| 摘要 |
A GC/MS includes a sample conduit 22 between a gas chromatographic column and an ionizing chamber 31 which is placed in a vacuum housing 35, and the heating mechanism for the sample conduit 22 and the ionizing chamber 31 includes: a heating unit 23 provided in contact with the sample conduit 22 for heating the sample conduit 22; a connecting bar 25 provided between the heating unit 23 and the ionizing chamber 31 for conducting heat from the heating unit 23 to the ionizing chamber 31 with a first thermal resistance; and a depressed cap 26 provided between the ionizing chamber 31 and the vacuum housing 35 for conducting heat from the ionizing chamber 31 to the vacuum housing 35 with a second thermal resistance. Since the sample conduit 22 is heated directly by the heating unit 23, the temperature of the sample conduit 22 is almost the same as that of the heating unit 23. Since the vacuum housing 35 has a large heat capacity and it is normally at room temperature, heat is conducted from the heating unit 23 to the ionizing chamber 31 via the connecting bar 25, and heat is conducted from the ionizing chamber 31 to the vacuum housing 35 via the depressed cap 26. At equilibrium, the temperature of the ionizing chamber 31 is at a value between those of the heating unit 23 and the vacuum housing 35, and the value can be determined by appropriately setting the ratio of the first and second thermal resistances of the thermal conducting members 25 and 26.
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