WO1995004287A1 - Magnetic sensor and magnetic detector - Google Patents
Magnetic sensor and magnetic detector Download PDFInfo
- Publication number
- WO1995004287A1 WO1995004287A1 PCT/JP1993/001081 JP9301081W WO9504287A1 WO 1995004287 A1 WO1995004287 A1 WO 1995004287A1 JP 9301081 W JP9301081 W JP 9301081W WO 9504287 A1 WO9504287 A1 WO 9504287A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- bobbin
- magnetic
- cryogenic
- resin
- magnetic sensor
- Prior art date
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/035—Measuring direction or magnitude of magnetic fields or magnetic flux using superconductive devices
- G01R33/0354—SQUIDS
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/035—Measuring direction or magnitude of magnetic fields or magnetic flux using superconductive devices
- G01R33/0354—SQUIDS
- G01R33/0358—SQUIDS coupling the flux to the SQUID
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F5/00—Coils
- H01F5/02—Coils wound on non-magnetic supports, e.g. formers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S505/00—Superconductor technology: apparatus, material, process
- Y10S505/825—Apparatus per se, device per se, or process of making or operating same
- Y10S505/842—Measuring and testing
- Y10S505/843—Electrical
- Y10S505/845—Magnetometer
- Y10S505/846—Magnetometer using superconductive quantum interference device, i.e. squid
Definitions
- the present invention relates to a magnetic sensor including an S QU ID element (S QU ID: Superconductive Quantum Interference Device 0 ) which is in a superconducting state at a cryogenic level, and a cryogenic sensor.
- S QU ID element S QU ID: Superconductive Quantum Interference Device 0
- the present invention relates to a magnetic detection device combined with a refrigerator, and particularly to a heat transfer structure of a superconducting pickup coil in a magnetic flux input circuit connected to a SQUID element.
- an SQUID element using the Josephson effect has been known as one of superconducting devices.
- a magnetic flux input circuit with a superconducting pickup coil By connecting a magnetic flux input circuit with a superconducting pickup coil to this S QU ID element, extremely weak magnetic fields such as a magnetic field due to a minute current flowing in a living body such as a cardiac magnetic field and a magnetic field from a minute magnetic body in the body can be obtained.
- An SQUID magnetometer as a type of magnetic sensor that measures magnetic flux can be obtained.
- the S QU ID magnetometer is cooled to a cryogenic level, that is, a cryogenic level in a cryostat, where the S QU ID element and the superconducting coil are cooled to a superconducting state.
- a liquid helm is stored and a SQUID magnetometer is immersed in the liquid helm and cooled. In that case, usually low temperature
- the cooler of the refrigerator for generating cold is inserted into the holding container, and the vaporized vapor in the container is condensed and liquefied by the refrigerator.
- the SQUID magnetometer since the SQUID magnetometer is immersed in liquid helium, the SQUID magnetometer can be cooled in a short time.
- the cooling system becomes large and the operability deteriorates because the hemisphere in the cryostat is interposed for cooling the SQUID magnetometer.
- the handling of the liquid helm requires skill, and there is a risk of mishandling.
- the SQUID magnetometer, pickup coil, etc. were thermally coupled to the final cooling stage, which was cooled to below the superconducting transition temperature by a cryogenic refrigerator. It is attached in a state. Therefore, the superconducting state and the normal conducting state can be selected only by controlling the operation of the cryogenic refrigerator, and there is no need to move the SQUID element or the pickup coil.
- cooling the SQUID magnetometer with a refrigerator has the following two problems. That is, first, the pickup coil of the magnetic flux input circuit is usually wound in a loop around a cylindrical bobbin made of a resin material. However, since the heat conductivity of the resin material of this bobbin is small, as described above, the SQUID When a magnetometer is cooled directly by a refrigerator, it is extremely difficult to cool the pickup coil on the bobbin to its superconducting transition temperature.
- the bobbin may be made of a metal having high thermal conductivity, such as copper or aluminum, even in a very low temperature range.However, in the bobbin, a loop in which a normal conductive current flows near the magnetic flux input circuit is formed. The mutual inductance between the current loop and the current of the pickup coil causes a new problem that the output characteristics of the SQUID magnetometer with respect to the input change at a specific frequency.
- the second problem is explained as follows.
- a structure in which the SQUID element is connected to a cryogenic refrigerator so as to be able to conduct heat is cooled to a temperature below the superconducting transition temperature (for example, about 4 K) using a cryogenic refrigerator.
- a superconducting shield member for accommodating the SQUID element is arranged, and a heat transfer block member is arranged so as to sandwich and superimpose the superconducting shield member.
- a bobbin around which a pickup coil is wound is erected at the center of the surface.
- the superconducting shield member is cooled to a temperature below the superconducting transition temperature by the 4K stage, and the effect of external magnetic flux on the internal SQUID element can be prevented.
- a wire for connecting the SQUID element and the pick-up coil and a wire for connecting the SQUID element and electronic components arranged on the room temperature side are inserted through predetermined positions of the superconducting shield member. A hole is formed.
- the size of the superconducting shield, the heat transfer block, and the bobbin may be reduced.However, if the diameter of the bobbin is reduced, the magnetic flux detection sensitivity decreases. It cannot be downsized.
- the size of the superconducting shield member is determined by the SQUID element housed in the superconducting shield member. Therefore, there is a limit to miniaturization of the heat transfer block arranged so as to straddle the superconducting shield member.
- the pickup coil is wound on a bobbin so as to be a primary or secondary differential type, so the following work process is required. This aspect also limits downsizing. That is,
- the pickup coil is wound with the heat transfer block and bobbin mounted, and the lead wire from the pickup coil is thermally coupled to the bobbin and heat transfer block to the SQUID element and electrically connected by superconducting solder. Make a connection. Therefore, the internal space of the heat transfer block must be large enough to allow the electrical connection work, specifically, large enough to allow the insertion of solder and fingers. Since the size of the internal space of the heat transfer block is limited in this way, the planar shape of the SQUID magnetometer cannot be made very small. Of course, complicated work processes are required, and the time required for assembling the SQUID magnetometer is prolonged.
