| 摘要 |
PURPOSE:To economically obtain a magnetron with high mass-productivity and reliability by forming the third electrode which provides spiral protrusion and is disposed at the area near the cathode as a half-completed products divided into plural segments through the sintering of a high melting point metal. CONSTITUTION:A third electrode 60 is provided at the area near the cathode 25, this electrode 60 is provided with a conductive cylindrical base material 61 which is smaller than the spiral internal diameter of cathode 25 at the internal side of cathode 25, and a spiral protrusion 62 which is protruded at the circumference of the base material 61 and between each spiral parts of cathode 25 is also integrally provided. Moreover, this third electrode 60 is formed with a single material selected from infusible metals such as W, Mo, Ta, Ti etc. or alloy of them in such surface condition which shows bad primary and secondary electron emitting characteristic and is located in such a position as is near the cathode and is not interfering the flow of electrons from the cathode to anode. Thereby, a magnetron ensuring mass-productivity and high reliability can be obtained economically. |
