A cryogenic insert for AC magnetic susceptibility measurements

Abstract

A kind of low temperature insert for AC magnetic susceptibility test, including terminal box, sample tube, sample rod and protective cover, characterized by: the terminal box, sample tube, protective cover are hollow structure capable of accommodating sample rod, and are connected in turn from top to bottom;Coil group is provided in the protective cover, the coil group includes excitation coil and secondary coil, the excitation coil and secondary coil are wound on two coil holders respectively, constitute concentric cylindrical structure, and the excitation coil is located in the outer layer of the secondary coil;Electrical connector is provided on the outer wall of the terminal box, for connecting the coil group via electrical lead line.The technical scheme based on the present application simplifies the manufacturing process of low temperature insert and maintenance replacement cost, while reducing error, and the test result is accurate.

Description

Technical Field

[0001] This invention relates to the field of low-temperature sample testing technology, and more specifically, to a low-temperature plug-in for AC magnetic susceptibility testing. Background Technology

[0002] Currently, alternating current magnetic susceptibility (AC MF) has been widely used in condensed matter physics as an important method for measuring physical properties. It is particularly valuable for accurately characterizing the magnetic properties of samples. AC MF refers to the slope of the magnetization curve, which is the differential form of magnetization and magnetic field strength, dM / dH. It is measured by superimposing small AC perturbations under a large DC magnetic field to determine the response of the material under test to these perturbations. Typically, when measuring superconducting materials, magnetic materials, and other similar substances, the variation of AC MF with temperature is considered, and the phase transition temperature of the magnetic material is obtained based on this. Measuring the material under test using AC MF minimizes the impact on material properties during the measurement process, and the measurement process is minimally disturbed. It can be performed under various external conditions, effectively obtaining multiple phase diagrams of the material under different conditions for a better understanding of its properties.

[0003] In existing technologies, AC magnetic susceptibility testing modules are typically used to test the sample. The excitation coil in the testing module generates a changing magnetic field under the excitation of a current source, which in turn affects the magnetization of the sample located inside the excitation coil, causing a change in the magnetic field strength of the sample and thus inducing an electromotive force (EMF) in the secondary coil. By measuring the induced EMF, the magnetization and magnetic susceptibility of the material can be obtained. However, in existing AC magnetic susceptibility testing modules, the excitation coil and secondary coil in the coil assembly are usually wound on the same coil holder, making the manufacturing process complex and difficult to replace and maintain. Furthermore, the sample rod carrying the sample is prone to deformation during movement, causing sample swaying and affecting the induced EMF generated by the secondary coil.

[0004] Therefore, there is an urgent need for a new low-temperature plug-in for AC magnetic susceptibility testing. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a low-temperature plug-in for AC magnetic susceptibility testing, which simplifies the manufacturing process and reduces maintenance and replacement costs by separately winding the excitation coil and secondary coil.

[0006] The present invention adopts the following technical solution. A low-temperature plug-in for AC magnetic susceptibility testing includes a junction box 1, a sample tube 8, a sample rod 9, and a protective cover 10. The junction box 1, the sample tube 8, and the protective cover 10 are all hollow structures capable of accommodating the sample rod 9, and are connected sequentially from top to bottom. A coil group 13 is provided in the protective cover 10. The coil group 13 includes an excitation coil 14 and a secondary coil. The excitation coil 14 and the secondary coil are respectively wound on two coil holders to form a concentric cylindrical structure, and the excitation coil 14 is located on the outer layer of the secondary coil. An electrical connector 4 is provided on the outer wall of the junction box 1 for connecting the coil group 13 via an electrical lead 17.

[0007] Preferably, the secondary coil includes a primary coil 15 and a secondary coil 16, which are wound symmetrically in opposite directions using a single conductor.

[0008] Preferably, the number of turns and the spacing between each turn of the primary coil 15 and the secondary coil 16 are the same; and the coil holder is made of G10 material.

[0009] Preferably, the electrical connector is a power plug or a PC adapter.

