Traveling-wave Output Structures Research Articles

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, 2π−π/10 and 2π−2π/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.

Preliminary research of a V-band coaxial relativistic transit-time oscillator with traveling wave output structure

A V-band coaxial relativistic transit time oscillator is presented. Different from the traditional transit time oscillator, in order to improve the power handling capacity, we replace the traditional standing wave extractor with a traveling wave output structure. The operation characteristic of modulation cavity is also different from traditional transit time oscillators. The electron load conductance of modulation cavity is designed to be positive to reduce the maximum surface electric field. The device is investigated by particle-in-cell (PIC) simulation and preliminary experiment. In PIC simulation, an output microwave of 689 MW at 60.16 GHz is obtained with a diode voltage of 400 kV and beam current of 5.0 kA. The saturation time is 22 ns and efficiency is 34.5%. In experiment, the radiation pattern of the system is measured, and output power is calculated. A 135 MW V-band microwave at 60.20 GHz is obtained with a diode voltage of 405 kV and beam current of 5.1 kA.