571 results about "Liquid helium" patented technology

A closed-cycle refrigerator provides cooling to extremely low temperatures, particularly in the range of 0.5 K to 2.0 K. A 4 K pulse-tube cryocooler cold head or G-M cryocooler cold head liquefies helium in a first cooling chamber at a pressure at approximately 1 atmosphere. Liquid helium flows from the first cooling chamber, through a Joule-Thomson valve, and into a second cooling chamber under a pressure differential created by a pump. Helium vapor extracted from the second cooling chamber by the pump is routed back to the first cooling chamber to be re-condensed. This closed-cycle design provides continuous cooling below 2 K. Cryocooler cold head cold sections have no physical contact with subsequent cooling elements, such as the first and second cooling chambers to reduce vibration transfer. In some embodiments the cryocooler cold head is connected to a vacuum chamber via a vibration damping coupler to further reduce vibration transfer.

The invention relates to a conduction-cooled superconducting magnet Dewar with easy loading-unloading, comprising a Dewar cylinder. The conduction-cooled superconducting magnet Dewar is characterized in that the Dewar cylinder is a hollow annular cylinder, the middle of the annular cylinder is provided with a room temperature hole, an annular copper cold shield is arranged in the Dewar cylinder, a refrigerator and a superconducting magnet are arranged in the copper cold shield, a vacuum pumping port is arranged on the Dewar cylinder, a measuring device is arranged on an upper cover of the Dewar cylinder and the Dewar cylinder is in a vacuum state. Compared with the prior Dewar container, the conduction-cooled superconducting magnet Dewar is simpler, has small conduction heat leakage, and has the advantages of easy installation and disassembly; the refrigerator is used for conducting and cooling without a low temperature liquid (such as liquid helium and so on) cooling system; because of simple and safe system, a first-level cold junction of the refrigerator is operated under a temperature of 77K, thereby realizing heat sink of the copper cold shield, an electric lead and a support device; the first-level cold junction of the refrigerator adopts soft connection, thereby reducing temperature increment of the magnet due to vibration of the refrigerator; and the conduction-cooled superconducting magnet Dewar has the advantages of easy operation of manufacture, processing and installation, and is applicable to scale production.

A positive electrode active material for lithium-ion rechargeable batteries of general formula Li_1+xNi_αMn_βA_γO₂ and further wherein A is Mg, Zn, Al, Co, Ga, B, Zr, or Ti and 0<x<0.2, 0.1≦α≦0.5, 0.4≦β≦0.6, 0≦γ≦0.1 and a method of manufacturing the same. Such an active material is manufactured by employing either a solid state reaction method or an aqueous solution method or a sol-gel method which is followed by a rapid quenching from high temperatures into liquid nitrogen or liquid helium.

A high-temperature superconducting magnetic levitation motor is formed by a superconducting motor rotor (1), a motor stator (2), superconducting bearing rotors (3), permanent magnetic bearing stators (4), a rotary dewar (5), an electromagnetic screen (6), torque tubes (7), mechanical protection bearings (8), a main shaft (9), a low-temperature liquid (gas) inlet pipeline (10) and a low-temperature liquid (gas) outlet pipeline (11). The superconducting motor rotor (1) and the superconducting bearing rotors (3) are arranged in the rotary dewar (5) and are cooled by liquid nitrogen or liquid neon or liquid helium or cold helium, the motor stator (2) and the permanent magnetic bearing stators (4) are arranged outside the rotary dewar (5) and are coaxial with the rotary dewar (5), and the two mechanical protection bearings (8) are used in a left and right mode in the radial direction for protecting against the influence brought by the failure of superconducting bearings.

The disclosed adaptor between cold junction of leading wire in heavy current of high-temperature superconductor and low resistance of superconducting transmission line includes structure: welding piles of high-temperature superconductor arranged in spaces to outer wall of support tube made from stainless steel in low thermal conductance; welding warm end in piles of high-temperature superconductor to transition piece of copper; through braze welding, cold end in piles is joined to NbTi/Cu superconducting line; cross winding NbTi/Cu line on inner copper tube sheathed inside outer copper tube; cooling superconducting line and copper connector by using liquid helium between inner and outer copper tubes. Features are: simple structure, suitable to connection under 20kA. In the invention, resistance of adaptor is lowered as 1.4-4.6n ohm. In supercritical quantity of helium flow 4g/s, all loss of 6 pieces of adaptor and 12 pieces of butt end of transmission line is less than 0.1Mpa.