[0010] Preferably, the junction box 1 is provided with a sample inlet 2 with a cover on the top, and a linear displacement manipulator 3 is provided inside the junction box 1 for fixing the top of the sample rod 9. The sample to be tested is loaded at the bottom of the sample rod 9, and the sample rod 9 is moved or positioned based on the operation control of the control software.

[0011] Preferably, the linear displacement manipulator 3 is connected to the power plug and the PC adapter via electrical leads 17, and the PC adapter is connected to a PC device with built-in control software.

[0012] Preferably, the sample tube 8 is made of highly polished stainless steel, and the sample rod 9 is a solid columnar rod made of graphite fiber.

[0013] Preferably, multiple heat radiation shields 7 are provided at equal intervals on the upper part of the sample rod 9, and the heat radiation shields 7 are round pieces made of high-polished stainless steel.

[0014] Preferably, the protective cover 10 includes an outer protective cover 11 and an inner protective cover 12 with a concentric cylindrical structure. The outer protective cover 11 is made of G10 material, and the inner protective cover 12 is made of sapphire material.

[0015] Preferably, a thermometer 18 and a heater 19 are provided at the bottom of the inner layer of the protective cover 10. The thermometer 18 and the heater 19 are connected to the temperature controller through an electrical lead 17 and an electrical connector 4, respectively. The heater 19 is a resistance heater. The thermometer 18 is a low-temperature thermometer whose temperature curve is independent of the magnetic field.

[0016] Preferably, the electrical lead 17 of the thermometer 18 is phosphor bronze wire, the electrical lead 17 of the heater 19 is pure copper wire, and the electrical lead 17 of the coil group is a flexible microwave coaxial cable.

[0017] The beneficial effect of the present invention is that, compared with the prior art, the low-temperature plug-in for AC magnetic susceptibility testing in the present invention simplifies the manufacturing process and reduces maintenance and replacement costs by separately winding the excitation coil and the secondary coil.

[0018] The beneficial effects of the present invention also include:

[0019] 1. Two reverse-wound secondary coils were set up, and the sample was placed at the same position on the two secondary coils for testing. This eliminated the systematic error caused by the inconsistency between the induced electromotive force generated by the secondary coil during the manufacturing process and the design expectation.

[0020] 2. The sample rod, protective cover, and electrical leads are manufactured using special materials to reduce systematic errors in the sample measurement process from various aspects, such as preventing sample shaking and preventing environmental interference.

[0021] 3. The sample testing temperature is controlled by a built-in thermometer and heater, and an external temperature controller, thereby ensuring that the sample is tested in a constant temperature environment. Attached Figure Description

[0022] Figure 1 This is a front view of the overall structure of a low-temperature plug-in for AC magnetic susceptibility testing according to the present invention.

[0023] Figure 2 This is a projected view of a protective cover in a cryogenic plug-in for AC magnetic susceptibility testing according to the present invention.

[0024] Figure label:

[0025] 1- Junction Box

[0026] 2-Sample Inlet

[0027] 3-Linear displacement manipulator

[0028] 4-Electrical Connector 1

[0029] 5-Electrical Connector 2

[0030] 6-Electrical connector 3

[0031] 7-Heat radiation shield

[0032] 8-sample tubes

[0033] 9-Sample rod

[0034] 10-Protective Cover

[0035] 11-Outer layer of protective cover

[0036] 12-Inner layer of protective cover

[0037] 13-Coil Group

[0038] 14-Excitation Coil

[0039] 15-First stage coil

[0040] 16-Secondary stage coil

[0041] 17-Electrical Leads

[0042] 18-Thermometer

[0043] 19-Heater Detailed Implementation

[0044] The present application will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and should not be construed as limiting the scope of protection of the present application.

[0045] Figure 1 This is a front view of the overall structure of a low-temperature plug-in for AC magnetic susceptibility testing according to the present invention. Figure 2 This is a projected view of a protective cover in a cryogenic insert for AC magnetic susceptibility testing according to the present invention. Figure 1 and Figure 2 As shown, a low-temperature plug-in for AC magnetic susceptibility testing includes a junction box 1, a sample tube 8, a sample rod 9, and a protective cover 10.

