134 results about "Liquid helium" patented technology

The invention discloses a conduction cooling type superconducting isochronous cyclotron, and belongs to the technical field of superconducting isochronous cyclotrons. Comprising an accelerator main support, the accelerator main support is integrally of a base frame structure composed of a plurality of vertical supports, vertically-arranged hydraulic lifting systems are further fixedly installed on the side walls of each set of vertical supports, and a first magnet yoke is fixedly installed at the top of the accelerator main support; a refrigerating machine direct conduction cooling technology is adopted, a traditional liquid helium soaking cooling system is replaced, and the problem that a superconducting cyclotron depends on a complex liquid helium refrigeration unit and is redundant in structure is solved. While the magnetic field intensity is maintained, heavy parts such as a liquid helium pool, a recondenser and a multi-layer heat insulation pipeline are completely abandoned, so that the system height and the sealing complexity are remarkably reduced, and high operation and maintenance cost caused by dependence of liquid helium resources is also avoided.

The invention provides a high-sensitivity superconducting magnetic detection device and method based on an NV color center under high pressure and low temperature. The high-sensitivity superconducting magnetic detection device comprises a microwave emission module, an optical excitation module, an imaging module, a fluorescence collection module, a data collection and control module, a diamond anvil cell, a low-temperature test module and a magnet module. The method has the beneficial effects that the diamond injected with the NV color center serves as the anvil cell of the diamond anvil cell, and high-pressure and low-temperature conditions are synchronously obtained in liquid helium and liquid nitrogen temperature zones; according to the invention, in-situ pressure measurement can be realized under high pressure, and ruby or Raman standard pressure is not needed; a sample is placed in the diamond anvil cell, the diamond anvil cell is placed in the low-temperature cavity, the lowest temperature of 4K and in-situ pressurization can be realized by using the low-temperature test module, and the quality of a microwave signal transmitted by the low-temperature semi-steel cable is higher and the loss is smaller by using the low-temperature semi-steel cable. And the superconducting property of the material at low temperature and high pressure is quantitatively tested under the condition of high integration.

The invention belongs to the technical field of magnetic refrigeration, and particularly discloses a rare earth europium-based zirconate magnetic refrigeration material and a preparation method and application thereof. The general chemical formula of the rare earth europium-based zirconate magnetic refrigeration material is (Eu1-xMx) (Zr1-yNy) O3, M is any one of Ca, Sr or Ba, N is any one of Nb, Ta, Ti or Hf, x is more than or equal to 0 and less than or equal to 0.5, y is more than or equal to 0 and less than or equal to 0.5, and the magnetic phase transition temperature of the rare earth europium-based zirconate magnetic refrigeration material is less than 10K. The magnetic refrigeration material shows excellent magnetocaloric performance near the liquid helium temperature, and is expected to be applied to the liquid helium temperature zone magnetic refrigeration technology; and the preparation method is simple in process, safe and environment-friendly, and can be applied to industrial production.

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.

The invention relates to the technical field of fusion devices, and discloses a composite multi-channel multi-medium pipeline for a fusion device.The composite multi-channel multi-medium pipeline comprises a heat shielding part, a vacuum pipeline, a liquid helium conveying assembly and a first gas helium conveying assembly, and the interior of the heat shielding part is hollow to form a first containing space; the vacuum pipeline sleeves the periphery of the heat shielding part, the vacuum pipeline and the heat shielding part are arranged at an interval, a second accommodating space is formed between the heat shielding part and the vacuum pipeline, and the heat shielding part is used for shielding heat transfer between the first accommodating space and the second accommodating space; the liquid helium conveying assembly is used for conveying liquid helium and arranged in the first containing space to be fixedly connected with the heat shielding piece. The first gaseous helium conveying assembly is used for conveying first gaseous helium and arranged in the second containing space to be fixedly connected with the heat shielding piece and the vacuum pipeline. The composite multi-channel multi-medium pipeline for the fusion device is not only suitable for transmission of different media, but also capable of avoiding heat transfer between the different media.

The invention relates to the technical field of low-temperature system integration, in particular to a helium liquefaction and recondensation chip test low-temperature system which comprises a liquid helium test cavity, a pulse tube refrigerating machine and a helium tank, the pulse tube refrigerating machine comprises a refrigerating machine compressor, a refrigerating machine cold head and a refrigerating machine cold screen, and the refrigerating machine cold head is connected with a condensation heat exchanger. The liquid helium testing cavity and the condensing heat exchanger are located in the refrigerating machine cold screen, the refrigerating machine cold head is communicated with the liquid helium testing cavity through a cold helium return pipeline, and the condensing heat exchanger is communicated with the liquid helium testing cavity through a liquid helium return pipeline. The helium tank is connected with the refrigerator cold head through a pipeline. The liquid helium testing cavity is used for containing liquid helium to provide a soaking testing environment, the problem of electromagnetic interference is avoided, cold helium evaporated in the liquid helium testing cavity flows back into the liquid helium testing cavity from the liquid helium backflow pipeline after being condensed through the condensation heat exchanger, and zero evaporation of the liquid helium in the superconducting chip testing process is achieved. And long-term test requirements of large-scale superconducting chips can be met.

