JP7072800B2 - Nuclear magnetic resonance measuring device and method - Google Patents

Description

The present invention relates to nuclear magnetic resonance measuring devices and methods, and more particularly to superconducting materials used in the detection of nuclear magnetic resonance.

Nuclear Magnetic Resonance (NMR) is a phenomenon in which atomic nuclei placed in a static magnetic field interact with electromagnetic waves having their own frequencies. The device for measuring the phenomenon is a nuclear magnetic resonance measuring device. An MRI (Magnetic Resonance Imaging) device is also a type of nuclear magnetic resonance measuring device.

A typical nuclear magnetic resonance measuring device has a spectrometer and a probe for measuring nuclear magnetic resonance (NMR probe). The NMR probe is provided with a detection coil that irradiates the sample to be measured with an electromagnetic wave and detects a nuclear magnetic resonance signal from the sample. Recently, research is underway to construct the detection coil with a superconducting material, particularly a high temperature superconductor (HTS) material (see Patent Documents 1-3). If the detection coil is constructed of a superconducting material, its electrical resistance becomes zero in the cooled state, so that a very high Q value can be realized, that is, measurement with high sensitivity and high resolution can be realized. Conventionally, the detection coil is made of one kind of superconducting material.

In addition, Patent Document 4 discloses a magnetization correction material configured by alternately laminating a metal foil having paramagnetism and a metal foil having diamagnetism. However, Patent Document 4 does not disclose a combination of a plurality of superconducting materials.

US Pat. No. 9,274,199 Japanese Patent No. 5904326 Japanese Unexamined Patent Publication No. 2016-151494 Japanese Patent Application Laid-Open No. 2003-11268

Yu Shiohara "Development of REBCO High-Temperature Superconducting Wires-Microstructure and Critical Current Characteristics-" Journal of the Japan Institute of Metals, Vol. 80, No. 7, 2106, pp.406-419.

When the detection coil is made of a superconducting material, the Meissner effect typically causes diamagnetic magnetization (negative magnetization) in the superconducting material so as to cancel the external static magnetic field. This magnetization causes turbulence (non-uniformity) of the static magnetic field in the vicinity of the measurement target. Disturbances in the static magnetic field cause a decrease in resolution and the like. A similar problem occurs when a member other than the detection coil is made of a superconducting material.

An object of the present invention is to suppress the disturbance of the static magnetic field in the vicinity of the measurement target or to increase the uniformity of the static magnetic field in the vicinity of the measurement target when detecting nuclear magnetic resonance using a superconducting material. be.

The nuclear magnetic resonance measuring apparatus according to the embodiment is a material provided around the accommodation space accommodating the measurement object and functions in detecting the nuclear magnetic resonance generated in the measurement object, and causes negative magnetization in the superconducting state. Negative magnetization type material, which is a superconducting material, and a superconducting material, which is provided around the accommodation space and functions in detecting nuclear magnetic resonance generated in the measurement target, and which causes positive magnetization in the superconducting state. It is characterized by including certain positively magnetized materials.

According to the above configuration, since the negative magnetization type material and the positive magnetization type material are juxtaposed around the accommodation space, the magnetic field due to the negative magnetization and the magnetic field due to the positive magnetization cancel each other out in the accommodation space. .. That is, when only a single superconducting material is placed, the turbulence of the static magnetic field occurs due to its magnetization, but by arranging two types of superconducting materials in a complementary relationship, the turbulence of the static magnetic field is eliminated or improved. can.

The superconducting state of the second-class superconducting material includes a mixed state (a state in which the normal-conducting state and the Meissner state are mixed), and on the premise of this, the second-class superconducting material should be appropriately selected. Therefore, it is possible to obtain the above-mentioned positive magnetization type material. In general, it is possible to generate positive magnetization as residual magnetization in the superconducting state by going through the process of cooling in a static magnetic field.

In embodiments, all or part of at least one of the negatively magnetized material and the positively magnetized material exhibits at least one of the transmit, receive and shield functions. Desirably, one or both of the negatively magnetized material and the positively magnetized material constitute a transmit coil, a receive coil, or a transmit and receive coil. In that case, in combination with the suppression of the disturbance of the static magnetic field, the NMR measurement with high sensitivity and high resolution is realized. From a different point of view, the above configuration improves or solves the unique problem that arises when the coil for nuclear magnetic resonance detection is composed of a superconducting material by adding another superconducting material that is complementary to it. It is something to do. The concept of a transmitting coil may include both a coil that irradiates an observed nucleus with an electromagnetic wave and a coil that irradiates a non-observed nucleus with an electromagnetic wave.

