Study of Optimizing Stable Work of Q-band Space TWT by Mearsuring the Hot-State Distance Variations of Cathode-Focusing Electrode

In this paper, the hot-state electrode distance measuring device based on 3D vision technology of Q-band space traveling wave tube (TWT) electron gun is designed and constructed, which is packaged into a planar diode structure. The optical measurement system is used to measure the hot state distance between the cathode and focusing electrodes. The test results show that the actual measured value hot state distance between the cathode and focusing electrodes of the electron gun is consistent with the simulation values, which is about 0.287mm~0.285mm. After 5000 times of switching on-off, the hot state distance between electrodes is further shortened by 0.006mm-0.11mm, which will change the electronic optical size of electron gun, the position of the injection waist and the radius of the injection waist changes from 13.23mm to 12.96mm and 0.1466mm to 0.1734mm, respectively. The changes in critical dimensions of electron beam can well explain the helix current changes of Q-band space traveling wave tube in the actual testing process.