PURPOSE:To make it possible to decrease the evaporating amount of a cryogenic refrigerant by using phosphorus deoxidized copper or phosphorus deoxidized copper iron wherein phosphorus is added for one metal of the material whose base material is copper and which constitutes a thermocouple for a cryogenic apparatus. CONSTITUTION:A refrigerant container 1 contains cryogenic refrigerant, e.g. liquid helium 2. A vacuum container 3 contains the refrigerant container 1 in the inside. A radiation shielding mechanism 4 is contained in the vacuum container 3 and shields the refrigerant container 1. Vacuum adiabatic layers 5 are formed between the refrigerant container 1 and the radiation shielding mechanism 4, in the radiation shielding mechanism 4 and between the radiation shielding mechanism 4 and the wall of the vacuum container 3. A compact refrigerating machine 6 cools the radiation shielding mechanism 4 and the like. A thermocouple 7 is arranged so that the connecting parts are located in the refrigerant 2. The thermocouple 7 is formed by connecting the end part of a phosphorus deoxidized copper wire or phosphorus deoxidized copper iron wire and the end part of a constantan (copper-nickel alloy) wire. Thus the required temperature and the like can be measured under the state wherein heat intruded from the outside is decreased and suppressed to a large extent.
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