An underlying film forming section forming an underlying film on a semiconductor substrate is provided to an apparatus of fabricating a semiconductor device. The apparatus is further provided with a cooling section cooling the semiconductor substrate and a plasma nitriding section introducing active nitrogen into the underlying film while keeping the temperature of the semiconductor substrate cooled by the cooling section at 100° C. or below. The semiconductor substrate is cooled by using liquid nitrogen or liquid helium, and by cooling a stage on which the semiconductor substrate is placed.

The invention discloses a multi-field coupling test system for a superconducting material at the temperature of between 373 and 4.2K. The system comprises a large-sized temperature alternating experiment box, a liquid helium ultralow temperature vacuum Dewar flask, a Dewar flask bracket, a mechanical test experiment device, a liquid helium injection pipe, a plurality of heating bodies, an air circulating device and an air circulating fan, wherein the liquid helium ultralow temperature vacuum Dewar flask is sleeved inside the large-sized temperature alternating experiment box; the Dewar flask bracket is arranged at the bottom of a box body at the bottom of the liquid helium ultralow temperature vacuum Dewar flask; the mechanical test experiment device and the liquid helium injection pipe are arranged in coordination with the liquid helium ultralow temperature vacuum Dewar flask and the large-sized temperature alternating experiment box; the plurality of heating bodies are arranged inside the large-sized temperature alternating experiment box; the air circulating device is arranged behind the box body of the large-sized temperature alternating experiment box; and the air circulating fan is connected with the air circulating device through a bearing. By the multi-field coupling test system for the superconducting material at the temperature of between 373 and 4.2K, the defects of poor functions, small application ranges, long test time, high cost and the like in the prior art can be overcome, so that the system has the advantages of making a test sample conveniently replaced and saving test time, along with a powerful function, a wide application range and low cost.

The invention discloses a hydrogen liquefaction process comprising a nitrogen refrigeration cycle, a helium refrigeration cycle and a hydrogen refrigeration cycle. In the technical scheme, liquid helium generated by a liquid helium and air separating device is used as a refrigeration working medium, refrigerating capacity required by hydrogen condensation and liquefaction is provided by the liquid helium, rewarmed helium gas and nitrogen gas are respectively recycled and can be turned into the liquid helium and liquid nitrogen after being processed correspondingly when the refrigerating capacity is provided for the hydrogen liquefaction by the liquid helium and the liquid nitrogen, thus the continuous refrigerating capacity is provided for the hydrogen refrigeration cycle by the helium refrigeration cycle and the nitrogen refrigeration cycle, waste caused by directly discharging the helium gas or the nitrogen gas is avoided, and energy sources are saved. In the intention, operation that any one of the three refrigeration cycles is independent of the other two refrigeration cycles is realized, and heat quantity exchange is carried out among the three refrigeration cycles, thus liquid hydrogen generation is finally completed, and the liquefaction of hydrogen gas is realized by sequentially utilizing the refrigerating capacity of the liquid helium and the liquid nitrogen in the hydrogen refrigeration cycle.

The invention discloses a low-temperature scanning tunneling microscope using a closed-cycle refrigerator to achieve refrigeration. The low-temperature scanning tunneling microscope comprises a closed-cycle refrigerator system, a helium heat exchange gas refrigeration vibration isolation interface system, a low-temperature scanning tunneling microscope scanning head system, a vacuum system, a vibration reduction platform and a scanning tunnel microscope control system. According to the low-temperature scanning tunneling microscope, under the condition that no liquid helium is consumed, atomic-scale resolution low-temperature ultrahigh-vacuum scanning tunnel microscopy space imaging and high-energy resolution scanning tunnel spectrum accurate measurement can be achieved like a liquid helium refrigeration system. The technical scheme of closed-cycle refrigeration can also be used for other applications needing lower temperature and low-vibration environments like other members of scanning probe microscope families. Large-range temperature changes can also be achieved through feedback combination of heating elements and temperature measuring elements.

