JP5999599B2 - probe - Google Patents

Description

  The present invention relates to a probe used in, for example, a nuclear magnetic resonance apparatus.

  A nuclear magnetic resonance apparatus (hereinafter also referred to as “NMR apparatus”) places an object to be measured (sample) in a strong static magnetic field, irradiates a high-frequency radio wave to cause nuclear magnetic resonance, This is an apparatus for analyzing the molecular structure of an object to be measured by detecting an electrical signal (hereinafter, also referred to as “NMR signal”) generated when a constituent molecule returns to its original stable state.

  A probe used in an NMR apparatus is a device that generates high-frequency radio waves by a detection coil provided inside and irradiates the object to be measured, and detects an NMR signal emitted from the object to be measured by the detection coil. In the probe, the detection coil and the preamplifier constituting the signal detection unit are cooled by the cryogen so that the NMR signal can be detected with higher sensitivity.

  Conventionally, as a cryogen for cooling the signal detection unit of the probe, a cooling gas produced by a refrigerator is generally used, but an NMR apparatus using liquid helium as a cryogen is also known (see Patent Document 1). ). An NMR apparatus using liquid nitrogen as a cryogen is also becoming widespread.

JP 2008-241493 A

  The cryogen that cools the signal detection unit of the probe is stored in a container called a liquid reservoir, and the detection coil is cooled by the container being in thermal contact with the detection coil. When liquid nitrogen is used as the cryogen, the detection coil that is in thermal contact with the liquid nitrogen stored in the liquid reservoir is cooled by removing heat of vaporization. Thus, when liquid nitrogen is used as a cryogen, liquid nitrogen is consumed by vaporization. Therefore, in order to continue cooling the detection coil stably, liquid nitrogen is replenished in the liquid reservoir, and the liquid nitrogen is consumed. It is necessary to maintain the liquid level of the liquid nitrogen stored in the reservoir in a predetermined range. The conventional probe regularly replenishes the liquid reservoir with a preset amount of liquid nitrogen. Therefore, if the amount of liquid nitrogen vaporized fluctuates greatly, the level of the liquid nitrogen level in the liquid reservoir Is difficult to keep within a predetermined range. Therefore, a probe that can detect NMR signals with higher accuracy has been demanded.

  The present invention provides a probe that cools a signal detection unit using liquid nitrogen as a cryogen and stabilizes the temperature and cooling capacity of the signal detection unit to detect an NMR signal with higher accuracy. The purpose is to provide.

  The present invention includes a signal detection unit that detects an electrical signal generated by nuclear magnetic resonance by a measurement object mounted on a nuclear magnetic resonance apparatus, a liquid phase unit that stores cryogen, and a gas phase unit that stores vaporized cryogen. And a cooling unit that cools the signal detection unit when the liquid storage unit and the signal detection unit are in thermal contact with each other, and the liquid storage includes a first temperature provided at an upper end side. A detecting means and a second temperature detecting means provided on the lower end side of the first temperature detecting means, and the temperature detected by the first and second temperature detecting means can be output as a detected temperature value. Related to the probe.

  The probe includes a cryogen supply line capable of supplying a cryogen from a cryogen supply source to the liquid phase part of the liquid reservoir, and a cryogen capable of discharging vaporized cryogen from the gas phase part of the liquid reservoir to the outside. And a discharge line.

  In the probe, the signal detection unit includes a detection coil that generates a high-frequency radio wave for causing the object to be measured to nuclear magnetic resonance, the cryogen stored in the liquid reservoir, and the signal detection unit It is preferable that the detection coil is cooled by being in thermal contact with the detection coil via the liquid reservoir.

  In the probe, the signal detection unit includes a preamplifier that amplifies an electric signal generated by nuclear magnetic resonance, and the vaporized cryogen flowing through the cryogen discharge line and the preamplifier pass through the cryogen discharge line. It is preferable that the preamplifier is configured to be cooled by being brought into thermal contact.

  ADVANTAGE OF THE INVENTION According to this invention, the temperature and cooling capability of a signal detection part can be stabilized, and the probe which can detect an NMR signal with higher precision can be provided.

It is a figure which shows the whole structure of the NMR apparatus 1 in 1st Embodiment. It is the schematic which shows the structure of the probe 3 and the liquid nitrogen supply apparatus 5 in 1st Embodiment. 3 is a flowchart showing a control processing procedure for supplying liquid nitrogen LN1 to a liquid reservoir 330 in the control unit 100. It is the schematic which shows the structure of the probe 3 and liquid nitrogen supply apparatus 5A in 2nd Embodiment.

[First Embodiment]
Hereinafter, an NMR apparatus using the probe according to the present invention will be described as a first embodiment. FIG. 1 is a diagram showing an overall configuration of an NMR apparatus 1 in the first embodiment.