According to the light helium storage spray pipe with the integrated efficiency of efficiency increasing, pushing changing, phase change heat prevention and infrared stealth, by means of the high phase change latent heat characteristic of liquid helium, the liquid helium is directly injected into the spray pipe to be mixed with high-temperature fuel gas; the temperature of fuel gas and thermal stress borne by a spray pipe material are remarkably reduced through phase change heat absorption, heat convection and gas film cooling, efficient thermal protection is achieved, the infrared radiation intensity of exhaust plume is effectively restrained, and the infrared stealth effect is achieved; the characteristic that helium is small in molecular weight is utilized, the expansion power capability of mixed gas and the propulsive efficiency and specific impulse of the engine are improved, meanwhile, through real-time regulation and control of helium injection flow, thrust adjustment to a certain degree can be achieved, and the maneuverability of the engine is enhanced. According to the designed composite interlayer structure, the thickness of the wall face of the spray pipe can be greatly reduced, the structural strength of the spray pipe is improved, and then the overall mass of an engine is reduced.

The invention discloses a helium magnetocaloric phase change circulation power device which comprises a liquid helium tank, a plunger pump, a helium compressor, a heat exchange tank, a first surge tank, a countercurrent heat exchanger, a second surge tank and a turbo expander. Liquid helium and gas helium are stored in the liquid helium tank; the plunger pump is used for pressurizing liquid helium in the liquid helium tank to set pressure; the heat exchange tank internally comprises a magnetocaloric working medium, a rotating magnetic field, a cold source helium heat exchange pipeline and a heat source helium heat exchange pipeline, and the magnetocaloric working medium based on the magnetocaloric inverse heat effect is used as a medium, so that a heat source and cold and heat source helium are subjected to inverse heat exchange; the first surge tank and the second surge tank are used for stabilizing the inlet and outlet air pressure of the expansion machine so as to stabilize the working efficiency of the expansion machine; the countercurrent heat exchanger is used for carrying out heat exchange on high-pressure helium output by the first surge tank and a heat exchange medium for absorbing environmental heat energy; the expansion machine is used for converting heat energy of gas into mechanical energy and then converting the mechanical energy into electric energy through the generator, and recycling of environment low-temperature heat energy is achieved.

The invention relates to the technical field of low-temperature imaging, in particular to a low-temperature microscopic imaging system. The low-temperature microscopic imaging system comprises a helium medium circulation assembly, a cold transfer assembly and an imaging assembly, liquid helium is stored in the helium medium circulation assembly, the cold transfer assembly is connected with the helium medium circulation assembly, and the cold transfer assembly comprises a first cold transfer unit and a second cold transfer unit for liquid helium to flow; the imaging assembly comprises a sample table, a support and a low-temperature imaging piece, the support is connected with the sample table, and the low-temperature imaging piece is connected with the support; one end of the first cold transfer unit is communicated with the helium medium circulating assembly, the other end of the first cold transfer unit is communicated with the sample table, a throttle valve is arranged in the first cold transfer unit, one end of the second cold transfer unit is connected with the helium medium circulating assembly, and the other end of the second cold transfer unit is connected with the sample table. The device has the advantages that pre-cooling can be performed through the second cold transfer unit before a formal experiment, then cryogenic cooling is achieved through the first cold transfer unit, and the cooling efficiency is high.

The invention discloses an experimental device for testing the performance of a liquid hydrogen valve, and relates to the technical field of refrigeration and low-temperature engineering. Comprising a low-temperature medium storage system, a high-pressure purified gas storage device, a temperature measurement system, a valve test module, a vacuumizing device, a rewarming device, a gas recovery system, a leakage rate measurement system and a data acquisition system, and the low-temperature medium storage system is used for storing a low-temperature cooling medium. The temperature zone of the liquid helium can cover the liquid hydrogen, the safety of the liquid helium is far higher than that of the liquid hydrogen, the test safety is improved, the supply of the low-temperature medium can be accurately controlled, the reliable test of the valve at the preset temperature is ensured, the test requirement of the temperature range of 20K-300K is met, the application range is wider, and the application range is wider. The valve testing device can support a low-temperature environment from 20K to 300K, provides a high-pressure hydrogen condition, and meets various valve testing requirements.

