SU1747825A1 - Cryostat - Google Patents

Abstract

Usage: temperature control of individual objects in the temperature range of .4.5 - .. The cryostat contains a Hole vessel for a liquid Cryoagent, a vacuum chamber placed on it with a heat exchanger and an object holder with an electric heater, tubes for supplying and Discharging the cryoagent from the Dewar vessel to the chamber. The cryostat is equipped with a casing installed around the Dewar vessel with the formation between them of a vacuum cavity, a screen placed in it, an annular container with a substance that accumulates cold. The screen is installed with the formation of a gap between it and the Dewar vessel. The cryostat is provided with a pipeline for evacuating the vapor of the cryogenic agent from the Dewar vessel, located in the gap between the screen and the Dewar vessel to ensure thermal contact with the wall of the latter. The tube for removal of the cryogenic agent from the vacuum chamber has a section located under its bottom with ensuring thermal contact with it, and a section located in the annular container with the substance accumulating cold. 1 il. s / g

Description

The invention relates to cryogenic technology and can be applied in devices for thermostating small objects in the temperature range of 4.5 - 300 K.

A cryostat is known that contains a Dewar vessel with a reserve of a cryogenic agent, a heat exchanger located on the screen, the outlet tube of the heat exchanger serving to cool the screen of the cryoagent vapor, a vacuum chamber in thermal contact with the heat exchanger, and an object inbinder,

The disadvantage of this cryostat is that the thermal security of the vessel with a reserve of cryogenic agent depends on the level of temperature control and the coolant flow rate. In addition, in order to replace the tested sample in the indicated cryostat, it is necessary to merge the cryogenic agent from it into the reserve capacity.

Closest to the invention is a cryostat containing a Dewar vessel for a liquid cryoagent, a vacuum chamber with a heat exchanger and object holders placed on it, fixed on the last electric heater, tubes for supplying and discharging the cryoagent from the Dewar vessel.

The disadvantage of this device is the high consumption of the cryogenic agent with frequent changes of the studied samples.

The purpose of the invention is to improve ease of operation.

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The drawing shows the proposed cryostat

The cryostat contains a Dewar vessel 1 for a liquid cryoagent, a vacuum chamber 2 with a heat exchanger 3 and an object holder 4, a tube for supplying 5 and a discharge 6 of a cryoagent from the Dewar vessel 1 to the chamber placed on it. The heater 7 is strengthened with a heater 8 mounted around the vessel Dewar 1 with the formation of a vacuum cavity 9 between them. In cavity 9 a screen 10 is placed, installed to form a gap between it and Dewar 1, and an annular container 11 with a cold-accumulating substance. The cryostat is equipped with a pipeline House 12 for removal of the cryogenic vapor from the Dewar 1 located in the gap between the screen 10 and the Dewar 1 with ensuring thermal contact with the wall of the latter. Tube 6 for removing the cryoagent from the vacuum chamber 2 has a section located under its bottom 13 providing thermal contact with it. and a portion 14 located in the annular container 11c with a cold-accumulating substance. The vacuum chamber 2 contains a removable cap 15 with a heat shield 16 fixed on the bottom 13 of the vacuum chamber 2. The tube 6 is equipped with a valve 17, the cryogenic agent is poured into the Dewar 1 through the tube 18 through the valve 19, and the pipeline 12 is equipped with the valve 20.

The cryostat operates as follows.

Before the experiments, the Dewar 1 is filled with a cryoagent through the tube 18, for which the valves 19 and 20 are opened when the vent 17 is closed. Dewar 1 is cooled down. The vapor of the evaporated cryoagent passes through the duct 12 and additionally cools the Dewar 1. After the cooling down process is completed and refill the Dewar 1 valve 19 close

The test specimen is placed on the heat exchanger 3, after which a removable heat shield 16 and removable cap 15 are installed, and then chamber 2 is evacuated. For the experiment, the cryoagent is fed to the heat exchanger 3, for which the valve 17 is opened smoothly through the tube 5 to the heat exchanger 3 thus cooling the sample. The flow rate of the cryoagent is controlled by the valves 17 and 20 After passing through the heat exchanger 3, the pairs of the cryoagent cool the bottom 13 of the chamber 3 And the heat shield 16 and then enter the annular tank 11 through the tube section 14 6 Since during cryostatting of an object in the lower temperature range, the flow rate of the cryoagent through the heat exchanger 3 is increased, it is not useful to use all of its cold when cooling the screen 16

The remaining part of the cold is used to cool the gas in the gas-filled tank 11. After passing through section 14 f of the chop, the cryoagent is output from the cryostat through valve 17 with a temperature close to

0 room. Thus, when conducting low-temperature experiments in the tank 11, the cold accumulator remaining after the cryoagent of the heat exchanger 3 and the tube 6 is accumulated. The amount of accumulated cold and its temperature level depend on the flow rate of the cryoagent through the gas heat exchanger filling the tank 11, and its quantities in it. With the passage of a cryoagent plot

0 14 its cold is successively consumed first for cooling the gas in the tank 11, then for detaching the latent heat of evaporation from it and condensation and for cooling the gas already liquefied in the tank 11, then on

5 away from liquefied gas of latent heat and for further cooling of solid gas. The cold accumulated in tank 11 is used to cool screen 10 during and between experiments, which improves the thermal safety of the cryoagent in Dewar 1 and increases its storage time and reduces the consumption of cryoagents. To replace the sample, ventilator 17 is closed and, after depressurization of chamber 2, the cap 15 and the heat shield 16 are removed. When the experiment is repeated, the mass of the heat shield 16, heat exchanger 3, sample and tube 6 is small, the cryoagent consumption for their cooling is insignificant

The use of the invention allows for laboratory studies of objects in a wide temperature range.

5 with low intrinsic heat generation. Due to the accumulation of cold waste vapor and its exploratory beneficial use, the flow rate of the cryoagent remains at an acceptable level, with

This achieves the convenience of operating a cryostat with repeated and frequent replacement of the object of study during the experiment.

Claims (1)

Invention Formula 5 A cryostat containing a Dewar vessel for a liquid cryoagent placed on it a vacuum chamber with a heat exchanger and an object holder fixed on the last tube electric heater for supplying and discharging the crisagent from the Dewar vessel to the chamber, characterized in that the cryoagent vapor from the Dewar respo vessel in order to increase convenience when operated in the gap between the screen and the arrangement, the cryostat is equipped with a casing, the Dyoara house is installed with the provision of thermal around the Dewar vessel of contact with the wall of the latter while the formation between them of a vacuum polo-5 tube for the removal of cryoa. enta from vacuum placed in the cavity, the ec-chamber has a section located under wound, installed with the formation of the bottom with the provision of thermal contour between it and the Dewar vessel, a stake with it, and the area located in The target tank with the accumulating Olod-ring tank with the accumulating collector, and the pipeline for removal of 10 substances. wv one  - ...; ..-. ../ .-:,; . ;; .. L.u g ..; ./. 20 BUT ...- .. ..; ;, , .... ".. XV :::. :: -. ::;. V-X-V-V: . "     . .- .. -ixH "P l „...  . .. „J .-. :::::;: g,: / 4 eleven / d  H. - .. ..; .., .. - ..: .- / ... ::. ::;:.:. .. ... :: -.::::::;;L LL /: ::