In an embodiment, the negatively magnetized material and the positively magnetized material have a magnetic field generated by the negative magnetization and a magnetic field generated by the positive magnetization completely or partially mutually in at least a part of the accommodation space. Arranged to be countered. In that case, preferably, the position, form, physical quantity, etc. of each material are adjusted so that the uniformity of the static magnetic field is further increased. The position and orientation of one or both of the negatively magnetized material and the positively magnetized material may be variable. Desirably, the two materials are arranged symmetrically with respect to the accommodation space. A combination of three or more types of superconducting materials may be adopted.

In an embodiment, the negatively magnetized material constitutes a plurality of negatively magnetized material layers, the positively magnetized material constitutes a plurality of positively magnetized material layers, and the plurality of negatively magnetized material layers and the plurality of. The positively magnetized material layer is arranged so that the magnetic field generated by the negative magnetization and the magnetic field generated by the positive magnetization cancel each other out completely or partially in at least a part of the accommodation space. For example, each material layer constitutes a coil.

In an embodiment, the plurality of negatively magnetized material layers include a first negatively magnetized material layer and a second negatively magnetized material layer, and the plurality of positively magnetized material layers are first positively magnetized materials. A layer and a second positive magnetization type material layer are included, and the first negative magnetization type material layer and the first positive magnetization type material layer are provided on one side of the accommodation space, and the other side of the accommodation space is provided. Is provided with the second negative magnetization type material layer and the second positive magnetization type material layer. According to this configuration, when viewed from the accommodation space, the negative magnetization and the positive magnetization cancel each other out macroscopically on one side and the other side, respectively. Desirably, the two substrates are provided in parallel. In that case, since the material layer arrangement on one side and the material layer arrangement on the other side are symmetrical, it is easy to suppress the disturbance of the static magnetic field, and the uniformity of the static magnetic field can be enhanced over the entire accommodation space.

In the embodiment, the first laminated body is provided on one side of the accommodation space, and the second laminated body having a laminated structure symmetric with respect to the first laminated body is provided on the other side of the accommodation space. The first laminated body comprises a first substrate, and the first negatively magnetized material layer and the first positively magnetized material layer laminated on the first substrate in a predetermined order, and the second one. The laminate comprises a second substrate, and the second negatively magnetized material layer and the second positively magnetized material layer laminated on the second substrate in the predetermined order. According to this configuration, the production of each laminated body is facilitated. The laminate may be formed on the front surface of each substrate (the surface facing the accommodation space), or the laminate may be formed on the rear surface of each substrate (the surface opposite to the surface facing the accommodation space). Desirably, an intermediate layer is provided between the negative magnetic material layer and the positive magnetic material layer.

In the embodiment, the first negative magnetization type material layer and the first positive magnetization type material layer form a laminated coil on one side, and the second negative magnetization type material layer and the second positive magnetization type material layer. The material layer constitutes the laminated coil on the other side, and the laminated coil on the one side and the laminated coil on the other side have a shape symmetrical to each other. Desirably, each laminated coil constitutes a transmission / reception coil. For the purpose of adjusting the resonance frequency or for other purposes, a mechanism for changing the posture of one or both of the two laminated coils may be provided.

In an embodiment, the negatively magnetized material constitutes at least one receiving coil and the positively magnetized material constitutes at least one transmitting coil. As the positively magnetized material, a second-class superconducting material containing magnetic ions is usually used. If the magnetic ion functions as a pinning center in the material, the critical current value becomes large. The same applies when other pinning centers are present. From this point of view, it is desirable to construct the transmission coil with a positively magnetized material. In that case, the receiving coil may be constructed of a negatively magnetized material. The negative magnetization type material may be composed of a second-class superconducting material that can be expected to have a pinning effect.

The nuclear magnetic resonance measuring method according to the embodiment is a negative magnetic field type material which is a superconducting material in which negative magnetization occurs in a superconducting state around a housing space in which a measurement target is housed in a static magnetic field space, and a superconducting state. In the step of arranging the positively magnetized material, which is a superconducting material in which positive magnetization occurs, and the negatively magnetized material and the positively magnetized material are cooled to bring them into a superconducting state, whereby at least a part of the accommodation space. In the step of causing a state in which the magnetic field generated by the negative magnetization and the magnetic field generated by the positive magnetization cancel each other out completely or partially, and the negative magnetized material and the positive magnetized material are superconducting. It is characterized by including a step of detecting a nuclear magnetic resonance generated in the measurement target by utilizing at least one of the negative magnetizing type material and the positively magnetizing type material under the condition of being in a conducting state. Is. For example, a negative magnetization type material and a positive magnetization type material are provided in the probe head of the NMR probe, the probe head is inserted into the static magnetic field generator in the static magnetic field generation state, and then the probe head is cooled. As a result, positive magnetization remains in the positive magnetization type material.

