| 摘要 |
PURPOSE:To prevent the destruction of an oscillating tube caused by reflected micro waves, by covering a tube antenna enclosed inside a vacuum seal part with a conductive outer tube with a gap, and electrically connecting the atmospheric pressure side end part of the conductive outer tube to the tube antenna. CONSTITUTION:A tube antenna 4 passing through the aperture 3 of a wave guide 2 is covered by a conductive outer tube 7 with a gap, and the atmospheric pressure side end part of the conductive outer tube 7 is electrically connected to the antenna 4. The length of the conductive outer tube 7 between the vacuum side end part and the atmospheric pressure side end part is let to be a quarter of the wave length of the micro-wave in use and the impedance of the antenna 4 from the vacuum side to the atmospheric pressure side is infinite. Generation of reflected waves of micro-waves at an electrically connected part 9 are prevented by permitting the diameter of the conductive tube 7's connected part 9 to decrease gradually from the vacuum side to atmospheric pressure side. A vacuum seal part 5 is soldered to a cylindrical kovar material 10 which is arc welded on the wave guide 2, and the impedance of the cylindrical kovar material 10 from the vacuum side to the atmospheric pressure side is infinite.
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