Used for 3 Sample rod and measurement method for He ultra-low temperature, pulsed high magnetic field NMR measurement

Abstract

The present application belongs to the field of solid-state nuclear magnetic resonance and specifically discloses a method for 3 He ultra-low temperature, pulsed high magnetic field NMR measurement sample rod and measurement method. 3 The He refrigeration plug-in creates an extremely low temperature environment below 1K for the tail of the insertion part. The position of the sample in the magnetic field is adjusted by the position adjustment component so that it is within the range of a highly uniform magnetic field. A dual-channel measurement circuit is adopted, in which one channel measures the NMR signal of the sample and the other channel measures the NMR signal of the standard sample to calibrate the precise intensity of the instantaneous magnetic field. Combining the dual-channel measurement, the chemical (Night) shift of the sample can be obtained, reducing the error of the nuclear magnetic resonance experiment, thereby realizing nuclear magnetic resonance measurement under extremely low temperature and pulsed strong magnetic field.

Description

Technical Field

[0001] The present invention relates to the field of solid-state nuclear magnetic resonance, and more specifically to a method for 3 Sample holder and measurement method for He ultra-low temperature, pulsed high magnetic field NMR measurement. Background Art

[0002] In actual nuclear magnetic resonance measurements (NMR) related to condensed matter physics, extreme conditions such as extremely low temperatures (below 1K) and high magnetic fields (above 45T) are often required. The higher the magnetic field that can be achieved and the lower the temperature, the more important scientific problems can be solved. At the same time, the resolution of NMR measurements is positively correlated with the magnetic field strength. The greater the applied magnetic field, the higher the measurement resolution and the larger the frequency range that can be measured. The magnetic field that can be provided by the steady-state superconducting magnets used in conventional NMR measurements is relatively small. A higher magnetic field can be obtained by using pulsed magnets. Since pulsed strong magnetic fields have their own particularities compared to conventional steady-state magnetic fields, the structure of the sample rod for NMR measurements will also be different accordingly. First, NMR measurements have high requirements for the spatial uniformity of the magnetic field, while the uniformity of pulsed magnetic fields is usually low, and the magnetic field often has a high uniformity only in the range of 2mm-5mm. Secondly, the pulsed magnetic field is an instantaneous magnetic field, and the magnitude of the magnetic field is difficult to measure directly and accurately, which brings great uncertainty to the measurement of the chemical (Knight) shift.

[0003] At present, there are relatively few NMR measurement devices used in extreme environments in the field of condensed matter. In the field of low-temperature nuclear magnetic resonance, patent US7288939B1 designs an NMR probe that can be used at low temperatures (25K), evacuates the measuring probe, and controls the temperature of the sample through a cold head; patent CN106596671A provides an NMR measuring rod that can achieve temperature control near the liquid nitrogen temperature zone (77K); patent CN115112703B designs a sample rod suitable for steady-state field low-temperature nuclear magnetic resonance measurement system without discharge, so that the measurement temperature can reach the liquid helium temperature zone (4.2K) and achieve temperature control. The above methods cannot meet the measurement under extremely low temperature (below 1K) conditions. In high-magnetic field nuclear magnetic resonance, patent CN110531292A provides a radio frequency signal source for a nuclear magnetic resonance system under a pulsed strong magnetic field, which can generate a high signal-to-noise ratio sinusoidal signal with a wide frequency range of 1MHz-1.4GHz; but higher magnetic fields often require higher resonance frequencies and better magnetic field uniformity. Due to the great challenges of low temperature control and high magnetic field, there is currently no nuclear magnetic resonance measurement rod that can adapt to both pulsed strong magnetic field and extremely low temperature conditions. Summary of the invention

[0004] In view of the defects of the prior art, the purpose of this application is to provide a 3The sample rod and measurement method for He ultra-low temperature and pulsed high magnetic field NMR measurement are designed to solve the problem that the existing nuclear magnetic resonance measurement rod cannot adapt to pulsed high magnetic field and ultra-low temperature conditions at the same time.

