Mode conversion of a gyrotron output into a Gaussian beam for its various applications

High frequency gyrotrons offer clear advantages in the millimeter to the submillimeter wavelength range due to their high output powers. In addition, gyrotrons have the advantage of tuning the output frequency by selecting the operating mode. In order to widen the use of the high frequency gyrotron, we need a quasi-optical system to handle gyrotron output as a structure of a Gaussian beam (TEM/sub 00/ mode) which is suitable for transmission and application because of a linearly-polarization, simple intensity profile and wave front.