185 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 discloses an inverted 2K liquid-helium-free low-temperature probe station based on a GM refrigerating machine. The inverted 2K liquid-helium-free low-temperature probe station comprises a 2K plate, a vacuum cavity, a refrigerating system and a heat insulation assembly. The refrigerating system comprises a GM refrigerating machine, a thermal switch and a helium circulating system, and the GM refrigerating machine adopts a two-stage GM refrigerating machine, is inverted and extends into the vacuum cavity; the helium circulation system comprises a superflow helium pool installed at the bottom of the 2K plate, the helium circulation system takes away the cooling capacity of the refrigerating machine through circulation helium, the temperature is further reduced through throttling cooling and evacuation pressure reduction, and a 2K low-temperature environment is achieved at the 2K plate. The thermal switch provides cooling capacity for the 2K plate during initial operation so as to realize cooling; the heat insulation assembly comprises multiple stages of heat radiation screens and is used for reducing radiation heat leakage to the vacuum cavity. The 2K plate layout with the 2K plate temperature lower than 2K and the upward direction can be provided, and extra refrigerating working media such as liquid helium are not consumed.

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 utility model discloses a helium cooler for a liquid helium temperature zone. The helium cooler comprises a vacuum cavity and a vacuum flange cover fixed above the vacuum cavity in a sealed mode. A cold shield, a liquid helium cavity, a liquid nitrogen cavity and a liquid helium cavity suspender are arranged in the vacuum cavity; the liquid helium cavity and the liquid nitrogen cavity are both arranged in the cold shield, and the liquid nitrogen cavity is located above the liquid helium cavity. The upper end of the liquid helium cavity suspender is fixed with the vacuum flange cover, the lower end of the liquid helium cavity suspender is fixed with the liquid helium cavity, and the middle section of the liquid helium cavity suspender is fixed with the inner side of the cold shield; a heat exchange coil pipe and a liquid level meter are installed in the liquid helium cavity, a cold shield coil pipe is installed on the outer side of the cold shield, and the cold shield coil pipe is connected with the liquid nitrogen cavity; the vacuum flange cover is provided with a heat exchange coil inlet pipe and a heat exchange coil outlet pipe, and the heat coil inlet pipe and the heat exchange coil outlet pipe are connected with the two ends of the heat exchange coil respectively. According to the utility model, the helium working medium in other states is cooled to a liquid helium temperature area by using liquid helium, so that the low heat leakage is ensured, and the structural strength is good.

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 present invention discloses a method for preparing a rare earth-based multivalent manganese oxide low-temperature magnetic refrigeration material by a molten salt method, which relates to the technical field of magnetic functional materials. The steps are as follows: Weigh manganese dioxide powder and rare earth oxide powder according to the stoichiometric ratio of the rare earth-based multivalent manganese oxide, mix them with sodium chloride, and grind to obtain a mixed powder; sinter the mixed powder at a high temperature and cool it to room temperature with the furnace to obtain a sintered powder; wash the sintered powder with water to remove sodium chloride and dry it to obtain the product. The process of the present invention is simple and low in cost. The prepared rare earth-based multivalent manganese oxide has a large magnetocaloric effect near the liquid helium temperature range. Among them, the REMn2O5-type rare earth-based multivalent manganese oxide has an isothermal magnetic entropy change of up to 12.61 J kg ‑1 K ‑1 , and the relative cooling power RCP is up to 338 J kg ‑1 . It can be used as a low-temperature magnetic refrigeration material in low-temperature engineering, aerospace, medical devices and other fields.

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 thermophysical property measurement, in particular to a high-precision liquid helium temperature zone material thermal conductivity measurement device and method. A low-temperature refrigeration module is used for generating an ultralow-temperature measurement condition in a set temperature range; the vacuum heat insulation module comprises an anti-radiation secondary cold shield, a multi-layer heat insulation primary cold shield and a vacuum cavity which are sequentially arranged in the outer side space of the sample; the pressure-bearing sample table module comprises an oxygen-free copper clamp used for fixing a sample, a thermal damping fin is arranged in the oxygen-free copper clamp and abuts against a cold head temperature adjusting heater, the cold head temperature adjusting heater is located on the upper surface of a pressure-bearing cold disc, and the lower bottom face of the pressure-bearing cold disc is connected with a solid polytetrafluoroethylene supporting rod through a solid epoxy resin supporting rod. The lower bottom face of the solid polytetrafluoroethylene supporting rod is connected to the stainless steel supporting rod. The thickness measurement and control module controls and measures the thickness between sample interfaces by utilizing a servo linear motor and a transmission rod; the temperature measurement and control module is used for acquiring and controlling the temperature at the axis of the heat flow meter.

