JP2010232613A - Superconducting magnet device capable of monitoring internal temperature abnormality - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superconducting magnet device that monitors an internal temperature abnormality without being affected by a magnetic field, with a small increase in mass and a small amount of heat intrusion without the necessity for an installation space. <P>SOLUTION: In the superconducting magnet device of helium immersion cooling system, which monitors an internal temperature abnormality, an optical fiber temperature sensor 11 is provided with: load support heat insulators 2; a power lead 3; a coolant pipe 5; an internal tank container 7; and radiation shields 8 and 9. The optical fiber temperature sensor 11 is connected to a measuring device 12 so as to monitor the temperature abnormality in the superconducting magnet device. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a superconducting magnet device that can monitor internal temperature abnormalities, and in particular, it is possible to monitor internal heat generation and heat penetration of superconducting magnets used for floating railways, medical equipment, power storage, etc. It is.

  Conventionally, when there is an increase in heat penetration due to abnormal internal heat generation of the superconducting coil, poor circulation of the refrigerant, poor heat insulation, etc., the superconducting magnet will not be able to maintain the superconducting state because the superconducting coil partly or entirely rises above the critical temperature. Quench. When a quench occurs, it not only loses its function as a superconducting magnet, but also has a significant impact, such as the location where the quench occurs and its surroundings are burnt out and require repairs.

  For this reason, it is necessary to capture in advance the temperature rise inside the superconducting magnet, which is a sign of quenching, but there are a wide variety of locations where the temperature should be measured, such as superconducting coils, refrigerant containers, refrigerant piping, and heat insulating material mounting parts. It is necessary to measure in a distributed manner. However, when measuring such a temperature distribution with a thermocouple or resistance thermometer, which is a conventional general temperature sensor, the number of sensors and measurement wiring becomes enormous, which only increases the space and mass for installation. In addition, there were problems such as consideration of insulation against the generated voltage during excitation and demagnetization, and increased heat penetration from the measurement wiring. Therefore, there is a need for a temperature distribution measurement method that does not require installation space, has a small increase in mass, has a small amount of heat penetration, and is not affected by a magnetic field.

  Under such circumstances, a superconducting device capable of detecting the temperature rise of the internal superconducting wire has been proposed (see Patent Document 1 below), and the superconducting device has the following characteristics.

  (1) An optical fiber is installed near the superconducting wire inside the superconducting device, and the internal temperature distribution is measured and monitored with Brillouin scattered light.

  (2) One or two optical fibers are wound around a superconducting wire.

  (3) An optical fiber is disposed in the gap between the superconducting coils.

  Regarding the FBG (Fiber Bragg Grating) method, the present inventors have confirmed that the FBG method can measure up to about 8K, the BOTDR method and the BOCDA method can measure up to about 50K, and is not affected by the magnetic field. By improving the FBG fiber, there is an experimental result that the resolution can be measured high up to about 15K and it is not affected by the magnetic field (see Non-Patent Document 1 below).

  The FBG method is based on Bragg's law by Mr. Bragg, a British physicist. That is, when incident light is reflected and scattered, reflected waves in a specific direction that interfere with each other and in phase have high intensity, and reflected lines in a direction that cancels the phase have low intensity. Bragg's law is based on the relationship between the lattice spacing, the incident angle of light, and the wavelength. It utilizes the fact that a grating (grating) with a fixed period is processed in an optical fiber, and reflected light of a specific wavelength returns when light is incident. Since the wavelength of reflected light changes when the lattice spacing changes due to the temperature expansion and contraction of the optical fiber, it can be converted into temperature by measuring the wavelength variation. Advantages of comparing this FBG method with the BOTDR method and BOCDA method, which are other optical fiber measurement methods, are that the measurement resolution is high, the measurement time is short, and the measuring instrument is inexpensive. However, it is a multipoint measurement and cannot be distributed. The maximum number of points that can be measured simultaneously is about 30 to 40 at present.

