RELATIVISTIC BACKWARD WAVE OSCILLATOR WITH A GAUSSIAN RADIATION PATTERN AND RELATED TECHNOLOGIES
type: CreativeWork
description: Short pulse high power microwave (HPM) devices with Gaussian radiation pattern are attractive for many applications. The importance of the Gaussian microwave beam is that its maximum energy density is concentrated on axis. The purpose of this study is to use a backward wave oscillator (BWO), which is typically known to radiate in the TM01 mode, to produce an HPM Gaussian wave beam. A BWO generates an electromagnetic wave with negative group velocity where the wave is traveling in the direction opposite to the electron beam. Thus, to extract the microwave signal axially, a cavity resonator reflector or cutoff waveguide section are widely used to reflect the TM01 mode backward wave to a TM01 mode forward wave. To provide a HPM Gaussian-like TE11 wave beam, an X-band relativistic BWO (RBWO) is proposed that uses a Bragg reflector instead of a cavity resonator reflector. Therefore, the device of interest is a RBWO consisting of two periodic slow wave structures (SWSs). In the original design, the inner radii of both SWSs were the same. For a uniform electron beam, a Bragg structure that is placed at the cathode (upstream) end, unfavorably perturbed the electron beam. Thus, two designs were proposed to minimize the interaction between the electron beam and the Bragg reflector structure. First, a uniform magnetic field was used with increased radial gap between the electron beam and the structure by optimizing the Bragg structure dimensions. This configuration generated a single frequency at X-band. The second design used a nonuniform magnetic field to control the gap between the electron beam and the SWSs, and to optimize the electron beam-Bragg structure interaction for C-band radiation generation. This is a dual-band RBWO operation with a possibility of generating a TE11-mode with linear polarization at single or dual frequencies (X- and C-bands). The radiation at C-band was generated in the Bragg structure as an asymmetric mode. The only known way to extract such a wa…
abstract: Short pulse high power microwave (HPM) devices with Gaussian radiation pattern are attractive for many applications. The importance of the Gaussian microwave beam is that its maximum energy density is concentrated on axis. The purpose of this study is to use a backward wave oscillator (BWO), which is typically known to radiate in the TM01 mode, to produce an HPM Gaussian wave beam. A BWO generates an electromagnetic wave with negative group velocity where the wave is traveling in the direction opposite to the electron beam. Thus, to extract the microwave signal axially, a cavity resonator reflector or cutoff waveguide section are widely used to reflect the TM01 mode backward wave to a TM01 mode forward wave. To provide a HPM Gaussian-like TE11 wave beam, an X-band relativistic BWO (RBWO) is proposed that uses a Bragg reflector instead of a cavity resonator reflector. Therefore, the device of interest is a RBWO consisting of two periodic slow wave structures (SWSs). In the original design, the inner radii of both SWSs were the same. For a uniform electron beam, a Bragg structure that is placed at the cathode (upstream) end, unfavorably perturbed the electron beam. Thus, two designs were proposed to minimize the interaction between the electron beam and the Bragg reflector structure. First, a uniform magnetic field was used with increased radial gap between the electron beam and the structure by optimizing the Bragg structure dimensions. This configuration generated a single frequency at X-band. The second design used a nonuniform magnetic field to control the gap between the electron beam and the SWSs, and to optimize the electron beam-Bragg structure interaction for C-band radiation generation. This is a dual-band RBWO operation with a possibility of generating a TE11-mode with linear polarization at single or dual frequencies (X- and C-bands). The radiation at C-band was generated in the Bragg structure as an asymmetric mode. The only known way to extract such a wa…
author: Elfrgani, Ahmed
language: English
keywords: Relativistic Backward Wave Oscilator, Bragg Reflector, Dual Band Source, Power Combiner, Gaussian Radiation Pattern
date published: 2016-02-01T08:00:00Z
date modified: 2026-07-24T05:27:19Z
provider: University of New Mexico
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of New Mexico