According to the present invention, when nuclear magnetic resonance is detected by using a superconducting material, it is possible to suppress the disturbance of the static magnetic field in the vicinity of the measurement target, or to increase the uniformity of the static magnetic field in the vicinity of the measurement target.

It is a block diagram which shows the structural example of the nuclear magnetic resonance measuring apparatus which concerns on embodiment. It is a figure which shows the structure in the probe head (the first arrangement example of an n-type HTS material and a p-type HTS material). It is a perspective view which shows the structure in the probe head. It is a figure which shows the Bohr magneton number and the like for each rare earth element in ReBCO. It is a figure which shows the n-type HTS material and p-type HTS material. It is a figure which shows the characteristic of YBCO as an n-type HTS material. It is a figure which shows the characteristic of DyBCO as a p-type HTS material. It is a figure which shows the 2nd arrangement example of an n-type HTS material and a p-type HTS material. It is a figure which shows the 3rd arrangement example of an n-type HTS material and a p-type HTS material. It is a figure which shows the 4th arrangement example of an n-type HTS material and a p-type HTS material. It is a figure which shows the 5th arrangement example of an n-type HTS material and a p-type HTS material. It is a figure which shows the modification of the 5th arrangement example. It is a flow chart which shows the nuclear magnetic resonance measurement method which concerns on embodiment.

Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 shows a configuration example of the NMR measuring device according to the embodiment. The illustrated NMR measuring device causes nuclear magnetic resonance in a specific atomic nucleus in a sample by irradiating the sample to be measured with an electromagnetic wave, and observes a signal (FID signal) generated thereafter. Examples of the sample include a gas sample, a liquid sample and a solid sample. The NMR measuring device is composed of a control unit 10, a measuring unit 12, and a cooler 14. The z direction is the vertical direction, the x direction is the first horizontal direction, and the y direction is the second horizontal direction.

The measuring unit 12 is composed of an NMR probe 16 and a static magnetic field generator 18. The static magnetic field generator 18 generates a uniform static magnetic field parallel to the z direction in the space where the sample exists. The static magnetic field generator 18 has a bore 18A as a through hole formed along the z direction. The NMR probe 16 is roughly classified into an insertion portion 16A and a base portion 16B. The insertion portion 16A is inserted into the bore 18A. A sample tube, a detection coil, a pickup coil (relay coil), and the like are provided in the probe head 28, which is the upper part of the insertion portion 16A. The internal structure of the probe head 28 will be described later with reference to FIGS. 2 and 3.

The inside of the NMR probe 16 is in a vacuum state. The cooler 14 is for cooling each element (particularly the detection coil, the pickup coil, and the electric circuit) in the probe head 28. The detection coil is composed of two types of oxide high-temperature superconducting materials having a complementary relationship (n-type HTS material as a negative magnetization type material and p-type HTS material as a positive magnetization type material, which will be described later). By cooling the detection coil, both of the two types of oxide high-temperature superconducting materials that compose it are in a superconducting state. By the way, the cooling is performed in a static magnetic field (Field Cooling method). In the embodiment, the cooler 14 feeds liquid helium or low temperature helium gas into the NMR probe 16 through the pipe 26. Other liquids or gases may be used as the refrigerant. A shimming unit is also arranged in the bore 18A, but this is not shown.

The control unit 10 functions as a spectrometer. Specifically, the control unit 10 has a transmission unit 20, a reception unit 22, and an arithmetic control unit 24. In FIG. 1, only the main configuration of the control unit 10 is shown, and the details thereof are not shown. The transmission unit 20 generates a transmission signal (RF signal) according to the transmission pulse sequence and sends it to the NMR probe 16. As a result, electromagnetic waves are emitted from the detection coil to the sample. A signal representing nuclear magnetic resonance generated in the sample is detected in the detection coil, whereby the received signal is sent from the NMR probe 16 to the receiving unit 22. In the receiving unit, an NMR spectrum is generated by processing the received signal. The data is sent to the arithmetic control unit 24. An NMR spectrum may be generated in the arithmetic control unit 24. The arithmetic control unit 24 has a function of controlling the operation of each configuration shown in FIG. 1 and analyzing the acquired data.