A high-resolution NMR probe is offered which is simple in structure and can be fabricated at low cost. The inside of the probe is maintained in a vacuum to adiabatically isolate the inside from the outside. Liquid helium is sent into a first heat exchanger located immediately close to a measurement portion via the innermost region of a triple tube placed in the vacuum. The helium is evaporated in the exchanger to cool a transmit-receive coil and a variable capacitor. The evaporated helium gas is returned via the outermost region of the triple tube. At this time, a radiation shield placed in the vacuum is cooled by a second heat exchanger placed in the return path.

The invention discloses a strong magnetic iron remover with low temperature superconductivity, a cryostat is arranged on an outer cover of the invention, and the cryostat is hoisted on an inner wall of the outer cover through a pull-rod. The cryostat is provided with an indoor temperature Dewar, a 4.2K Dewar is arranged in the indoor temperature Dewar, a heat radiation screen is arranged between the indoor temperature Dewar and the 4.2K Dewar, gaps are arranged in perimeters between the indoor temperature Dewar and the heat radiation screen and between the heat radiation screen and the 4.2K Dewar, a superconducting coil can be coiled in insulation on an inner cylinder of the 4.2K Dewar, and power can be provided for the superconducting coil by a pair of two-dimensional electric currents lead-in wires. A vacuum state is between the indoor temperature Dewar and the 4.2K Dewar, and the 4.2K Dewar is filled with liquid helium20. The invention has great magnetic induction intensity, and can suck out tiny iron magnetic substances from materials, and has high working stability.

A cryostat configuration for keeping liquid helium comprises an outer jacket (1) surrounding a helium container (2) connected at at least two suspension tubes (3) to the outer jacket (1), and with a neck tube (4) whose upper warm end (5) is connected to the outer jacket (1) and whose lower cold end (6) is connected to the helium container (2) and into which a multi-stage cold head of a cryocooler (7) is installed, wherein the outer jacket (1), the helium container (2), the suspension tubes (3) and the neck tube (4) delimit an evacuated space, and the helium container (2) is surrounded by at least one radiation shield (8) which is connected in a heat-conducting fashion to the suspension tubes (3) and also to a contact surface (9) on the neck tube (4) of the helium container (2). The cryostat configuration is characterized by a gas gap (13) between one or more cold stages of the cold head (7) and one or more contact surfaces (9) in the neck tube (4) which are each connected in a heat-conducting manner to a radiation shield (8) via a fixed, rigid or flexible thermal bridge (12), heat being transferred through the gas gap (13) from the respective radiation shield (8) to the corresponding cold stage of the cold head (7). A cryostat configuration of this type ensures that no vibrations of the cold head (7) stages pass detectably into the cryostat configuration, wherein the quality of the thermal connection between the cold head (7) and the radiation shield(s) (8) is nevertheless sufficient.

The invention provides a clean vacuum system used for engine plume test research and a vacuuminzing and repressing method thereof, belonging to the technical field of engine vacuum science. The clean vacuum system comprises a low vacuum system, a low vacuum liquid nitrogen cold trap system, a high vacuum system, a high vacuum liquid nitrogen cold trap system, a low temperature pump liquid nitrogen supply system A, a low temperature pump liquid nitrogen supply system B, an air repressing system, a nitrogen repressing system, a container vacuum measuring system, a residual gas analysis system, a liquid nitrogen heat sink, and a liquid nitrogen heat sink and plume adsorption pump. In the clean vacuum system, the vacuum is obtained mainly relying on the clean low vacuum system, the high vacuum system and the liquid nitrogen heat sink, the liquid nitrogen heat sink and plume adsorption pump; various clean vacuum degrees required by the plume test can be obtained, and the highest ultrahigh dynamic vacuum degree of 10<-6> Pa can be obtained. Both the low vacuum system and the high vacuum system are configured with the liquid nitrogen cold trap system which is used for absorbing the oil steam produced by working of a mechanical pump, so that the cleanness of the vacuum container can be ensured.

