Numerical Simulation Of Beam-Wave Interaction In The Gyrotron Oscillators

The gyrotron, which can be used to generate high power and high efficiency electromagnetic radiation in millimeter and sub-millimeter wavelength range, is a kind of fast-wave vaccum electron device based on electron cyclotron maser instability. Potential applications of the gyrotron include millimeter wave radar, plasma heating and diagnostic of controlled thermonuclear fusion, directed-energy weapons and materials processing. These prospects have motivated widely theoretic and experimental investigations into the physics of gyrotrons.The study of beam-wave interaction is one of the most important subjects in the gyrotron field. The electromagnetic particle-in-cell (PIC) simulation technology, which bases on the time-domain finite difference (FDTD) algorithm and the concept of finite-size particle, can solve the Maxwell equations and the motion equations of electrons directly. Comparing with the large-signal numerical simulation, the PIC simulation can investigate the interaction process much more thoroughly. In addition, the PIC simulation consumes less human and material resources than the experimental study does. With the improvement of computer performance, the PIC technology has been applied to the computer simulation of the beam-wave interaction in the gyrotron gradually.In this thesis, a general design process of the gyrotron oscillator is presented as follows. Firstly, the linear theories of gyrotron are used to determine the preliminary parameters of the design for studied gyrotron interaction circuits. Then, the PIC...