| 摘要 |
PURPOSE:To obtain an electron gun having a large electron current without changing an electron emittig material by providing a cathode in the position surrounding a control electrode on an axial core. CONSTITUTION:An electron emitting ring zone 2 provided on a cathode 1 is facing the axial direction. Electrons emitted from the electron emitting zone 2 are accelerated while rotating, in the direction of an anode 5 after nearing a control electrode 4. The electron starting point of said electron gun is to be located on the side of a large radius thus enabling to provide large band length of the electron emitting ring zone 2. Further, when the thickness of a ring-shaped electron beam is prescribed, the band thickness of the electron emitting ring zone can be correspondingly increased due to the increased radius of the electron starting point. On account of acid two effects, the area of the electron emitting ring zone can be remarkably increased. |