  As shown in FIG. 1, the NMR apparatus 1 according to the first embodiment includes a superconducting magnet unit 2, a probe 3, a connecting tube 4, and a liquid nitrogen supply device 5 as a cryogen supply source. The NMR apparatus 1 also includes a vacuum pump 6, an air shutoff valve 7, and an air discharge line L <b> 20.

  The superconducting magnet unit 2 is a device that generates a strong static magnetic field in one direction by electric power supplied from an external power source (not shown). A main coil (not shown) configured by winding a superconducting wire is disposed inside the superconducting magnet. The main coil is cooled to a very low temperature by, for example, liquid nitrogen, liquid helium, or the like. The superconducting magnet unit 2 is provided with a cylindrical hole 21 in which the probe 3 can be mounted. The hole 21 is formed along the central axis of the superconducting magnet unit 2. The probe 3 to be described later is inserted upward from the lower opening of the hole 21.

  The probe 3 is a device that detects a weak electric signal that is generated when the object to be measured undergoes nuclear magnetic resonance. A probe (not shown) is attached to the probe 3. The configuration of the probe 3 will be described later.

  The connecting tube 4 is a tube that connects the probe 3 and the liquid nitrogen supply device 5. The connection tube 4 includes a probe joint 41 and a transfer tube 42. The probe joint 41 is a component for connecting low-temperature lines. The transfer tube 42 is a component that connects between the probe joint 41 and the liquid nitrogen supply device 5. By connecting the probe joint 41 and the liquid nitrogen supply device 5 with a flexible transfer tube 42, the probe 3 and the liquid nitrogen supply device 5 can be easily attached and detached. In addition, it is possible to prevent vibration generated during operation of the liquid nitrogen supply device 5 from being transmitted to the probe 3. Note that a liquid nitrogen supply line L11 and a nitrogen gas discharge line L22 (not shown), which will be described later, are accommodated in the connection tube 4.

  The liquid nitrogen supply device 5 is a device that supplies liquid nitrogen LN1 as a cryogen to the probe 3 and collects nitrogen gas LN2 from the probe 3. The configuration of the liquid nitrogen supply device 5 will be described later.

  The vacuum pump 6 is a device for evacuating the inside of the probe 3. During operation of the NMR apparatus 1, the inside of the probe 3 is kept in a vacuum state for heat insulation. The probe 3 and the vacuum pump 6 are connected by an air discharge line L20. The air discharge line L20 is a path through which the gas discharged from the probe 3 flows. An air shutoff valve 7 is provided in the middle of the air discharge line L20. The air shutoff valve 7 is a valve for opening and closing the air discharge line L20, and is controlled to be open until the inside of the probe 3 is in a vacuum state.

  FIG. 2 is a schematic diagram showing the configuration of the probe 3 and the liquid nitrogen supply device 5 in the first embodiment. In FIG. 2, the shape, arrangement, and the like of each part constituting the probe 3 and the liquid nitrogen supply device 5 are schematically drawn. In FIG. 2, the electrical connection is indicated by a broken line.

  First, the probe 3 will be described. The probe 3 includes a detection coil 31 and a preamplifier 32 as a signal detection unit, a cooling unit 33, a shielding pipe 34, a probe-side connector 35, and a probe-side joint 36. The probe 3 also includes a liquid nitrogen supply line L21 as a cryogen supply line and a nitrogen gas discharge line L22 as a cryogen discharge line.

  The probe 3 is a hollow container formed in a substantially cylindrical shape. The inside of the probe 3 is kept in a vacuum state by the vacuum pump 6 described above. A shielding pipe 34 is disposed at the center of the probe 3. The shielding pipe 34 is a cylindrical member that penetrates from the upper end side to the lower end side of the probe 3. A sample SP as an object to be measured is inserted into the shielding pipe 34 from the upper end side. The shielding pipe 34 insulates between the sample SP and the low-temperature detection coil 31. A temperature variable gas for temperature adjustment is supplied from the lower end side of the shielding pipe 34.

  The detection coil 31 irradiates the sample SP inserted into the shielding pipe 34 of the probe 3 with high frequency radio waves. The detection coil 31 is connected to a high-frequency oscillator (not shown), and generates a high-frequency radio wave shaped into a pulse by a high-frequency signal supplied from the high-frequency oscillator. In addition, the detection coil 31 detects a NMR signal emitted from the sample SP after inducing magnetic resonance in the target nuclear spin included in the sample SP by being irradiated with high-frequency radio waves. This NMR signal is sent to the preamplifier 32.

  The preamplifier 32 is an electric circuit that amplifies the NMR signal detected by the detection coil 31. The amplified NMR signal is transmitted to an external analyzer (not shown). The preamplifier 32 is configured to be in thermal contact with a nitrogen gas discharge line L22 (described later).

  The cooling unit 33 is a part that cools the detection coil 31 and includes a liquid reservoir 330. The liquid reservoir 330 is a container that mainly stores liquid nitrogen LN1. The liquid reservoir 330 is positioned so as to be in thermal contact with the detection coil 31 with a thermal ring 37 provided with a tuning circuit (not shown) interposed therebetween.