FIG. 2 shows the structure of the probe head 28 according to the embodiment (first arrangement example of two types of HTS materials). The shield 29 has, for example, a cylindrical shape. Electromagnetic waves coming from the outside world are blocked by the shield 29. A probe container (not shown) is provided on the outside of the shield 29. The inside 28A of the probe container is an airtight chamber, which is in a vacuum state.

The pedestal 34 has a horizontally widened disk-like shape, which is composed of, for example, a metal having good thermal conductivity, for example, copper. The heat exchanger to which the refrigerant from the cooler is supplied and the heat conductive member provided between the heat exchanger and the pedestal 34 are not shown. A tube 30 as an inner partition wall is provided so as to penetrate the probe head 28 in the z direction. Atmosphere exists inside the tube 30, and the temperature inside the tube 30 is room temperature. At the time of measurement, the sample tube 32 is arranged inside the tube 30. The sample to be measured is housed in the sample tube 32. For example, a gas having a predetermined temperature may be poured into the tube 30 to control the temperature of the sample.

The coil unit 36 is arranged in an upright posture on one side of the pipe 30 on the pedestal 34, and the coil unit 38 is arranged in an upright posture on the other side of the pipe 30 on the pedestal 34. The coil units 36 and 38 have a parallel relationship with each other and have a symmetrical configuration when viewed from the center of the sample.

In the illustrated configuration example, the coil unit 36 has a substrate 40 and two coils 44, 46. The substrate 40 is made of sapphire glass or the like as an insulating material. The substrate 40 has a front surface 40a facing the sample tube 32 side and a rear surface 40b on the opposite side. A coil 44 is provided on the front surface 40a. In the illustrated configuration example, the coil 44 is configured as a thin layer or film made of a first oxide high temperature superconducting material (n-type HTS material) that causes negative magnetization in the superconducting state, for example a one-turn type. It is a planar coil of. A coil 46 is provided on the rear surface 40b. The coil 46 is configured as a thin layer or film made of a second oxide high temperature superconducting material (p-type HTS material) that causes positive magnetization in the superconducting state after undergoing a predetermined process, for example, like the coil 44. It is a one-turn type planar coil. In the illustrated configuration example, the coil 44 and the coil 46 have the same shape (coil pattern) when viewed from the x direction.

The coil unit 38 has the same configuration as the coil unit 36. That is, the coil unit 38 has a substrate 48 and two coils 52, 54. The substrate 48 is made of sapphire glass or the like, like the substrate 40. The substrate 48 has a front surface 48a and a rear surface 48b. A coil 52 is provided on the front surface 48a. Like the coil 44, the coil 52 is configured as a thin layer or film made of a first oxide high-temperature superconducting material (n-type HTS material), which is, for example, a one-turn type planar coil. A coil 54 is provided on the rear surface 48b. Like the coil 46, the coil 54 is configured as a thin layer or film made of a second oxide high-temperature superconducting material (p-type HTS material), which is, for example, a one-turn type planar coil. In the illustrated configuration example, the coils 44, 46, 52, and 54 all have the same shape (coil pattern) when viewed from the x direction.

When only one of the n-type HTS material and the p-type HTS material is provided in the vicinity of the accommodation space containing the sample, the magnetization generated in the HTS material causes the disturbance of the static magnetic field in the accommodation space. On the other hand, if both the n-type HTS material and the p-type HTS material are provided in the vicinity of the accommodation space as in the above configuration, the first force generated in the accommodation space due to the negative magnetization generated in the n-type HTS material. And the second magnetic field generated in the accommodation space by the positive magnetization generated by the p-type HTS material cancel or cancel each other, so that the disturbance of the static magnetic field caused by the arrangement of the HTS material can be suppressed. .. Ideally, the first and second magnetic fields are completely canceled, but the turbulence of the static magnetic field is ameliorated as long as at least a partial cancellation occurs in at least a portion of the containment space. In other words, the above configuration uses two HTS materials that work complementarily together to obtain the effect of canceling the magnetization macroscopically. In the configuration of FIG. 2, it can be said that the magnetization canceling action occurs on one side and the other side of the sample, respectively.

The size, thickness, position, posture or shape of each coil 44, 46, 52, 54 may be changed in order to suppress the disturbance of the static magnetic field. The coils 44 and 52 may be formed of a p-type HTS material, and the coils 46 and 54 may be formed of an n-type HTS material. As long as the positive and negative magnetic fields cancel each other out in the vicinity of the sample, the n-type HTS material and the p-type HTS material may be placed only on one side of the sample, or the n-type HTS material may be placed on one side of the sample. May be placed and the p-type HTS material may be placed on the other side of the sample. Later, various arrangement examples will be described with reference to FIGS. 8 to 12.

