81 results about "Liquid helium" patented technology

The invention relates to a storage cryostat (2) for liquid helium (7), suitable for transferring liquid helium (7) from the storage cryostat (2) into an application cryostat (3), wherein the storage cryostat (2) comprises: - a vacuum-insulated helium vessel (6) for liquid helium (7), the helium vessel (6) having a vertical height HHB that can be filled with liquid helium (7), - a transfer line (4) for liquid helium (7), having an inlet opening (20) which opens into a lower region of the helium vessel (6), in particular into a lower fifth of the helium vessel (6), and - a convection-suppression system (9) which is arranged within the helium vessel (6) and impedes vertical convection of liquid helium (7) in the helium vessel (6), characterised in that the convection-suppression system (9) is formed in the helium vessel (6) over a height interval (IKS) with a vertical height HKS, where HKS ≥ 0.50 × HHB, and in that the convection-suppression system (9) impedes the vertical convection of liquid helium (7) in the helium vessel (6) over the region of the height interval (IKS) of the convection-suppression system (9). The invention provides a storage cryostat that enables simple and rapid transfer of liquid helium from the storage cryostat into the application cryostat, with minimised helium losses.

The invention relates to the technical field of material mechanical property testing, and provides an ultralow-temperature slow strain mechanical tensile test platform which comprises a vacuum Dewar unit, a liquid helium temperature control unit, a slow strain tensile unit, a measuring unit and a control unit, the vacuum Dewar unit comprises a vacuum Dewar body and is used for providing a closed low-temperature test environment; the liquid helium temperature control unit comprises a direct injection module and a recovery module, the direct injection module is used for directly injecting liquid helium to the gauge length section of the sample for cooling, and the recovery module is used for recovering and recycling unevaporated liquid helium; the slow strain stretching unit is used for stretching a sample arranged in the vacuum Dewar body at a low strain rate; the measuring unit is arranged in the vacuum Dewar body and is used for monitoring the temperature, the force value and the strain data of the sample in real time. Liquid helium is used as a cold source, the liquid helium is directly aligned to the gauge length section of the sample through the direct injection module, and compared with a traditional liquid helium steam natural convection heat exchange mode, the heat exchange coefficient is increased, and automatic precise temperature control is achieved.

To improve the accuracy of measuring pressure inside a helium container. [Solution] A magnetic resonance imaging apparatus according to one embodiment comprises a superconducting coil, a helium container, a first pressure gauge, a second pressure gauge, a valve, and a control circuit. The superconducting coil generates a static magnetic field. The helium container houses liquid helium for cooling the superconducting coil together with the superconducting coil. The first pressure gauge measures the pressure inside the helium container within a first pressure measurement range. The second pressure gauge measures the pressure inside the helium container within a second pressure measurement range that is narrower than the first pressure measurement range. The valve switches the second pressure gauge to be used for measuring the pressure inside the helium container. The control circuit controls the opening and closing of the valve based on the measurement value of the first pressure gauge.

The invention provides a cavern helium storage method which comprises the following steps: S1, after salt cavern cavity construction is finished, carrying out gas injection and brine discharge for the first time through a gas injection and brine discharge system to form a gas storage space; s2, helium in the helium tube bundle truck is subjected to first-stage pressure reduction, second-stage pressure reduction, water removal and oil removal, then gas injection, brine discharge and gas storage are conducted through a gas injection and brine discharge system, and the helium is injected into a salt cavern to be stored; s3, starting a salt cavern helium extraction pump to extract helium, and measuring the pressure and temperature data of the extracted helium; s4, the extracted helium is purified; s5, the purified helium is liquefied; and S6, filling liquid helium. The salt cavern helium storage method is suitable for storing helium which is high in price and prone to leakage, and normal supply of helium in China is guaranteed.

