Exploration of a High-Efficiency $G$ -Band Klystron Combined With Multigap Cavity and Kladistron Principles

In this article, a new bunching method, which was inspired by the kladistron technology, is proposed to enable high-efficiency operation of klystrons in high-frequency bands. This new bunching method combines the kladistron principle and the extended interaction klystron (EIK), and a
$G$
-band klystron based on it is designed to verify the new bunching method. Based on the same unit cell, an EIK and a klystron based on kladistron principle are designed for comparison. With a beam current of 0.6 A and a voltage of 18.8 kV, the 3-D particle-in-cell (PIC) results show a maximum output power of 644.41 W and an electron efficiency of 5.71
$\%$
, which is higher than the EIK (533.66 W and 4.73
$\%$
) and the klystron based on kladistron principle (554.45 W and 4.92
$\%$
). The output cavity was optimized by adjusting the positions of the coupling holes and velocity tapering, resulting in a saturated output power of 712.15 W and an electron efficiency of 6.31
$\%$
.