  The liquid reservoir 330 has a liquid phase part 331 and a gas phase part 332 as regions formed therein. The liquid phase part 331 is an area for storing liquid nitrogen LN1. The gas phase part 332 is an area where nitrogen gas LN2 which is vaporized liquid nitrogen stays. In the cooling unit 33, when the liquid nitrogen LN1 stored in the liquid phase part 331 of the liquid reservoir 330 is vaporized, the detection coil 31 that is in thermal contact with the gas phase part 332 via the heat ring 37 is deprived of the heat of vaporization. To be cooled.

  The liquid reservoir 330 includes a first temperature sensor S1 as a first temperature detection unit and a second temperature sensor S2 as a second temperature detection unit. The first temperature sensor S <b> 1 is provided on the upper end side of the liquid reservoir 330. The second temperature sensor S2 is provided at the lower end side of the liquid reservoir 330 relative to the first temperature sensor S1.

The first temperature sensor S1 and the second temperature sensor S2 are electrically connected to a control unit 100 (described later) of the liquid nitrogen supply device 5. The temperature (detected temperature value T ₁ ) detected by the first temperature sensor S1 is output to the control unit 100 as a first temperature detection signal. In addition, the temperature (detected temperature value T ₂ ) detected by the second temperature sensor S2 is output to the control unit 100 as a second temperature detection signal.

  The probe-side connector 35 is a component that is electrically connected to the first temperature sensor S1 and the second temperature sensor S2. The probe-side connector 35 includes electrode terminals (not shown) that are electrically connected to the first temperature sensor S1 and the second temperature sensor S2. The probe side connector 35 is configured to be connectable to a main body side connector 54 connected to a communication cable (not shown) of the liquid nitrogen supply device 5. By connecting the probe-side connector 35 and the main body-side connector 54, the detection signals output from the first temperature sensor S1 and the second temperature sensor S2 are transmitted to the control unit 100 of the liquid nitrogen supply device 5. Can do.

  The liquid reservoir 330 is connected to a liquid nitrogen supply line L21 and a nitrogen gas discharge line L22. The liquid nitrogen supply line L <b> 21 is a pipe for sending the liquid nitrogen LN <b> 1 supplied from the liquid nitrogen supply device 5 to the liquid phase part 331 of the liquid reservoir 330. The upstream end of the liquid nitrogen supply line L21 is connected to a probe side joint 36 (described later). The downstream end of the liquid nitrogen supply line L 21 is connected to the bottom of the liquid reservoir 330.

The nitrogen gas discharge line L <b> 22 is a pipe for discharging the nitrogen gas LN <b> 2 staying in the gas phase part 332 of the liquid reservoir 330 to the liquid nitrogen supply device 5. An upstream end portion of the nitrogen gas discharge line L <b> 22 is opened to the gas phase portion 332 of the liquid reservoir 330. The downstream end of the nitrogen gas discharge line L22 is connected to the probe-side joint 36.
The nitrogen gas discharge line L22 is configured to be in thermal contact with the preamplifier 32 provided in the probe 3 in the middle of the path. The preamplifier 32 is cooled by the low temperature nitrogen gas LN2 flowing through the nitrogen gas discharge line L22 and the preamplifier 32 being in thermal contact with each other via the nitrogen gas discharge line L22.

  The probe side joint 36 is a component for connecting the liquid nitrogen supply line L21 and the nitrogen gas discharge line L22 to the external liquid nitrogen supply line L11 and the nitrogen gas discharge line L12. A cap (not shown) provided at each end of the liquid nitrogen supply line L21 and the nitrogen gas discharge line L22 is attached to the probe side joint 36. The probe side joint 36 is configured to be connectable to the probe joint 41 of the liquid nitrogen supply device 5. In FIG. 2, only the portion of the probe joint 41 that is connected to the probe-side joint 36 is illustrated. In FIG. 2, the transfer tube 42 (see FIG. 1) is not shown.

  By connecting the probe side joint 36 and the probe joint 41, the liquid nitrogen supply line L11 on the liquid nitrogen supply device 5 side, the liquid nitrogen supply line L21 on the probe 3 side, and the nitrogen gas discharge line on the liquid nitrogen supply device 5 side. L12 and the nitrogen gas discharge line L22 on the probe 3 side are electrically connected.

  In this way, by connecting the probe-side joint 36 and the probe joint 41, the liquid nitrogen LN1 stored in the liquid nitrogen vessel 51 (described later) of the liquid nitrogen supply device 5 is replaced with the liquid nitrogen supply line L11 and the liquid nitrogen. It can be supplied to the liquid reservoir 330 (liquid phase portion 331) of the probe 3 via the supply line L21. Further, the nitrogen gas LN2 staying in the gas phase portion 332 of the liquid reservoir 330 is sent to a nitrogen gas discharge pump 52 (described later) of the liquid nitrogen supply device 5 through the nitrogen gas discharge line L12 and the nitrogen gas discharge line L22. be able to.