In the configuration example shown in FIG. 2, a plurality of coils 44, 46, 52, 54 are coupled by mutual inductance. The plurality of coils 44, 46, 52, 54 constitute a coil row 56, which functions as a detection coil. That is, a plurality of coils 44, 46, 52, 54 cooperate to exert a transmission / reception function. Specifically, the coil train 56 irradiates the observation nucleus with an electromagnetic wave at the time of transmission, and detects a nuclear magnetic resonance signal from the observation nucleus at the time of reception. However, the individual coils 44, 46, 52, 54 may be configured to carry out their own functions. For example, a part of the coils 44, 46, 52, 54 may be made to function as a transmission / reception coil, and the other part may be made to function as a transmission coil for irradiating a specific nucleus with an electromagnetic wave. That is, double resonance or multiple resonance may be generated. Other than that, various configurations are conceivable.

In the embodiment, the pickup coil 58 as a relay coil is inductively coupled to the coil row 56 as the detection coil. That is, the coil row 56 and the pickup coil 58 are wirelessly and electrically connected. At the time of transmission, a transmission signal is transmitted from the pickup coil 58 to the coil row 56. At the time of reception, a reception signal (detection signal) is transmitted from the coil row 56 to the pickup coil 58. The wireless connection prevents various problems (decrease in Q value, etc.) caused by wiring to a coil train made of a superconducting material. The pickup coil 58 is supported by the support column 60. The support column 60 has a coaxial structure, and the pickup coil 58 is connected to the tuning matching electric circuit via the support column 60. As the form of the pickup coil 58, a linear one-turn coil, a tubular one-turn coil, or a coil having another form may be adopted. The resonance frequency of the coil row 56 can be adjusted by moving an object (dielectric, metal, etc.) closer to or further away from the coils 44, 46, 52, 54. Signal lines may be connected to the individual coils 44, 46, 52, 54.

FIG. 3 shows the configuration inside the probe head as a perspective view. Mounts 62 and 64 are provided on the pedestal 34, and the coil units 36 and 38 are held by the mounts 62 and 64. The coil unit 36 includes coils 44 and 46 formed on both sides of the substrate, and the coil unit 38 has coils 52 and 54 formed on both sides of the substrate. The sample tube 32 is housed in the tube 30.

Next, the n-type HTS material and the p-type HTS material will be described in detail. Oxide high-temperature superconductors generally have an ion layer (insulating layer) containing rare earth elements and the like. In YBa ₂ Cu ₃ O _{7 + δ} (hereinafter referred to as YBCO), the Y layer is an ionic layer. In DyBa ₂ CuO _{8 + δ} (hereinafter referred to as DyBCO), the Dy layer is an ionic layer. In Bi ₂ Sr ₂ CaCu ₂ O _{8 + δ} , the Bi layer is an ionic layer. In ReBa ₂ CuOy (however, Re is a rare earth element), the Re layer is an ionic layer. These materials are collectively referred to as ReBCO for convenience.

In Fig. 4, regarding ReBCO, the effective diameter of rare earth ions (upper), superconducting transition temperature TC (middle), and the number of Bohr magnetons of rare earth elements g√ (J + 1) (where g is the g factor of Lande). Yes, J is the spin number of rare earth ions) (lower) is shown. The rare earth element Re is stabilized as a +3 valent ion in any of the crystals. In FIG. 4, the effective diameter of the rare earth ion and the superconducting transition temperature TC are described in Table 1 of Non-Patent Document 1. The Bohr magneton number indicates magnetism.

The rare earth element Re includes an element having zero Bohr magneton and no magnetism. Y, Eu, Bi, La, etc. are non-magnetic ions in ReBCO. On the other hand, among the rare earth elements Re, there is an element whose Bohr magneton number is not zero but has a value, that is, has magnetism. For example, Nd, Sm, Dy, Gd, Ho, Yb and the like become magnetic ions in ReBCO. When the oxide high-temperature superconducting material is transferred from a normal-conducting body to a superconducting state through the process of field cooling in which the oxide high-temperature superconducting material is cooled in a static magnetic field, the magnetization as shown in FIG. 5 occurs. Conceivable.

