Thermal management of a quasi-optical mirror in a millimetre-wave gyrotron

摘要

A quasi-optical mirror of a millimetre-wave gyrotron was thermally analysed considering three different surface heat loads on mirror surface. The heat load on reflecting surface of the mirror were considered: i) over the full reflecting surface, ii) over the circular cross section similar to that of RF beam, and iii) over the circular cross section in Gaussian distribution. Thermal images were captured under these three considerations. Values and locations of highest temperature attained on the mirror were observed. Maximum temperature reached in three considerations of heat load were 348.72, 330.53 and 391.64 degrees C, respectively. Further, three cooling channel routings: i) cooling cavity, ii) rectangular serpentine, and iii) circular serpentine were implemented behind the mirror. The rectangular serpentine cooling channel was the most effective for the considered millimetre-wave mirror. The maximum localised temperature reached under consideration of Gaussian heat load was below 400 degrees C (allowable maximum temperature). Therefore, the present cooling proposal would be suitable for the heat load of 5 kW on reflecting surface of the mirror.