The application provides a main group element ion doped zero-dimensional metal halide fluorescent sensing material and a preparation method and application thereof, and belongs to the technical field of fluorescent sensing materials. The main group element ion doped zero-dimensional metal halide microcrystal is synthesized by a solvothermal method, the strong dependence of two thermal coupling energy levels of the main group element ion on temperature is utilized, the main group element ion doped zero-dimensional metal halide shows an obvious temperature dependence evolution trend of fluorescence lifetime and fluorescence intensity at low temperature, and dual-mode (fluorescence intensity ratio / fluorescence lifetime) high-sensitivity temperature detection in a liquid helium temperature region can be realized. The synthesis method is simple in process and easy to control in synthesis conditions, the obtained material shows extremely high relative sensitivity in the liquid helium temperature region, has high practical application value, can be used as a novel optical temperature sensing material, and can be used for temperature detection in various extreme temperature regions.

The invention relates to the technical field of extremely low temperature, in particular to a gas adsorption type rapid cooling system and method for an extremely low temperature system. The system comprises a refrigeration mechanism, the refrigeration mechanism comprises a refrigeration unit, and the gas adsorption type rapid cooling system for the extremely low temperature system further comprises an inner shell arranged outside the refrigeration unit in a covering mode, a middle shell arranged outside the inner shell in a covering mode and an adsorber arranged in the inner shell. The adsorber is internally provided with activated carbon or an MOFs (Metal-Organic Frameworks) adsorption material; liquid helium is arranged between the inner shell and the middle shell, and the inner shell is filled with helium with the pressure ranging from 0.1 Pa to 10 Pa. The cooling time of the ultra-low-temperature refrigerating system is shortened by more than half compared with that of a traditional cooling method, and meanwhile extra heat leakage is not caused at the ultra-low temperature.

The application provides a liquid helium filling and transfer device with cold energy recovery, and particularly relates to the technical field of cold energy recovery.The liquid helium filling and transfer device with cold energy recovery comprises a liquid inlet unit, a cold energy recovery unit, a helium recovery unit, a switching unit and a storage unit.The liquid inlet unit comprises a liquid helium source.The storage unit comprises a first liquid helium storage tank, a second liquid helium storage tank and a third liquid helium storage tank.The helium recovery unit comprises a helium storage tank, a compression module and a recovery module.The switching unit is used for switching liquid helium or helium.The cold energy recovery unit comprises a heat exchanger group and an ejector.The helium recovery unit and the cold energy recovery unit can recycle cold energy, and the convenience of cold energy recovery is improved.

A circulating refrigeration system without liquid helium consumption. The system comprises: a liquid-helium-free refrigerating machine (40); a copper shielding tube (10), one end of the copper shielding tube (10) being connected to a shielding cylinder (5) of the liquid-helium-free refrigerating machine (40), and a first-stage cold head connector (11) and a second-stage cold head connector (13) being provided at the other end of the copper shielding tube (10); a first-stage cold shield, which is connected to the first-stage cold head connector (11) by means of a copper braid and is arranged on the outer ring of a μ metal cover; the μ metal cover, which is connected to the first-stage cold head connector (11) by means of the copper braid and is connected to the first-stage cold shield by means of a first-stage cold shield copper braid, wherein the μ metal cover, as a fixing ring, is in vacuum connection with a lower pole piece of an electron microscope, and the μ metal cover is connected to a Z-axis piezoelectric ceramic holder in a sample chamber (8) by means of a thermally insulating gasket; and a sample stage fixing member (28), which is connected to the second-stage cold head connector (13) by means of the copper braid. The present application can achieve a required liquid-helium temperature range environment for a long time, thereby greatly reducing the experiment cost, reducing mechanical vibrations, improving the transverse resolution, and thus realizing an ultrahigh resolution of an electron microscope.

The utility model relates to the technical field of low-temperature heat preservation devices, in particular to a liquid helium low-temperature instrument heat preservation device which comprises a heat preservation box, the heat preservation box is sequentially provided with a liquid helium tank, an inner vacuum layer, an inner heat insulation layer, a liquid nitrogen layer, a middle heat insulation layer, an outer vacuum layer and an outer heat insulation layer from inside to outside, a sample basket is arranged in the liquid helium tank, and a sample is arranged in the sample basket. According to the low-temperature device adopting liquid helium for refrigeration, the lowest temperature reaches 269 DEG C, the excellent heat preservation performance of the heat preservation device is ensured, the loss of liquid helium is greatly reduced, and the use cost is reduced.