- a heat transfer block is generally constructed by sequentially mounting a plurality of blocks with screws or the like, the thermal resistance varies due to the state of contact between the blocks, and the temperature of the pickup coil becomes S
- Each QU ID element can be different, and in the worst case, it is not possible to cool the pickup coil of at least one S QU ID element below the superconducting transition temperature.
- the present invention has been made in view of the above points, and a first object of the present invention is to improve the structure of a bobbin around which a big coil is wound in the above SQUID magnetometer, thereby improving the input / output of the SQUID magnetometer.
- the purpose is to increase the cooling efficiency of the pickup coil without affecting the characteristics, and to make the cooling of the SQUID magnetometer effective by the refrigerator.
- a second object of the present invention is to easily achieve multi-channel S QU ID magnetometers that are heat-transfer-cooled by a cryogenic refrigerator, simplify the assembly work, and perform maintenance and repair. To significantly improve the workability of It is in.
- a pickup coil of the magnetic flux input circuit is provided in a magnetic sensor including a SQUID element that is in a superconducting state at a cryogenic level and a magnetic flux input circuit connected to the SQUID element.
- a pickup coil of the magnetic flux input circuit is provided. Is wound around a cylindrical resin bobbin, and a large number of wires made of a non-magnetic material with high thermal conductivity, such as copper or aluminum, each of which is coated with a resin film, are placed inside the bobbin.
- wires made of a non-magnetic material with high thermal conductivity, such as copper or aluminum, each of which is coated with a resin film
- the heat conduction characteristics of the bobbin as a whole are substantially improved in the substantially central axis direction and the substantially circumferential direction. Therefore, when the magnetic sensor is cooled by a cryogenic refrigerator, the bobbin is connected to the cooling stage of the refrigerator so that heat can be transferred, so that the cold heat from the cooling stage is smoothly transmitted to the bobbin and the bobbin is easily cooled.
- the pick-up coil wound around the bobbin can be cooled to the superconducting transition temperature in a short time. can do.
- each of the wires constituting the bobbin is coated with a resin, even if the wires are made of metal such as copper or aluminum, the wires intersecting each other do not come into direct contact with each other. It is also possible to prevent the ends of the wires extending in the substantially circumferential direction from coming into contact with each other, so that the loop of the normal current flows only in the cross section of each wire and becomes extremely small. Changes in input / output characteristics can be suppressed.
- the wire extending substantially in the central axis direction of the bobbin may have a larger diameter than the wire extending substantially in the circumferential direction. According to this configuration, the heat conduction characteristics in the direction of the axis of the bobbin are substantially improved. Even if, for example, the end of the bobbin is connected to the cooling stage of the refrigerator so as to be able to conduct heat, the cooling heat from the cooling stage smoothly flows to the bobbin. Thus, the bobbin and the pick-up coil wound thereon can be cooled to the superconducting transition temperature in a short time.
- the inside of the cylindrical resin bobbin around which the pickup coil of the magnetic flux input circuit is wound is made of non-magnetic material with high thermal conductivity such as resin-coated net or aluminum.
- a large number of wires made of a non-conductive material such as glass fiber so that the wire made of a non-magnetic material with high thermal conductivity as described above extends in the direction of the approximate center of the bobbin. They can be arranged in a shape so that they are woven together.
- the wires constituting the bobbin only the wires in the substantially centerline direction are made of a non-magnetic material having high thermal conductivity such as resin-coated copper or aluminum, and are substantially in the circumferential direction. Since the wire rod is made of non-conductive material such as glass fiber, the heat conduction characteristics in the direction of the center of the bobbin are improved, and the bobbin and pickup coil are moved to the superconducting transition temperature in a short time by the cooling stage of the refrigerator. Can be cooled. In addition, the generation of a current loop in the bobbin in a substantially circumferential direction can be more reliably suppressed, and the change in the input / output characteristics of the magnetic sensor can be more effectively suppressed.
- a cylindrical pobin around which the pickup coil of the magnetic flux input circuit is wound is formed by joining a resin body and a resin body in the circumferential direction so as to extend substantially in the direction of the center axis of the pobin.
- a structure having a large number of wires made of a non-magnetic material with high thermal conductivity such as aluminum, which are embedded at intervals, can be provided, and the same effect as the above-mentioned invention can be obtained.
- the cylindrical bobbin includes a high thermal conductive resin layer containing a non-magnetic material having a high thermal conductivity such as a copper alloy, and the inside and outside of the high thermal conductive resin layer. It is also possible to adopt a configuration having a three-layer wall portion arranged on both sides and a fiber-reinforced resin layer made of a non-conductive material such as glass fiber. According to this configuration, the high heat conductive resin layer is disposed in the middle part of the bobbin in the thickness direction, and a non-magnetic material having high heat conductivity is mixed in the resin layer.
- the cooling stage of the refrigerator can cool the bobbin and the pick-up coil to the superconducting transition temperature in a short time. Can be reliably suppressed, and a change in the input / output characteristics of the magnetic sensor can be more effectively suppressed.
- the magnetic sensor of each configuration described above is combined with a cryogenic refrigerator that cools a cryogenic member to a cryogenic level, and the resin bobbin in the magnetic sensor is connected to the cryogenic member so as to be able to conduct heat.
- a detection device can also be provided.
- one end is connected to a bobbin and the other end is cooled to a cryogenic level by a cryogenic refrigerator.
- a good heat conducting member detachably attached to a predetermined position of the cryogenic member to be detached, and a superconducting shield detachably attached to a predetermined position on a side surface of the good heat conducting member and accommodating the SQUID element in the attached state. And a member.