  On the other hand, a distributed BOTDR (Brillouin Optical Time Domain Reflectometry) system has a characteristic that weak scattered light is generated and returned when light is passed through an optical fiber. The Brillouin scattered light therein has a frequency that changes in proportion to the strain or temperature expansion / contraction of the optical fiber. By measuring the change in frequency, it can be converted into temperature.

  Moreover, the position with respect to a measurement result can be grasped | ascertained by the reflection time of the Brillouin scattered light with respect to the incident light. Since the position can be measured continuously, the temperature can be measured in a distributed manner.

  The BOCDA (Brillouin Optical Correlation Domain Analysis) method measures the frequency change of the Brillouin scattered light according to the temperature change in the same manner as the BOTDR method. It is a system that can increase the measurement accuracy and shorten the measurement time compared with the BOTDR method by continuously propagating the continuous light of the frequency difference corresponding to the Brillouin frequency in advance from both ends of the optical fiber and enhancing the Brillouin scattering by generating the induction effect. . In addition, by modulating the oscillation frequency of continuous light, the induced Brillouin scattered light is generated locally, so it is possible to sweep the position by changing the modulation frequency of continuous light, thus distributing the temperature Can be measured automatically.

JP 2007-141713 A

Ranji-Kumar, M .; Suesser, K. et al. G. Narayankhedkar, G.M. Krieg, M .; D. Atrey, “Performance of metal-coated fiber Bragg grating sensors for sensing cryogenic temperature”, Cryogenics 48, (2008), pp. 228 142-147

  However, in the case of a superconducting magnet device, it is necessary to simultaneously measure and monitor the temperatures of the superconducting coil, the refrigerant container, the refrigerant piping, the radiation shield, and the heat insulating material mounting portion inside the superconducting magnet.

  In view of the above situation, the present invention can monitor an internal temperature abnormality that does not require an installation space, has a small increase in mass, has a small amount of heat penetration, and is not affected by a magnetic field in the temperature distribution measurement method. An object of the present invention is to provide a superconducting magnet device.

In order to achieve the above object, the present invention provides
[1] In a superconducting magnet device capable of monitoring internal temperature abnormalities, an optical fiber temperature sensor is installed on the load supporting insulation, power lead, helium refrigerant piping, inner tank vessel and radiation shield in the helium immersion cooling superconducting magnet device. The optical fiber temperature sensor is laid and connected to a measuring instrument, and temperature abnormality inside the superconducting magnet device is monitored.

  [2] In a superconducting magnet device capable of monitoring internal temperature abnormalities, an optical fiber temperature sensor is installed on the load supporting insulation, power lead, and radiation shield in the direct cooling superconducting magnet device, and this optical fiber temperature sensor is measured. It is connected to a vessel, and temperature abnormality inside the superconducting magnet device is monitored.

  [3] In the superconducting magnet device capable of monitoring the internal temperature abnormality described in [1] or [2] above, the optical fiber temperature sensor is a distributed measurement method using Brillouin scattered light, which is a BOTDR method or a BOCDA method. It is characterized by being.

  [4] In the superconducting magnet apparatus capable of monitoring an internal temperature abnormality as described in [1] or [2] above, the optical fiber temperature sensor is an FBG method which is a multipoint measurement method.

  [5] In the superconducting magnet device capable of monitoring an internal temperature abnormality as described in [2] above, a superconducting coil is added to the laying position of the optical fiber temperature sensor, and the optical fiber temperature sensor is a multipoint measurement method. It is characterized by being.

  ADVANTAGE OF THE INVENTION According to this invention, the temperature of the required location inside a superconducting magnet apparatus can be distributed and measured. Thereby, the occurrence of quenching of the superconducting magnet can be prevented in advance, and the occurrence frequency of repairs due to sudden operation stop during operation or burning of the superconducting coil can be reduced. Further, by constantly monitoring the superconducting magnet device, it is possible to detect an abnormal temperature rise for a shorter period of time, and it is possible to make a safe operation stop during operation, and to make an appropriate check or repair decision.