The present application relates to the technical field of cold storage. Specifically disclosed are a cold storage material, and a preparation method therefor and the use thereof. The cold storage material comprises a Gd2O2Se crystal. The cold storage material in the present application comprises the Gd2O2Se crystal, and the Gd2O2Se crystal has a phase transformation near 6.22 K, a relatively large specific heat in a temperature range of 1-10 K, and an obvious magnetothermal effect and can be used as a cold storage material at a liquid helium temperature.

The invention discloses a superfluid helium low-temperature visualization device suitable for neutron fluorescence tracing and an experiment method, and a low-temperature heat insulation system module in the superfluid helium low-temperature visualization device comprises a cavity, a liquid nitrogen pool, a 77K cold screen, a superfluid helium pool and a 4K cold screen; the vacuum pumping and circulating reliquefaction module is used for recycling gasified helium; the temperature and liquid level monitoring control module is used for monitoring the temperature, the liquid level and the pressure in real time; the experimental observation and visualization module is used for neutron incidence, laser excitation and fluorescence signal observation path penetration, so as to realize visual observation of excimer fluorescence in the superfluid helium flow field; and the convection driving and mode switching module is used for realizing two experimental modes of mechanical driving forced convection and thermal driving internal convection. The device can stably obtain a superfluid helium environment below 2.17 K, and has the advantages of being excellent in heat insulation performance, high in liquid helium utilization rate, detachable and replaceable in structure, stable in operation, suitable for neutron fluorescence flow field observation and the like.

The invention relates to the technical field of superconducting magnets, discloses a superconducting magnet helium supplementing device, and aims at solving the problems that in the existing helium supplementing process, a liquid conveying opening is frosted, connection is difficult, pressure unbalance depends on manual adjustment, and the operation risk is high. The device comprises a connector flange, a closed cavity and a communicating cavity are formed in the connector flange, a piston cover plate is slidably connected into the closed cavity, a liquid conveying cylinder is arranged in the piston cover plate, a flow guide mechanism is arranged in the communicating cavity, a feedback mechanism is arranged above the piston cover plate, and a locking mechanism and a cooling assembly are arranged on the outer side of the connector flange. During helium supplementing operation, helium leakage and frosting of a liquid conveying opening can be effectively avoided, meanwhile, the feedback mechanism adaptively adjusts the liquid helium flow speed, the locking mechanism stabilizes the sealing state, continuous manual monitoring is not needed, the helium supplementing safety, convenience and automation degree are greatly improved, and the magnet quenching risk is reduced.

The invention belongs to the technical field of extremely low temperature tests, and particularly discloses a double-layer sample rod suitable for an extremely low temperature test in a pulsed magnet liquid helium Dewar, which comprises a first rod section, a second rod section and a switching assembly, the first rod section comprises a first outer pipe and a first inner pipe which are coaxially arranged in a sleeved mode, a condensation layer is formed between the first outer pipe and the first inner pipe, and a vacuum layer is formed in the first inner pipe. The second rod section comprises a second outer pipe and a second inner pipe which are coaxially sleeved, a feeding port is formed in the upper end of the second outer pipe, the lower end of the second outer pipe is sealed, a sample cavity is formed between the second outer pipe and the second inner pipe, and a sample clamp is hermetically mounted at the lower end of the second inner pipe; the switching assembly comprises a first switching piece, a condensation pipe, a second switching piece and a sealing plate. According to the structural design, the extremely low temperature condition is guaranteed, and controllable thermal isolation between the sample cavity and the external refrigerating working medium serving as a cold source is effectively achieved.