[0005] To achieve the above objectives, in a first aspect, the present application provides a 3 He ultra-low temperature, pulsed high magnetic field NMR measurement dual channel sample holder, including: sample holder body and 3 He cooling plug-in;

[0006] Said 3 The He cooling plug-in supports the insertion of a part of the sample rod body and is detachably connected to the sample rod body to form a sealed environment for the inserted part. 3 He connection port for access and extraction 3 He, to create an extremely low temperature environment below 1K for the tail of the insertion part;

[0007] The sample holder body comprises: a sleeve, a temperature control component, a main body support component, a position adjustment component, a dual-channel NMR signal transmission circuit and a first KF cross-connect;

[0008] The sleeve is detachably connected to the tail of the main support member to form a sample chamber, and the sample chamber is used to place and protect the sample to be tested and its signal collection coil, the standard sample and its signal collection coil;

[0009] The temperature control component is fixed to the tail of the main support component and connected to the temperature controller through the first KF cross-connection to detect and adjust the temperature of the sample;

[0010] The main body support member is used to support and connect the position adjustment member and the sample chamber;

[0011] The position adjustment member is used to adjust the horizontal position and / or vertical height of the sample in the magnetic field;

[0012] The dual-channel NMR signal transmission circuit passes through the interior of the main support member and the position adjustment member, and is connected to the nuclear magnetic resonance spectrometer through the first KF cross-connect, so as to simultaneously measure the nuclear magnetic resonance signals of the sample to be tested and the standard sample;

[0013] The first KF cross-connection provides a temperature controller interface and a nuclear magnetic resonance spectrometer interface externally, and is detachably connected to a position adjustment component internally.

[0014] Preferably, the position adjustment component comprises: a connecting rod, a height adjustment screw, a height adjustment nut, a buckle and a cover plate;

[0015] One end of the connecting rod is connected to the first KF cross, and the other end passes through the height adjustment screw and the height adjustment nut and is connected to the main support member clamp;

[0016] The buckle is fixed to the groove on the outer wall of the connecting rod and placed in the groove on the upper end of the height-adjusting nut, and the bottom of the buckle is restricted in the height-adjusting nut by the cover plate, so that the buckle can rotate, and the main supporting member is driven by rotating the buckle to change the direction of the sample signal acquisition coil;

[0017] One end of the height adjustment screw is threadedly connected to the height adjustment nut, and the other end is connected to the KF flange, so that the vertical height of the sample signal acquisition coil can be changed by adjusting the height adjustment nut to drive the main support component.

[0018] Preferably, the 3 The He refrigeration plug-in includes: an upper shell, a lower shell, a magnetic field collection coil, a second KF cross-connection and a two-hole Lemo joint;

[0019] The upper and lower shell layers are both double-layer structures, which can effectively achieve heat preservation;

[0020] One end of the upper shell is connected to the second KF cross-connection, and the other end is connected to the lower shell to isolate 3 He and the external environment create extremely low temperature conditions;

[0021] The upper shell layer has reserved wire grooves so that the twisted pair wires can enter the upper shell layer interlayer and pass therethrough;

[0022] The magnetic field collection coil is wrapped around the outer wall of the lower shell layer so that it has the same height as the sample and is used to measure the magnitude of the pulsed magnetic field;

[0023] The second KF cross, the first end is used to connect to the outside 3 He control cabinet, the second end is connected to the upper shell, the third end is used to fix the two-hole Lemo joint, and the fourth end is connected to the sample rod body through the KF flange;

[0024] The two-hole Lemo connector is used to connect to an external controller to output a pulsed magnetic field acquisition signal.

[0025] Preferably, the dual-channel NMR signal transmission circuit comprises: two independent transmission loops, each loop comprising a connected semi-rigid coaxial line and a signal acquisition connector;

[0026] One end of the signal acquisition connector is connected to a semi-rigid coaxial line, and the other end is connected to an external nuclear magnetic resonance spectrometer;

[0027] The shielding layer of the semi-rigid coaxial line is used to connect to the other end of the fixed capacitor connected to one end of the sample signal acquisition coil, and the core wire is used to connect to the other end of the sample signal acquisition coil that is not connected to the fixed capacitor;

[0028] The shielding layer and core wire of the semi-rigid coaxial line are respectively used to connect to the two ends of the matching capacitor / inductor.