[0046] The junction box 1, sample tube 8, and protective cover 10 are all hollow structures capable of accommodating the sample rod 9, and are connected sequentially from top to bottom. A coil assembly 13 is housed within the protective cover 10. The coil assembly 13 includes an excitation coil 14 and secondary coils 15 and 16. The excitation coil 14 and secondary coils 15 and 16 are wound around two coil holders, forming a concentric cylindrical structure, with the excitation coil 14 located on the outer layer of the secondary coils 15 and 16. An electrical connector 4 is provided on the outer wall of the junction box 1 for connecting the coil assembly 13 via an electrical lead 17.

[0047] In one embodiment of the present invention, the sample is located at the bottom of the sample rod 9, and the upper part of the sample rod is located in the junction box 1. The excitation coil 14 inside the protective cover 10 is driven by a current source to generate a magnetic field, giving the sample magnetic properties, thereby inducing an electromotive force (EMF) in the secondary coils 15 and 16. The induced EMF is measured via the electrical leads 17 and an external testing device. By analyzing the induced EMF data, the properties of the test sample can be obtained.

[0048] Because the excitation coil 14 and the secondary coil 15 or 16 in coil group 13 are wound separately and then combined, the manufacturing method of the coil and the low temperature plug-in is simple, and the replacement and maintenance are convenient.

[0049] Preferably, the secondary coil includes a primary coil 15 and a secondary coil 16, which are wound symmetrically in opposite directions using a single conductor. Typically, the same conductor can be wound in two parts on a single coil holder, with the two parts wound in opposite directions. Because the two secondary coils are wound in opposite directions, and because a two-position testing method can be used, the sample can be tested at corresponding positions on both secondary coils, accurately obtaining the induced electromotive force generated by each coil, thereby eliminating systematic errors.

[0050] Preferably, the number of turns and the spacing between each turn of the primary coil 15 and the secondary coil 16 are the same; and the coil holder is made of G10 material.

[0051] G10 material is a composite material made of fiberglass cloth and epoxy resin. It is non-magnetic and will not generate interfering magnetic fields during sample testing. Furthermore, this material is not easily deformed, is not easily permeated by moisture or liquids, and possesses insulating, acid and alkali resistant properties. It also has low density and is lightweight. Therefore, coil holders made of G10 material are easy to maintain and store, have a long service life, and offer high measurement accuracy.

[0052] Preferably, the electrical connectors 4-6 can be power plugs or PC adapters. The electrical connectors 4-6 can be connected not only to the individual coils in the coil group via electrical wires 17, but also to other electrical devices inside or outside the test module. For example, when the module contains devices such as linear displacement actuators, thermometers, and heaters internally, and temperature controllers and PC devices externally, these devices can be connected to them via the electrical connectors. Furthermore, to achieve different functions, such as power supply and actuator control, different electrical plugs, such as power plugs or PC adapters, are required to ensure compatibility with various components.

[0053] Preferably, the junction box 1 has a covered sample inlet 2 at its top for inserting the sample rod 9 into the sample tube. When the cryogenic insert starts working, it can first be inserted into the sample chamber of an existing cryogenic device and secured. Then, the sample is loaded to the bottom of the sample rod 9, the cover of the sample inlet 2 at the top of the junction box 1 is opened, and the sample rod 9 is inserted into the sample tube 8. After the top of the sample rod is fixed to the linear displacement manipulator, the cover of the sample inlet 2 can be tightened.

[0054] The junction box 1 contains a linear displacement manipulator 3, which is used to fix the top of the sample rod 9. The sample to be tested is loaded at the bottom of the sample rod 9, and the manipulator moves or positions the sample rod 9 based on the operation control of the control software. The linear displacement manipulator 3 is connected to the power plug and the PC adapter via electrical leads 17. The PC adapter is connected to a PC device with built-in control software.

