length slots structure is adopted to extend bandwidth. The new designed structure has the characteristic of shorter width of coupling cavity, which helps to improve the high-frequency features with larger effective characteristic impedance and stronger electric field. By comparing the wide-coupled structure and narrow-coupled structure through PIC simulation, we find that the narrow-coupled structure has higher output power and wider bandwidth than that of the wide-coupled one. Such structure shows some potential in the performance improvement of millimeter-wave and terahertz EIK.