- the magnetic sensor can be easily mounted by mounting the good heat conducting member connected to the bobbin around which the pick-up coil is wound to the cryogenic member.
- the superconducting shield member accommodating the SQUID element is detachably mounted at a predetermined position on the side surface of the good heat conductive member, there is almost no possibility of adversely affecting the mounting of the magnetic sensor.
- electrical connection between the SQUID element and the pickup coil was achieved before mounting the good heat conducting member to the cryogenic member. This eliminates the need for wiring and soldering in narrow spaces, which simplifies the assembly work of the magnetic sensor, and simplifies maintenance and repair work.
- the flat shape can be significantly reduced compared to the structure that straddles the superconducting shield member by the good heat conducting member, and the cryogenic member does not become large.
- Multi-channel magnetic sensors can be easily achieved.
- space efficiency can be improved by mounting multiple SQUID elements and corresponding superconducting shield members without increasing the required planar shape. Can be increased. That is, multichanneling can be easily achieved in a relatively narrow range. Also, for example, by providing two sets of primary differential type pickup coils on the bobbin, it is possible to obtain a fully balanced secondary differential type equivalent coil, and to use one for signal detection.
- the pick-up coil can be reliably cooled to a temperature lower than the superconducting transition temperature.
- the good heat conducting member has a recess at a predetermined position on a side surface, and the superconducting shield member is mounted in the recess.
- a heat conductive member with a recess at a predetermined position on the side surface is adopted, and the superconducting shield member is mounted in the recess, preventing interference with other magnetic sensors etc. during mounting operation
- the planar shape required for the operation can be reduced, and the space utilization efficiency can be further improved. That is, the number of magnetic sensors that can be mounted in a relatively narrow range can be further increased.
- the end of the good heat conducting member detachably attached to a predetermined position of the cryogenic member has a through hole for passing a wiring to a room temperature side. I do.
- the end of the good heat conducting member attached to the predetermined position of the cryogenic member has a through hole for inserting the wiring to the room temperature side, so that the magnetic sensor can be attached to the cryogenic member.
- the wiring to the normal temperature side can be connected to the SQUID element, and after mounting the magnetic sensor on the cryogenic member, only the back side of the cryogenic member without routing the wiring on the front side of the cryogenic member The wiring can be routed at, and the wiring routing work can be simplified.
- FIG. 1 is an enlarged perspective view of a main part of a bobbin according to the first embodiment of the present invention.
- FIG. 2 is an enlarged sectional view of a main part of the cryogenic refrigerator in the first embodiment.
- FIG. 3 is a cross-sectional view schematically showing the cryogenic refrigerator and the SQUID magnetometer according to the first embodiment.
- FIG. 4 is a diagram corresponding to FIG. 1 in the second embodiment.
- FIG. 5 is a diagram corresponding to FIG. 1 in the third embodiment.
- FIG. 6 is a diagram corresponding to FIG. 1 in the fourth embodiment.
- FIG. 7 is a partially cutaway front view of a bobbin according to the fifth embodiment.
- FIG. 8 is a front view showing a magnetometer unit according to the sixth embodiment.
- FIG. 9 is a central longitudinal sectional view of the magnetometer unit of the sixth embodiment.
- FIG. 10 is a central longitudinal sectional view schematically showing the configuration of a multi-channel measurement system equipped with 32 magnetometer units according to the sixth embodiment.
- FIG. 11 is a cross-sectional view taken along the line XI—XI of FIG.
- FIG. 12 is a top view of the printed wiring board according to the sixth embodiment.
- FIG. 13 is a bottom view of the cryogenic member according to the sixth embodiment.
- FIG. 3 shows the overall configuration of Embodiment 1 of the present invention.
- a SQUID magnetometer as a magnetic sensor is used to detect a magnetocardiogram of a human body.
- (1) is a support on which a subject (M) for detecting a magnetocardiogram is mounted, which is installed inside an electromagnetic shield room or a magnetic shield room.
- a cylindrical pedestal (2) is installed below the support base (1), and a closed vacuum vessel (3) is provided at the lower end of the cylindrical pedestal (2) on the cylindrical pedestal (2). It is immersed in and fixedly supported.
- the inside of the vacuum vessel (3) is kept in a vacuum state, and a magnetic
- the S QU ID magnetometer (B) as an air sensor is housed.
- (A) is a two-circuit helium refrigerator that cools the SQUID magnetometer (B) to an operable cryogenic level.
- the vacuum vessel (3) is equipped with the expander (5) of the pre-cooling refrigeration circuit (4), which forms part of the refrigerator (A), and the expansion unit (11) of the J-T circuit (10). Have been.
- the pre-cooling refrigeration circuit (4) consists of a GM (Gifford * McMahon) cycle refrigerator, which compresses and expands the helium gas in the J-T circuit (10) to pre-cool helium gas. Yes, a pre-cooling compressor (not shown) and the expander (5) are connected in a closed circuit.
- the expander (5) is attached to the bottom wall of the vacuum vessel (3) with vibration insulated.
- This expander (5) is composed of a casing (6) fixed to the lower surface of the bottom wall of the vacuum vessel (3), and a two-stage cylinder (7) connected to the upper part of the casing (6).
- the casing (6) has a high-pressure gas inlet (6a) connected to the discharge side of the pre-cooling compressor and a low-pressure gas outlet (6b) connected to the suction side. ing.
- the cylinder (7) extends upward through the bottom wall of the vacuum vessel (3) in an airtight manner, and the upper end of the large diameter portion is maintained at a temperature level of 55-60K.
- the first heat station (8) has a second heat station (9) at the upper end of the small diameter portion, which is maintained at a temperature level of 15 to 20 K lower than that of the first heat station (8).
- the cylinder (7) has a displacer (replacer) which defines an expansion chamber at a position corresponding to the heat stations (8) and (9) in the cylinder (7). ) Is reciprocally fitted.