[0055] It is worth noting that the linear displacement manipulator 3 is equipped with a controller and encoder, and its linear displacement can be controlled by control software. A plug-in power cord is connected to the linear displacement manipulator 3 to supply power. A PC adapter connects the linear displacement manipulator 3 to a PC device. The PC device may have built-in control software, which controls the linear displacement manipulator 3 to perform linear displacement or remain in a fixed state. Typically, under the control of the software, the linear displacement manipulator 3 will drive the operating rod 9 to move and position rapidly and accurately along the concentric axis of the sample tube 8, protective cover 10, and coil group 13, thereby making the measurement results of the measuring plug more accurate and the measurement process faster.

[0056] Preferably, the sample tube 8 is made of highly polished stainless steel. Highly polished stainless steel has relatively poor thermal conductivity, which effectively reduces heat leakage caused by ambient temperature to the test insert and prevents excessively high temperatures at the sample end. The sample rod 9 is a solid columnar rod made of graphite fiber. Graphite fiber is lightweight and non-deformable, and when used as a sample rod, it allows for accurate and easy placement of the sample in the measurement position without causing shaking during rod movement, thus enabling stable and accurate measurement of the electromotive force generated by the secondary coil.

[0057] Preferably, multiple heat-resistant radiation baffles 7 are evenly spaced on the upper part of the sample tube 9. The heat-resistant radiation baffles 7 are circular pieces made of highly polished stainless steel. These heat-resistant radiation baffles 7 can be used to reduce heat radiation from the top of the sample tube and limit air convection in the environment where the sample tube is located, so that the sample can obtain the lowest possible temperature. The electrical leads 17 are thermally anchored to the sample tube 8.

[0058] Preferably, the protective cover 10 includes an outer protective cover 11 and an inner protective cover 12 with a concentric cylindrical structure. The outer protective cover 11 is made of G10 material, and the inner protective cover 12 is made of sapphire material.

[0059] The protective shield consists of two concentric cylindrical structures made of different materials, providing a non-magnetic and temperature-uniform sample environment. The outer layer is made of G10 material, which is non-magnetic, while the inner layer is made of sapphire, which has excellent thermal conductivity and provides an isothermal zone for the sample.

[0060] Preferably, a thermometer 18 and a heater 19 are disposed at the bottom of the inner layer of the protective cover 10. The thermometer 18 and the heater 19 are connected to a temperature controller disposed outside the plug-in via electrical leads 17 and electrical connectors 4, respectively. The thermometer is used to monitor the temperature of the area near the sample in real time, and the temperature curve generated by the thermometer is independent of the magnetic field. The heater 19 can be a resistance heater, which can be used to heat the sample to different degrees. Furthermore, the heater 19 can also work with the thermometer 18 and the temperature controller to control and adjust the temperature of the sample.

[0061] Before starting the sample testing process, the external temperature controller can be turned on and the sample temperature set. Once the sample temperature reaches the set temperature and stabilizes for a certain period of time, the test can begin.

[0062] In addition, a temperature controller can be used to place the sample at different temperatures. By measuring the induced electromotive force of the secondary coil at different temperatures, the AC magnetic susceptibility curve of the sample at different temperatures can be obtained.

[0063] Preferably, the electrical lead 17 of the thermometer 18 is phosphor bronze wire, the electrical lead 17 of the heater 19 is pure copper wire, and the electrical lead 17 of the coil group can be a gold flexible microwave coaxial cable.

[0064] The beneficial effect of the present invention is that, compared with the prior art, the low-temperature plug-in for AC magnetic susceptibility testing in the present invention simplifies the manufacturing process and reduces maintenance and replacement costs by separately winding the excitation coil and the secondary coil.

[0065] The beneficial effects of the present invention also include:

[0066] 1. Two reverse-wound secondary coils were set up, and the sample was placed at the same position on the two secondary coils for testing. This eliminated the systematic error caused by the inconsistency between the induced electromotive force generated by the secondary coil during the manufacturing process and the design expectation.

