G-Band Broad Bandwidth Extended Interaction Klystron with Traveling-Wave Output Structure

In this paper, we investigate a large-sized beam tunnel, G-band extended interaction klystron (EIK) with a traveling wave output structure for the development of broad bandwidth EIKs. The high-quality factor F was introduced to estimate the bandwidth characteristics of the cluster cavities, and the optimal cluster cavity structure parameters were obtained based on this factor. The simulation mode of the device was designed by the 3D particle-in-cell (PIC) commercial simulation software. Four cluster cavities with a staggered distribution of frequencies were employed to expand the bunching bandwidth, and two traveling wave modes, 2 pi-pi/10 and 2 pi-2 pi/10, were used as the operating modes in the output structure, effectively increasing the output bandwidth. The simulation findings show that the maximum output power is 170 W, the corresponding gain is 37.5 dB, and the 3-dB bandwidth is up to 1.25 GHz. The three-hole coupling structure with a large-sized beam tunnel provides convenience for the fabrication of devices in the G-band, and our study shows a potential method for the realization of a G-band broadband EIK.