電子迴旋脈射之諧波作用研究

Abstract

The electron cyclotron maser (ECM) is an electron radiation mechanism that originates from the interaction between electrons and an electromagnetic wave with a relativistic effect involved. The synchronism condition for sustained interaction requires the electron cyclotron frequency multiplied by cyclotron harmonic number s to be close to the electromagnetic wave frequency. Hence, higher harmonic interactions are of critical importance to the generation of high frequency radiation with a manageable magnetic field. However, the coupling strength decreases as harmonic number increases, which may suggest greater beam power for building up efficient interactions. Also the efficiency in higher harmonic case is usually lower than what is obtainable in the fundamental harmonic case. In this thesis, the optimization conditions for ECM interactions by using both large-orbit electron beam and small-orbit electron beam are examined via fundamental to fourth harmonics, and the efficiency enhancement in a tapered magnetic field are observed through simulation works.