  Next, the liquid nitrogen supply device 5 will be described. As shown in FIG. 2, the liquid nitrogen supply device 5 includes a liquid nitrogen vessel 51, a nitrogen gas discharge pump 52, a flow rate adjustment valve 53, a liquid nitrogen supply line L11, a nitrogen gas discharge line L12, and a control unit 100. And comprising.

  The liquid nitrogen vessel 51 is a container that stores liquid nitrogen LN1 supplied to the probe 3. The liquid nitrogen vessel 51 is connected to the upstream end of the liquid nitrogen supply line L11. In the liquid nitrogen vessel 51, the upstream end of the liquid nitrogen supply line L11 is opened close to the bottom surface.

  The nitrogen gas discharge pump 52 depressurizes the nitrogen gas discharge line L12 (and L22), and sucks the nitrogen gas LN2 staying in the gas phase portion 332 (liquid reservoir 330) of the probe 3 to the liquid nitrogen supply device 5 side. It is a pump. The nitrogen gas discharge pump 52 is configured by, for example, a diaphragm pump. The nitrogen gas discharge pump 52 is connected to the downstream end of the nitrogen gas discharge line L12.

  The upstream end of the nitrogen gas discharge line L13 is connected to the discharge port of the nitrogen gas discharge pump 52. The downstream end of the nitrogen gas discharge line L13 opens toward the outside of the liquid nitrogen supply device 5.

  The flow rate adjusting valve 53 is a valve that adjusts the flow rate of the nitrogen gas LN2 flowing through the nitrogen gas discharge line L12, and has a function of measuring the flow rate value per unit time of the nitrogen gas LN2 flowing through the nitrogen gas discharge line L12. Prepare. The flow rate adjustment valve 53 is provided in the middle of the nitrogen gas discharge line L12. The flow rate adjustment valve 53 is electrically connected to the control unit 100. The opening degree of the valve body in the flow rate adjusting valve 53 is controlled by a drive signal transmitted from the control unit 100. Further, the flow rate value of the nitrogen gas LN2 measured by the flow rate adjusting valve 53 is output to the control unit 100 as a flow rate detection signal.

  The liquid nitrogen supply line L11 is a pipe for sending out the liquid nitrogen LN1 stored in the liquid nitrogen vessel 51 toward the probe 3 (liquid phase portion 331 of the liquid reservoir 330). The upstream end of the liquid nitrogen supply line L11 is connected to the liquid nitrogen vessel 51. The downstream end of the liquid nitrogen supply line L11 is connected to the probe joint 41.

  The nitrogen gas discharge line L12 is a pipe for sending the nitrogen gas LN2 discharged from the probe 3 (the gas phase portion 332 of the liquid reservoir 330) to the nitrogen gas discharge pump 52. The upstream end of the nitrogen gas discharge line L12 is connected to the probe joint 41. The downstream end of the nitrogen gas discharge line L12 is connected to the nitrogen gas discharge pump 52.

  The control unit 100 includes a microprocessor (not shown) including a CPU and a memory. The CPU transmits and receives data via a memory and a data bus (not shown). The CPU executes a program read from the memory (ROM), thereby executing processing corresponding to the content of the program. The memory includes a RAM having a function of temporarily storing various data and a function as a work area at the time of calculation, and a ROM having a function as a flash memory for storing various programs.

  The control unit 100 outputs the first temperature detection signal output from the first temperature sensor S1 of the probe 3 (liquid reservoir 330), the second temperature detection signal output from the second temperature sensor S2, and the flow rate adjustment valve 53. Based on the detected flow rate detection signal, the flow rate adjusting valve 53 is adjusted so that the flow rate of the nitrogen gas LN2 flowing from the nitrogen gas discharge line L22 on the probe 3 side to the nitrogen gas discharge line L12 on the liquid nitrogen supply device 5 side is adjusted. To control the valve opening.

  In the liquid reservoir 330 of the probe 3, liquid nitrogen LN 1 is stored in the liquid phase portion 331, and gaseous nitrogen gas LN 2 is retained in the gas phase portion 332. When a predetermined amount of liquid nitrogen LN1 is stored in the liquid phase portion 331, the temperature detected by the second temperature sensor S2 provided at the bottom of the liquid reservoir 330, and the detection coil 31 and the heat via the heat ring 37 A predetermined temperature difference is generated between the temperature and the temperature detected by the first temperature sensor S <b> 1 provided on the upper part of the liquid reservoir 330 in contact. This is because the second temperature sensor S2 is provided at a position that is in direct thermal contact with the liquid phase portion 331 that absorbs heat as the heat of vaporization, and the first temperature sensor S1 is a loss heat due to RF irradiation. This is because the heat amount balance of each temperature sensor is different because it is provided between the detection coil 31 that absorbs radiant heat from the probe wall surface or the like at room temperature. The temperature difference generated between the first temperature sensor S1 and the second temperature sensor S2 decreases as the liquid level of the liquid phase portion 331 increases. This is because the distance between the first temperature sensor S1 and the liquid phase part 331 approaches as the region of the gas phase part 332 decreases, and the temperature detected by the first temperature sensor S1 is detected by the second temperature sensor S2. This is because it approximates the temperature.