- the valve is opened each time it rotates, and the helium gas flowing in from the high pressure gas inlet (6a) is supplied to the expansion chamber in the cylinder (7) or in the expansion chamber.
- the J-T circuit (10) is a refrigeration circuit that compresses the Helium gas and expands it by Joule-Thomson to generate a cryogenic level of about 4 K, which compresses the Helium gas.
- T compressor (not shown) and its compressed
- An expansion unit (11) for expanding helium gas with Joule and Thomson is provided.
- the expansion unit (11) has a first J-T heat exchanger (12) that penetrates the bottom wall of the vacuum vessel (3) in an airtight manner, and the first J-T heat exchanger
- the (12) is connected to the second and third JT heat exchangers (13) and (14) arranged inside the vacuum vessel (3).
- the primary side of the first J-T heat exchanger (12) is It is connected to the discharge side. Also, the first and second:! _T heat exchanger (12),
- Each primary side of (13) is connected via a first precooler (15) consisting of a heat exchanger arranged on the outer periphery of the first heat station (8) of the expander (5).
- the primary sides of the second and third J-T heat exchangers (13) and (14) are connected to the second heat station (9) of the expander (5). It is connected via a second precooler (16) consisting of a vessel.
- the primary side of the third J-T heat exchanger (14) is connected to a cooler (18) via a J-T valve (17) for expanding high-pressure helium gas with Joule-Thomson. ing.
- the opening of the J-T valve (17) is adjusted by the operation rod (not shown) from outside the vacuum vessel (3).
- the cooler (18) consists of a coiled pipe wound around the outer periphery of the cooling part (19a) on the lower surface of the circular cryogenic member (19) (cooling plate).
- the cryogenic member (19) comes into contact with the cooler (18) so that it can conduct heat, It is kept at about 4 K stage at the same temperature.
- the above S QU ID magnetometer ( ⁇ ) is integrally mounted on the upper surface of the cryogenic member (19) so as to be able to conduct heat.
- cooler (18) is connected to the third and second J-I T heat exchangers (14),
- the secondary side of the first J-T heat exchanger (1 2) is connected to the secondary side of the first J-T heat exchanger (1 2) via each secondary side of (1 3) Is connected to the suction side of the J-T compressor. Therefore, in the J-T circuit (10), the J-T compressor compresses the helm gas to a high pressure and supplies it to the vacuum vessel (3) side, which supplies it to the first to third vacuum chambers (3). In the J-T heat exchangers (12) to (14), heat is exchanged with the low-temperature, low-pressure helm gas returning to the compressor side, and the first and second precoolers (15),
- Joule-Thomson is expanded at J-T valve (17).
- Cooler (18) converts helium into a gas-liquid mixture of 1 atm and approx. 4 K.
- the cryogenic member (19) and the S QU ID magnetometer (B) in contact with it by the latent heat of vaporization of this helium. Cooled and maintained at a cryogenic level of 4 K. After that, the hemi-gas, which had been reduced in pressure by the above expansion, was converted into the first to third J-T heat exchangers (1 2)
- the S QU ID magnetometer (B) includes a S QU ID element (not shown) that is in a superconducting state at a cryogenic level and a magnetic flux connected to the S QU ID element
- An input circuit (32) wherein the SQUID element is mounted and fixed on the upper surface of the cryogenic member (19) so as to be able to conduct heat while being accommodated in a superconducting shield member (31).
- the magnetic flux input circuit (32) has a pickup coil (33) composed of a superconducting wire wound in a loop around a cylindrical bobbin (34).
- the SQUID magnetometer (B) constitutes a gradiometer that measures the magnetic field gradient with a pickup coil (33) wound around four loops (33a) to (33d).
- a heat transfer bracket (20) is mounted on the upper surface of the cryogenic member (19) so as to cover a superconducting shield member (31) containing the SQUID element from above.
- the bobbin (34) is set up on the upper surface.
- the bobbin (34) has a length of about 200 to 30 Omm, and extends upward in the upper bulge (3a) formed at the center of the upper wall of the vacuum vessel (3), and is picked up at the upper part thereof.
- a coil (33) is wound around the bobbin (34) to cool the pickup coil (33) below its superconducting transition temperature.
- C The bulge (3a) of the vacuum vessel (3)
- the upper end of the support base (1) center opening (la), and through this opening (la), the magnetocardiogram of the subject (M) on the support (1) is measured.
- the feature of the present invention lies in the structure of the bobbin (34) around which the pickup coil (33) is wound.
- a large number of wire rods (35) with a high thermal conductivity and a non-magnetic material with a wire diameter of about 0.5 are coated with resin coating inside a resin bobbin (34).
- (35) are arranged in an intersecting manner so as to extend in the central axis direction and circumferential direction of the bobbin (34), and are knitted in a cylindrical shape.
- an aluminum wire can be used instead of a copper wire.
- (21) covers the cryogenic member (19), the superconducting shield member (31) for accommodating the SQUID element, the bracket (20), and the lower part of the bobbin (34).
- the radiation shield placed in the upper part of the vacuum vessel (3) contacts the first heat station (8) in the expander of the pre-cooling refrigeration circuit (4) and maintains it at about 80K.
- (22) is a super-insulation concentrically arranged around the bobbin (34).
- the operation of the above embodiment will be described.
- the S QU ID magnetometer (B) As the helium refrigerator (A) is operated, the S QU ID magnetometer (B) is cooled, and when the temperature of the S QU ID magnetometer (B) drops to a cryogenic level of about 4 K, The ID magnetometer (B) is activated.