When an oxide high-temperature superconducting material (n-type HTS material) containing a non-magnetic rare earth ion layer is in a superconducting state, diamagnetism is predominantly generated by the Meissner effect. That is, magnetization having a negative sign (negative magnetization) occurs in the material. On the other hand, when the oxide high-temperature superconducting material (p-type HTS material) containing the magnetic rare earth ion layer is in a superconducting state, the magnetic flux invaded by the external magnetic field remains in the material as quantum magnetic flux. That is, a mixed state in which paramagnetism and diamagnetism coexist is formed. At that time, if paramagnetism due to rare earth ions becomes dominant, magnetization having a positive sign (positive magnetization) occurs in the material. The n-type HTS material belongs to the first-class superconducting material or the second-class superconducting material. The p-type HTS material belongs to the second kind superconducting material. By selecting the second type superconducting material, both n-type HTS material and p-type HTS material can be obtained.

The experimental results are shown in FIGS. 6 and 7. FIG. 6 shows the temperature dependence 68 of the magnetization of YBCO under an external magnetic field (50 kOe) (YBCO thickness is 300 nm). Negative magnetization increases as the temperature decreases. YBCO exhibits the characteristics as an n-type HTS material. FIG. 7 shows the temperature dependence 65 of the magnetization of DyBCO that has undergone the Field Cooling process under an external magnetic field (50 kOe) (DyBCO thickness is 250 nm). Positive magnetization increases as the temperature decreases. DyBCO exhibits the characteristics as a p-type HTS material. In FIG. 7, the broken line 66 is the result of fitting the experimental results according to the Curie rule. At that time, the effective magnetic moment was assumed to be 9 μB. Its effective magnetic moment is close to the Bohr magneton number of Dy shown in FIG. It can be inferred that positive magnetization occurs depending on the magnitude of the Bohr magneton. In FIGS. 6 and 7, at the same temperature of 15 K, -0.42 × 10 ^-3 emu / cm ³ was obtained as the magnetization of YBCO, and +4.5 × 10 ^-3 emu / cm ³ was obtained as the magnetization of DyBCO. ing. A difference in sign and a difference in absolute value are observed between the two.

When arranging the combination of the n-type HTS material and the p-type HTS material, it is desirable to consider the magnitude relationship between the two magnetizations. For example, when YBCO is used as the n-type HTS material and DyBCO is used as the p-type HTS material, if they are arranged on both sides of the sample at the same distance from the sample, the thickness of the DyBCO is relative to the thickness of the YBCO. The thickness should be multiplied by 0.093 (= 0.42 / 4.5). With such a configuration, it is possible to offset the negative magnetization and the positive magnetization macroscopically. In other words, it is possible to realize the cancellation of the magnetic field due to negative magnetization and the magnetic field due to positive magnetization at the center of the sample. The above cancellation may be realized by adjusting the distance or the like instead of adjusting the physical quantity. It is desirable to place the n-type HTS material and the p-type HTS material so that good cancellation occurs throughout the accommodation space where the sample is located. The two may be laminated so that the magnetization cancels out when viewed as the whole laminated body.

In the p-type HTS material, when the magnetic ion in the rare earth ion layer functions as a pinning center, a large critical current value can be expected. That is, the critical current value of the p-type HTS material can be expected to be larger than the critical current value of the n-type HTS material. In view of such properties, the transmission coil may be configured with the p-type HTS material, and the receive coil may be configured with the n-type HTS material.

FIG. 8 shows a second arrangement example of the n-type HTS material and the p-type HTS material as a front view. FIG. 8 shows the inside of the probe head. The same components as those shown in FIG. 2 are designated by the same reference numerals.

In FIG. 8, a pair of coil units 70 and 72 are arranged in parallel on both sides of the pipe 30 on the pedestal 34. The coil unit 70 has a substrate 74 and a laminated body 76 formed on the front surface 74a thereof. The coil unit 72 has a substrate 84 and a laminated body 86 formed on the front surface 84a thereof. The laminated body 76 and the laminated body 86 have a laminated structure symmetrical to each other. Specifically, in the illustrated example, the laminated body 76 includes a coil 78 as a lower layer made of a p-type HTS material, an intermediate layer 80, and a coil 82 as an upper layer made of an n-type HTS material. The laminated body 76 as a whole constitutes, for example, a one-turn type coil pattern. In the illustrated example, the laminate 86 includes a coil 88 as a lower layer made of a p-type HTS material, an intermediate layer 90, and a coil 92 as an upper layer made of an n-type HTS material. As a whole, the laminated body 86 constitutes, for example, a one-turn type coil pattern, similarly to the laminated body 76. The coil pattern can be easily manufactured by etching, deposition or other methods. The intermediate layers 80 and 90 function as an underlayer or a separating layer for avoiding direct contact between the n-type HTS material and the p-type HTS material. The intermediate layers 80 and 90 may be removed as long as the n-type HTS material and the p-type HTS material function properly.

