Nuclear magnetic resonance apparatus

Abstract

To provide a nuclear magnetic resonance apparatus for preventing entry of a metal object and a precision apparatus worn or possessed by a worker into a range in which a strong magnetic field occurs when adjusting characteristics of a probe.SOLUTION: A nuclear magnetic resonance apparatus includes: a probe 14 for applying electromagnetic waves to a sample and detecting a nuclear magnetic resonance signal from the sample; strong magnetic field protection members 17a to 17c at least surrounding a space in which strength of a magnetic field generated by a superconductor 12 becomes a first threshold or larger; weak magnetic field protection members 18a to 18c that are further mounted to the outside of the strong magnetic field protection members 17a to 17c and at least surround a space in which strength of a magnetic field generated by the superconductor 12 becomes a second threshold that is weaker than the first threshold or larger; an opening 45 provided in the weak magnetic field protection members 18a to 18c; and a probe adjustment section 24 that is disposed outside the strong magnetic field protection members 17a to 17c and inside the weak magnetic field protection members 18a to 18c and near the opening 45, and adjusts the characteristics of the probe 14 by receiving a worker's operation.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a nuclear magnetic resonance apparatus equipped with a magnetic field generating unit. [Background technology]

[0002] Various analytical and diagnostic imaging technologies using nuclear magnetic resonance (NMR) have been put to practical use. Nuclear magnetic resonance is a phenomenon in which, when an atomic nucleus is exposed to a magnetic field and an external electromagnetic wave is irradiated onto it, the atomic nucleus absorbs a specific electromagnetic wave according to its chemical environment. Examples of nuclear magnetic resonance devices that utilize this nuclear magnetic resonance phenomenon include nuclear magnetic resonance analyzers (NMR analyzers) that use the nuclear magnetic resonance phenomenon to analyze the structure of a sample, and magnetic resonance imaging devices (MRI devices) that use the nuclear magnetic resonance phenomenon to create images of information inside living organisms.

[0003] These nuclear magnetic resonance instruments (hereinafter referred to as NMR instruments) are equipped with a device called a probe as a means for irradiating the electromagnetic waves and detecting a nuclear magnetic resonance signal indicating the amount of energy absorbed by the nuclear magnetic resonance phenomenon. To accurately analyze samples, the probe's characteristics had to be individually adjusted (tuned) according to the NMR instrument in which it was installed. Therefore, as in Japanese Patent Application Laid-Open No. 2023-061460, the probe has traditionally been equipped with an operating unit for adjusting the characteristics, and the operator adjusts the probe's characteristics by operating the operating unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-061460 A (paragraph 0044, Figure 4) Summary of the Invention [Problem to be solved by the invention]

[0005] Here, an NMR apparatus is equipped with a magnetic field generating unit that generates a magnetic field as part of the apparatus, and since the stronger the generated magnetic field, the higher the signal sensitivity and resolution of an NMR apparatus, it is desirable for the NMR apparatus to be equipped with a magnetic field generating unit that generates a strong magnetic field. However, if a magnetic field generating unit that generates such a strong magnetic field is provided, when adjusting the characteristics by operating an operation unit provided on the probe as in Patent Document 1, there is a possibility that metal objects worn or held by the operator operating the operation unit may be attracted to the unit, resulting in malfunction of the precision equipment.

[0006] The present invention has been made to solve the above-mentioned problems in the conventional art, and aims to provide a nuclear magnetic resonance apparatus that reliably prevents metal objects or precision instruments worn or carried by the operator from entering the area where a strong magnetic field is generated when adjusting the characteristics of a probe, while also reducing the workload on the operator. [Means for solving the problem]

[0007] In order to achieve the above object, the nuclear magnetic resonance apparatus of the present invention comprises a magnetic field generating unit that generates a magnetic field, a sample container that is held in the magnetic field generated by the magnetic field generating unit and that contains a sample to be analyzed, a probe that irradiates electromagnetic waves onto the sample and detects nuclear magnetic resonance signals from the sample, a first protective cover that encloses at least a space in which the intensity of the magnetic field generated by the magnetic field generating unit is equal to or greater than a first threshold, a second protective cover that is further attached to the outside of the first protective cover and that encloses at least a space in which the intensity of the magnetic field generated by the magnetic field generating unit is equal to or greater than a second threshold that is weaker than the first threshold, an opening provided in the second protective cover, and a probe adjustment unit that is positioned outside the first protective cover and inside the second protective cover, near the opening, and that adjusts the characteristics of the probe by receiving operation from an operator. [Effects of the Invention]

[0008] The nuclear magnetic resonance apparatus according to the present invention having the above-described configuration includes a first protective cover and a second protective cover around the magnetic field generating unit, and a probe adjustment unit for adjusting the characteristics of the probe outside the first protective cover, which makes it possible to reliably prevent metal objects or precision instruments worn or carried by an operator from entering the area where a strong magnetic field is generated when adjusting the characteristics of the probe. On the other hand, since the probe adjustment unit is provided inside the second protective cover, the opportunity for contact with the probe adjustment unit is reduced except when the probe characteristics are being adjusted, and the loss of the adjusted state due to erroneous operation can be prevented. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an external view showing the entire NMR analyzer according to the present embodiment. [Figure 2] FIG. 1 is an external view showing the entire NMR analyzer with the protective cover covering the outside of the apparatus removed. [Figure 3] FIG. 2 is a cross-sectional view showing the NMR analyzer, particularly the periphery of the main body. [Figure 4] FIG. 10 is a diagram showing a state in which the probe is assembled to the container. [Figure 5] FIG. 2 is a diagram showing a probe and a probe adjustment unit. [Figure 6] FIG. [Figure 7] 10 is a diagram showing a space surrounded by a strong magnetic field protection member and a weak magnetic field protection member. FIG. [Figure 8] FIG. 10 is a diagram showing the vicinity of the opening of the main body with the door open. [Figure 9] FIG. 10 is a diagram showing an example of a dial of a probe adjustment unit. [Figure 10] FIG. 1 is a diagram showing a schematic configuration of an NMR analyzer. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a detailed description will be given of specific embodiments of a nuclear magnetic resonance apparatus according to the present invention with reference to the drawings. In the following, a nuclear magnetic resonance analyzer (hereinafter referred to as an NMR analyzer) that analyzes the structure of a sample by utilizing the nuclear magnetic resonance phenomenon will be given as an example of the nuclear magnetic resonance apparatus.