- the compressors of the pre-cooling refrigeration circuit (4) and the J-T circuit (10) When the helium refrigerator (A) is started and is in a steady state of operation, the high-pressure helium gas supplied from the precooling compressor expands in the expander (5) in the precooling refrigeration circuit (4), and this gas expands. As a result, the first heat station (8) of the cylinder (7) is brought to a temperature level of 55-6 ⁇ K and the second heat station
- This cooled gas enters the primary side of the second J-T heat exchanger (13), and is similarly cooled to about 20 K by heat exchange with the secondary side low-pressure helium gas.
- the high-pressure helium gas is throttled and expanded by Joule-Thomson to become helium in a gas-liquid mixed state at 1 atm and about 4K.
- J—T valve (17) Supplied to the cooler (18) downstream. Then, in the cooler (18), the cryogenic member (19) is cooled by the latent heat of vaporization of the liquid portion in the helium in the gas-liquid mixed state.
- the S QU ID element of the S QU ID magnetometer ( ⁇ ) that is in heat-transferable contact with the cryogenic member (19), and houses the S QU ID element.
- the superconducting shield member (31), the bobbin (34), and the pickup coil (33) of the magnetic flux input circuit (32) are also cooled.
- the evaporated low-pressure helium gas returns from the cooler (18) to the secondary side of the third JT heat exchanger (14), and becomes a saturated gas of about 4 K in the meantime.
- the temperature After passing through the secondary side of the first J-T heat exchangers (13) and (12) and cooling the high-pressure helium gas on the primary side in order, the temperature finally rises to about 300 K (room temperature). Return to the suction side of the compressor.
- one cycle of the precooling refrigeration circuit (4) and the J-T circuit (10) is completed, and thereafter, the same cycle is repeated to perform the refrigeration operation of the refrigerator (A).
- the temperature of the S QU ID magnetometer (B) drops toward the cryogenic level (operating temperature level), and after reaching the cryogenic level, the S QU ID magnetometer (B) is activated.
- a resin coating is applied to a mesh wire having a high thermal conductivity inside a resin bobbin (34) around which a pickup coil (33) made of the superconducting wire is wound. Since the wires (35), (35),... that are applied are woven vertically and horizontally, the center axis and the circle of the bobbin (34) are smaller than when the entire bobbin is formed of resin material alone. The heat conduction characteristics in the circumferential direction are improved. For this reason, cold heat can be smoothly transmitted to the bobbin (34) from the cryogenic member (19) cooled to the 4 K level by the refrigerator (A), and the bobbin (34) can be cooled easily.
- the pickup coil (33) wound around 34) can be cooled to a very low temperature level in a short time.
- the wire (35) formed inside the resin bobbin (34) is a copper wire, its surface is covered with a resin coating that is an insulating material, so that the wires (35) and (35) There is no direct contact at intersections in the vertical and horizontal directions or at the ends in the circumferential direction.
- the loop of the normal current does not occur in a large area, but only in the cross section of each wire (35), and becomes extremely small. Therefore, the S QU ID magnetometer ( The change in the input / output characteristics of B) can be suppressed.
- the force in which both the central and circumferential wires (35) and (35) formed inside the resin bobbin (34) have the same diameter see FIG. 4
- the diameter of the wire rod (35) in the center axis direction of the bobbin (34) may be larger than the diameter of the wire rod (35) in the circumferential direction.
- the heat conduction characteristics in the center axis direction of the bobbin (34) are further improved as compared with the circumferential direction, and Even if the lower end of the bobbin (34) is in heat-transfer contact with the cryogenic member (19) of the refrigerator (A) as in the structure, the cold heat from the cryogenic member (19) 34), the cooling efficiency for the bobbin (34) and the pickup coil (33) wound around it can be increased.
- FIG. 5 shows Embodiment 3 of the present invention, in which a wire in the circumferential direction inside the resin bobbin (34) is changed. That is, in this embodiment, the magnetic flux input circuit (3
- a wire is woven in a crosswise manner in the center axis direction and circumferential direction in the same manner as in Examples 1 and 2 above.
- the wire in the center axis direction (35) is made of resin-coated copper wire (or aluminum 'wire, etc.), while the wire in the circumferential direction (36) is made of glass fiber. And the like.
- the wire (35) in the center axis direction formed inside the bobbin (34) is made of a copper wire or an aluminum wire coated with a resin coating. ),
- the bobbin (34) and the pickup coil (33) are cooled to the superconducting transition temperature in a short time by the cryogenic member (19) of the refrigerator (A). Can be.
- the circumferential wire (36) inside the bobbin (34) is made of a non-conductive material such as glass fiber, it is more reliable to generate a circumferential current loop on the bobbin (34).
- the S QU ID magnetometer (B) To suppress the change in input / output characteristics of the S QU ID magnetometer (B).
- FIG. 6 shows Example 4.
- the resin bobbin (34) has a cylindrical resin body (37), and inside the resin body (37) is a large number of wires (35) made of a non-magnetic material with high thermal conductivity such as copper and aluminum. , (35), ... are buried at intervals so as to extend in the direction of the center axis of the bobbin (34).
- the cooling heat from the cryogenic member (19) of the refrigerator (A) passes through the wires (35), (35), ... in the resin body (37), in the direction of the center axis of the bobbin (34).
- the heat conduction characteristics of the bobbin (34) in the central axis direction can be improved.
- wires (35), (35), ... are arranged at intervals in the circumferential direction of the bobbin (34), a current loop may occur in the circumferential direction of the bobbin (34).
- FIG. 7 shows a fifth embodiment.
- the resin bobbin (34) is made of a high thermal conductive resin layer ( ⁇ 38) in which a non-magnetic material having a high thermal conductivity such as copper foil is mixed. And a fiber reinforced resin layer (39) made of a non-conductive material such as glass fiber, which is disposed on both inside and outside of the high thermal conductive resin layer (38). ).
- a fiber reinforced resin layer (39) made of a non-conductive material such as glass fiber, which is disposed on both inside and outside of the high thermal conductive resin layer (38).
- three annular grooves (40), (40), Are recessed so as to extend in parallel with each other in the circumferential direction.