According to the second arrangement example shown in FIG. 8, in the space where the sample exists, the magnetic field generated by the negative magnetization of the n-type HTS material and the magnetic field generated by the positive magnetization of the p-type HTS material cancel each other out. The effect can be enhanced. Further, the production of the coil units 70 and 72 is facilitated.

Even when only one of the two coil units 70 and 72 is arranged, since two types of HTS materials are present in the vicinity of the sample, a constant magnetic field canceling effect can be expected. In each of the above-mentioned laminated bodies 76 and 86, the upper layer and the lower layer may be exchanged. Further, the thickness of each layer may be adjusted to increase the uniformity of the static magnetic field.

FIG. 9 shows a third arrangement example of the n-type HTS material and the p-type HTS material as a plan view. Reference numeral 102 indicates a coil made of an n-type HTS material, and reference numeral 104 indicates a coil made of a p-type HTS material. In the illustrated example, the coils 102 and 104 are provided equidistant from the center 100a (center x1 in the x direction) of the space 100 accommodating the sample (see reference numerals 106 and 108). According to this third arrangement example, for example, the effect of canceling the magnetic fields can be expected in the space 100. However, it cannot be expected that there will be a uniform cancellation in the x direction. For example, both the coils 102 and 104 function as transmission / reception coils. Only one of them may function as a transmit / receive coil.

FIG. 10 shows a fourth arrangement example of the n-type HTS material and the p-type HTS material as a plan view. Reference numerals 110 and 112 indicate coils made of n-type HTS material, and reference numerals 114 and 116 indicate coils made of p-type HTS material. For example, the coils 110 and 112 function as receiving coils, and the coils 114 and 116 function as transmitting coils. Alternatively, the coils 110 and 112 function as transmission / reception coils for the observation nucleus, and the coils 114 and 116 function as transmission coils for the irradiation nucleus. According to the latter configuration, double resonance or multiple resonance can be realized.

FIG. 11 shows a fifth arrangement example of the n-type HTS material and the p-type HTS material as a front view. The tube 120 extends in the z direction, and the inside thereof is a space 100 for accommodating a sample. Reference numerals 122 and 124 indicate transmission / reception coils made of p-type HTS material. Reference numerals 126, 128, 130 and 132 indicate a plate-shaped shield made of n-type HTS material. Each shield 126, 128, 130, 132 has the property of blocking or canceling electromagnetic waves. On one side of the space 100, the shields 126 and 130 define the electromagnetic wave passage width 100b in the vertical direction, and on the other side of the space 100, the shields 128 and 132 define the electromagnetic wave passage width 100b in the vertical direction. The intermediate height is indicated by z1. In this way, parts other than the coil may be manufactured from the HTS material.

FIG. 12 shows a modified example of the fifth arrangement example as a plan view. Transmission / reception coils 122 and 124 made of p-type HTS material are provided on both sides of the space 100. Plate-shaped shields 134 and 136 made of n-type HTS material are provided on the front side (on the sample side) of them. The shields 134 and 136 have openings 134A and 136A, respectively, and electromagnetic waves pass through the openings 134A and 136A, respectively. That is, in the example shown in FIG. 12, the electromagnetic wave passing range is limited in the y direction.

In any of the installation examples shown above, since the n-type HTS material and the p-type HTS material are installed in the vicinity of the sample, the magnetic field due to negative magnetization and the magnetic field due to positive magnetization are completely or partially canceled. You can expect a match, that is, you can expect to suppress the disturbance of the static magnetic field.

FIG. 13 shows the nuclear magnetic resonance measuring method according to the embodiment as a flow chart. In S10, the probe head of the NMR probe is inserted into the static magnetic field generator that generates the static magnetic field. Both n-type HTS material and p-type HTS material are provided in the probe head. Then, in S12, the inside of the probe head is cooled. As a result, the n-type HTS material becomes a superconducting state, and negative magnetization as diamagnetic magnetization occurs due to the Meissner effect. On the other hand, the p-type HTS material also becomes a superconducting state, and a residual magnetic flux is generated as a quantized magnetic flux. In that case, if paramagnetism predominates, positive magnetization occurs. In S14, nuclear magnetic resonance is measured in a situation where the negative magnetization and the positive magnetization cancel each other out.