[0011] First, the schematic configuration of an NMR analyzer 1 according to this embodiment will be described with reference to Figures 1 and 2. Figure 1 is an external view showing the entire NMR analyzer 1 according to this embodiment, and Figure 2 is an external view showing the entire NMR analyzer 1 with protective covers (weak magnetic field protective members 18a to 18c, described below) covering the outside of the apparatus removed.

[0012] 1 and 2, the NMR analyzer 1 according to this embodiment basically comprises a main body 2 having therein a sample container for accommodating a sample to be analyzed, a probe for analyzing the sample, and a superconductor (magnetic field generator) for generating a static magnetic field; an external device 4 connected to the main body 2 via piping 3 and cables and equipped with a compressor for supplying a refrigerant for cooling the superconductor in the main body 2 and a pump for evacuating the inside of the main body 2; and a cart 5 on which the main body 2 and the external device 4 can be placed and moved together. However, the cart 5 is not essential for the NMR analyzer 1 according to this embodiment, and the main body 2 and the external device 4 may be installed on the floor.

[0013] First, the following will explain the main body 2 of the NMR analyzer 1. Figure 3 is a cross-sectional view showing the NMR analyzer 1, particularly the main body 2 and its periphery. As shown in FIG. 3, the main body 2 includes a sample container 11 for accommodating a sample to be analyzed therein, a cylindrical superconductor 12 arranged around the sample container 11, a similarly cylindrical container 13 for accommodating the superconductor 12 therein, a probe 14 for irradiating the sample in the sample container 11 with electromagnetic waves and detecting a nuclear magnetic resonance signal (NMR signal) from the sample, a disk-shaped stay (upper fixing member) 15 arranged around the container 13, a vacuum insulation container 16 for insulating the superconductor 12 by creating a vacuum inside the container 13, strong magnetic field protection members (first protective covers) 17a to 17c arranged so as to surround a space of a strong magnetic field where the strength of the magnetic field generated by the superconductor 12 outside the container 13 is equal to or greater than a first threshold, and a second magnetic field protection member (second protective cover) 17b to 17c arranged further outside the strong magnetic field protection members 17a to 17c for detecting a second threshold The system includes weak-magnetic-field protection members (second protective covers) 18a-18c, which are protective covers arranged to surround the weak-magnetic-field space described above, a cold head 19 of a refrigerator 19a that generates cold by expanding a compressed refrigerant (e.g., He gas, Ne gas, H gas, N gas, or liquefied versions of these) supplied from an external device 4, a heat transfer body 20 for transferring the cold generated in the cold head 19 of the refrigerator 19a to the superconductor 12, a disk-shaped central fixing member 21 and a lower fixing member 22 arranged around the container 13 below the stay 15 and fixing the weak-magnetic-field protection members 18a-18c together with the stay 15, a fixed support 23 for supporting the main body 2, and a probe adjustment unit 24 (see FIG. 2 ) attached to the fixed support 23 and operated by an operator to adjust (tune) the characteristics of the probe 14. The stay 15 is held at a predetermined position (height) from the bottom end of the container 13 by the fixed support 23. In this embodiment, the strong magnetic field protective members 17a to 17c and the weak magnetic field protective members 18a to 18c are divided into three, but they may also be formed as an integrated protective cover. As shown in Fig. 1, the side of the main body 2 is provided with a window 25 made of a transparent member that allows an operator to visually check the inside of the main body 2, and below the window 25 is an opening / closing door 26 that is opened and closed when operating the probe adjustment unit 24, as described below. The probe adjustment unit 24 is attached outside a space of 500 gauss or more, as shown in Fig. 7.In this embodiment, probe adjustment unit 24 is attached outside a space of 500 gauss or more and inside weak-magnetic-field protection members 18a to 18c, and is covered with opening / closing door 26 to prevent an operator from touching probe adjustment unit 24 after adjustment, but the present invention is not limited to this configuration and other configurations are also possible. As an example, an inexpensive configuration may be considered in which probe adjustment unit 24 is embedded in weak-magnetic-field protection members 18a to 18c and dials 32a to 32d of probe adjustment unit 24 are exposed toward the outside of weak-magnetic-field protection members 18a to 18c.

[0014] Although not described here, the main body 2 also includes various other devices and components required for analyzing a sample in the NMR analyzer 1.