[0029] Preferably, the temperature control component comprises: a heater, a thermometer, a temperature control lead and a six-hole Lemo plug;

[0030] The six-hole Lemo plug is used to connect an external temperature controller;

[0031] The heater is connected to a six-hole Lemo connector via two twisted-pair temperature-controlled leads for heating the sample;

[0032] The thermometer is connected to a six-hole Lemo connector via four twisted-pair temperature control leads for measuring sample temperature;

[0033] The temperature control lead is connected to the heater and the six-hole Lemo plug, and to the thermometer and the six-hole Lemo plug, for transmitting the thermometer and heater signals;

[0034] The sample temperature is measured and regulated through a PID loop of a temperature controller between the heater and the thermometer.

[0035] Preferably, the main body support member comprises: a glass fiber disc, a KF flange, a glass fiber tube and a first KF cross;

[0036] The fiberglass disc is connected to the fiberglass tube and the semi-rigid coaxial line and is used to fix the fiberglass tube and the semi-rigid coaxial line to avoid deflection;

[0037] The KF flange is connected to the height adjustment screw at one end and to the second KF cross at the other end, so as to allow the sample rod body and 3 Connected to the refrigeration plug-in to form a sealed environment;

[0038] The glass fiber tube connects the sample cavity and the position adjustment component, is used to support the sample rod body, and protects the semi-rigid coaxial line and the temperature control lead wire.

[0039] Preferably, the sample chamber is a carbon fiber sample chamber, and the carbon fiber sample chamber comprises: a carbon fiber base and a carbon fiber sleeve;

[0040] The carbon fiber base is fixed to the tail of the sample rod body, and a heater and a thermometer are fixed thereon;

[0041] The carbon fiber sleeve is connected to the base to form a sample cavity, which prevents the sample from being 3 He touches the inner cavity of the cooling plug-in.

[0042] Preferably, the carbon fiber sleeve is cut into eight equal parts to reduce the temperature rise of the sample caused by the eddy current effect in the pulsed magnetic field as much as possible.

[0043] To achieve the above-mentioned purpose, in a second aspect, the present application provides an NMR measurement method based on the dual-channel sample rod described in the first aspect, comprising:

[0044] One end of the signal acquisition coil equipped with the sample to be tested is welded to the fixed capacitor, and the other end is welded to the core wire of a semi-rigid coaxial line. The other end of the fixed capacitor is welded to the shielding layer of the semi-rigid coaxial line, and the two ends of the additional matching inductor / capacitor are connected to the shielding layer and the core wire of the semi-rigid coaxial line respectively.

[0045] Weld the signal acquisition coil equipped with the standard sample to another semi-rigid coaxial line in the same way;

[0046] Place the sample holder body into 3 He cooling insert and fixed to the top of the second KF cross;

[0047] Will 3 Insert the He cooling plug into the external pulse magnet so that the magnetic field collection coil is at the geometric center of the magnet. 3 The second KF cross of the He cooling insert 3 Connect with control cabinet;

[0048] Adjust the height nut to the desired position and direction;

[0049] To control the magnet, first use liquid 4 He creates a low temperature environment. When the sample chamber temperature drops below 2K, 3 He refrigeration plug-in 3 He gas, condensing it into liquid in the sample chamber;

[0050] operate 3 He control cabinet extraction 3 He cooling plug-in 3 He liquid, produces extremely low temperature, and is heated by a temperature controller to stabilize the sample temperature at a target temperature, which is lower than 1K;

[0051] The two signal collection connectors are respectively connected to a dual-channel nuclear magnetic resonance spectrometer;

[0052] Control the discharge of pulsed magnets and measure nuclear magnetic resonance signals.

[0053] Preferably, by measuring the nuclear magnetic resonance frequency of the standard sample, according to the formula The pulse magnetic field is calibrated, where K is the Knight shift, which is known for the standard sample, f is the measured resonant frequency, γ is the gyromagnetic ratio of the standard sample, and H0 is the external magnetic field for calibration; the two signal acquisition coils are as perpendicular to each other as possible to reduce the interference between the two measurement signals.

[0054] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art:

[0055] This application provides 3 He ultra-low temperature, pulsed high magnetic field NMR measurement sample rod and measurement method, through 3 The He refrigeration plug-in creates an extremely low temperature environment below 1K for the tail of the insertion part. The position of the sample in the magnetic field is adjusted by the position adjustment component so that it is within the range of a highly uniform magnetic field. A dual-channel measurement circuit is adopted, in which one channel measures the NMR signal of the sample and the other channel measures the NMR signal of the standard sample to calibrate the precise intensity of the instantaneous magnetic field. Combining the dual-channel measurement, the chemical (Night) shift of the sample can be obtained, reducing the error of the nuclear magnetic resonance experiment, thereby realizing nuclear magnetic resonance measurement under extremely low temperature and pulsed strong magnetic field. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 The present invention provides a method for 3 Schematic diagram of the dual-channel sample rod structure for He ultra-low temperature, pulsed high magnetic field NMR measurement.

