| 摘要 |
PURPOSE:To always obtain a stable electron beam on an axis with simple structure by providing in an electron gun chamber, a heating element which positively preheats and degasses an electrode member in a vacuum and a deflector which deflects an emitted electron toward the central axis. CONSTITUTION:Both a heating element 6 and a deflector 6A are provided in proximity to the external wall of the cylindrical section of the first anode 4. Besides, an insulator 16 is provided on a part of the wall 8 of an electron gun chamber 16 and an exhaust pipe 9 is mounted on a part of this wall 8. The lead wire 10 of the heating element 6, the lead wire 10A of the deflector 6A, the heating power supply 12 of the heating element 6, the deflection source of the deflector 6A, the switch 11 of the heating power supply 12 for those devices and a deflecting power supply 13 are also provided on a part of this wall 8. As a result, a stable electron beam can always be obtained on an axis without any deterioration of the degree of vacuum caused by collision of the field emission electron. |