[0015] Each of the components of the main body 2 will be described below in order. The storage vessel 13 is, for example, a sealed, generally cylindrical container. The storage vessel 13 has a communication space 101 that radially penetrates the storage vessel 13 between the weak magnetic field protection member 18a and the cold head 19 of the refrigerator 19a. A room-temperature bore space 102 that extends in the axial direction of the storage vessel 13 is provided around the central axis of the storage vessel 13. A first opening 103 that faces the weak magnetic field protection member 18a is provided at one end of the room-temperature bore space 102, and a second opening 104 that opens into the communication space 101 is provided at the other end of the room-temperature bore space 102. The room-temperature bore space 102 and the communication space 101 are partitioned and spatially isolated from the internal space of the storage vessel 13. By maintaining the internal space of the storage vessel 13 at a vacuum, the internal space of the storage vessel 13 is thermally isolated from the room-temperature bore space 102 and the communication space 101, and the storage vessel 13 becomes a vacuum insulated container 16. When using the NMR analyzer 1, various samples, such as organic compounds, inorganic compounds, and biological materials, from various fields such as medicine, biotechnology, and materials, are placed in the sample container 11. Then, the weak magnetic field protection member 18a is removed, and the sample container 11 is inserted into the room-temperature bore space 102 of the storage container 13 through the first opening 103 toward the superconductor 12. The NMR analyzer 1 according to this embodiment then irradiates the sample container 11, placed in the static magnetic field generated by the superconductor 12, with pulsed electromagnetic waves from the probe 14 to excite nuclear magnetic resonance, and detects the nuclear magnetic resonance signal generated by the nuclear magnetic resonance, thereby analyzing the crystalline structure of the sample in the sample container 11. Although not shown, the NMR analyzer 1 is also connected to a monitor for displaying the analysis results, a storage device for storing the analysis results, a keyboard, a mouse, and other devices for the operator to operate the NMR analyzer 1.

[0016] On the other hand, the superconductor 12 serves as a magnetic field source (magnetic pole) in the NMR analyzer 1, generating a static magnetic field for analyzing samples. A superconducting bulk magnet, particularly a high-temperature superconducting bulk magnet with a relatively high superconducting transition temperature (critical temperature), is used as the superconductor 12, with the objective of generating a strong static magnetic field with excellent stability and enabling the miniaturization of the device. For example, a high-temperature oxide superconductor such as RE-Ba-Cu-O (RE is a rare earth element including Y) is desirable. However, the superconductor 12 is not limited to the above example, and may also be an Nd-, Sm-, or Gd-based superconducting bulk magnet. Furthermore, a magnet other than a high-temperature superconducting bulk magnet may be used as long as it can be kept below the superconducting transition temperature.

[0017] The superconductor 12 according to this embodiment is formed in a cylindrical shape so as to surround the sample container 11 as shown in FIG. 3, and is placed in a container 13 which also has a cylindrical shape. In particular, in this embodiment, the superconductor 12 is formed by stacking a plurality of (e.g., 3 to 10) cylindrical superconducting bulk magnets along the axial direction. However, the superconductor 12 may be formed by a single superconducting bulk magnet instead of a plurality of superconducting bulk magnets. Furthermore, the superconductor 12 is thermally connected to the cold head 19 of the refrigerator 19a via a heat transfer body 20 as described below, and the cold generated by the cold head 19 of the refrigerator 19a can be transferred to the superconductor 12.

[0018] Furthermore, the above-mentioned superconducting bulk magnet does not require energization to maintain a magnetic field, but the following magnetization steps (1) to (3) must be carried out in advance. (1) Magnetic field application process A magnetic field is applied to the superconductor by an external magnetic field generating device (hereinafter referred to as a magnetizing device) so that a magnetic field is generated in the inner space of the superconductor 12 at a temperature higher than the superconducting transition temperature (critical temperature) of the superconductor 12, causing magnetic flux to pass axially. (2) Cooling process in magnetic field The superconductor 12 to which the magnetic field has been applied by the magnetizing device as described above is cooled to a temperature T0 below the superconducting transition temperature. Specifically, while the magnetic field is being applied to the superconductor 12 by the operation of the magnetizing device, the refrigerator 19a is operated. This causes the refrigerator 19a to generate cold energy, which is transferred via the cold head 19 to the superconductor 12 thermally connected to the cold head 19. This causes the superconductor 12 to be cooled to a temperature T0 below the superconducting transition temperature. Thereafter, the superconductor 12 is maintained in a cooled state. (3) Demagnetization process While maintaining the temperature of the superconductor 12 at temperature T0, the operation of the magnetizing device is stopped. This removes the magnetic field applied to the superconductor 12, which has been cooled to a temperature below the superconducting transition temperature (i.e., placed in a superconducting state). Then, in response to the change in magnetic field strength caused by the removal of the applied magnetic field, a supercurrent is induced in the superconductor 12 to restore the magnetic field state. The supercurrent is a circular current that flows around the central axis of the superconductor 12 in a plane perpendicular to the central axis of the superconductor 12. A magnetic field is generated when the induced supercurrent flows within the superconductor 12. In other words, the superconductor 12 is magnetized. The magnetic field generated by magnetizing the superconductor 12 is basically the same as the applied magnetic field generated by the operation of the magnetizing device. In other words, when a supercurrent flows through the superconductor 12, the superconductor 12 captures the applied magnetic field generated by the operation of the magnetizing device. When the superconductor 12 captures the applied magnetic field, a magnetic field (trapped magnetic field) in which magnetic flux passes in the axial direction is formed within the inner space of the superconductor 12. Since the sample container 11 is located within the inner space of the superconductor 12 where the trapped magnetic field is generated, a sample can be placed within the static magnetic field, and as described above, the sample can be analyzed by applying electromagnetic waves from the probe 14 to the sample placed within the strong static magnetic field.

