High-Harmonic Coaxial Gyrotron Based on a Two-Dimensional Lattice

Abstract

Summary form only given. High power millimetre-wave sources which produce coherent radiation (masers) are very important for a number of applications in science and engineering. To observe coherent radiation, the interaction between electrons rotating in a static magnetic field and an electromagnetic wave must take place inside the gyrotron's cavity. The gyrotron is one of the best known broadly applied masers capable of generating continuous millimeter wave radiation at MW power levels due to the electron beam interaction taking place in an oversized (w.r.t. wavelength of operation) cavity with a mode close to cut-off. The cavity and electron beam parameters are designed and tuned in such a way as to observe single mode excitation from the whole spectrum of the cavity eigenmodes. The studies have shown that due to various types of modes present in the oversized interaction region the excitation of parasitic modes, reduces gyrotron efficiency and other unwanted effects can be expected. The study of the nonlinear dynamics of mode interaction is therefore an extremely important topic of study, hi this work we present the concept of a high-harmonic coaxial gyrotron based on a 2D periodic lattice. The aim of this project is to design and build the gyrotron, with the fundamental interaction occurring at 20GHz and the gyrotron operating frequency located in the W-band (75-110GHz). The coaxial cavity with mean radius of 3.5 cm and based on 2D periodic lattice will be used to ensure the mode selection along the azimuthal index as well as to synchronize radiation from different parts of an oversized electron beam. The model considered will be discussed and the results of preliminary studies of the gyrotron dynamics will be presented.