Abstract: A low-temperature end of a pulse tube (1) and a low-temperature end of a cold accumulator (2) are communicated with each other through an endothermic connection passage (3), so that refrigerant gas to be supplied from a compressor (7) to a high-temperature end of the cold accumulator (2) through a refrigerant gas passage (28) is introduced from the low-temperature end of the pulse tube (1) to the high-temperature end thereof through the cold accumulator (2) and the endothermic connection passage (3). A buffer tank (30) is connected to the high-temperature end of the pulse tube (1) through a first orifice (31). A sub gas passage (32) branched off from the refrigerant gas passage (28) is connected to the the buffer tank (30) through a second orifice (33).

Abstract: Two three-way valves (12) (13) of the rotary type are arranged in parallel in a high-pressure refrigerant gas passage (15) of a compressor (7). A high-temperature end portion of a cold accumulator (2) is communicated with one three-way valve (12) of the rotary type through a main gas passage (19) as well as a high-temperature end of a pulse tube (1) is communicated with the other three-way valve (13) of the rotary type through a sub gas passage (20). A low-pressure port of each three-way valve (12)(13) is communicated with a low-pressure refrigerant gas return passage (17) of the compressor (7) respectively. A flow regulating member (21) is interposed in the sub gas passage (20). Both the three-way valves (12) (13) are synchronously rotated. A valve opening-closing timing of the one three-way valve (12) or (13) is adjustably changed relative to that of the other three-way valve (13) or (12).

Abstract: In an apparatus for producing liquid nitrogen by supplying to a nitrogen gas separated from the atmosphere and then purified by an air separating device (4) into an insulated container (1) equipped with an extremely low temperature refrigerator, there are provided a pressure sensor (21) for detecting a pressure within a product vessel (20) of the air separating device (4) and a negative pressure sensor (16) for detecting a negative pressure within the insulated vessel (1) respectively. When at least one of both sensors (21) (16) detects a freezing of an impurity gas contained in the supplied nitrogen gas by reaching a predetermined pressure, an operation of the extremely low temperature refrigerator is stopped depending on the detection by one of both the sensors.

Abstract: The present invention relates to an apparatus for preventing evaporation of liquefied gas in a liquefied gas reservoir used for cooling an energy dispersive spectrometer type X-ray detector (EDS detector) and its control method. A cold head of a cryogenic refrigerator is disposed in an upper opening of the liquefied gas reservoir, the cryogenic refrigerator is adapted to be put into automatic operation depending on temperature inside the liquefied gas reservoir, wherein the automatic operation mode of the cryogenic refrigerator is put into rest by remote control during the use of the EDS detector, while the cryogenic refrigerator is put into automatic operation with a previous alarm issued when the temperature inside the liquefied gas reservoir increases over a set temperature with the EDS detector being out of use, thereby allowing vaporized gas to be reliquefied with gas consumption reduced.

Abstract: In a cryostat vacuum chamber encompassing a refrigerator and a sample table cooled by the refrigerator, a heater is provided for controlling a temperature of the sample table, and the refrigerator is also provided with separate heaters.

Abstract: A device for preventing evaporation of liquefied gas in a liquefied gas reservoir used to cool an EDS detector of an electron microscope or the like is disclosed. A cold head of a cryogenic refrigerator is disposed so as to fit an opening of the top of the liquefied gas reservoir and moreover a temperature measuring instrument or a level gauge is disposed within the liquefied gas reservoir so that the cryogenic refrigerator is automatically operated depending on the temperature within the liquefied gas reservoir or on change in the liquid level of liquefied gas. In the manner vaporized gas is condensed and reliquefied, thus suppressing wasteful dissipation of vaporized gas.