[0057] Figure 2 It is a cross-sectional view of the position adjustment component provided by the present invention.

[0058] Figure 3 It is a schematic diagram of the structure of the tail of the sample rod provided by the present invention.

[0059] Figure 4 The present invention provides 3 Cross-section of the He cooling plug-in.

[0060] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0061] 1-six-hole Lemo connector; 2-KF four-way connector; 3-signal acquisition connector; 4-connecting rod; 5-clip; 6-cover plate; 7-heightening nut; 8-heightening screw; 9-KF flange; 10-glass fiber tube; 11-upper shell; 12-lower shell; 13-glass fiber disc; 14-heater; 15-carbon fiber base; 16-semi-rigid coaxial line; 17-thermometer; 18-carbon fiber sleeve; 19-magnetic field acquisition coil; 20-two-hole Lemo plug; 21-plug-in guide. DETAILED DESCRIPTION

[0062] For ease of understanding, the English abbreviations and related technical terms involved in the embodiments of the present application are explained and described below.

[0063] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0064] like Figure 1 As shown, the present application provides a method for 3He ultra-low temperature, pulsed high magnetic field NMR measurement dual channel sample holder, including: sample holder body and 3 He cooling plug-in;

[0065] Said 3 The He cooling plug-in supports the insertion of a part of the sample rod body and is detachably connected to the sample rod body to form a sealed environment for the inserted part. 3 He connection port for access and extraction 3 He, to create an extremely low temperature environment below 1K for the tail of the insertion part;

[0066] The sample holder body comprises: a sleeve, a temperature control component, a main body support component, a position adjustment component, a dual-channel NMR signal transmission circuit and a first KF cross-connect;

[0067] The sleeve (including 18, 21) is detachably connected to the tail of the main support member to form a sample chamber, and the sample chamber is used to place and protect the sample to be tested and its signal collection coil, the standard sample and its signal collection coil;

[0068] The temperature control member (including 14, 17) is fixed to the tail of the main support member and connected to the temperature controller through the first KF cross-connection to detect and adjust the temperature of the sample;

[0069] The main body support member (including 10, 13, 15) is used to support and connect the position adjustment member and the sample chamber;

[0070] The position adjustment member (including 4, 5, 6, 7, 8) is used to adjust the horizontal position and / or vertical height of the sample in the magnetic field;

[0071] The dual-channel NMR signal transmission circuit 16 passes through the interior of the main support member and the position adjustment member, and is connected to the nuclear magnetic resonance spectrometer through the first KF cross-connection, so as to simultaneously measure the nuclear magnetic resonance signals of the sample to be tested and the standard sample;

[0072] The first KF cross-connect 2 provides an interface for a temperature controller and an interface for a nuclear magnetic resonance spectrometer externally, and is detachably connected to a position adjustment component internally.

[0073] It should be noted that the sample is connected to the signal collection coil, the signal collection coil is connected to the semi-steel coaxial line, the semi-steel coaxial line is connected to the main support member, and the sample cavity is connected to the bottom of the main support part. The sample cavity space contains the collection coil and the sample, but they are not directly connected.

[0074] Preferably, the main support member is made of fiberglass.

[0075] Preferably, the position adjustment component comprises: a connecting rod 4, a height adjustment screw 8, a height adjustment nut 7, a buckle 5 and a cover plate 6;

[0076] One end of the connecting rod 4 is connected to the first KF cross 2, and the other end passes through the height adjustment screw 8 and the height adjustment nut 7, and is connected to the main support member clamp;

[0077] The buckle 5 is fixed to the groove on the outer wall of the connecting rod 4 and placed in the groove on the upper end of the height-adjusting nut 7. The bottom of the buckle 5 is restricted in the height-adjusting nut 7 by the cover plate 6, so that the buckle 5 can rotate, and the main supporting member is driven by rotating the buckle 5 to change the direction of the sample signal acquisition coil;

[0078] One end of the height adjustment screw 8 is threadedly connected to the height adjustment nut 7, and the other end is connected to the KF flange 9, so that the height of the sample signal acquisition coil can be changed by adjusting the height adjustment nut 7 to drive the main support member.