[0019] After the magnetization steps (1) to (3) are performed, the state in which a strong magnetic field is generated (superconducting characteristics) can be maintained for a long period of time by maintaining the magnetized superconductor 12 at a temperature below the superconducting transition temperature using the cold head 19 of the refrigerator 19a and the heat transfer body 20. Even if the strong magnetic field is subsequently lost due to a temperature rise or other reasons, the state in which a strong magnetic field is generated can be restored by performing the magnetization steps again.

[0020] 2 and 3, the accommodation vessel 13 has a long cylindrical shape and accommodates the superconductor 12, particularly around the sample vessel 11 near the top. Furthermore, a heat transfer member 20 (described later) is accommodated in the center of the accommodation vessel 13, and a cold head 19 of a refrigerator 19a is accommodated below the accommodation vessel 13. Around the accommodation vessel 13, a stay 15, a middle fixing member 21, and a lower fixing member 22 are arranged. The refrigerator 19a and its cold head 19 are fixed and supported on the carriage 5. The heat transfer member 20 is supported and fixed to the cold head 19 of the refrigerator 19a. The heat transfer member 20 is provided inside the accommodation vessel 13, in a position surrounding the communicating space 101. The superconductor 12 is supported and fixed to the heat transfer member 20. The superconductor 12 is provided inside the accommodation vessel 13, in a position surrounding the room-temperature bore space 102.

[0021] Furthermore, probe 14 has a cylindrical shape that is thinner than room-temperature bore space 102 of storage vessel 13, and is inserted into room-temperature bore space 102 formed near the central axis of storage vessel 13 through communication space 101 and second opening 104 for assembly. As shown in Fig. 3, probe 14 in the assembled state is located in the internal space of cylindrical superconductor 12, i.e., in the static magnetic field generated by superconductor 12. Fig. 4 is a diagram showing probe 14 in the assembled state to storage vessel 13. Fig. 5 is a diagram showing probe 14 and probe adjustment unit 24 connected to probe 14 extracted from within NMR analyzer 1.

[0022] Here, the probe 14 includes, for example, a high-frequency generator that generates electromagnetic waves, a coil that irradiates the sample container 11 with the electromagnetic waves and through which nuclear magnetic resonance signals (NMR signals) from the sample container 11 flow, a detection unit that amplifies and detects the nuclear magnetic resonance signals that flow through the coil, and a control unit that controls these components. The sample is irradiated with the electromagnetic waves generated by the high-frequency generator, and the nuclear magnetic resonance signals from the sample are detected. The detected nuclear magnetic resonance signals are then converted into a function of frequency using a Fourier transform, and are finally stored in an externally connected computer as an NMR spectrum, which can be displayed on a monitor or the like.

[0023] Meanwhile, the main body of probe 14 is equipped with adjustment shafts 30a-30d for adjusting (tuning) the characteristics of the probe. Furthermore, adjustment shaft 30a is connected to dial 32a of probe adjustment unit 24 (described below) by a connecting means capable of applying a rotational force, such as wire 31. As a result, when an operator rotates dial 32a, the rotational force is transmitted to adjustment shaft 30a via wire 31, allowing adjustment shaft 30a to rotate. Therefore, an operator can remotely control adjustment shaft 30a by rotating dial 32a. Similarly, adjustment shaft 30b is connected to dial 32b of probe adjustment unit 24, adjustment shaft 30c is connected to dial 32c of probe adjustment unit 24, and adjustment shaft 30d is connected to dial 32d of probe adjustment unit 24.

[0024] Adjusting the characteristics of the probe 14 using the adjustment axes 30a-30d refers to, for example, matching the frequency at which atomic nuclei resonate in the nuclear magnetic resonance phenomenon with the frequency of the pulses output by the probe. Specifically, the capacitance of the tuning capacitor and the matching capacitor are changed to minimize the reflection of the irradiated signal at the resonance frequency. Drift correction for the superconductor 12 (e.g., adjusting the amplification factor and phase of the lock signal) can also be performed, improving spectral sensitivity and resolution through these adjustments. For example, the capacitance of the capacitors is adjusted using the adjustment axes 30a-30b, and drift correction is performed using the adjustment axes 30c-30d. Improper adjustments can lead to a deterioration in the S / N ratio and an increase in the required pulse width. Therefore, for example, during initial installation or periodic maintenance of the NMR analyzer 1, an operator performs adjustments using a sample for adjustment while checking the NMR spectrum displayed on the monitor. At that time, the operator does not need to directly operate adjustment shafts 30a to 30d, but can perform the work by operating dials 32a to 32d of probe adjustment unit 24 located at a distance.

[0025] Here, as described below, the probe 14 is located in a space with a strong magnetic field where the magnetic field strength is equal to or greater than a first threshold, while the probe adjustment unit 24 is located in a space with a weaker magnetic field where the magnetic field is weaker, that is, less than the first threshold and equal to or greater than a second threshold, so it is possible to prevent the probe 14 from attracting metal objects worn or held by the worker or causing malfunctions in precision equipment.

[0026] On the other hand, the stay 15 has a disk shape and is made of a non-magnetic material (for example, a resin material, titanium, aluminum, etc.), and is arranged around the container 13. The stay 15 has many screw holes and the like formed therein, and corresponds to a fixing member used to fix the strong magnetic field protection members 17a to 17c and the weak magnetic field protection members 18a to 18c, which will be described later, to the main body 2.