This invention relates to the field of cryogenic tank containers / tank containers, specifically to a large-capacity, zero-evaporation liquid helium tank container / tank container, comprising: an inner container of the liquid helium tank, a cooling coil for the inner container, liquid helium inlet and outlet pipes, composite multi-layer insulation material, an inner copper shield, a flash vapor transfer pipe, insulation support, an outer copper shield, an outer container of the liquid helium tank, a steel frame for the liquid helium tank, a liquid helium inlet transfer pipeline, a cooling medium inner container, a cooling coil for the inner container, composite multi-layer insulation material II, inner copper shield II, insulation support II, outer copper shield II, a cryogenic cold head, a cryogenic refrigerator, and a one-way liquid filling control valve. This invention can address the rapid increase in internal pressure that easily occurs during long-term pressurized storage of liquid helium and long-distance transportation of liquid helium, achieving long-term zero-evaporation storage.

This invention relates to the field of tank container technology, specifically disclosing a tank container for cryogenic storage and transportation of liquid helium. The container includes an outer frame and an outer tank disposed inside the outer frame. An inner tank for liquid helium storage is disposed inside the outer tank. The outer tank and the outer frame are connected by a flexible hinged support mechanism. A cold shield structure is provided between the outer tank and the inner tank, and the interlayer between the inner tank, the cold shield structure, and the outer tank forms a first vacuum layer and a second vacuum layer from the inside out. The flexible hinged support mechanism consists of a bottom longitudinal beam, a lower hinge seat, a carrier plate, an upper hinge seat, a ball core, and connecting rods. This tank container for cryogenic storage and transportation of liquid helium significantly improves thermal insulation and transportation stability through double-layer vacuum insulation and flexible hinged support. It is also equipped with a helium recovery and liquefaction reinjection system for efficient utilization of helium resources and features full-parameter intelligent monitoring to ensure safe and reliable storage and transportation.

This utility model relates to the field of superconducting magnet technology and discloses a liquid helium-free zero-evaporation superconducting hollow magnet, including a shell. A first support column is fixedly connected inside the shell. A hinge is fixedly connected to the outer wall of the first support column. A second support column is fixedly connected to the outer wall of the hinge. The outer wall of the second support column is disposed on the outer wall of the first support column. A caster wheel is provided on the lower surface of the second support column. A first fixing block is fixedly connected to the outer wall of the second support column. A support assembly is provided on the outer wall of the first fixing block. The support assembly is used to support the caster wheel for movement. In this utility model, by pushing the hook, the second fixing block rotates, and the first spring is compressed as the second fixing block rotates. Finally, the shell can be moved or fixed in place, allowing for flexible position adjustment, making the spatial layout more reasonable, improving space utilization, and enhancing the comfort of the working environment.

This invention discloses an automated method for preparing supercooled superfluid helium, comprising: injecting liquid helium from a liquid helium source into a storage tank, and splitting the liquid helium into a first portion and a second portion in the storage tank; injecting the first portion of liquid helium into a subcooling cavity to cool the magnet coil therein; throttling and cooling the second portion of liquid helium through a negative pressure regenerator pipeline to obtain saturated superfluid helium; controlling the saturated superfluid helium to exchange heat with the first portion of liquid helium in an evaporator to obtain supercooled superfluid helium in the subcooling cavity; sending the low-temperature saturated helium gas formed by the heat exchange and evaporation of the saturated superfluid helium into a regenerator to recover the cold energy, and then sending it to a liquefaction unit to be reliquefied into liquid nitrogen, and returning the liquid nitrogen to the liquid helium source. This invention achieves fully automated adjustment of the entire process, including liquid helium injection, throttling and cooling, helium heating, and safe venting, through multi-sensor collaborative control, realizing automated preparation of supercooled superfluid helium, reducing the need for manual intervention, and improving system response speed and operational stability.