1 is a schematic diagram of a superconducting magnet device capable of monitoring an internal temperature abnormality according to a first embodiment of the present invention. It is a schematic diagram of the superconducting magnet apparatus which can monitor the internal temperature abnormality which shows 2nd Example of this invention. It is a schematic diagram of the superconducting magnet apparatus which can monitor the internal temperature abnormality which shows 3rd Example of this invention. It is the characteristic view which showed the correlation with the temperature actual value with the reflected wave wavelength shift by the FBG system sensor of this invention. It is the characteristic figure which showed the correlation with the frequency shift of the Brillouin scattered light by the BOCDA system sensor of this invention, and temperature measurement value.

  The superconducting magnet device capable of monitoring an internal temperature abnormality according to the present invention has an optical fiber temperature sensor laid along each component inside the device, and this optical fiber temperature sensor is connected to a measuring instrument. Monitor temperature abnormalities.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 1 is a schematic diagram of a superconducting magnet device capable of monitoring an internal temperature abnormality according to a first embodiment of the present invention.

  In this figure, 1 is a superconducting coil, 2 is a load-supporting heat insulating material for the superconducting coil 1, 3 is a power lead connected to the superconducting coil 1, 4 is a helium cooling pipe, 5 is a helium refrigerant pipe for cooling the superconducting coil 1, 6 is a service port of the helium refrigerant pipe 5, 7 is an inner tank container of the superconducting coil 1, 8 is a low-temperature radiation shield covering the inner tank container 7, 9 is a high-temperature radiation shield covering the low-temperature radiation shield 8, and 10 is a low-temperature radiation shield 8 Refrigerator 11 connected to the load 11 is a load supporting heat insulating material 2, power lead 3, helium refrigerant pipe 5, inner tank container 7, low temperature radiation shield 8 and high temperature radiation shield 9. It is a measuring instrument that monitors a temperature abnormality connected to the optical fiber temperature sensor 11.

  In this way, the optical fiber temperature sensor 11 is moved along the load supporting heat insulating material 2, power lead 3, refrigerant pipe 5, inner tank container 7, low temperature radiation shield 8 and high temperature radiation shield 9 of the helium immersion cooling type superconducting magnet device. The optical fiber temperature sensor 11 is connected to the measuring device 12 and the output from the optical fiber temperature sensor 11 is measured by the measuring device 12 to monitor the temperature abnormality inside the superconducting magnet device.

  As the optical fiber temperature sensor 11, an FBG system as a multi-point measurement type optical fiber temperature sensor or a BOTDR system or a BOCDA system as a distributed optical fiber temperature sensor can be considered. In the case of a multi-point measurement type optical fiber temperature sensor, the measurement point is placed in advance on the optical fiber temperature sensor 11 so that the measurement point can be close to a place where the temperature needs to be measured and monitored, such as the load supporting insulation 2 and the helium refrigerant pipe 5. Set and lay. In the case of a distributed measurement type optical fiber temperature sensor, the scattered light is a system using Brillouin scattered light that can be applied to cryogenic temperatures.

  The terminal of the optical fiber temperature sensor 11 is installed outside the superconducting magnet device and diagnoses whether there is an abnormality by connecting the measuring device 12 during regular inspection, or is always in operation by connecting the measuring device 12 at all times. Detects abnormal temperature rise at the measurement location.

  As shown in FIG. 1, the first embodiment shows a temperature monitoring configuration of a superconducting magnet apparatus of a liquid helium immersion cooling system. As will be described later, the optical fiber temperature sensor has a resolution of 8K to 50K or more according to experiments by the inventors. Therefore, as shown in FIG. 1, leakage or blockage of the refrigerant pipe 5 for cooling the superconducting coil 1 and insufficient amount of liquid, poor heat insulation, temperature abnormality such as radiation shield and power lead, etc. are used as the FBG method or BOTDR as a distributed measurement method. By detecting by a system or BOCDA system optical fiber temperature sensor 11, a sign of cooling abnormality of the superconducting coil 1 is monitored.

