| 摘要 |
PROBLEM TO BE SOLVED: To reduce action which gives unexpected deflection to electron beam, which is caused by flow of a part of a current, flowing into the ground of a device, to a mirror body. SOLUTION: Each shielding ground of coaxial cables 4, 15 at the side of an electron beam mirror body 7 is connected to a conductive member 23, and one place of the conductive member 23 and one place of the electron beam mirror body 7 are connected by a ground line 22. Furthermore, the conductive member 23 is connected to a ground 20 by a ground earth line 19, and all the current I2, which causes deflection in electron beam 10, is made to flow via the conductive member 23. Thereby, the electric potential of the electron beam mirror body 7 is made the same potential as that of the conductive member 23, which is held at the ground potential.
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