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 present invention discloses a liquid helium storage tank, belonging to the field of liquid helium storage technology. The liquid helium storage tank comprises an outer shell, a cold shield, and an inner container, arranged sequentially from the outside to the inside. The cold shield is wrapped around the inner container, and the outer shell is wrapped around the cold shield, forming a three-layer straight cylindrical horizontal structure. The liquid helium storage tank uses the cold shield as a boundary and fulcrum to divide the tank support into two temperature ranges. The inner container is supported on the cold shield and the outer shell, and the cold shield is supported on the outer shell. The hot end temperature of the inner container support structure can be reduced from 293K to 77K, thereby significantly reducing radiative heat transfer. The liquid helium storage tank is also provided with a helium pipeline. When the helium pipeline is discharged, a shielding layer is formed outside the liquid helium pipeline to absorb external heat transfer, effectively reducing evaporation loss of liquid helium in the liquid helium pipeline. By providing a thermal bridge and a vacuum pipeline, a vacuum shielding layer is formed, thereby reducing the conduction of external heat into the liquid helium pipeline. At the same time, the thermal bridge can meet the deformation coordination under the action of temperature difference.

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 present invention belongs to the technical field related to refrigeration and cryogenic containers, and discloses a eddy-current-free liquid helium cryostat for use in a pulsed high-magnetic field environment. The cryostat comprises a sample rod, a helium chamber, a liquid nitrogen layer, a vacuum chamber, and a tail pipe. The tail pipe is composed of an inner epoxy tail pipe and an outer epoxy tail pipe, each of which is mounted via metal flanges. The epoxy tail pipe and the metal flanges are bonded together with epoxy sealant. The vacuum interlayer between the helium chamber and the vacuum chamber is interconnected with the vacuum interlayer between the inner epoxy tail pipe and the outer epoxy tail pipe. In addition, the metal flange of the inner tail pipe is precisely mounted concentrically from top to bottom, and a removable metal seal is achieved between the metal flange of the inner tail pipe and the bottom flange of the helium chamber. The present invention effectively solves the problem of liquid helium loss caused by Joule heat generated by induced eddy currents in a pulsed high-magnetic field environment in the prior art, while significantly improving the measurement accuracy of scientific experiments in a high-field pulsed high-magnetic field environment.

The present invention provides a device for inspecting and treating needle valve blockage in a liquid helium dewar, relating to the technical field of needle valve blockage detection. The device comprises an adapter and a transparent tube. The adapter includes multiple KF ports, and the transparent tube is connected to one of the multiple KF ports of the adapter. The transparent tube contains one or more functional modules including an imaging module, a temperature measurement component, and a heating component. The functional modules correspond one-to-one with and are electrically connected to the adapter ports in the remaining KF ports that match the functional modules. The device has a simple structure and can quickly and accurately determine the cause of a needle valve blockage, allowing for timely unblocking and treatment based on the cause.

The application is a liquid helium supply mechanism, which provides cold source for low-temperature superconducting material in superconducting particle radiotherapy equipment. The mechanism comprises a liquid helium preparation mechanism for preparing liquid helium by using helium gas, and the prepared liquid helium flows into a liquid helium terminal for cooling the low-temperature superconducting material. The mechanism also comprises a liquid helium compensation mechanism, which collects the helium gas vaporized due to heat absorption of the low-temperature superconducting material in each liquid helium terminal and delivers the helium gas to the liquid helium preparation mechanism. The liquid helium supply mechanism of the application comprises the liquid helium preparation mechanism and the liquid helium compensation mechanism, which overcomes the deficiency of the current liquid helium supply equipment that only provides liquid helium preparation equipment and cannot automatically compensate liquid helium.

The present invention belongs to the field of research on the application of nanomaterial heterostructures. In response to the problems that traditional gallium arsenide-aluminum gallium arsenide requires harsh quantum Hall resistance platform measurement conditions such as temperatures below liquid helium and magnetic fields above 10T, a method for defining a standard resistance for a CrOCl-supported graphene quantum Hall platform is disclosed. The CrOCl-supported graphene system, by means of the interface coupling of the CrOCl antiferromagnetic insulator to the graphene, can achieve electron transport regulation of the graphene. Compared with the harsh quantum Hall resistance platform measurement conditions of traditional gallium arsenide-aluminum gallium arsenide, gate voltage regulation can be used to achieve a larger parameter space, i.e., a magnetic field requirement as low as 0.2T and a temperature as high as above liquid nitrogen temperature (77K), achieving a stable quantized transverse conductance platform. This greatly reduces the threshold for quantum resistance standards, making it more convenient to use quantum resistance standards to replace the original physical resistance standards, becoming a new generation of resistance benchmarks, and is expected to be widely used in quantum metrology.

