MICROWAVE-TUBE EXPERIMENTS UTILIZING FERROELECTRIC-CATHODE ELECTRON-GUN

摘要

The intensive research on ferroelectric electron-emission mechanisms in the last decade has yielded a better understanding of the physical characteristics of this plasma-assisted electron source. However, radiation sources employing this cathode have been hardly presented yet. In this study, an electron-gun based on a ferroelectric cathode has been developed and operated in gyrotron and free-electron maser (FEM) experiments. In this gun, the electrons separated from the cathode surface plasma are accelerated in two stages. The electron energy spread is reduced sufficiently for gyrotron and FEM experiments in the microwave regime. An e-beam of 14 keV and 1-2A is obtained in a 0.1-2.1 μs pulse width. The pulse repetition frequency (PRF) attains 3.1 MHz in a ～50% duty-cucle. Gyrotron experiments using this gun generate microwave output of 1.5 kW at ～7 GHz with a 12% electronic efficiency. The same gun has been used in an FEM oscillator experiment operating around 3 GHz. This paper presents experimental results, and discusses the applicability of ferroelectric guns in microwave tubes.