| 摘要 |
PROBLEM TO BE SOLVED: To prevent deformation during lighting a filament and its degradation due to chemical reaction. SOLUTION: A switch 24 is opened from a state that both switch 24 and a switch 25 are closed when a filament is turned on for the first time after vacuum exhaust. Thereby, an output voltage is gradually raised by an integrator composed of an operational amplifier 21, a capacitor 22 and a resistor 23 and a current if also gradually increases. Accordingly, the temperature rise of the filament 4 is also gentle and chemical reaction caused by thermal strain or the rapid vaporization of residual moleculars is restrained. When turning on and off the filament with the vacuum atmosphere maintained, the switch 24 is opened and closed while the switch 25 is kept opened. Therefore, the current rapidly flows through the filament 4 at the time of turning on the filament, so that an analysis can immediately be started.
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