| 摘要 |
PROBLEM TO BE SOLVED: To accurately, easily position in the axis direction of a grid electrode constituting a micro electrode by forming a grid electrode with a plate-like base part having an opening through which electrons are passed and a cylinder integratedly formed in the base part and through which electrons are passed, and forming a cylinder coming in contact with a focusing electrode at the end. SOLUTION: A first grid electrode 71 is formed in almost a disc shape, and a cylinder 74 having a cathode 73 and a heater 76 on the opposite side to a focusing electrode 25 side of the first grid electrode 71 is supported through an insulator 75. A cylinder 78 integratedly formed in a base part 77 of a second grid electrode 79 is formed in a cylindrical shape so as to be capable of passing electrons 80 moving from the cathode 73 to a target 32, has the specified length in the axis direction, and an opened end 78b comes in contact with the focusing electrode 25. The distance between the base part 77 and the focusing electrode 25 is set in a specified value, positioning in the axis direction (the electrode arranging direction) of the base part 77 (micro electron lense) is made accurate and easy, quality is enhanced, and assembly cost is reduced.
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