| 摘要 |
PURPOSE:To replace a filament without breaking the vacuum of an electron gun chamber, by opening or closing a shutoff valve to connect or disconnect the electron gun chamber and a spare chamber with each other. CONSTITUTION:When a screw bar 16 is turned to move a nut 20 rightward as to the drawing, a holder 26 is pushed down and a Wehnelt mount 4 is removed from a fitting metal 3. After that, the screw bar 16 is turned in the opposite direction to move the nut 20 leftward as to the drawing to displace a Wehnelt electrode 5 into a spare chamber 12 through a hole 13. The hole 13 is then closed by a shutoff valve 14 to disconnect an electron gun chamber 1 and the spare chamber 12 from each other. The spare chamber 12 is unsealed to pull a cylinder 15 out of the chamber to fit a new filament 6 on the Wehnelt mount 4. After filament replacement, reverse operation is effected to fit the Wehnelt mount 4 in the metal 3 to connect the new filament 6 to socket terminals 11a, 11b. |
