Terahertz Brewster Window for Ultrabroadband Gyrotron Application

A terahertz (THz) Brewster vacuum window has been developed for the newly emerged ultrabroadband gyrotron application. In the simulation, the influences of the slant angle, the thickness, and the dielectric constant of the window plate on the results were systematically analyzed. In the experimental measurement, two THz high-directivity horn antennas were used to produce and collect a quasi-plane wave that travels through the window. The measurement shows that the window transmission coefficient between 0.33 and 0.50 THz is higher than -1 dB. A conventional Brewster window uses an elliptical window plate, resulting in the asymmetrical stress distribution. In this letter, a novel circular symmetrical ceramic-Kovar brazing scheme is applied to mitigate the challenging asymmetrical stress distribution. This Brewster window would promote the development of the broadband THz gyrotron and other high-power THz systems.