  Further, when the temperature detected by the second temperature sensor S2 provided at the bottom of the liquid reservoir 330 is higher than the boiling point of the liquid nitrogen LN1, it indicates that the liquid nitrogen LN1 is not stored in the liquid reservoir 330. . On the other hand, when the temperature detected by the second temperature sensor S2 substantially matches the boiling point of the liquid nitrogen LN1, it indicates that the liquid nitrogen LN1 has accumulated in the liquid reservoir 330.

  Further, when the temperature detected by the second temperature sensor S2 substantially matches the boiling point of the liquid nitrogen LN1, the flow rate value detected by the flow rate adjustment valve 53 exceeds a predetermined flow rate value set in advance. The inside of the liquid reservoir 330 is filled with the liquid nitrogen LN1, which indicates that the liquid nitrogen LN1 has overflowed into the nitrogen gas discharge line L12. On the other hand, when the temperature detected by the second temperature sensor S2 substantially matches the boiling point of the liquid nitrogen LN1, the flow rate value detected by the flow rate adjustment valve 53 is lower than a predetermined flow rate value set in advance. This suggests that the liquid nitrogen LN1 has changed to a solid inside the liquid reservoir 330.

  Therefore, during operation of the nitrogen gas discharge pump 52, the control unit 100 monitors the second temperature detection signal output from the second temperature sensor S2 in order to store the liquid nitrogen LN1 in the liquid reservoir 330, and the second temperature detection signal. Control is performed so that the valve body of the flow rate adjustment valve 53 reaches the maximum opening degree until the temperature value indicated by the temperature detection signal approaches a predetermined temperature (the boiling point of the liquid nitrogen LN1).

  When the control body 100 controls the valve body of the flow rate adjustment valve 53 to a predetermined opening, the nitrogen gas discharge line L12 (and L22) is depressurized. As a result, the nitrogen gas LN2 staying in the gas phase portion 332 of the liquid reservoir 330 is sucked into the nitrogen gas discharge pump 52 via the nitrogen gas discharge lines L22 to L12 and discharged to the outside from the nitrogen gas discharge line L13. Further, when the nitrogen gas discharge line L12 (and L22) is depressurized, the gas phase portion 332 of the liquid reservoir 330 becomes negative pressure. Therefore, the liquid nitrogen LN1 stored in the liquid nitrogen vessel 51 is sucked into the liquid nitrogen supply line L11 and supplied to the liquid phase portion 331 of the liquid reservoir 330 via the liquid nitrogen supply line L21.

  When the liquid nitrogen LN1 begins to accumulate in the liquid reservoir 330, the control unit 100 sets the first temperature detection signal output from the first temperature sensor S1 and the second temperature sensor in order to keep the liquid level constant. A temperature difference from the second temperature detection signal output from S2 is calculated. If the temperature difference is less than a preset temperature difference threshold, the control unit 100 controls the valve body of the flow rate adjustment valve 53 to have a predetermined opening (for example, maximum opening), When the temperature difference is greater than or equal to a preset temperature difference threshold, control is performed so that the valve body of the flow rate adjustment valve 53 is closed.

  However, during operation of the nitrogen gas discharge pump 52, the control unit 100 needs to monitor so that the liquid nitrogen LN1 does not change into a solid phase. Therefore, the control unit 100 monitors the flow rate value of the nitrogen gas LN2 measured by the flow rate adjustment valve 53, and when the flow rate value falls below a predetermined value set in advance, the valve body in the flow rate adjustment valve 53 The degree of pressure reduction of the liquid nitrogen supply line L21 and the nitrogen gas discharge line L22 is controlled so as to approach normal pressure.

  Further, during the operation of the nitrogen gas discharge pump 52, the control unit 100 needs to monitor the liquid storage 330 so that the liquid nitrogen LN1 does not overflow. For this purpose, the control unit 100 determines that the second temperature detection signal output from the second temperature sensor S2 is close to the boiling point of the liquid nitrogen LN1, and the flow rate value measured by the flow rate adjustment valve 53 is a predetermined value set in advance. When exceeding, the opening degree of the valve body in the flow rate adjusting valve 53 is decreased, and the flow rate of the liquid nitrogen LN1 flowing through the liquid nitrogen supply line L21 is controlled.

  Next, a processing procedure for controlling the controller 100 to supply the liquid nitrogen LN1 to the liquid reservoir 330 based on the temperature detection signal output from each temperature sensor will be described with reference to the flowchart of FIG. The process of the flowchart shown in FIG. 3 is repeatedly executed at predetermined time intervals while the NMR apparatus 1 is in operation.