[0079] It should be noted that the height adjustment nut and height adjustment screw are respectively connected to the support structure body and 3 He cooling plug-in connection, used to adjust the height of the sample in the direction perpendicular to the magnetic field. The cover plate restricts the buckle fixed to the connecting rod in the groove of the height adjustment nut, so that the vertical height of the sample is fixed but can be rotated in the horizontal plane, which can be used to detect the uniformity of the magnet.

[0080] The sample rod itself has no cooling capability. The magnet used in the NMR can reach a temperature of about 2K, but if you want to reach a temperature below 1K, you must use 3 He refrigeration plug-in refrigeration. 3 The He cooling plug-in provides a 3 He's holding chamber is filled with 3 He, and then pump out the gas to achieve heat absorption from liquid to gas, thereby achieving cooling.

[0081] Preferably, the 3 The He refrigeration plug-in includes: an upper shell, a lower shell, a magnetic field collection coil, a second KF cross-connection and a two-hole Lemo joint;

[0082] The upper and lower shell layers are both double-layer structures, which can effectively achieve heat preservation;

[0083] One end of the upper shell is connected to the second KF cross-connection, and the other end is connected to the lower shell to isolate 3 He and the external environment create extremely low temperature conditions;

[0084] The upper shell layer has reserved wire grooves so that the twisted pair wires can enter the upper shell layer interlayer and pass therethrough to avoid being scratched during repeated use;

[0085] The magnetic field collection coil is wrapped around the outer wall of the lower shell layer so that it has the same height as the sample and is used to measure the magnitude of the pulsed magnetic field;

[0086] The second KF cross, the first end is used to connect to the outside 3 He control cabinet, the second end is connected to the upper shell, the third end is used to fix the two-hole Lemo joint, and the fourth end is connected to the sample rod body through the KF flange;

[0087] The two-hole Lemo connector is used to connect to an external controller to output a pulsed magnetic field acquisition signal.

[0088] It should be noted that the middle of the upper shell is 3 He gas, the two shells are not sealed, and the twisted pair wires from the magnetic field collection coil below will pass through the upper shell. The middle of the lower shell is a vacuum, which can better insulate heat.

[0089] Preferably, the cable duct is sealed with 2850 epoxy glue to avoid air leakage.

[0090] Preferably, the dual-channel NMR signal transmission circuit comprises: two independent transmission loops, each loop comprising a connected semi-rigid coaxial line and a signal acquisition connector;

[0091] One end of the signal acquisition connector is connected to a semi-rigid coaxial line, and the other end is connected to an external nuclear magnetic resonance spectrometer;

[0092] The shielding layer of the semi-rigid coaxial line is used to connect to the other end of the fixed capacitor connected to one end of the sample signal acquisition coil, and the core wire is used to connect to the other end of the sample signal acquisition coil that is not connected to the fixed capacitor;

[0093] The shielding layer and core wire of the semi-rigid coaxial line are respectively used to connect to the two ends of the matching capacitor / inductor.

[0094] Preferably, the semi-rigid coaxial line adopts a 047 type semi-rigid coaxial line to reduce the attenuation of the measurement signal.

[0095] Preferably, the temperature control component comprises: a heater, a thermometer, a temperature control lead and a six-hole Lemo plug;

[0096] The six-hole Lemo plug is used to connect an external temperature controller;

[0097] The heater is connected to a six-hole Lemo connector via two twisted-pair temperature-controlled leads for heating the sample;

[0098] The thermometer is connected to a six-hole Lemo connector via four twisted-pair temperature control leads for measuring sample temperature;

[0099] The temperature control lead is connected to the heater and the six-hole Lemo plug, and to the thermometer and the six-hole Lemo plug, for transmitting the thermometer and heater signals;

[0100] The sample temperature is measured and regulated through a PID loop of a temperature controller between the heater and the thermometer.

[0101] Preferably, the heater is a 25W high-power heater, which can make the sample heating rate faster and shorten the sample heating time.

