MICROWAVE ELECTRONIC TUBE

PROBLEM TO BE SOLVED: To reduce the emission of electrons from an electric wave absorber so as to stabilize the operation by connecting a part of an electric wave absorber to the surface of a beam tunnel electrode so that the heat can be transmitted. SOLUTION: An electric wave absorber 22 is arranged at a distance from an electron gun so as to reduce the collision of the electron, which is emitted from a cathode electrode 11. Influence by the heat radiation of the electrode 11 is reduced, and the heat generation of the absorber 22 is restricted. Furthermore, since the absorber 22 is connected to a body electrode 18 and a beam tunnel electrode 19, which are made of copper with the excellent heat conductivity, the absorber 22 is cooled by the cooling water, which flows in a cooling water passage 21 of an electrode 19 main body, through the electrodes 18, 19, and the heat generation of the absorber 22 can be restricted. As a result, emission of the electron and discharge of the gas from the absorber 22 can be reduced so as to stabilize the operation.