  For this reason, the optical fiber temperature sensor 11 is laid along the surface of the inner tank container 7, the mounting location of the load supporting heat insulating material 2, the refrigerant pipe 5, the power lead cooling pipe 4, the low temperature radiation shield 8 and the high temperature radiation shield 9, and FBG In the case of a system optical fiber temperature sensor, the temperature change is measured by selecting a point where the temperature change is noticeable at the time of abnormality as a measurement point (currently about 30 to 40 points at the maximum). When these measured values are different from the normal values, it is judged as abnormal.

  FIG. 2 is a schematic diagram of a superconducting magnet device capable of monitoring an internal temperature abnormality according to a second embodiment of the present invention.

  In this figure, 21 is a superconducting coil, 22 is a load-supporting heat insulating material, 23 is a power lead, 24 is a radiation shield, 25 is a refrigerator in which a refrigerator cold head 25A is connected to the superconducting coil 21, 26 is an optical fiber temperature sensor, 27 Is a measuring instrument connected to the optical fiber temperature sensor 26.

  In the second embodiment, a temperature monitoring configuration of a superconducting magnet device using a high-temperature superconducting material of a refrigerator direct cooling system is shown. The superconducting magnet device using the superconducting coil 21 that uses a high-temperature superconducting wire instead of liquid helium immersion cooling and maintains the superconducting state by direct conduction cooling by the refrigerator 25 is the liquid helium container and piping shown in FIG. However, there is a possibility that the temperature rises locally due to fluctuations in the operating condition of the refrigerator 25 and causes quenching. For this reason, an optical fiber temperature sensor 26 is laid on the load supporting heat insulating material 22, the power lead 23, and the radiation shield 24 in the direct cooling type superconducting magnet device, and the optical fiber temperature sensor 26 is connected to the measuring device 27, thereby superconducting magnet device. Monitor internal temperature abnormalities.

  As the optical fiber temperature sensor 26, an FBG method as a multi-point measurement type optical fiber temperature sensor or a BOTDR method or a BOCDA method as a distributed measurement type optical fiber temperature sensor can be considered. In the case of a multi-point measurement type optical fiber temperature sensor, the optical fiber temperature sensor 26 is arranged so that the measurement point can be close to a place where the temperature needs to be measured and monitored, such as the load supporting heat insulating material 22, the power lead 23, and the radiation shield 24. Set the measurement points in advance and install them. In the case of a distributed measurement type optical fiber temperature sensor, the scattered light is a system using Brillouin scattered light.

  FIG. 3 is a schematic diagram of a superconducting magnet device capable of monitoring an internal temperature abnormality according to a third embodiment of the present invention.

  In this figure, 31 is a superconducting coil, 32 is a load supporting heat insulating material, 33 is a power lead, 34 is a radiation shield, 35 is a refrigerator having a refrigerator cold head 35A connected to the superconducting coil 31, 36 is an optical fiber temperature sensor, 37 Is a measuring instrument connected to the optical fiber temperature sensor 36.

  In the third embodiment, a temperature monitoring configuration of a superconducting magnet apparatus using a high-temperature superconducting material of a refrigerator direct cooling system is shown. A superconducting magnet device using a superconducting coil 31 that uses a high-temperature superconducting wire instead of immersion cooling of liquid helium and maintains a superconducting state by direct conduction cooling by the refrigerator 35 is the liquid helium container and piping shown in FIG. However, there is a possibility that the temperature rises locally due to a change in the operating condition of the refrigerator 35 and quenching occurs. Therefore, a multipoint FBG type optical fiber temperature sensor 36 is laid on the load supporting heat insulating material 32, the power lead 33, the radiation shield 34, and the superconducting coil 31 in the direct cooling type superconducting magnet device. The sensor 36 is connected to the measuring device 37, and the temperature abnormality of the superconducting coil 31 and the refrigerator cold head 35A, the heat insulation failure, and the temperature abnormality such as the radiation shield 34 and the power lead 33 are detected by the optical fiber temperature sensor 36. Monitor 31 for signs of cooling failure.

  In this way, the multi-point FBG type optical fiber temperature sensor 36 is laid on the periphery of the superconducting coil 31, the location where the load supporting heat insulating material 32 is attached, the refrigerator cold head 35A, the radiation shield 34, and the power lead 33, and the measurement points. To measure and monitor these temperature distributions. When these measured values are different from the normal values, it is judged as abnormal.

