| 摘要 |
PURPOSE:To measure a length of a non-operating area length formed of non- condensible gas by a temperature sensor at each channel by forming a plurality of channels in an envelope, and forming a slit between the plurality of the channels, thereby increasing a thermal resistance between the channels. CONSTITUTION:A slit 9 is formed between channels 2a and 2b of ends of an envelope 4 to increase only a thermal resistance between the channels 2a and 2b of the ends. The one end of the envelope 4 is heated by a heat generator 5, and the end of the other slit 9 is cooled by a heat absorber 6. A non-operating area 7 of non-condensible gas is formed at the end of the channel having the slit 9. Since the thermal resistance of the end is increased between the channels 2 with the slit 9, heat supply is decreased. Accordingly, since the temperature of a tube wall is lowered from the absorber 6, a temperature is measured by a temperature sensor 8 to measure a length of the area. |