[0027] As shown in FIG. 6 , the stay 15 includes a cylindrical portion 35 that surrounds the outer wall portion, which is the outer periphery of the storage container 13, and a flange portion 36 that extends radially from the lower end of the cylindrical portion 35. The cylindrical portion 35 has a cylindrical shape corresponding to the storage container 13, and is disposed at a predetermined position (height) from the lower end of the storage container 13 so as to surround the outer wall portion, which is the outer periphery of the storage container 13. The inner diameter of the cylindrical portion 35 is set to a length that corresponds to the outer diameter of the storage container 13 (the inner diameter of the cylindrical portion 35 is slightly larger than the outer diameter of the storage container 13, and is a length that allows the storage container 13 to pass inside the cylindrical portion 35 and allows the relative position to be fixed when no load is applied). The stay 15 and the storage container 13 are assembled, for example, by an interference fit using the cylindrical portion 35. However, before assembly, the stay 15 can be moved axially relative to the storage container 13 by applying a load (the height position can be adjusted), and the axial position of the stay 15 (the position from the bottom end of the storage container 13) is finally determined by the worker assembling the fixed support 23.

[0028] 6, the flange 36 has a number of threaded holes 37 formed in the axial direction (vertical direction). Furthermore, the flange 36 has radially-oriented threaded holes 38 formed on its outer circumferential surface. Here, as shown in FIG. 3, the axial threaded holes 37 are used to secure the strong magnetic field protection members 17a to 17c. Specifically, the strong magnetic field protection member 17a and the strong magnetic field protection member 17b are secured to the upper side of the stay 15 with screws (however, the strong magnetic field protection member 17a is not secured directly to the stay 15 but is secured via the strong magnetic field protection member 17b), and the strong magnetic field protection member 17c is secured to the lower side of the stay 15 with screws.

[0029] 6, the radial screw holes 38 are used to secure the weak-magnetic-field protection members 18a to 18c. Specifically, the weak-magnetic-field protection members 18a and 18b are secured to the stay 15 on the upper side by screws (however, the weak-magnetic-field protection member 18a is not secured directly to the stay 15 but is fitted onto the weak-magnetic-field protection member 18b as a cover), and the weak-magnetic-field protection member 18c is secured to the stay 15 on the lower side by screws. The weak-magnetic-field protection member 18c is also secured to the middle fixing member 21 and the lower fixing member 22, which are positioned below the stay 15, by screws.

[0030] On the other hand, as shown in Figure 6, the flange portion 36 has a gear shape when viewed from above, with multiple gaps 39 between the teeth. These gaps 39 can be used as passageways for cables and piping that pass between the upper and lower parts of the stay 15 inside the main body portion 2. Because multiple gaps 39 exist in the radial direction, the gap 39 through which the cables and piping pass can be freely selected depending on their positions. As a result, as shown in Figures 2 and 3, it is also possible to take out cables and piping that connect to the top of the container 13 from the bottom end of the main body portion 2. Note that the flange portion 36 may have a shape other than a gear shape as long as it has gaps 39 for passing cables and piping through.

[0031] On the other hand, the vacuum insulating container 16 is disposed inside the storage container 13. The above-mentioned superconductor 12 is disposed further inside the vacuum insulating container 16. The vacuum insulating container 16 has an internal space, which is in a vacuum state. By evacuating the internal space, it is possible to insulate the superconductor 12 disposed inside.

[0032] The strong-magnetic-field protection members 17a-17c are made of a non-magnetic material (e.g., resin, titanium, aluminum, etc.) and are protective covers arranged outside the container 13 to surround a space where the magnetic field generated by the superconductor 12 exceeds a first threshold. Here, the first threshold is, for example, 500 gauss. The space where the magnetic field exceeds the first threshold corresponds to a space where magnetic objects must be prevented from approaching the superconductor 12. By surrounding the space where the magnetic field exceeds the first threshold with the strong-magnetic-field protection members 17a-17c as shown in FIG. 7, it is possible to reliably prevent the intrusion of metal objects worn or carried by workers into the space. The strong-magnetic-field protection members 17a-17c may surround a larger area as long as they can at least surround the space where the magnetic field generated by the superconductor 12 exceeds the first threshold. However, it is desirable to make the size as small as possible within the range that satisfies the requirement to surround the space where the magnetic field exceeds the first threshold, in order to reduce the size of the device.

[0033] Similarly, the weak-magnetic-field protection members 18a-18c are made of a non-magnetic material (e.g., resin, titanium, aluminum, etc.) and are protective covers arranged outside the strong-magnetic-field protection members 17a-17c so as to surround a weak-magnetic-field space where the strength of the magnetic field generated by the superconductor 12 is equal to or greater than a second threshold. Here, the second threshold is, for example, 250 gauss. The weak-magnetic-field space where the strength is equal to or greater than the second threshold corresponds to a space where precision equipment must be prohibited from approaching the superconductor 12. By surrounding the weak-magnetic-field protection members 18a-18c where the strength is equal to or greater than the second threshold as shown in FIG. 7, it becomes possible to reliably prevent precision equipment worn or carried by workers from entering the area. The weak-magnetic-field protection members 18a to 18c may surround a larger area as long as they can at least surround the space with a weak magnetic field where the strength of the magnetic field generated by the superconductor 12 is equal to or greater than the second threshold. However, in order to reduce the size of the device, it is desirable to make the size as small as possible within a range that satisfies the condition for surrounding the space with a strong magnetic field where the strength of the magnetic field is equal to or greater than the second threshold. As a result, in this embodiment, the main body 2 has a diameter (inverted triangle shape) that is longer at the top than at the bottom, as shown in Figure 1.