  In step ST101 shown in FIG. 3, the control unit 100 acquires the first temperature detection signal output from the first temperature sensor S1 and the second temperature detection signal output from the second temperature sensor S2.

In step ST 102, the control unit 100 calculates the detected temperature value _{T 1} indicated by the first temperature detection signal, the temperature difference _{T D} between the detected temperature value _{T 2} indicated by the second temperature detection signal.

In step ST 103, the control unit 100 obtains the flow rate value _{F 1} measured by the flow regulating valve 53.

In step ST 104, the control unit 100 detects the temperature value _{T 1} indicated by the first temperature detection signal, determines whether the temperature threshold value _{T L} less than or set in advance. In the determination of step ST 104, the control unit 100, if the detected temperature value _{T 1} is determined to be less than the temperature threshold value _{T L} (YES), i.e., it is determined that liquid nitrogen LN1 is accumulated in the liquid accumulated 330 If YES, the process proceeds to step ST105. Further, in the determination of step ST 104, the control unit 100, and the detected temperature value _{T 1} is when it is determined that the temperature threshold value _{T L} or more (NO), ie, liquid nitrogen LN1 is not accumulated in the liquid accumulated 330 determines If so, the process proceeds to step ST110.

Step ST105: In (step ST 104 YES), the control unit 100, the range rate value _{F 1} obtained in step ST103 are from preset flow rate lower threshold _{F l,} until also preset flow-rate upper threshold _{F U} It is determined whether or not. In this step ST105, the control unit 100, the flow rate value _{F 1} is, when it is determined to have entered a range from the flow lower threshold _{F l} to flow-rate upper threshold _{F U} (YES), i.e., the liquid from the liquid accumulated 330 When it is determined that the nitrogen LN1 does not overflow and the liquid nitrogen LN1 is in a normal state in which the liquid nitrogen LN1 does not change into a solid state inside the liquid reservoir 330, the process proceeds to step ST106. Further, in step ST105, the control unit 100, the flow rate value _{F 1} is, when it is determined from the flow rate lower threshold _{F l} is not within the range of flow rates up to the upper threshold _{F U} and (NO), the processing step ST108 Migrate to

In step ST 106, the control unit 100 determines the temperature difference _{T D} calculated in step ST102 is, whether previously less than the set temperature difference threshold _{T TH.} In the determination of step ST 106, the control unit 100, if the temperature difference _{T D} is determined to be less than the temperature difference threshold value _{T TH} (YES), i.e. the level of the liquid nitrogen LN1 in the liquid accumulated 330 requires replenishing If so, the process proceeds to step ST107. Further, in the determination of step ST 106, the control unit 100, if the temperature difference _{T D} is determined to be equal to or greater than the temperature difference threshold value _{T TH} (NO), i.e. the level of the liquid nitrogen LN1 in the liquid accumulated 330, replenishment If not so low as necessary, the process proceeds to step ST108.

  In step ST107 (step ST106: YES), the control unit 100 transmits a drive signal to the flow rate adjustment valve 53 so that the valve body of the flow rate adjustment valve 53 has a predetermined opening degree. Thereby, the process of this flowchart is complete | finished.

  When the valve body of the flow rate adjusting valve 53 reaches a predetermined opening by the process of step ST107, the nitrogen gas discharge line L12 (and L22) is depressurized, so that the nitrogen gas LN2 staying in the gas phase portion 332 of the liquid reservoir 330 Is discharged to the outside through the nitrogen gas discharge lines L22, L12 and L13. Further, since the gas phase portion 332 of the liquid reservoir 330 has a negative pressure, the liquid nitrogen LN1 stored in the liquid nitrogen vessel 51 passes through the liquid nitrogen supply line L11 to L21 and the liquid phase portion 331 of the liquid reservoir 330. Supplied to. As a result, a part of the liquid nitrogen LN1 stored in the liquid nitrogen vessel 51 is replenished to the liquid phase part 331 of the liquid reservoir 330.

  In step ST108 (step ST105 or step ST106: NO), the control unit 100 determines whether or not the valve body of the flow rate adjustment valve 53 is open. In step ST108, when the control unit 100 determines that the valve body of the flow rate adjustment valve 53 is open (YES), the process proceeds to step ST109. In step ST108, when the control unit 100 determines that the valve body of the flow rate adjustment valve 53 is not in the open state (NO), the process of this flowchart ends.

  In step ST109 (step ST108: YES), the control unit 100 transmits a drive signal to the flow rate adjustment valve 53 so that the valve body of the flow rate adjustment valve 53 is closed by a predetermined amount. Thereby, the process of this flowchart is complete | finished.

  In step ST110 (step ST104: NO), the control unit 100 transmits a drive signal to the flow rate adjustment valve 53 so that the valve body of the flow rate adjustment valve 53 has the maximum opening. Thereby, the process of this flowchart is complete | finished.

  By repeatedly executing the above-described control at predetermined time intervals in the control unit 100, the liquid level of the liquid nitrogen LN1 in the liquid reservoir 330 can be maintained within a predetermined range.