A device for transferring liquid helium into an application cryostat comprises a storage dewar, a transfer line with a first transfer line end in the storage dewar and a second transfer line end for insertion into the application cryostat. An apparatus is provided for generating a pressure difference between the storage dewar and the application cryostat. A condensation heat exchanger, cooled by a cryocooler, condenses helium gas to liquid helium for insertion into the application cryostat. A control apparatus, using a measure of gas pressure in the application cryostat provides a control output to the apparatus for generating a pressure difference such that a volume of liquid helium transferred through the transfer line per unit of time is approximately equal to the change in volume of the helium which condenses from helium gas to liquid helium per unit of time at the condensation heat exchanger.

The utility model relates to a liquid-helium-free open type nuclear magnetic resonance superconducting magnet system which comprises an open type main body and a low-temperature superconducting device, comprising a mounting space, and a low-temperature superconducting device is mounted in the mounting space of the open main body; the low-temperature superconducting device comprises a superconducting magnet installed on the upper inner wall of the installation space and a superconducting magnet installed on the lower inner wall of the installation space, the superconducting magnet is refrigerated through an ultralow-temperature refrigerator, a 45K cold shield and a 4K superconducting coil in the superconducting magnet are suspended through a pull rod and a supporting piece, risks caused by magnet quenching do not exist, and the service life of the superconducting magnet is prolonged. And a heat sink (heat cut-off) effect is directly achieved, so that the heat leakage rate is greatly reduced.

The invention relates to a test chamber (1) on a test device for the characterization of materials, in particular for the in-situ characterization of fatigue behavior, in an environment containing cold liquid hydrogen (LH2), wherein the test chamber (1) has a multi-layered chamber system (4, 6, 8) in which the exterior of the material sample (2) to be tested is exposed to contact with liquid helium in an inner chamber (4), the inner chamber (4) is surrounded by a middle chamber (6) in which a vacuum prevails, and the middle vacuum chamber (6) is surrounded by an outer chamber (12) filled with liquid nitrogen, wherein the hydrogen in gaseous form can be introduced into the interior of the material sample (2) in the interior of the test chamber (1) via connecting lines (13, 14), which is at least partially hollow.

The invention relates to a method for preparing an AgBiSe2 low-temperature sensitive material by a solid-phase reaction method, which is characterized in that a single and stable cubic-phase AgBiSe2 block material can be obtained by combining normal-pressure sintering with a liquid nitrogen cold quenching process through ball-milling mixing, vacuum tube sealing high-temperature sintering, rapid cold quenching and secondary densification treatment. The method does not need expensive equipment such as discharge plasma sintering and the like, does not need long-time multi-step heat treatment, and is simple and convenient in process, low in cost and good in repeatability. The obtained material shows a clear negative temperature coefficient characteristic in a 10-300 K interval, is suitable for the extremely low temperature fields of deep space exploration, quantum calculation, liquid helium temperature zone temperature measurement and the like, can also be expanded to the direction of functional materials of infrared detectors, solar cells, thermoelectric devices and the like, and has good application prospects and industrialization values. And potential temperature-sensitive application value is realized in an extremely-low-temperature region. The problems of complex process, expensive equipment, easy formation of multiple phases in the cooling process, poor cubic phase stability and the like in the existing solid phase method for preparing AgBiSe2 are solved.

The application discloses a kind of quantum voltage chip based on graphene liquid helium temperature work, belong to electrical quantum precision measurement technical field.It includes Si / SiO2 substrate, Josephson junction unit prepared on substrate and microwave antenna.Josephson junction unit includes left and right Ti / Nb superconducting electrode and the graphene unit located therebetween, and the graphene unit is sandwich structure consisting of lower hexagonal boron nitride insulating layer, graphene layer and upper hexagonal boron nitride insulating layer.The application significantly improves the working temperature of the device by optimizing the contact process of superconducting electrode and graphene and improving the design of microwave antenna, can work stably at liquid helium temperature of about 4.2 K, and can output accurate quantized voltage signal by applying microwave irradiation, and can output quantized resistance signal by applying magnetic field.The application solves the problem of low working temperature of existing graphene Josephson junction, reduces system power consumption and dependence on refrigeration equipment, and provides a basis for integrated multi-parameter quantum metrology chip.

