| 摘要 |
PROBLEM TO BE SOLVED: To accurately adjust frequencies of a crystal vibrator by a method wherein an ion gun having an anode and a thermal cathode is contained in a vacuum container, a discharge current between this anode and the thermal cathode is monitored, and power for the thermal cathode is controlled so as to keep constant this discharge current. SOLUTION: After a stock chamber 1 is evacuated to 10-3 Pa or less, a partition valve 12 is opened, and a crystal vibrator 22 mounted on a carrier 27 is conveyed in front of an ion gun 15. A lower voltage DC discharge E1 and a discharge current monitor mechanism 25 are connected between a potential of an ion gun body 15 and an anode 18, and an output of a discharge current monitor of this discharge current monitor mechanism 25 is applied to a discharge current control circuit 24 for controlling a power control AC power adjuster 26 of a thermal cathode 17. A constant voltage DC high voltage power supply E2 is connected between a screen grid 20 and an acceleration grid 21, and the discharge current control circuit 24 corresponding to the output of the discharge current monitor controls a supply of power to the thermal cathode so that a discharge current is fixed.
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