  As described above, the probe 3 of the present embodiment has the liquid reservoir 330 having the first temperature sensor S1 as the first temperature detection means and the second temperature sensor S2 as the second temperature detection means. Yes. The probe 3 is configured to be able to output the temperature detected by each temperature sensor provided in the liquid reservoir 330 as a detected temperature value. Therefore, when the probe 3 is combined with the liquid nitrogen supply device 5 as shown in the present embodiment, the liquid nitrogen LN1 liquid in the liquid reservoir 330 even when the vaporization amount of the liquid nitrogen LN1 fluctuates more than usual. The height of the surface can be kept within a predetermined range. According to this, since the temperature of the liquid nitrogen LN1 stored in the liquid phase part 331 of the liquid reservoir 330 can be stabilized at a temperature close to the boiling point thereof, the detection coil 31 and the preamplifier 32 serving as a signal detection part The temperature and the cooling capacity of the cooling unit 33 can be stabilized. Therefore, according to the probe 3 of the present embodiment, the NMR signal can be detected with higher accuracy.

  Further, the liquid nitrogen supply device 5 of the present embodiment reduces the nitrogen gas discharge line L12 (and L22) by the nitrogen gas discharge pump 52 and generates a negative pressure in the gas phase portion 332 of the liquid reservoir 330. The liquid nitrogen LN1 is supplied from the liquid nitrogen vessel 51 to the probe 3. According to this configuration, it is not necessary to pressurize the liquid nitrogen vessel 51 when supplying the liquid nitrogen LN1 to the probe 3. Therefore, in the liquid nitrogen supply device 5, the liquid nitrogen LN 1 can be added to the liquid nitrogen vessel 51 and the liquid nitrogen vessel 51 can be replaced more safely during the operation of the NMR device 1.

[Second Embodiment]
Next, as a second embodiment, an embodiment in which the probe 3 of the first embodiment is applied to a liquid nitrogen supply device 5A including a liquid nitrogen reliquefaction device 55 will be described. The overall configuration of the NMR apparatus 1A according to the second embodiment is the same as that of the NMR apparatus 1 according to the first embodiment (see FIG. 1), and thus description thereof is omitted. In the second embodiment, only differences from the first embodiment will be described. For this reason, in the second embodiment, descriptions of parts common to the first embodiment are omitted as appropriate.

  FIG. 4 is a schematic diagram showing the configuration of the probe 3 and the liquid nitrogen supply device 5A in the second embodiment. In addition, in FIG. 4, the shape, arrangement | positioning, etc. of each part which comprise the probe 3 and the liquid nitrogen supply apparatus 5A are drawn typically. Moreover, in FIG. 4, electrical connection is shown with the broken line.

  As shown in FIG. 4, the liquid nitrogen supply device 5 </ b> A of this embodiment includes a liquid nitrogen reliquefaction device 55. The liquid nitrogen reliquefaction device 55 is a device that liquefies nitrogen gas LN2 to produce liquid nitrogen LN1. The nitrogen gas discharge pump 52 and the liquid nitrogen reliquefaction device 55 are connected by a nitrogen gas recovery line L14. The nitrogen gas recovery line L14 is a line for recovering the nitrogen gas LN2 discharged from the probe 3 to the liquid nitrogen reliquefaction device 55. The upstream end of the nitrogen gas recovery line L14 is connected to a nitrogen gas LN2 discharge port (not shown) in the nitrogen gas discharge pump 52. The downstream end of the nitrogen gas recovery line L14 is connected to an inlet (not shown) for the nitrogen gas LN2 in the liquid nitrogen reliquefaction device 55.

  The liquid nitrogen reliquefaction device 55 and the liquid nitrogen vessel 51 are connected by a liquid nitrogen recovery line L15. The liquid nitrogen recovery line L15 is a line for recovering the liquid nitrogen LN1 liquefied in the liquid nitrogen reliquefaction device 55 to the liquid nitrogen vessel 51. The upstream end of the liquid nitrogen recovery line L15 is connected to a discharge port (not shown) of the liquid nitrogen LN1 in the liquid nitrogen reliquefaction device 55. The downstream end of the liquid nitrogen recovery line L15 is connected to an inlet (not shown) for the liquid nitrogen LN1 in the liquid nitrogen vessel 51.

  In the liquid nitrogen supply device 5A of the present embodiment, the nitrogen gas discharge line L12 (and L22) is depressurized, so that the nitrogen gas LN2 sucked into the nitrogen gas discharge pump 52 becomes liquid via the nitrogen gas recovery line L14. It is recovered by the nitrogen reliquefaction device 55. In the liquid nitrogen reliquefaction device 55, the nitrogen gas LN2 is liquefied to produce liquid nitrogen LN1. The liquid nitrogen LN1 produced in the liquid nitrogen reliquefaction device 55 is recovered in the liquid nitrogen vessel 51 via the liquid nitrogen recovery line L15.

