Effect of Bean Prebunching on Gain and Efficiency in High Power Microwave Devices

Abstract

The thesis focuses on the effect of beam pre-bunching on gain and efficiency in high power microwave devices. High power microwave generation has been an important field of research for many years. A general trend has been to achieve higher power levels, higher operating frequencies and higher efficiency. Today, issues like efficiency, reliability are becoming more important considerations. Conventional microwave devices, like the Klystron, Magnetron and Travelling Wave Tube (TWT) employed non-relativistic beams producing microwave radiation power at megawatt level with high efficiency at centimeter wavelengths. In order to generate high-powered coherent radiation at millimeter and sub-millimeter wavelengths work is being carried out by employing relativistic electron beams. Free electron laser (FEL) and Cerenkov free electron laser (CFEL) have emerged two most noticeable high power microwave devices employing relativistic electron beams and have become attractive devices at millimeter to infrared and are capable of generating even much shorter wavelengths. newlineRecently, study of FEL and CFEL by modulated and pre-bunched relativistic electron beam (REB) has become a fascinating field of research. If one employs an electron beam already pre-bunched at appropriate frequency and wave number then the efficiency and the power output of the device are expected to be significantly enhanced. The present research work deals with the detailed study and analysis of pre-bunched FEL and CFEL...