| 摘要 |
PURPOSE:To increase an electromagnetic wave output drawn out to an electromagnetic wave discharge terminal, and to improve the efficiency, by making the area of the cross section of a part of an electromagnetic wave drawing out conductor, that is, the area penetrating a permeable hole, smaller than the area penetrating a metallic cylinder. CONSTITUTION:A part of an electromagnetic wave drawing-out conductor 1 0 which extends from an anode vane 2, and penetrates a permeable hole 4 and a metallic cylinder 5 without contacting them, that is, the area 10a penetrating the permeable hole 4, is made smaller than the other part of the conductor 10, that is, the area 10b penetrating the metallic cylinder 5, in the section area. The closer the ratio D1 of the diameter DA of the hole 4 to the diameter Da of the area 10a of the conductor penetrating the hole 4, to the ratio D2 of the diameter DB of the metallic sylinder 5 to the diameter Db of the conductor 10 at the area 10b penetrating the cylinder 5, the higher the electromagnetic wave transmission efficiency. Therefore, the diameter Da at the area 10a of the conductor 10 is made smaller than the diameter Db at the area 10b penetrating the metallic cylinder 5.
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