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 a preparation method of a superconducting nanowire single-photon detector capable of keeping high detection efficiency in a liquid helium temperature region. The preparation method comprises the following steps: adopting a double-layer substrate formed by silicon oxide and silicon; the method comprises the following steps: growing a niobium nitride film on a silicon oxide surface of a substrate through radio frequency magnetron sputtering to serve as a buffer layer, growing a niobium nitride film through direct current magnetron sputtering, and accurately measuring and controlling the thickness through XRR; the method comprises the following steps: preparing a double-line parallel nanowire structure in a manner of exposing PMMA A4 electron beam glue by electron beams, and transferring a nanowire pattern to a niobium nitride film in a reactive ion etching manner; the method comprises the following steps of: removing photoresist above a region needing to be etched on a silicon oxide surface of a substrate in a manner of exposing the AZ4620 photoresist through ultraviolet laser direct writing, and then etching silicon oxide and silicon from the silicon oxide surface of a device through reactive ion etching to prepare a suspension bridge structure. The high detection efficiency of the device is ensured while the working temperature of the device is greatly improved.

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.

According to the refrigerating system of the magneto-optical measuring device and the control method of the refrigerating system, a GM refrigerating machine is externally arranged, a helium circulation throttling expansion structure is utilized, and ultralow-temperature liquid helium at the temperature of 2K or below is obtained through the GM refrigerating machine under the condition that a large amount of liquid helium is not consumed; the GM refrigerating machine and the optical strong magnetic thermostat are connected through the low-loss infusion tube, and the low-loss infusion tube is fixed through the fixing frame, so that vibration transmitted by the GM refrigerating machine part is filtered out, and the experiment conditions of ultralow temperature, strong magnetic field and ultralow vibration are achieved; meanwhile, after entering the optical strong magnetic thermostat, the cooled liquid helium is divided into two parts which do not influence each other and is respectively used for cooling the sample area and the magnet cold shield, so that the cooling efficiency is improved, and the consumption of the liquid helium is reduced.

The invention relates to an efficient heat exchange system for a liquid helium closed circulation system and a refrigeration method of the efficient heat exchange system. A multi-layer thin-wall stainless steel cylinder structure; a heat exchange copper pipe assembly; the heat exchange modules comprise a first-stage heat exchange module, a second-stage heat exchange module and a third-stage heat exchange module; liquid helium is vaporized in the 4.2 K liquid helium pool, so that refrigeration power is generated; the multi-layer thin-wall stainless steel cylinder structure is used for connecting the mounting flange, the heat exchange modules and the 4.2 K liquid helium pool, the distance between the mounting flange and the 4.2 K liquid helium pool is prolonged, and the heat conduction power is reduced; the heat exchange copper pipe assembly is connected with the multi-layer thin-wall stainless steel cylinder structure or the heat exchange modules. 4.2 K helium generated by the 4.2 K liquid helium pool sequentially flows through the third-stage heat exchange module, the second-stage heat exchange module and the first-stage heat exchange module, and a 30K refrigeration environment is formed at the third-stage heat exchange module. According to the efficient heat exchange system for the liquid helium closed circulation system, by arranging the multiple stages of heat exchange modules, the temperature of cold helium is gradually increased under different temperature gradients, the 4.2 K low-temperature interface heat load is reduced, and meanwhile the precooling refrigerating capacity is provided for experiments or equipment with different temperature 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 present invention provides a refrigeration system for a magneto-optical measurement device and its control method. The GM refrigerator is externally placed and a helium gas circulation throttling expansion structure is adopted to obtain ultra-low temperature liquid helium at 2K and below using the GM refrigerator without consuming a large amount of liquid helium. Moreover, a low-loss liquid delivery pipe is used to connect the GM refrigerator and the optical high magnetic field thermostat, and a fixing bracket is used to fix the low-loss liquid delivery pipe, thereby filtering out the vibration transmitted from the GM refrigerator part, achieving experimental conditions of ultra-low temperature, high magnetic field, and ultra-low vibration. At the same time, after the cooled liquid helium enters the optical high magnetic field thermostat, it is divided into two parts without mutual influence and is respectively used to cool the sample area and the magnet cold shield, thereby improving the cooling efficiency and reducing the consumption of liquid helium.

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 discloses a dry-type superconducting switch without a liquid helium conduction magnet, and relates to the technical field of magnetic resonance components. Comprising a switch cold conduction device, the switch cold conduction device is composed of a cylindrical installation inner cavity and an arc-sheet-shaped cold conduction bridge, a switch framework is arranged in the installation inner cavity, a superconducting coil is wound on the middle section of the switch framework, a heating sheet is arranged on the outer side of the superconducting coil, and one end, far away from the installation inner cavity, of the cold conduction bridge of the switch cold conduction device is connected with a cold source. In the using process, the superconducting switch is short in switching-on and switching-off time and high in response speed during excitation and field reduction; thermal power brought to other surrounding low-temperature parts is small, the critical temperature of the superconductor is well protected, and a large amount of refrigerant consumed like a traditional superconducting switch does not need to be used; and the performance of the superconducting wire material of the superconducting switch cannot be degraded due to high temperature generated by opening and closing the switch, so that the stable operation of a magnetic field is ensured.

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.