The utility model relates to a cold head mounting structure and a cooling device. The cold head installation structure comprises a cold head cavity and an elastic heat conduction mechanism. The cold head cavity is provided with a sealing end, the sealing end is used for separating the cold head cavity from the refrigerant bin, and a cold head is arranged in the cold head cavity. The elastic heat conduction mechanism comprises an elastic piece and a transition heat conduction piece, the transition heat conduction piece is connected with the inner wall of the cold head cavity through the elastic piece, and the transition heat conduction piece is used for abutting against the cold head so that the cold head can keep thermal contact with the inner wall of the cold head cavity. The cold head cavity and the refrigerant bin body are separated by the sealing end, so that the cold head can be directly taken out from the cold head cavity during maintenance, and liquid helium cannot be leaked from the cold head cavity. In addition, the elastic heat conduction mechanism comprises an elastic piece and a transition heat conduction piece, when the cold head stretches into the cold head cavity, due to the elastic effect of the elastic piece, the cold head can make thermal contact with the transition heat conduction piece all the time in the working period, and then the refrigeration efficiency of the cold head is guaranteed.

This invention relates to the field of fusion device technology and discloses a composite multi-channel multi-medium pipeline for fusion devices. The composite multi-channel multi-medium pipeline includes a heat shield, a vacuum pipeline, a liquid helium delivery assembly, and a first gaseous helium delivery assembly. The heat shield has a hollow interior forming a first accommodating space. The vacuum pipeline is sleeved around the outer periphery of the heat shield and spaced apart from it. A second accommodating space is formed between the heat shield and the vacuum pipeline. The heat shield is used to shield heat transfer between the first and second accommodating spaces. The liquid helium delivery assembly is used to deliver liquid helium and is located within the first accommodating space and fixedly connected to the heat shield. The first gaseous helium delivery assembly is used to deliver first gaseous helium and is located within the second accommodating space and fixedly connected to both the heat shield and the vacuum pipeline. This composite multi-channel multi-medium pipeline for fusion devices is not only suitable for the transmission of different media but also avoids heat transfer between different media.

This invention discloses an automatic lifting device and method for lowering a sample rod in RRR (Reduced Rate of Change) testing of superconducting wires. The device includes a mounting bracket, a positioning part and a lifting part mounted on the mounting bracket, and a sample rod fixing part mounted on the lifting part. The lifting part is vertically movable. The sample rod is located on the sample rod fixing part and can be horizontally moved along it. A position adjustment part is provided on the outer periphery of the sample rod for fine-tuning its horizontal position. The positioning part is used to fix a Dewar flask, and the sample rod can freely rise and fall within the Dewar flask opening. This invention improves the automation level of the lowering process in RRR cryogenic testing of superconducting wires, significantly increases the efficiency of RRR cryogenic testing, reduces liquid helium evaporation during lowering, lowers testing costs, and powerfully promotes the development of equipment for superconducting wire production.

The integrated liquid helium loading system provided by the application integrates a helium liquefier, a liquid helium distribution valve box, a liquid helium container, a helium gas pressurizing unit, a low-temperature helium gas rewarming unit, a gas placement purification unit, and a liquid helium filling and transfer control unit. Through cooperation with a multi-channel composite low-temperature transmission pipeline and a liquid helium transmission pipeline, the loading system can realize intelligent regulation and control of multiple working modes of gas placement purification, precooling, liquid helium accumulation and filling, and transfer loading. The liquid helium can be filled and transferred to other containers at the same time, without causing a large amount of loss and waste of liquid helium, and avoiding the safety hazards of pressure increase and the like of the container during the liquid helium transfer process, so as to realize safe and effective distribution and high-efficiency transfer of liquid helium. Meanwhile, the low-temperature helium gas in the filling and transfer process returns to the helium liquefier, and the cold energy of the low-temperature helium gas in the filling and transfer process can be effectively utilized.

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.

The invention provides an extremely-low-temperature environment simulation device for testing mechanical properties of materials. The extremely-low-temperature environment simulation device comprises a box body and a heat preservation door hinged to the side edge of the box body. The box body comprises a first thermal insulation layer and a first refrigeration layer group, a mounting sleeve and a lower supporting rod are arranged on the upper side and the lower side in a penetrating manner, an upper sliding rod is arranged in the mounting sleeve, a concave area formed by the first liquid helium layer is a test cavity, and one side, close to the test cavity, of the first liquid helium layer is a corrugated surface; and a temperature sensor penetrates through the box body. By means of the multi-layer cooling and heat preservation structure, the temperature can be effectively reduced to the required low-temperature interval, liquid nitrogen and liquid helium are used for cooling the interior layer by layer, and the cooling effect can be achieved while it is ensured that the liquid nitrogen and the liquid helium are fully utilized.

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.