According to the above embodiment, when nuclear magnetic resonance is detected using a superconducting material, it is possible to suppress the disturbance of the static magnetic field in the vicinity of the measurement target, or to increase the uniformity of the static magnetic field in the vicinity of the measurement target. .. It is also possible to apply a combination of n-type HTS material and p-type HTS material to an MRI apparatus.

10 control unit, 12 measurement unit, 14 cooler, 16 NMR probe, 18 static magnetic field generator, 44 coil (n-type HTS material), 46 coil (p-type HTS material), 52 coil (n-type HTS material), 54 Coil (p-type HTS material), 58 pickup coil.

Claims (8)

A negative magnetization type material that is provided around the accommodation space that accommodates the measurement target and that functions in detecting nuclear magnetic resonance that occurs in the measurement target and is a superconducting material that causes negative magnetization in the superconducting state.
A positive magnetization type material which is provided around the accommodation space and functions in detecting nuclear magnetic resonance generated in the measurement target and is a superconducting material which causes positive magnetization in a superconducting state.
Including
The negative magnetization type material includes a first negative magnetization type material layer and a second negative magnetization type material layer.
The positively magnetized material includes a first positively magnetized material layer and a second positively magnetized material layer.
The first negative magnetization type material layer and the first positive magnetization type material layer are provided on one side of the accommodation space.
The second negative magnetization type material layer and the second positive magnetization type material layer are provided on the other side of the accommodation space.
A nuclear magnetic resonance measuring device characterized by this. In the apparatus according to claim 1,
All or part of at least one of the negatively magnetized material and the positively magnetized material exerts at least one of the transmitting, receiving and shielding functions.
A nuclear magnetic resonance measuring device characterized by this. In the apparatus according to claim 1,
The positive magnetization is the magnetization remaining in the positive magnetization type material after cooling the positive magnetization type material in a static magnetic field to bring it into a superconducting state.
A nuclear magnetic resonance measuring device characterized by this. In the apparatus according to claim 1,
The negatively magnetized material and the positively magnetized material are such that the magnetic field generated by the negative magnetization and the magnetic field generated by the positive magnetization cancel each other out in at least a part of the accommodation space. , Placed,
A nuclear magnetic resonance measuring device characterized by this. In the apparatus according to claim 1 ,
A first laminated body is provided on one side of the accommodation space, and the first laminated body is provided.
A second laminated body having a laminated structure symmetrical with respect to the first laminated body is provided on the other side of the accommodation space.
The first laminated body includes a first substrate, and the first negatively magnetized material layer and the first positively magnetized material layer laminated on the first substrate in a predetermined order.
The second laminated body includes a second substrate, and the second negatively magnetized material layer and the second positively magnetized material layer laminated on the second substrate in the predetermined order.
A nuclear magnetic resonance measuring device characterized by this. In the apparatus according to claim 5 ,
The first negative magnetization type material layer and the first positive magnetization type material layer form a laminated coil on one side.
The second negative magnetization type material layer and the second positive magnetization type material layer form a laminated coil on the other side.
The laminated coil on one side and the laminated coil on the other side have symmetrical forms.
A nuclear magnetic resonance measuring device characterized by this. In the apparatus according to claim 1,
The negatively magnetized material constitutes at least one receiving coil.
The positively magnetized material constitutes at least one transmit coil.
A nuclear magnetic resonance measuring device characterized by this. Negative magnetization type material, which is a superconducting material that causes negative magnetization in the superconducting state, and positive, which is a superconducting material that causes positive magnetization in the superconducting state, around the accommodation space that accommodates the measurement target in the static magnetic field space. The process of arranging the magnetized material and
The negatively magnetized material and the positively magnetized material are cooled to bring them into a superconducting state, whereby the magnetic field generated by the negative magnetization and the magnetic field generated by the positive magnetization are generated in at least a part of the accommodation space. The process of creating a state in which they are totally or partially mutually cancelled,
In a situation where the negatively magnetized material and the positively magnetized material are in the superconducting state, nuclear magnetism generated in the measurement target by utilizing at least one of the negatively magnetized material and the positively magnetized material. The process of detecting resonance and
Including
The negative magnetization type material includes a first negative magnetization type material layer and a second negative magnetization type material layer.
The positively magnetized material includes a first positively magnetized material layer and a second positively magnetized material layer.
The first negative magnetization type material layer and the first positive magnetization type material layer are provided on one side of the accommodation space.
The second negative magnetization type material layer and the second positive magnetization type material layer are provided on the other side of the accommodation space.
A nuclear magnetic resonance measurement method characterized by this.

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