The invention relates to an apparatus and a method for transferring liquid helium to an application cryostat, the apparatus comprising: a storage reservoir; a transfer line comprising a first transfer line end in the storage reservoir and a second transfer line end for insertion into the application cryostat; means for generating a pressure difference between the storage reservoir and the application cryostat; a condensation heat exchanger for condensing helium gas into liquid helium; a cryocooler for cooling the condensation heat exchanger; and a control device having a measurement input for a pressure sensor and a control output for the means, the control device being programmed to control the means such that the volume of liquid helium transferred through the transfer line per unit of time is approximately equal to the change in volume of helium condensed from helium gas into liquid helium at the condensation heat exchanger per unit of time. With this apparatus, the helium loss when transferring liquid helium is minimized in a simple manner.

The utility model discloses a dry-type closed-cycle cryogenic system adaptive to a pulse paramagnetic resonance spectrometer. The dry-type closed-cycle cryogenic system comprises a liquefier assembly, a low-loss infusion tube assembly, a cryostat module assembly, a pulse probe and a circulating gas circuit assembly. According to the dry-type closed-cycle low-temperature system adaptive to the pulse paramagnetic resonance spectrometer, liquid helium used for reducing ultralow temperature and ultralow vibration is provided, the temperature of a low-temperature experiment environment is as low as 2.5 k, the vibration is smaller than 20 nm, a special structure that a GM refrigerating machine is externally arranged and helium circulation is utilized is adopted, the experiment conditions of ultralow temperature and ultralow vibration are achieved, and the experiment efficiency is improved. The low-temperature thermostat is connected through the low-loss infusion tube, the low-loss infusion tube is fixed through the fixing frame, at the moment, vibration transmitted by the liquefier part is filtered, and therefore the effect of ultralow vibration is achieved.

The invention belongs to the field of superconducting testing, and discloses a superconducting cable and magnet low-temperature testing device and method based on combined refrigeration. The device comprises an outer Dewar used for providing a main body vacuum environment; the sample cavity is hung in the outer Dewar; the sample cavity comprises a cylindrical barrel, two ends of the cylindrical barrel adopt cover bodies with semi-ellipsoid structures, or the whole sample cavity is in an ellipsoid shape; the superconducting sample is hoisted in the sample cavity; the liquid helium pipeline comprises an inlet pipe and an outlet pipe; one ends of the inlet pipe and the outlet pipe are hermetically led out of the outer Dewar, and the other ends are connected with the sample cavity; the ends, led out of the outer Dewar, of the inlet pipe and the outlet pipe are connected with an external liquid helium supply source and a helium recovery device respectively. According to the invention, the liquid helium pipeline realizes introduction of liquid helium and recovery of helium, on one hand, a medium channel required by liquid helium cooling is provided for the superconducting sample, the refrigeration requirement of low-temperature testing is guaranteed, and on the other hand, working medium recycling is realized through helium recovery, and liquid helium consumption and testing cost are reduced.

The liquid hydrogen bottle comprises an outer shell and an inner tank body which are coaxially and separately arranged together in a sleeved mode, an inner cavity of the inner tank body is a liquid storage cavity, the heat insulation gas chamber is arranged on the circumferential side wall of the inner tank body in a circle surrounding mode, and a gas phase balance pipe is arranged between the liquid storage cavity and the heat insulation gas chamber. One end of the gas-phase balance pipe is communicated with the gas-phase space, close to the top, of the liquid storage chamber, the other end of the gas-phase balance pipe is communicated with the interior of the heat-insulating gas chamber, and the gas-phase balance pipe enables gas in the heat-insulating gas chamber and gas in the liquid storage chamber to circulate, so that the gas pressure in the heat-insulating gas chamber and the gas pressure in the liquid storage chamber tend to be consistent. The gasified low-temperature hydrogen or helium can enter the heat insulation gas chamber, a low-temperature hydrogen or low-temperature helium gas layer is formed on the circumferential side wall of the inner tank body, a low-temperature gas barrier is formed, the gas layer effectively isolates low-temperature liquid hydrogen or liquid helium from directly transferring cold energy to the inner side wall of the inner tank body, and low-temperature loss is reduced.