The invention discloses a high-temperature superconductive magnet system for a magnetically confined plasma propeller, which comprises two magnetic mirror units in the same structure, wherein each magnetic mirror unit comprises a Dewar barrel and two high-temperature superconductive magnets; and a refrigerator is used for cooling the two high-temperature superconductive magnets in each magnetic mirror unit. mode by a conductive cooling mode and uses the refrigerator to cool the two superconductive magnets in a conductive manner, so that the high-temperature superconductive magnet system for the magnetically confined plasma propeller greatly simplifies the structure, realizes high vacuum, reduces dependence on liquid nitrogen and high-cost operations, avoids a large-size low-temperature system and equipment used in the low-temperature liquid cooling mode, eliminates risks caused by the evaporation of a low-temperature liquid, cools the magnet to a temperature below 77 K and realizes a high field by increasing the critical current of the magnets, thus a superconductive low-temperature system is compact, efficient, safe and convenient, and is beneficial for integrating a superconductive apparatus with a low-temperature device.

The invention relates to a high voltage insulation current lead for a superconductive electric device. A low temperature end B of a red copper conductor (1) is inserted into a low temperature container, and the tail end of the low temperature end B is provided with a connection terminal (2). The red copper conductor (1) is inserted into an insulation sleeve (3) from a room temperature end C of the insulation sleeve (3), a room temperature end A of the red copper conductor (1) is exposed out of the room temperature end C of the insulation sleeve (3); and screw threads (4) are arranged in the middle of the insulation sleeve (3). A connection nose (6) is pressed and connected with the end of the part of the room temperature end A of the red copper conductor (1), which is exposed out of the insulation sleeve (3), so as to form an insulation lead main body (7). A low temperature end F of the insulation lead main body (7) is arranged below the liquid level of liquid nitrogen or liquid helium in the low temperature container. A seal O ring and an insulator (11) are axially fixed on a low temperature container flange (14) by nuts and coaxial with the insulation lead main body (7). The room temperature end of the red copper conductor adopts a variable cross-section truncated cone structure from the flange position of the low temperature container to the low temperature end.

The invention discloses a chromatograph on-line analysis method for source rock by closed ball milling, heating analysis and cold trap trapping, which is used for analyzing light fraction compound and percentage composition thereof in the dispersed organic matter of the source rock, and is characterized by comprising the following steps: carrying out vacuum sealing and ball milling on a source rock sample, carrying out ball milling, crushing, then heating to 300DEG C, and carrying out thermal desorption; blowing the pyrolysed hydrocarbon to a liquid helium cold trap by utilizing helium; placing the cold trap into a chromatograph furnace; and trapping, then carrying out chromatograph or Chromatographic-MS on-line analysis to obtain the qualitative data of chromatograph fine separation and/or Chromatographic-MS analysis of the light fraction in the source rock. The separation degree of the sample can approximate to the separation effect of the light dydrocarbon chromatograph separation of crude oil; the invention has good repeatability, reduces the volatilization loss of the light fraction in the crushing process because of the large volume of the sample before being put in a ball milling tank; and the qualitative analysis result can be used for researching the maturity and the environment of sedimentation of the source rock and carrying out oil source comparison.

The present invention discloses a specialized device for measuring the resistance of a superconducting line joint, comprising a low temperature Dewar unit, a room temperature tube unit, a background magnet unit, an excitation magnet unit, a linkage frame unit, a weakening magnetic field measuring unit, etc. The specialized device has the advantages that only the room temperature tube is required to be moved out from the low temperature Dewar via a guide rail when a sample loop of the measured superconducting line joint is replaced, so that the volatilization amount of the liquid helium in an experimental process is reduced. The background magnet is positioned on the lateral side of a Hall element which measures the weakening magnetic field of the sample loop of the superconducting line joint. Compared with being positioned at the lower side of the Hall element, the background magnet positioned at the lateral side of the Hall element reduces the influence of the background magnet to the fact that the Hall element measures the weakening magnetic field generated by the sample loop of the superconducting joint. With the room temperature tube technical, the Hall element is arranged inside the room temperature tube, namely a normal temperature Hall sensor measures the weakening magnetic field of the sample loop of the superconducting joint. The cost of the device is reduced and the reliability of the measurement is improved.