[0102] Preferably, the main body support member comprises: a glass fiber disc, a KF flange, a glass fiber tube and a first KF cross;

[0103] The fiberglass disc is connected to the fiberglass tube and the semi-rigid coaxial line and is used to fix the fiberglass tube and the semi-rigid coaxial line to avoid deflection;

[0104] The KF flange is connected to the height adjustment screw at one end and to the second KF cross at the other end, so as to allow the sample rod body and 3 Connected to the refrigeration plug-in to form a sealed environment;

[0105] The glass fiber tube connects the sample cavity and the position adjustment component, is used to support the sample rod body, and protects the semi-rigid coaxial line and the temperature control lead wire.

[0106] Preferably, the sample chamber is a carbon fiber sample chamber, and the carbon fiber sample chamber comprises: a carbon fiber base and a carbon fiber sleeve;

[0107] The carbon fiber base is fixed to the tail of the sample rod body, and a heater and a thermometer are fixed thereon;

[0108] The carbon fiber sleeve is connected to the base to form a sample cavity, which prevents the sample from being 3 He touches the inner cavity of the cooling plug-in.

[0109] It should be noted that the sample cavity is made of carbon fiber, which has strong thermal conductivity and poor electrical conductivity, so that the sample cavity has good thermal conductivity while minimizing the sample temperature rise caused by the eddy current effect in the pulsed magnetic field. The diameter of the sample cavity is 11.6 mm.

[0110] Preferably, the carbon fiber sleeve is cut into eight equal parts to reduce the temperature rise of the sample caused by the eddy current effect in the pulsed magnetic field as much as possible.

[0111] Preferably, the carbon fiber bottom is connected to the plug-in guide so that the sample rod body can be smoothly inserted into the 3 He cooling plug-in.

[0112] The connecting rod is connected to the KF flange and the glass fiber tube respectively through the height adjustment screw and the height adjustment nut; the heater and the thermometer are connected to the six-hole Lemo connector on the top of the first KF cross-way through 2 and 4 temperature control leads respectively through the glass fiber tube and the temperature control leads of the connecting rod; the magnetic field collection coil is connected to the two-hole Lemo connector of the second KF cross-way through 2 twisted pair wires that pass through the reserved wire groove of the upper shell and enter the inner wall of the upper shell.

[0113] On the basis of the above, the present application provides an NMR measurement method based on the dual-channel sample rod of the first aspect, comprising:

[0114] One end of the signal acquisition coil equipped with the sample to be tested is welded to the fixed capacitor, and the other end is welded to the core wire of a semi-rigid coaxial line. The other end of the fixed capacitor is welded to the shielding layer of the semi-rigid coaxial line, and the two ends of the additional matching inductor / capacitor are connected to the shielding layer and the core wire of the semi-rigid coaxial line respectively.

[0115] Weld the signal acquisition coil equipped with the standard sample to another semi-rigid coaxial line in the same way;

[0116] Place the sample holder body into 3 He cooling insert and fixed to the top of the second KF cross;

[0117] Will 3 Insert the He cooling plug into the external pulse magnet so that the magnetic field collection coil is at the geometric center of the magnet. 3 The second KF cross of the He cooling insert 3 Connect with control cabinet;

[0118] Adjust the height adjustment nut to the desired position and direction, that is, the sample is in the most uniform position of the pulsed strong magnetic field;

[0119] To control the magnet, first use liquid 4 He creates a low temperature environment. When the sample chamber temperature drops below 2K, 3 He refrigeration plug-in 3 He gas, condensing it into liquid in the sample chamber;

[0120] operate 3 He control cabinet extraction 3 He cooling plug-in 3 He liquid, produces extremely low temperature, and is heated by a temperature controller to stabilize the sample temperature at a target temperature, which is lower than 1K;

[0121] The two signal collection connectors are respectively connected to a dual-channel nuclear magnetic resonance spectrometer;

[0122] Control the discharge of pulsed magnets and measure nuclear magnetic resonance signals.

[0123] It should be noted that liquid 3 He is only at the bottom of the sample rod, at least submerging the entire sample cavity.

[0124] Preferably, by measuring the nuclear magnetic resonance frequency of the standard sample, according to the formula The pulse magnetic field is calibrated, where K is the Knight shift, which is known for the standard sample, f is the measured resonant frequency, γ is the gyromagnetic ratio of the standard sample, and H0 is the external magnetic field for calibration; the two signal acquisition coils are as perpendicular to each other as possible to reduce the interference between the two measurement signals.