[0034] Furthermore, in this embodiment, after the superconductor 12 is magnetized, the strong magnetic field protection members 17a to 17c and the weak magnetic field protection members 18a to 18c are attached to the stay 15, and thereafter the strong magnetic field protection members 17a to 17c and the weak magnetic field protection members 18a to 18c are basically always attached until it is necessary to magnetize the superconductor 12 again (however, the weak magnetic field protection member 18a may be removed when setting the sample in the sample container 11). Therefore, not only when the NMR analyzer 1 is in use, but also during the exterior assembly process during transportation and installation, during regular maintenance, storage, etc., it is possible to prevent metal objects and precision instruments worn or carried by operators from entering the range of a magnetic field above the first threshold or above the second threshold from any direction until the completion of these tasks.

[0035] Furthermore, probe 14 is located inside strong magnetic field protection members 17a to 17c, i.e., in a space of a strong magnetic field where the magnetic field strength is equal to or greater than a first threshold, while probe adjustment unit 24 is located outside strong magnetic field protection members 17a to 17c, which have a weaker magnetic field, and inside weak magnetic field protection members 18a to 18c, i.e., in a space of a weak magnetic field where the magnetic field strength is less than the first threshold and equal to or greater than a second threshold. Therefore, when adjusting (tuning) the characteristics of probe 14 as described above, adjustment can be made by operating probe adjustment unit 24, so that metal objects and precision instruments worn or carried by the worker can be prevented from entering the range of a magnetic field at least equal to or greater than the first threshold from any direction until the work is completed.

[0036] On the other hand, refrigerator 19a is fixed airtightly below container 13 and expands a compressed refrigerant (e.g., He gas, Ne gas, H gas, N gas, or liquefied versions of any of these) supplied from external device 4 to generate cold in cold head 19 housed in container 13. While the type of refrigerator is not limited, it is desirable that it be as small as possible and be capable of generating cold enough to cool superconductor 12 to a temperature below its superconducting transition temperature (critical temperature). Examples include GM refrigerators, Stirling refrigerators, and pulse-tube refrigerators. One example is a pulse-tube refrigerator, which generates cold by generating periodic pressure oscillations in a pulse tube and expanding and contracting a so-called gas piston within the pulse tube. It should be noted that refrigerators other than those described in this embodiment can also be used as long as they are capable of generating the cold required for cold head 19.

[0037] Meanwhile, one end of the heat transfer body 20 is thermally connected to the cold head 19 of the refrigerator 19a and the other end is thermally connected to the superconductor 12, and transfers the cold generated in the cold head 19 of the refrigerator 19a to the superconductor 12. The heat transfer body 20 is made of a non-magnetic material (e.g., copper) that has high thermal conductivity. A vacuum state is maintained around the cold head 19 of the refrigerator 19a and the heat transfer body 20 to insulate them.

[0038] The probe adjustment unit 24 is an operating means for adjusting the characteristics of the probe 14 by receiving operation from an operator, and is fixed to the fixed support 23 as shown in FIG. 2 outside the strong magnetic field protection members 17a to 17c and inside the weak magnetic field protection members 18a to 18c. The fixed position is particularly near the opening / closing door 26 formed in the weak magnetic field protection member 18c (i.e., the opening 45 that is opened when the opening / closing door 26 is opened), particularly at a position facing (corresponding to) the opening 45 at the same height as the opening 45. FIG. 8 is a diagram showing the area around the opening 45 in the main body 2 when the opening / closing door 26 is open.

[0039] 8, probe adjustment unit 24 is located particularly in a position facing opening 45, that is, in a position that approaches opening 45 when opening door 26 is open, so that the operator can see dials 32a to 32d from opening 45 and can easily operate dials 32a to 32d by hand from opening 45. For example, adjustments can be easily made while checking the NMR spectrum displayed on a monitor.

[0040] As shown in FIG. 4, the probe adjustment unit 24 has a scale indicating the reference position (0 position) of each dial 32a to 32d and the amount of operation from the reference position, and the characteristics of the probe are adjusted by the amount of operation of the dial relative to the reference position. The adjustment details can be clearly identified by the numerical value in the scale. For example, if the adjustment details are recorded as "2" on the right and "3" on the left, the adjustment details can be shared among multiple workers, and readjustment work can be easily performed. In the example shown in FIG. 4, the reference position is the 12 o'clock position. A display unit for displaying the reference position of the dials 32a to 32d and the amount of operation from the reference position (e.g., -5 to 0 to +5) in numbers may be provided to make the amount of operation easily visible.

[0041] As described above, adjustment shafts 30a-30d are connected to dials 32a-32d of probe adjustment unit 24 via wires 31, and when an operator rotates dials 32a-32d, the rotational force is transmitted to adjustment shafts 30a-30d via wires 31, thereby rotating adjustment shafts 30a-30d. However, the rotation angles of dials 32a-32d of probe adjustment unit 24 and the rotation angles of adjustment shafts 30a-30d may or may not match. If the rotation ratios are not matched, as shown in FIG. 9, a speed increaser 46 (or a speed reducer) that changes the rotation ratio can be incorporated into dials 32a-32d, so that, for example, rotating dials 32a-32d by a predetermined angle rotates adjustment shafts 30a-30d by an angle greater than or less than the predetermined angle. The amount of rotation of the adjustment shafts 30a-30d relative to the dials 32a-32d can be adjusted appropriately by adjusting the gear ratio of the speed increaser 46. As a result, even in specifications where the variable capacitors or variable resistors integrated with the adjustment shafts 30a-30d require an adjustment margin of one or more rotations, the dials 32a-32d can be adjusted within one rotation.

[0042] Furthermore, window 25 is disposed on the side surface of the main body part, and is formed of, for example, a transparent member so that an operator can visually check the inside of main body part 2. Then, the operator can check the state of the inside of main body part 2 through window 25.

