A Three-stage Depressed Collector for 220 GHz Sheet Beam Traveling-wave Tubes

Abstract

In this paper, a three-stage depressed collector suitable for 220 GHz sheet beam traveling-wave tube (TWT) is studied. The condition of spent sheet beam is analyzed by using the CST 2016 Particle Studio. The positions distribution and velocity of the sheet beam are also obtained. Based on the analysis of the sheet beam at the entrance of the collector and the characteristics of the sheet beam after the interaction of 220 GHz sheet beam TWT, an efficient and low back streaming current three-stage depressed collector with the rectangular inlet and elliptical cavity shape is proposed. The collector efficiency is about 90% and the back streaming current is only 1.6 mA, which is accounting for 1% of the sheet beam current. This paper can provide some basic guidance for designing multistage depressed collector for 220 GHz sheet beam TWT.