INTRUDING HEAT MEASURING INSTRUMENT FOR CRYOSTAT

摘要

PURPOSE:To measure intruding heat in a short time without deteriorating the measurement accuracy by measuring the flow rate per unit time of a vaporized gas discharged from a very low temperature coolant storage tank. CONSTITUTION:The low-temperature section of an expanding machine is inserted into a cryostat 15 and thermally united with heat shield cylinders 5 and 6. The liquid helium in a liquid helium tank 4 is vaporized by heat intruded from the room temperature and the vaporized gas flows through a gas discharge tube 12 communicating a vacuum vessel 1 with the outside and is discharged to the outside through a check valve 13. At the time of measuring the intruded heat, the vaporized gas of the liquid helium flowing out from the valve 13 of the cryostat 15 is not discharged directly to the atmosphere, but through a precise pressure controller 17 which maintains the pressure in an entrance section at a fixed value with high accuracy. The flow rate of the vaporized gas is measured with a flowmeter 18 installed to a pressure-controlled flow passage.