[0125] It should be understood that expressions such as "including" and "may include" that may be used in the present application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In the present application, terms such as "including" and / or "having" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0126] In addition, in the present application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0127] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the relative position relationship after connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0128] In addition, in the embodiments of the present application, the mathematical concepts mentioned are symmetry, equality, parallelism, verticality, etc. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense, and allow a small amount of deviation, approximation to symmetry, approximation to equality, approximation to parallelism, approximation to verticality, etc. are all possible. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0129] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for 3 He ultra-low temperature, pulsed high magnetic field NMR measurement dual-channel sample holder, characterized by: include: Sample holder body and 3 He cooling plug-in; Said 3 The He cooling plug-in supports the insertion of a part of the sample rod body and is detachably connected to the sample rod body to form a sealed environment for the inserted part. 3 He connection port for access and extraction 3 He, to create an extremely low temperature environment below 1K for the tail of the insertion part; The sample holder body comprises: a sleeve, a temperature control component, a main body support component, a position adjustment component, a dual-channel NMR signal transmission circuit and a first KF cross-connect; The sleeve is detachably connected to the tail of the main support member to form a sample chamber, and the sample chamber is used to place and protect the sample to be tested and its signal collection coil, the standard sample and its signal collection coil; The temperature control component is fixed to the tail of the main support component and connected to the temperature controller through the first KF cross-connection to detect and adjust the temperature of the sample; The main body support member is used to support and connect the position adjustment member and the sample chamber; The position adjustment member is used to adjust the horizontal position and / or vertical height of the sample in the magnetic field; The dual-channel NMR signal transmission circuit passes through the interior of the main support member and the position adjustment member, and is connected to the nuclear magnetic resonance spectrometer through the first KF cross-connect, so as to simultaneously measure the nuclear magnetic resonance signals of the sample to be tested and the standard sample; The first KF cross-connect provides an interface for a temperature controller and an interface for a nuclear magnetic resonance spectrometer externally, and is detachably connected to a position adjustment component internally; Said 3 The He refrigeration insert includes: an upper shell, a lower shell, a magnetic field collection coil, a second KF cross-connection and a two-hole Lemo joint; The upper and lower shells are both double-layer structures; One end of the upper shell is connected to the second KF cross-connection, and the other end is connected to the lower shell to isolate 3 He and the external environment create extremely low temperature conditions; The upper shell layer has reserved wire grooves so that the twisted pair wires can enter the upper shell layer interlayer and pass therethrough; The magnetic field collection coil is wrapped around the outer wall of the lower shell layer so that it has the same height as the sample and is used to measure the magnitude of the pulsed magnetic field; The second KF cross, the first end is used to connect to the outside 3 He control cabinet, the second end is connected to the upper shell, the third end is used to fix the two-hole Lemo joint, and the fourth end is connected to the sample rod body through the KF flange; The two-hole Lemo connector is used to connect to an external controller to output a pulsed magnetic field acquisition signal.

2. The dual-channel sample holder according to claim 1, characterized in that: The position adjustment component comprises: a connecting rod (4), a height adjustment screw (8), a height adjustment nut (7), a buckle (5) and a cover plate (6); One end of the connecting rod (4) is connected to the first KF cross (2), and the other end passes through the inside of the height adjustment screw (8) and the height adjustment nut (7) and is connected to the clamp of the main support member; The buckle (5) is fixed to the groove on the outer wall of the connecting rod (4) and is placed in the groove at the upper end of the height adjustment nut (7). The bottom of the buckle (5) is restricted in the height adjustment nut (7) by the cover plate (6), so that the buckle (5) can be rotated, and the main body support member is driven by rotating the buckle (5) to change the direction of the sample signal collection coil; One end of the height adjustment screw (8) is threadedly connected to the height adjustment nut (7), and the other end is connected to the KF flange (9), so that the height of the sample signal collection coil in the vertical direction can be changed by adjusting the height adjustment nut (7) to drive the main support member.