The invention discloses a first-stage pullable binary coaxial current lead structure, and relates to a binary current lead technology. The structure comprises a first-stage current lead connected with a high-temperature part, a second-stage current lead connected with a low-temperature part and a pullable heat exchanger which is connected with the first-stage current lead and the second-stage current lead respectively and is positioned between the first-stage current lead and the second-stage current lead. The first-stage pullable binary coaxial current lead structure has the advantages of compact structure, stable performance, reliable operation, low heat leakage and convenience in disassembly and assembly, has the capacity of reducing heat leakage in an entire excitation process and subsequent normal operation, and is particularly suitable for a superconducting magnet with conduction cooling, less liquid helium and high magnetic field strength and operating in a closed loop.

The invention relates to a superconducting magnet system of an inserted YBCO-Bitter type high-temperature coil. The inserted YBCO-Bitter type high-temperature superconducting coil (8) is inserted into an inner hole of a peripheral superconducting coil (10) formed by NbTi and Nb3Sn. The inserted YBCO-Bitter type high-temperature superconducting coil (8) is positioned in a low-temperature container (9); the peripheral superconducting coil (10) is arranged in a low-temperature container (11); and the low-temperature containers (9 and 11) are filled with liquid helium (12). The inserted YBCO-Bitter type high-temperature superconducting coil (8) is formed by superposing of multiple YBCO ring pieces (1) which are embedded in a stainless steel ring (6). High-purity copper ring pieces (2) plated with an aluminum nitride film are arranged between the YBCO ring pieces (1). The multiple YBCO ring pieces (1) and the multiple high-purity copper ring pieces (2) are superposed along the same shaft, are assembled together by a stainless steel central hole tube (3) and an end flange (4), and are cured into a whole body after being soaked by epoxy resin. The superconducting magnet system has simplified structure, little heat leakage of system and stable generated magnetic field.

This is a tie-in of double pie loop for high temperature super conducting magnet and its jointing method. The tie-in composes a concave base, NbTi bridge and a convex cover. The concave base is the matrix of the tie-in and made by metal like copper of low resistivity, of a shape in arc and radial section in rectangle and is fixed to a magnet. The NbTi bridge is embedded in the groves[C1, C2] on the base, and the convex beam on the convex cover is also embedded in the groves to fix the NbTi bridge.

The invention relates to a low temperature scanning probe microscope system based on pulse tube refrigeration technology. Aimed at vibration source and characteristics, a multistage active/ passive damping device, including a sylphon bellowss, a piezoelectric ceramic tube and a spring are adopted. The sylphon bellowss is used for connecting a main system cavity and a refrigeration head of the pulse tube to realize vibration isolation of the whole system. As for low frequency vibration unique to a pulse tube refrigerator, an active damping device with a piezoelectric ceramic tube and a digital signal processor as the core is adopted. A beryllium copper spring and a damping magnet form a first stage passive damping device to isolate vibration. The system eliminates the vibration from the pulse tube refrigerator and the refrigeration head to the scanning probe, applies to other vibration sensitive occasions that require low temperature, saves a large amount of liquid helium refrigerant, simplifies equipment operation and maintenance, and significantly prolongs the retention time at low temperature.

The zero-backflow vent assembly (100) of the present invention prevents backflow into the magnet cryogen vessel (12) and therefore eliminates magnet icing. In general, the present invention employs a spring loaded valve in the magnet vent turret (38) to prevent the influx of air after a magnet quench event. The magnet vent turret (38) is the interface between the liquid helium vessel (12) in the magnet and the atmosphere (40). A vent stack is employed to channel any cryogenic exhaust gas out of the room, normally to the outside atmosphere (40).