[0043] The door 26 has a hinge or the like and is configured to be openable and closable by an operator. Opening the door 26 allows adjustment of the characteristics of the probe 14 through an opening 45, as shown in FIG. 8 , eliminating the need to remove the weak-magnetic-field protection members 18a-18c to adjust the probe 14. The door 26 is closed and sealed with an encapsulation seal or the like except when adjusting the characteristics of the probe 14. This reduces the chance of contacting the probe adjustment unit 24 except when adjusting the characteristics of the probe 14, preventing the loss of the adjusted state due to erroneous operation. Furthermore, in the above-described configuration (i.e., a configuration in which the probe adjustment unit 24 is embedded in the weak-magnetic-field protection members 18a-18c and the dials 32a-32d of the probe adjustment unit 24 are exposed to the outside of the weak-magnetic-field protection members 18a-18c), it is also possible to cover the entire dials 32a-32d with a separate cover after adjusting the dials 32a-32d to prevent erroneous operation by an operator.

[0044] Next, returning to FIG. 1 , the external device 4 of the NMR analyzer 1 will be described. The external device 4 is connected to the above-mentioned main body 2 via piping 3 and cables, and includes a compressor that supplies a refrigerant for cooling the superconductor 12, a pump for evacuating the inside of the main body 2, and the like. For example, a compressed refrigerant (e.g., He gas, Ne gas, H gas, N gas, or a liquefied version of any of these) is supplied from the external device 4, and the supplied refrigerant is expanded in the refrigerator 19a of the main body 2 to generate cold. In this embodiment, the main body 2 and the external device 4 are separate entities, but the external device 4 may be disposed inside the main body 2.

[0045] Finally, the dolly 5 of the NMR analyzer 1 will be described with reference to FIG. 1 . The dolly 5 has a base 41 on which the main body 2 and external device 4 are placed, wheels 42 attached to the underside of the base 41, and a handle 43 to be gripped by an operator. For example, an operator can easily move the main body 2 and external device 4 to any desired position by gripping the handle 43 and applying a load. In particular, the NMR analyzer 1 of this embodiment is smaller and lighter than conventional devices, so it can be easily moved by hand. Furthermore, the main body 2 and external device 4 are fixed to the base 41 by fixing means (e.g., bolts, etc.) not shown. The main body 2 and external device 4 are basically operated while mounted on the dolly 5, and are stored while mounted on the dolly 5 after operation. The wheels 42 also have a locking mechanism, so that they can be fixed in position to prevent movement during operation of the NMR analyzer 1.

[0046] Next, a brief description will be given of the control configuration of the NMR analyzer 1 having the above-described configuration. FIG.

[0047] The NMR analyzer 1 includes a magnetic field generator 51 for generating a magnetic field including the superconductor 12 and refrigerator 19a described above, a detection coil 52, and an analysis means 53. The detection coil 52 is disposed within the inner circumferential space of the superconductor 12, and a sample to be analyzed is placed on the inner circumferential side of the detection coil 52. A shim coil 54 is disposed on the outer circumferential side of the detection coil 52. The analysis means 53 further includes a high-frequency generator 61, a pulse programmer (transmitter) 62, a high-frequency amplifier 63, a preamplifier (signal amplifier) ​​64, a phase detector (receiver) 65, an analog-to-digital (A / D) converter 66, and a control unit 67.

[0048] When the magnetic field generator 51 is operating, a trapping magnetic field is formed within the inner space of the superconductor 12 as described above. Next, the trapping magnetic field is adjusted by the shim coil 54 to enhance the uniformity of the magnetic field strength of the trapping magnetic field. The trapping magnetic field is adjusted by the shim coil 54 so that the uniformity of the magnetic field strength within the space is 1 ppm or less. After the uniformity of the magnetic field strength is enhanced, a sample is placed in the sample container 11 located within the inner space of the superconductor 12. In this state, the high-frequency generator 61 is activated. A high-frequency pulse generated by the high-frequency generator 61 is then applied to the detection coil 52 via the pulse programmer 62 and high-frequency amplifier 63, irradiating the sample with pulsed electromagnetic waves. Nuclear magnetic resonance, which occurs when a sample placed in a magnetic field is irradiated with electromagnetic waves, causes a minute current to flow through the detection coil 52 located around the sample. A signal representing this minute current (NMR signal) is passed to the control unit 67 via the preamplifier 64, phase detector 65, and A / D converter 66. The control unit 67 calculates an NMR spectrum based on the received NMR signal, and analyzes the molecular structure of the sample from the obtained NMR spectrum.

