A Method to Separate Radiations From a Dual-Frequency Operation Gyrotron

A method was proposed to efficiently separate radiations from a dual-frequency operation gyrotron. The operation modes TE
₀₂
and TE
₀₄
are converted into linearly polarized Gaussian beams, and the theoretical predictions of the power conversion efficiency are 85% for TE
₀₂
mode and 90% for TE
₀₄
mode, respectively. The linearly polarized beams with different frequencies are oblique incident toward a spatial filter based on the frequency-selective surface, the beam at 0.11 THz is totally reflected, the beam at 0.22 THz is transmitted, and the transmittance is ~95%. The transmission characteristics of the spatial filter change a little when the incident angle ranges from 0° to 30°. The preliminary experiment for the transmission coefficient of the spatial filter is carried out when the incident angle is 0°, the trend of the transmission coefficient from the theoretical predictions agrees well with the experimental results, but there is a little difference at 0.11 and 0.22 THz due to the fabrication error.