  FIG. 4 is a characteristic diagram showing the correlation between the reflected wave wavelength shift by the FBG type sensor of the present invention and the measured temperature value, and FIG. 5 is the relationship between the frequency shift of the Brillouin scattered light and the measured temperature value by the BOCDA type sensor of the present invention. It is the characteristic view which showed the correlation. In both figures, the result of measurement with a magnetic field not applied (0T) and a strong magnetic field up to 5K is also shown.

  According to FIG. 4, in the FBG type sensor, the correlation between the actually measured temperature and the FBG reflected wave wavelength shift is observed from the absolute temperature of about 8K to 300K, and the temperature abnormality of the part inside the superconducting magnet device is observed in this temperature range. It can be seen that measurement and monitoring are possible. In addition, the measurement result under a strong magnetic field does not change compared to a state without a magnetic field, and it can be confirmed that there is no influence on the temperature measurement by the strong magnetic field.

  According to FIG. 5, the BOCDA type sensor shows a correlation between the measured temperature and the frequency shift of the Brillouin scattered light from an absolute temperature of about 50 K to 300 K. In the BOTDR type and BOCDA type sensors using the Brillouin scattered light, It can be seen that it is possible to measure and monitor the temperature abnormality of the portion inside the superconducting magnet device in this temperature range. In addition, the measurement result under a strong magnetic field does not change compared to a state without a magnetic field, and it can be confirmed that there is no influence on temperature measurement by a strong magnetic field, as in the FBG method.

  In addition, this invention is not limited to the said Example, Based on the meaning of this invention, a various deformation | transformation is possible and these are not excluded from the scope of the present invention.

  The superconducting magnet device of the present invention can be used as a superconducting magnet device that can distributely measure and monitor the temperature of necessary portions inside the superconducting magnet device and can be operated safely.

1,21,31 Superconducting coil 2,22,32 Load bearing insulation 3,23,33 Power lead 4 Power lead cooling piping 5 Refrigerant piping (helium piping)
6 Refrigerant piping service port 7 Inner tank container 8 Low temperature radiation shield 9 High temperature radiation shield 10, 25, 35 Refrigerator 11, 26, 36 Optical fiber temperature sensor 12, 27, 37 Measuring device 24, 34 Radiation shield 25A Refrigerator cold head 26 Optical fiber temperature sensor 35A Refrigerator cold head

Claims (5)

  An optical fiber temperature sensor is laid on the load-supporting heat insulating material, power lead, refrigerant pipe, inner tank vessel and radiation shield in the helium immersion cooling superconducting magnet apparatus, and the optical fiber temperature sensor is connected to a measuring instrument. A superconducting magnet device capable of monitoring an internal temperature abnormality, characterized by monitoring an internal temperature abnormality.   An optical fiber temperature sensor is laid on the load supporting insulation, power lead, and radiation shield in the direct cooling superconducting magnet device, and the optical fiber temperature sensor is connected to a measuring instrument to monitor the temperature abnormality inside the superconducting magnet device. A superconducting magnet device that can monitor internal temperature abnormalities.   3. The superconducting magnet apparatus capable of monitoring an internal temperature abnormality according to claim 1 or 2, wherein the optical fiber temperature sensor is a BOTDR system or a BOCDA system which is a distributed measurement system using Brillouin scattered light. A superconducting magnet device that can monitor internal temperature abnormalities.   3. The superconducting magnet apparatus capable of monitoring an internal temperature abnormality according to claim 1 or 2, wherein the optical fiber temperature sensor is an FBG method which is a multi-point measurement method, and can monitor an internal temperature abnormality. Superconducting magnet device.   3. A superconducting magnet device capable of monitoring an internal temperature abnormality according to claim 2, wherein a superconducting coil is added to a position where the optical fiber temperature sensor is laid, and the optical fiber temperature sensor is an FBG method which is a multipoint measurement method. A superconducting magnet device that can monitor internal temperature abnormalities.

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