| 摘要 |
PURPOSE:To stabiliize operation by a constitution wherein an electron beam focusing ratio of a helix type traveling-wave tube is less than a specific value and an end part of the helix on the side of the electron gun is located at the center of the magnet of the magnetic forcusing device which is the third nearest to the electron gun or nearer to the collector. CONSTITUTION:When the distribution of magnetic flux density and the traveling state of the electron beam of a traveling-wave tube is compared, the electron beam is swollen to a certain extent in the region from the cathode 1 to the end of the magnetic focusing device where magnetic field is relatively weak. Further, in the region of the first and second magnets of the magnetic focusing device 6 near the anode, sawe adjustment is made to match the distribution of the magnetic field on the central axis with the design value by gradually intensifying magnetic flux density but the electron beam is still fairly swollen. Further, the electron beam is stably focused toward the central axis near the third magnet and after that. Since the end part of the helix 7 is arranged at the center of the third magnet counted from the side of the anode or nearer to the collector, the electron beam does not contact with the helix. Thereby, the end part of the helix can be prevented from burning.
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