- a loop of the pickup coil (33) is wound around each annular groove (40).
- Reference numeral (41) denotes a female screw hole for mounting formed in the lower inner surface of the bobbin (34).
- a high thermal conductive resin layer (38) is disposed between the inner and outer fiber reinforced resin layers (39) and (39) at the middle part in the thickness direction of the bobbin (34). Since the non-magnetic material with high thermal conductivity is mixed in the conductive resin layer (38), the heat conduction characteristics of the bobbin (34) in the substantially central axis direction are improved, and the poles of the refrigerator (A) are improved.
- the low-temperature member (19) allows the bobbin (34) and the pickup coil (33) wound therearound to be cooled to the superconducting transition temperature in a short time, and the bobbin (34) has a substantially circumferential direction. The occurrence of a current loop can be reliably suppressed, and a change in the input / output characteristics of the SQUID magnetometer (B) can be more effectively suppressed.
- FIG. 8 to 13 show a sixth embodiment of the present invention. That is, FIG. 8 is a front view of the SQUID magnetometer according to the sixth embodiment, and FIG. 9 is a central longitudinal sectional view thereof.
- (51) is a good heat conducting member having male thread portions (51a) and (51b) at both ends, and a pair of recesses (51c), (51 c) is formed, and a superconducting shield member (52) for accommodating the SQUID element is detachably mounted in each of the recesses (51c).
- a bobbin wound with a pair of pickup coils (33) and (33) is wound on the upper male thread (5 lb). (34)
- the female screw (41) at the lower end is screwed together.
- the good heat conducting member (51) is entirely made of, for example, copper, and is opened at the center of the tip of the lower male screw portion (51a) and at a predetermined position of each recess (51c).
- the wiring through hole (51d) is formed through.
- the superconducting shield member (52) can be detached by screws, etc., with the base member (52a) embedded in each recess (51c) of the good heat conducting member (51).
- the cover member (52b) is provided with a cover member (52b), and a groove (52c) is formed at a predetermined position of the cover member (52b) for leading out a lead wire.
- a board (52e) on which a SQUID element (not shown) is mounted at a predetermined position of the base member (52a) is mounted via a spacer member (52d).
- a large-diameter flange portion (51e) is formed continuously on the upper side of the lower male screw portion (51a), and this flange portion (51e) allows the pole of the good heat conducting member (51) to be formed.
- the contact area with the low-temperature member (19) is increased.
- the bobbin (34) is the same as in the fifth embodiment.
- the pickup coil (33) is wound around the outer surface of the bobbin (34) so as to be of a first-order differential type, for example, and has annular grooves (40) formed at predetermined positions on the bobbin (34).
- Each loop of the pick-up coil (33) is wound in a state of being accommodated in.
- a pair of pickup coils (33) and (33) are wound around the bobbin (34).
- a pair of substrates (52 e) and (52 e) corresponding to each pickup coil (33) are accommodated in the superconducting shield members (52) and (52), respectively, and two S QUs are provided.
- the magnetometer unit (B) in which the ID magnetometer is integrated is obtained.
- the lead wire (33 e) of the pickup coil (33) is connected to the S QUID element of the substrate (52 e) through one groove (52 c), and the lead wire (52 f) of the SQUID element. Is drawn out through the wiring hole (51d), and a connector (52g) is provided at the end of the lead wire (52f).
- Fig. 10 is a central longitudinal sectional view schematically showing the configuration of a multi-channel measurement system equipped with 32 magnetometer units shown in Fig. 9, and Fig. 11 is a sectional view taken along line XI-XI in Fig. 10. It is.
- 32 magnetometer units (B), (B),... are screwed into the cryogenic member (19) at predetermined intervals.
- the cryogenic member (19) is cooled to a temperature below the superconducting transition temperature (for example, about 4 K) by a cryogenic refrigerator (not shown).
- (21a) and (21b) are radiation shield members.
- a printed wiring board (53) on which a connector (53d) is mounted in advance is arranged on the lower surface of the cryogenic member (19).
- the pins (53a) of the connector (53d) are exposed on the upper surface of the printed wiring board (53), and the corresponding pins (53a), (53a), ... electrical connection between
- - twenty one - Wiring pattern (53b) is formed.
- a through-hole (53c) through which the male screw portion (51a) of the magnetometer unit (B) penetrates is formed.
- a large-diameter hole () for allowing direct contact between the cooler (18), which is the final cooling unit of the cryogenic refrigerator, and the cryogenic member (19) is provided.
- FIG. 13 shows the lower surface of the cryogenic member (19).
- the lower surface of the cryogenic member (19) is located at a position corresponding to the through hole (53c), respectively.
- a female screw hole (54) for screwing the lower male screw part (51a) of the connector is formed, and a recess (55) for accommodating the pin (53a) at a position corresponding to the connector (53d). are formed respectively.
- the method of assembling the S QUA ID magnetometer unit (B) having the above configuration and the method of mounting it on the cryogenic member (19) will be described.
- the good heat conducting member (51) and the bobbin (34) will be described.
- the base member (52a) of the superconducting shield member (52) is attached to each of the recesses (51c) on the side of the good heat conducting member (51). )
- a pickup coil (33) is wound around the bobbin (34), and the lead wire (33 e) of the pickup coil (33) is electrically connected to the S QUID element by a large (52 e). Connect in place. Also, for S QU ID element A lead wire (52 f) for supplying bias power or extracting an electric signal from the SQUID element through the wiring hole (51 d) to the outside from the center of the end face of the external thread (51 a). A connector (52g) is connected to the free end of the lead wire (52f).
- the cover member (52b) of the superconducting shield member (52) is fixed to the good heat conducting member (51) with screws or the like, and the lead wires (33e) and (52f) are attached to the cover member (52b). ) In the groove (52c).
