| 摘要 |
PURPOSE:To prevent sample gas from flowing outside through a slit, suppress the oxidization of a thermal electron emitting heater due to sample gas such as exhalation gas, etc. and extend its life, and allow continuous measurement for a long time by fitting a cover at least at the periphery of the thermal electron emitting heater outside an ionization container. CONSTITUTION:Sample gas introduced into an ionization container 4 is ionized by being hit by thermal electrons emitted by a heater 6 and guided into the ionization container 4 through the first slit. In order to suppress the oxidization of the heater 6 due to oxygen in the sample gas, a cover 17 is fit outside the heater 6 fitting section of the ionization container 4 and also a discharge hole 18 for discharging part of the sample gas is formed on the outer wall of the ionization container 4, e.g., at the position facing the outlet of a gas guide pipe 1. In addition, the cover 17 is constituted so as to prevent the sample gas in the ionization container 4 from flowing outside the ionization container 4 through the slit 11. |