The utility model relates to the technical field of low-temperature impact test tools, in particular to a special tool for a low-temperature impact test in a liquid helium medium, a sample clamp and a detection device. The special tool comprises a supporting frame, a positioning guide rail is installed on the supporting frame, the lower end of the positioning guide rail is connected with a transverse guide rail, and the transverse guide rail is connected with a sample groove. The utility model further provides a sample clamp which is used for clamping the sample to be tested in the sample groove and comprises a sliding chuck and an auxiliary chuck, and the utility model further provides a detection device which comprises the special tool and a temperature control device. According to the utility model, the sample clamp slides downwards along the side edge of the positioning guide rail and performs clamping action from the outer side of one side of the positioning guide rail, and meanwhile, the sample groove is formed in one side of the positioning guide rail, so that the sample clamp can be quickly positioned to the position of the sample groove, and a to-be-tested sample in the sample groove can be quickly and accurately clamped.

The invention relates to the technical field of gas storage and management, in particular to a liquid helium filling process and a filling system.The liquid helium filling process comprises the following steps that firstly, a salt cavern helium extraction pump is started, the pressure and speed of the extraction pump are adjusted, extracted helium is obtained, then the pressure and temperature data of the extracted helium are measured, and whether the pressure and temperature data meet the primary treatment standard or not is verified; and obtaining preliminary measurement data. According to the invention, by adjusting the pressure and speed of the extraction pump, the initial extraction process of helium is optimized, so that the helium can better adapt to the quality fluctuation of original gas. And continuous monitoring and secondary detection steps are added in the purification stage, so that the purity of helium is improved, and the impurity content is reduced. In the liquefying and filling process, temperature and pressure parameters are set, the accuracy of the filling amount is ensured through measurement, and the stability and safety of products are guaranteed. In conclusion, the operation flexibility is enhanced, the overall performance of the product is improved, and wider commercial and scientific research requirements are met.

The invention provides a low-temperature system, relates to the technical field of gas purification, and is used for obtaining ultra-high-purity helium-4. The low-temperature system comprises a refrigerator, a heat exchanger assembly, a superfluid helium cavity, a pressure reduction assembly and an entropy filter assembly, the refrigerator is connected with the heat exchanger assembly, the heat exchanger assembly is connected with the pressure reduction assembly, the pressure reduction assembly is connected with the superfluid helium cavity, the superfluid helium cavity is connected with the entropy filter assembly, and the entropy filter assembly is used for obtaining ultra-pure helium-4. Cooling capacity can be provided for a low-temperature system through the refrigerating machine, helium at the room temperature can be liquefied through the heat exchanger assembly, then under the action of the pressure reduction assembly, liquid helium can flow into the superfluid helium cavity to become superfluid helium, under the filtering action of the entropy filter assembly, helium-4 can flow through the entropy filter assembly, and helium-3 cannot flow through the entropy filter assembly. Therefore, the low-temperature system can improve the helium-4 purity by two orders of magnitude.

The utility model discloses a cryostat, which belongs to the technical field of ultralow temperature refrigeration, and is characterized in that a first metal corrugated hose and a second metal corrugated hose are respectively arranged at one ends, close to a scanning electron microscope, of an air inlet pipe and an exhaust pipe, and are used for being connected with a sample table in the scanning electron microscope; during working, gas for cooling the sample table is introduced into the gas inlet pipe, and the gas sequentially flows through the gas inlet pipe, the first metal corrugated hose, the sample table, the second metal corrugated hose and the exhaust pipe. The problem that vibration is transmitted to the sample table in the gasification process of liquid nitrogen or liquid helium is effectively solved, so that stable and clear imaging quality is guaranteed, and the sample table can move freely in the working process through the connecting structure of the metal corrugated hose and is not affected by a low-temperature thermostat.