  According to the liquid nitrogen supply device 5A of the second embodiment described above, the same effect as the liquid nitrogen supply device 5 of the first embodiment can be obtained. In particular, in the liquid nitrogen supply device 5A of the second embodiment, the nitrogen gas LN2 discharged from the probe 3 is reliquefied in the liquid nitrogen reliquefaction device 55 without being discharged to the outside, and the liquid nitrogen vessel is used as the liquid nitrogen LN1. Recover to 51. Therefore, in the liquid nitrogen supply device 5A, the detection coil 31 and the preamplifier 32 of the probe 3 can be cooled without adding the liquid nitrogen LN1 of the liquid nitrogen vessel 51.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to the said embodiment, It can implement with a various form.

  In the above embodiment, the example in which the liquid reservoir 330 of the probe 3 is provided with the first temperature sensor S1 and the second temperature sensor S2 has been described. Not limited to this, the liquid reservoir 330 may be provided with three or more temperature sensors. By setting it as such a structure, in the liquid phase part 331, the height of the liquid level of liquid nitrogen LN1 can be detected more correctly. Further, the liquid reservoir 330 may be provided with one temperature sensor. With this configuration, the number of temperature sensors can be reduced.

In the above embodiment, when the temperature difference T _D in the liquid accumulated 330 is less than the temperature difference threshold value T _TH, as the valve body of the flow control valve 53 becomes the predetermined opening degree, i.e., a certain degree set in advance An example of controlling has been described. Not limited to this, when the temperature difference T _D in the liquid accumulated 330 is less than the temperature difference threshold value T _TH, depending on the magnitude of the temperature difference T _D, so as to adjust the opening degree of the valve body of the flow control valve 53 It may be. According to this, the pressure reduction amount in the nitrogen gas discharge line L12 (and L22) can be adjusted to an optimal value according to the height of the liquid nitrogen LN1 in the liquid reservoir 330.

  In the above embodiment, the example in which the liquid nitrogen LN1 that cools the detection coil 31 and the preamplifier 32 of the probe 3 is supplied from the liquid nitrogen supply device 5 (5A) has been described. However, the liquid nitrogen LN1 may be cooled in parallel from a liquid nitrogen reliquefaction device (not shown) used in the superconducting magnet unit 2 of the NMR apparatus 1. Alternatively, the liquid nitrogen LN1 may be directly supplied from a liquid nitrogen vessel that stores liquid nitrogen for precooling the superconducting magnet unit 2 and that includes a liquid nitrogen reliquefaction device.

  In the above embodiment, the example in which the probe according to the present invention is applied to the NMR apparatus has been described. However, the present invention is not limited to this, and the probe according to the present invention cools the detection system of the electric signal, thereby detecting sensitivity and resolution. The present invention can be applied to general devices in which

  1, 1A: NMR device, 2: superconducting magnet unit, 3: probe, 5, 5A: liquid nitrogen supply device, 31: detection coil, 32: preamplifier, 51: liquid nitrogen vessel, 52: nitrogen gas discharge pump, 53 : Flow control valve, 55: Liquid nitrogen reliquefaction device, 100: Control unit, 330: Liquid storage, 331: Liquid phase part, 332: Gas phase part, S1: First temperature sensor, S2: Second temperature sensor, L11 , L21: Liquid nitrogen supply line, L12, L13, L22: Nitrogen gas discharge line, L14: Nitrogen gas recovery line, L15: Liquid nitrogen recovery line, LN1: Liquid nitrogen, LN2: Nitrogen gas

Claims (4)

A signal detector that detects an electrical signal generated by nuclear magnetic resonance by an object mounted on the nuclear magnetic resonance apparatus; and
A cooling unit that has a liquid phase part that stores a cryogen and a gas phase part in which the vaporized cryogen stays, and that cools the signal detection unit by thermally contacting the liquid storage and the signal detection unit; ,
With
The liquid reservoir has first temperature detection means provided on the upper end side, and second temperature detection means provided on the lower end side relative to the first temperature detection means, and the first and second temperature detection means. A probe configured to output the detected temperature as a detected temperature value. A cryogen supply line capable of supplying the cryogen from the cryogen supply source to the liquid phase part of the liquid reservoir;
A cryogen discharge line capable of discharging vaporized cryogen to the outside from the gas phase part of the liquid reservoir;
The probe according to claim 1. The signal detection unit has a detection coil that generates high-frequency radio waves for nuclear magnetic resonance of the object to be measured,
The cryogen stored in the liquid reservoir and the detection coil of the signal detection unit are in thermal contact with each other through the liquid reservoir to cool the detection coil.
The probe according to claim 1 or 2. The signal detector has a preamplifier that amplifies an electric signal generated by nuclear magnetic resonance,
The preamplifier is cooled by thermally contacting the vaporized cryogen flowing through the cryogen discharge line and the preamplifier through the cryogen discharge line,
The probe according to claim 2 .

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