- a printed circuit board (53) is placed on the back (lower surface) of the cryogenic member (19) so that the cooler (18) of the cryogenic refrigerator directly contacts the lower surface of the central part of the cryogenic member (19).
- the cryogenic member (19) and the printed wiring board (53) are positioned and fixed in place. At this time, the wiring section of the printed wiring board also functions as a thermal anchor. In this state, since the pins (53a) of the connector (53d) are housed in the recesses (55) of the cryogenic member (19), the pins do not short-circuit.
- each magnetometer unit (B) is attached to the cryogenic member (19) by screwing the male screw (51a) into the female screw hole (54).
- each magnetometer unit (B) can be performed simply by screwing, and the superconducting shield member (52) is mounted in the recess (51c) of the good heat conducting member (51). Therefore, the space between adjacent magnetometer units (B), (B) can be minimized.
- each magnetometer unit (B) is attached to the cryogenic member (19)
- the lead wire (52f) with the connector (52g) attached to the free end will be connected to the printed wiring board (53). Since the connector hangs downward, if the connector (52 g) is connected to the corresponding connector (53 g) of the printed circuit board (53), the necessary wiring processing can be easily achieved by itself.
- the radiation shield members (21a) and (21b) are mounted, and the vacuum container ( 3) Attach. Then, the inside of the vacuum vessel (3) is evacuated, and the cryogenic refrigerator is operated to cool all the S QU ID magnetometers below the superconducting transition temperature. Etc. may be measured. In this measurement, since each magnetometer unit (B) has two SQUID magnetometers, if one of them is used for signal and the other is used for reference, A highly accurate magnetic field measurement signal can be obtained by removing noise components caused by a cryogenic refrigerator or the like.
- each S QU ID magnetometer has a primary differential pickup coil (33)
- the output of one S QU ID magnetometer is multiplied by a predetermined count
- the other S QU ID magnetometer is multiplied by a predetermined count.
- a single magnetic flux meter unit (B) can obtain the primary and secondary gradients of the magnetic field on the same axis, and the amount of information that can be obtained increases. it can.
- the present invention can of course be applied to a magnetic sensor including a SQUID magnetometer other than for measuring a magnetocardiogram.
- a SQUID element operating at a cryogenic level and a pick-up coil wound on a bobbin thereof are formed by using a liquid helm that requires skillful operation.
- Cryogenic refrigerator can cool the superconducting transition temperature or less, and in that case, the cooling heat from the cooling stage can be smoothly transmitted to the bobbin and the bobbin can be easily cooled, and the pickup coil can be shortened to the superconducting transition temperature. Can be cooled in time.
- Magnetic sensors and magnetic detectors that can detect weak magnetic fields with high sensitivity, such as measuring biomagnetic fields such as cardiac magnetic fields, can be realized, and their industrial applicability is extremely high.
Landscapes
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Measuring Magnetic Variables (AREA)
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
- Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
- Containers, Films, And Cooling For Superconductive Devices (AREA)
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/290,765 US5666052A (en) | 1992-03-06 | 1993-08-02 | Magnetic sensor having a superconducting quantum interference device and a pickup coil wound on a tubular resinous bobbin with embedded high thermal conductivity material |
EP93916252A EP0663599B1 (en) | 1992-03-06 | 1993-08-02 | Magnetic sensor and magnetic detector |
DE69310755T DE69310755T2 (de) | 1992-03-06 | 1993-08-02 | Magnetischer sensor und magnetischer detektor |
FI943868A FI943868A (fi) | 1992-03-06 | 1994-08-23 | Magneettinen anturi ja magneettinen ilmaisinlaite |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP4049397A JP2882167B2 (ja) | 1992-03-06 | 1992-03-06 | Squid磁束計 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1995004287A1 true WO1995004287A1 (en) | 1995-02-09 |
Family
ID=12829906
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP1993/001081 WO1995004287A1 (en) | 1992-03-06 | 1993-08-02 | Magnetic sensor and magnetic detector |
Country Status (6)
Country | Link |
---|---|
US (1) | US5666052A (ja) |
EP (1) | EP0663599B1 (ja) |
JP (1) | JP2882167B2 (ja) |
DE (1) | DE69310755T2 (ja) |
FI (1) | FI943868A (ja) |
WO (1) | WO1995004287A1 (ja) |
Cited By (6)
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---|---|---|---|---|
US9234877B2 (en) | 2013-03-13 | 2016-01-12 | Endomagnetics Ltd. | Magnetic detector |
US9239314B2 (en) | 2013-03-13 | 2016-01-19 | Endomagnetics Ltd. | Magnetic detector |
US9427186B2 (en) | 2009-12-04 | 2016-08-30 | Endomagnetics Ltd. | Magnetic probe apparatus |