[0049] As explained above in detail, the NMR analyzer 1 according to this embodiment comprises a superconductor 12 that generates a magnetic field, a sample container 11 that is held in the magnetic field generated by the superconductor 12 and that contains a sample to be analyzed, a probe 14 that irradiates the sample with electromagnetic waves and detects nuclear magnetic resonance signals from the sample, strong magnetic field protection members 17a to 17c that surround at least a space in which the strength of the magnetic field generated by the superconductor 12 is equal to or greater than a first threshold, and strong magnetic field protection members 17a to 17c that are further attached to the outside of the strong magnetic field protection members 17a to 17c and that surround a space in which the strength of the magnetic field generated by the superconductor 12 is equal to or greater than the first threshold. The apparatus includes weak-magnetic-field protection members 18a-18c that surround at least the space where the magnetic field is equal to or greater than the second threshold, opening 45 provided in weak-magnetic-field protection members 18a-18c, and probe adjustment unit 24 that is located outside strong-magnetic-field protection members 17a-17c and inside weak-magnetic-field protection members 18a-18c near opening 45 and that adjusts the characteristics of probe 14 in response to an operator's operation. This makes it possible to reliably prevent metal objects or precision instruments worn or carried by the operator from entering the area where the strong magnetic field is generated when adjusting the characteristics of probe 14. Meanwhile, since probe adjustment unit 24 is provided inside weak-magnetic-field protection members 18a-18c, the opportunity to come into contact with probe adjustment unit 24 is reduced except when the operator is adjusting the characteristics of probe 14, preventing the adjusted state from being lost due to an erroneous operation. Furthermore, probe adjustment unit 24 includes at least one operating unit (dials 32a to 32d) that can be operated by an operator, and the characteristics of probe 14 are adjusted by operating the operating unit, and probe adjustment unit 24 is positioned so that the operating unit faces opening 45, so that the operator can easily operate the operating unit from opening 45. This also makes it easy for the operator to make adjustments while checking the NMR spectrum displayed on the monitor. Furthermore, the probe adjustment unit 24 has a scale that indicates the reference position of the operation unit and the amount of operation from the reference position, and the characteristics of the probe 14 are adjusted according to the amount of operation relative to the reference position of the operation unit, so the adjustment details can be clearly identified by the numerical value in the scale. For example, if the adjustment details are recorded as "2" on the right and "3" on the left, the adjustment details can be shared among multiple workers, making the work easier when readjusting. Furthermore, the weak magnetic field protection members 18a to 18c are provided with an opening / closing door 26 that opens and closes the opening 45, so that specific adjustments of the probe can be easily made when the opening / closing door 26 is open, while when the opening / closing door 26 is closed, i.e., when not performing work to adjust the characteristics of the probe 14, the opportunity to come into contact with the probe adjustment section 24 is reduced, and the adjusted state can be prevented from being lost due to incorrect operation.

[0050] The present invention is not limited to the above-described embodiment, and it goes without saying that various improvements and modifications are possible within the scope of the present invention. For example, in this embodiment, the strong magnetic field protection members 17a to 17c surround the space around the superconductor 12 with a strong magnetic field of 500 Gauss or more, and the weak magnetic field protection members 18a to 18c surround the space around the superconductor 12 with a weak magnetic field of 250 Gauss or more, but the strength of the magnetic field of the surrounded space can be changed as appropriate. Furthermore, the shapes of the strong magnetic field protection members 17a to 17c and the weak magnetic field protection members 18a to 18c are not limited to those shown in Figs. 1 and 2.

[0051] In addition, in this embodiment, the probe adjustment unit 24 has four dials 32a to 32d as operating units, and the number of dials 32a to 32d corresponds to the number of adjustment axes 30a to 30d provided on the probe 14. Therefore, for example, if the number of adjustment axes provided on the probe 14 is only one, the number of dials will also be only one.

[0052] Furthermore, in this embodiment, adjustment shafts 30a-30d of probe 14 and dials 32a-32d of probe adjustment unit 24 are connected by wire 31, but they may be connected by means other than wire as long as it is capable of transmitting rotational force. For example, it is also possible to use shafts connected by one or more universal joints. Furthermore, electrical connection may be used instead of physical connection, and for example, actuators that are driven in response to operation of dials 32a-32d may be attached to adjustment shafts 30a-30d.

[0053] Furthermore, in this embodiment, a nuclear magnetic resonance analysis device that uses the nuclear magnetic resonance phenomenon to analyze the structure of a sample has been described as an example of a nuclear magnetic resonance device equipped with a magnetic field generating unit, but the present invention can also be applied to a magnetic resonance imaging device (MRI device) that uses the nuclear magnetic resonance phenomenon to create an image of internal information within a living body. [Explanation of symbols]

[0054] 1... NMR analyzer (nuclear magnetic resonance analyzer), 2... main body, 4... external device, 11... sample container, 12... superconductor (magnetic field generating unit), 13... storage container, 14... probe, 17a to 17c... strong magnetic field protection member (first protective cover), 18a to 18c... weak magnetic field protection member (second protective cover), 24... probe adjustment unit, 26... opening and closing door, 30a to 30d... adjustment shaft, 31... wire, 32a to 32d... dial (operation unit)

Claims

1. a magnetic field generating unit that generates a magnetic field; a sample container that is held in the magnetic field generated by the magnetic field generating unit and that contains a sample to be analyzed; a probe for irradiating the sample with electromagnetic waves and detecting nuclear magnetic resonance signals from the sample; a first protective cover that surrounds at least a space in which the strength of the magnetic field generated by the magnetic field generating unit is equal to or greater than a first threshold; a second protective cover that is further attached to the outside of the first protective cover and that encloses at least a space in which the strength of the magnetic field generated by the magnetic field generating unit is equal to or greater than a second threshold that is weaker than the first threshold; an opening provided in the second protective cover; a probe adjustment unit that is disposed outside the first protective cover and inside the second protective cover in the vicinity of the opening, and that adjusts characteristics of the probe by receiving operation by an operator.

2. the probe adjustment unit includes at least one operation unit operable by an operator; The characteristics of the probe are adjusted by operating the operation unit, The nuclear magnetic resonance spectrometer according to claim 1 , wherein the probe adjustment unit is disposed so that the operation unit faces the opening.

3. the probe adjustment unit has a scale drawn on it that indicates a reference position of the operation unit and an operation amount from the reference position; 3. The nuclear magnetic resonance apparatus according to claim 2, wherein the characteristics of the probe are adjusted by the amount of manipulation of the manipulation unit relative to a reference position.

4. 4. The nuclear magnetic resonance spectrometer according to claim 1, wherein the second protective cover includes an opening / closing door that opens and closes the opening.

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