Formation of Laminar Electron Flow for 300GHz High-Power Pulsed Gyrotron

Abstract

This report describes the design of a magnetron-injection gun，which is intended for use 100 kW，30 0 GHz gyrotron. With increases in power and frequency，performance of the gyrotron becomes quite sensitive to the quality of the electron beam. Formation of a laminar electron flow is essential for the realization of a high qua1ity beam with small velocity spread .In th is study，a new method is developed for the evaluation of the laminarity，and applied to the design optimization of the electrodes. It is found that the laminarity depends not on1y on the conventional design parameter of the cathode slant angle，but also on the spatial distribution of the electric field inside the beam. In a well laminated beam， it is revealed that the pitch factor of each electon trajectory is modified to adjust the spatial separation between the neighboring trajectories around the cathode and first anode. An electron gun which is suitable for the new gyrotron has been successfully designed. In the future， we plan to clarify the relation between the laminarity and the profile of the electric field inside the electron beam