3. The dual-channel sample holder according to claim 1, characterized in that: The dual-channel NMR signal transmission circuit comprises: two independent transmission loops, each loop comprising a connected semi-rigid coaxial line and a signal acquisition connector; One end of the signal acquisition connector is connected to a semi-rigid coaxial line, and the other end is connected to an external nuclear magnetic resonance spectrometer; The shielding layer of the semi-rigid coaxial line is used to connect to the other end of the fixed capacitor connected to one end of the sample signal acquisition coil, and the core wire is used to connect to the other end of the sample signal acquisition coil that is not connected to the fixed capacitor; The shielding layer and core wire of the semi-rigid coaxial line are respectively used to connect to the two ends of the matching capacitor / inductor.

4. The dual-channel sample holder according to claim 1, characterized in that: The temperature control component includes: a heater, a thermometer, a temperature control lead and a six-hole Lemo plug; The six-hole Lemo plug is used to connect an external temperature controller; The heater is connected to a six-hole Lemo connector via two twisted-pair temperature-controlled leads for heating the sample; The thermometer is connected to a six-hole Lemo connector via four twisted-pair temperature control leads for measuring sample temperature; The temperature control lead is connected to the heater and the six-hole Lemo plug, and to the thermometer and the six-hole Lemo plug, for transmitting the thermometer and heater signals; The sample temperature is measured and regulated through a PID loop of a temperature controller between the heater and the thermometer.

5. The dual-channel sample holder according to claim 1, characterized in that: The main body support member includes: a glass fiber disc, a KF flange, a glass fiber tube and a first KF cross; The fiberglass disc is connected to the fiberglass tube and the semi-rigid coaxial line and is used to fix the fiberglass tube and the semi-rigid coaxial line to avoid deflection; The KF flange is connected to the height adjustment screw at one end and to the second KF cross at the other end, so as to allow the sample rod body and 3 Connected to the refrigeration plug-in to form a sealed environment; The glass fiber tube connects the sample cavity and the position adjustment component, is used to support the sample rod body, and protects the semi-rigid coaxial line and the temperature control lead wire.

6. The dual-channel sample holder according to claim 1, characterized in that: The sample chamber is a carbon fiber sample chamber, and the carbon fiber sample chamber comprises: a carbon fiber base and a carbon fiber sleeve; The carbon fiber base is fixed to the tail of the sample rod body, and a heater and a thermometer are fixed thereon; The carbon fiber sleeve is connected to the base to form a sample cavity, which prevents the sample from being 3 He touches the inner cavity of the cooling plug-in.

7. The dual-channel sample holder according to claim 6, characterized in that: The carbon fiber sleeve is cut into eight equal parts to reduce the temperature rise of the sample caused by the eddy current effect in the pulse magnetic field as much as possible.

8. An NMR measurement method based on the dual-channel sample holder according to any one of claims 1 to 7, characterized in that: include: One end of the signal acquisition coil equipped with the sample to be tested is welded to the fixed capacitor, and the other end is welded to the core wire of a semi-rigid coaxial line. The other end of the fixed capacitor is welded to the shielding layer of the semi-rigid coaxial line, and the two ends of the additional matching inductor / capacitor are connected to the shielding layer and the core wire of the semi-rigid coaxial line respectively. Weld the signal acquisition coil equipped with the standard sample to another semi-rigid coaxial line in the same way; Place the sample holder body into 3 He cooling insert and fixed to the top of the second KF cross; Will 3 Insert the He cooling plug into the external pulse magnet so that the magnetic field collection coil is at the geometric center of the magnet. 3 The second KF cross of the He cooling insert 3 Connect with control cabinet; Adjust the height nut to the desired position and direction; To control the magnet, first use liquid 4 He creates a low temperature environment. When the sample chamber temperature drops below 2K, 3 He refrigeration plug-in 3 He gas, condensing it into liquid in the sample chamber; operate 3 He control cabinet extraction 3 He cooling plug-in 3 He liquid, produces extremely low temperature, and is heated by a temperature controller to stabilize the sample temperature at a target temperature, which is lower than 1K; The two signal collection connectors are respectively connected to a dual-channel nuclear magnetic resonance spectrometer; Control the discharge of pulsed magnets and measure nuclear magnetic resonance signals.

9. The method according to claim 8, characterized in that By measuring the nuclear magnetic resonance frequency of the standard sample, according to the formula The pulse magnetic field is calibrated, where: is the Knight shift. For the standard sample, its Knight shift is known. is the measured resonant frequency, is the gyromagnetic ratio of the standard sample, For calibration, the two signal acquisition coils are placed perpendicular to each other to reduce interference between the two measurement signals.

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