Study Of Multistage Depressed Collector Of Three-beam Travelling Wave Tube

TWT is the core device of microwave amplifier, it is widely used in weapon and communication systems. With the miniaturization of weapon and communication systems, many requirements are put forward, for example, much smaller, lighter weight, higher power, wider band and so on. As a new tube-type microwave device, multi-beam traveling wave tube can achieve these requirements to some extent. But this technology is immature, more research on this is needed. Therefore, study on multi-beam collector can be very clear understanding of the difference between multi-beam collector and single-beam collector, and also can provide some ways to get over the design difficulties. This study can provide a reference for the study of multi-beam traveling wave tube, which can improve the entire tube efficiency of multi-beam traveling wave tube. In this thesis, design for single-beam collector has been studied using the microwave tube simulator suit MTSS. Based on the research of single-beam collector, the difficulties of designing three-beam collector are easy to get. Then we can obtain some ways to get over the difficulties. The main research content of this paper includes the following several aspects:1. First of all, from the working principle of collector set forth the physical process of electronic collecting. Then the action principle of refocusing magnetic field is introduced. And the secondary electron emission mechanism and its impact on the efficiency of the collector are also explained. And the electronic state of the collector is analyzed. At last, the relationship between the collector efficiency and the overall efficiency is analyzed theoretically, which further illustrated the importance of highefficiency collector design.2. When the electronic efficiency and collector inlet conditions determined, collector structure is good or bad plays an important role on the level of collector efficiency. In order to achieve the way of rapid design of the collector, many collector structures are designed and some certain rules are summarized. Finally, a Ku-band highefficiency collector is designed by using the law of summary, the efficiency of this collector is more than 75%, and the reflux rate is controlled within 2%.3. Based on the research of single-beam depressed collector, the differences and difficulties between single-beam and three-beam depressed collector are analyzed, and some different kinds of three-beam depressed collector models are designed. By comparison and analysis of the model of these instances, we master the design characteristics of the three-beam depressed collector. Finally a high-efficiency threebeam depressed collector model is shown in this section, which provided some references of designing a three-beam depressed collector.