US9808539B2 (en) | 2013-03-11 | 2017-11-07 | Endomagnetics Ltd. | Hypoosmotic solutions for lymph node detection |
US10595957B2 (en) | 2015-06-04 | 2020-03-24 | Endomagnetics Ltd | Marker materials and forms for magnetic marker localization (MML) |
US10634741B2 (en) | 2009-12-04 | 2020-04-28 | Endomagnetics Ltd. | Magnetic probe apparatus |
Families Citing this family (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19545742C2 (de) * | 1995-12-10 | 1999-10-28 | Forschungszentrum Juelich Gmbh | SQUID-System mit Vorrichtung zur Halterung eines SQUID-Stabes in einem Kryostaten |
US5880583A (en) * | 1996-12-27 | 1999-03-09 | The United States Of America As Represented By The Secretary Of Commerce | Cryogenic current comparator based on liquid nitrogen temperature superconductors |
US6181530B1 (en) * | 1998-07-31 | 2001-01-30 | Seagate Technology Llc | Heat sink for a voice coil motor |
JP2001255358A (ja) * | 2000-03-10 | 2001-09-21 | Sumitomo Electric Ind Ltd | 磁気センサ |
JP4132720B2 (ja) * | 2001-05-07 | 2008-08-13 | 独立行政法人科学技術振興機構 | 量子干渉型磁束計の製造方法 |
US6600633B2 (en) | 2001-05-10 | 2003-07-29 | Seagate Technology Llc | Thermally conductive overmold for a disc drive actuator assembly |
GB2425610A (en) | 2005-04-29 | 2006-11-01 | Univ London | Magnetic properties sensing system |
JP5022660B2 (ja) * | 2006-10-06 | 2012-09-12 | 株式会社日立ハイテクノロジーズ | 磁場計測装置 |
JP5134447B2 (ja) * | 2008-06-10 | 2013-01-30 | 国立大学法人九州工業大学 | ピストンシリンダー型の高圧力発生装置 |
EP2766648B1 (en) * | 2011-10-14 | 2019-05-29 | Fas Medic S.A. | Solenoid valve with a tube bobbin and conductor board flange |
KR101403318B1 (ko) | 2012-10-29 | 2014-06-05 | 한국표준과학연구원 | 초전도 양자 간섭 소자의 간접 냉각 장치 및 그 방법 |
KR101520801B1 (ko) * | 2013-10-24 | 2015-05-18 | 한국표준과학연구원 | Squid 센서 모듈 및 뇌자도 측정 장치 |
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JPS59127563A (ja) * | 1983-01-10 | 1984-07-23 | Hitachi Ltd | 外側ボビン付円筒状超電導コイルの製作方法 |
JPS59182512A (ja) * | 1983-04-01 | 1984-10-17 | Hitachi Ltd | クライオスタツト |
JPH02302680A (ja) * | 1989-05-17 | 1990-12-14 | Daikin Ind Ltd | グラジオメータ冷却装置 |
JPH02302682A (ja) * | 1989-05-17 | 1990-12-14 | Daikin Ind Ltd | グラジオメータ |
JPH02302681A (ja) * | 1989-05-17 | 1990-12-14 | Daikin Ind Ltd | グラジオメータ |
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DE3568086D1 (en) * | 1984-11-19 | 1989-03-09 | Siemens Ag | Production method of a three-dimensional gradiometer for an apparatus for the single or multiple channel measurement of weak magnetic fields |
US4827217A (en) * | 1987-04-10 | 1989-05-02 | Biomagnetic Technologies, Inc. | Low noise cryogenic apparatus for making magnetic measurements |
JPH063427A (ja) * | 1992-06-23 | 1994-01-11 | Fujitsu Ltd | 磁気検出装置 |
-
1992
- 1992-03-06 JP JP4049397A patent/JP2882167B2/ja not_active Expired - Fee Related
-
1993
- 1993-08-02 DE DE69310755T patent/DE69310755T2/de not_active Expired - Fee Related
- 1993-08-02 EP EP93916252A patent/EP0663599B1/en not_active Expired - Lifetime
- 1993-08-02 US US08/290,765 patent/US5666052A/en not_active Expired - Fee Related
- 1993-08-02 WO PCT/JP1993/001081 patent/WO1995004287A1/ja active IP Right Grant
-
1994
- 1994-08-23 FI FI943868A patent/FI943868A/fi unknown
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JPS59127563A (ja) * | 1983-01-10 | 1984-07-23 | Hitachi Ltd | 外側ボビン付円筒状超電導コイルの製作方法 |
JPS59182512A (ja) * | 1983-04-01 | 1984-10-17 | Hitachi Ltd | クライオスタツト |
JPH02302680A (ja) * | 1989-05-17 | 1990-12-14 | Daikin Ind Ltd | グラジオメータ冷却装置 |
JPH02302682A (ja) * | 1989-05-17 | 1990-12-14 | Daikin Ind Ltd | グラジオメータ |
JPH02302681A (ja) * | 1989-05-17 | 1990-12-14 | Daikin Ind Ltd | グラジオメータ |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9427186B2 (en) | 2009-12-04 | 2016-08-30 | Endomagnetics Ltd. | Magnetic probe apparatus |
US10634741B2 (en) | 2009-12-04 | 2020-04-28 | Endomagnetics Ltd. | Magnetic probe apparatus |
US11592501B2 (en) | 2009-12-04 | 2023-02-28 | Endomagnetics Ltd. | Magnetic probe apparatus |
US12092708B2 (en) | 2009-12-04 | 2024-09-17 | Endomagnetics Ltd. | Magnetic probe apparatus |
US9808539B2 (en) | 2013-03-11 | 2017-11-07 | Endomagnetics Ltd. | Hypoosmotic solutions for lymph node detection |
US9234877B2 (en) | 2013-03-13 | 2016-01-12 | Endomagnetics Ltd. | Magnetic detector |
US9239314B2 (en) | 2013-03-13 | 2016-01-19 | Endomagnetics Ltd. | Magnetic detector |
US9523748B2 (en) | 2013-03-13 | 2016-12-20 | Endomagnetics Ltd | Magnetic detector |
US10595957B2 (en) | 2015-06-04 | 2020-03-24 | Endomagnetics Ltd | Marker materials and forms for magnetic marker localization (MML) |
US11504207B2 (en) | 2015-06-04 | 2022-11-22 | Endomagnetics Ltd | Marker materials and forms for magnetic marker localization (MML) |
Also Published As
Publication number | Publication date |
---|---|
US5666052A (en) | 1997-09-09 |
FI943868A0 (fi) | 1994-08-23 |
EP0663599A4 (en) | 1996-03-06 |
EP0663599A1 (en) | 1995-07-19 |
EP0663599B1 (en) | 1997-05-14 |
JP2882167B2 (ja) | 1999-04-12 |
JPH05251774A (ja) | 1993-09-28 |
DE69310755T2 (de) | 1997-08-28 |
FI943868A (fi) | 1994-08-23 |
DE69310755D1 (de) | 1997-06-19 |
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