[0067] 2. The sample rod, protective cover, and electrical leads are manufactured using special materials to reduce systematic errors in the sample measurement process from various aspects, such as preventing sample shaking and preventing environmental interference.

[0068] 3. The sample testing temperature is controlled by a built-in thermometer and heater, and an external temperature controller, thereby ensuring that the sample is tested in a constant temperature environment.

[0069] The applicant of this invention has provided a detailed description of the embodiments of the invention in conjunction with the accompanying drawings. However, those skilled in the art should understand that the above embodiments are merely preferred embodiments of the invention. The detailed description is only intended to help readers better understand the spirit of the invention and is not intended to limit the scope of protection of the invention. On the contrary, any improvements or modifications made based on the inventive spirit of the invention should fall within the scope of protection of the invention.

Claims

1. A low-temperature connector for AC magnetic susceptibility testing, comprising a junction box (1), a sample tube (8), a sample rod (9), and a protective cover (10), characterized in that: The junction box (1), sample tube (8), and protective cover (10) are all hollow structures capable of accommodating the sample rod (9), and are connected sequentially from top to bottom. The junction box (1) is provided with a sample inlet (2) with a cover on the top. The junction box (1) is provided with a linear displacement manipulator (3) for fixing the top of the sample rod (9). The sample rod (9) is loaded with the sample to be tested at the bottom and the sample rod (9) is moved or positioned based on the operation control of the control software. The sample tube (8) is made of high-polished stainless steel and is connected to a heat anchor. The sample rod (9) is a solid column rod made of graphene fiber. Multiple heat radiation shields (7) are evenly spaced on the upper part of the sample rod (9). The heat radiation shields (7) are circular pieces made of high-polished stainless steel. The protective cover (10) is provided with a coil group (13), which includes an excitation coil (14) and a secondary coil. The secondary coil includes a primary coil (15) and a secondary coil (16). The excitation coil (14) and the secondary coil are wound on two coil holders respectively, using a method of separate winding and recombination to form a concentric cylindrical structure. The excitation coil (14) is located on the outer layer of the secondary coil. The primary coil (15) and the secondary coil (16) are wound in two parts on a coil holder using a single wire, and the winding directions of the two parts are opposite. The number of turns and the spacing between each turn of the primary coil (15) and the secondary coil (16) are the same. The sample is placed in the corresponding position of the two secondary coils for testing. The junction box (1) is provided with an electrical connector (4) on its outer wall for connecting the coil group (13) via an electrical lead (17).

2. A low-temperature plug-in for AC magnetic susceptibility testing as described in claim 1, characterized in that: The coil holder is made of G10 material.

3. A low-temperature plug-in for AC magnetic susceptibility testing as described in claim 1, characterized in that: The electrical connector is a power plug or a PC adapter.

4. A low-temperature plug-in for AC magnetic susceptibility testing as described in claim 1, characterized in that: The linear displacement manipulator (3) is connected to the power plug and the PC adapter via electrical leads (17), and the PC adapter is connected to a PC device with built-in control software.

5. A low-temperature plug-in for AC magnetic susceptibility testing according to claim 1, characterized in that: The protective cover (10) includes a concentric cylindrical outer layer (11) and an inner layer (12). The outer layer (11) is made of G10 material, and the inner layer (12) is made of sapphire material.

6. A low-temperature plug-in for AC magnetic susceptibility testing according to claim 1, characterized in that: The bottom of the inner layer of the protective cover (10) is provided with a thermometer (18) and a heater (19), and the thermometer (18) and the heater (19) are respectively connected to the temperature controller through an electrical lead (17) and an electrical connector (4); The heater (19) is a resistance heater; The thermometer (18) is a low-temperature thermometer, and its temperature curve is independent of the magnetic field.

7. A low-temperature plug-in for AC magnetic susceptibility testing according to claim 6, characterized in that: The electrical leads (17) of the thermometer (18) are phosphor bronze wires, the electrical leads (17) of the heater (19) are pure copper wires, and the electrical leads (17) of the coil group are flexible microwave coaxial cables.

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