JP3379520B2 - Magnetic field measurement device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention measures a weak magnetic field in an apparatus for measuring a biomagnetic field generated from a human heart or brain, an inspection apparatus for nondestructively detecting a microcrack in a metal, and the like. Superconducting quantum interference device (SQUID: Superconducting Q)
quantum Interference Device
e) and a magnetic field measuring apparatus using the same, and more particularly, to a superconducting quantum interference device capable of canceling trapped magnetic flux and a magnetic field measuring apparatus using the same.

[0002]

2. Description of the Related Art Superconducting quantum interference devices (hereinafter referred to as SQUIDs)
Is a highly sensitive magnetic flux-voltage conversion element,
It is used as a sensor to measure a weak magnetic field in a measuring device for a magnetic field generated from the human heart or brain, an inspection device for nondestructively inspecting a microcrack in a metal, and the like. SQUI
D is Nb, YBa ₂ Cu ₃ O _7-x , Bi ₂ Sr ₂ CaCu ₂
It is generally formed on a substrate by a superconducting thin film such as O ₈ and Tl ₂ Ba ₂ CaCu ₂ O ₈ , and by cooling it below a critical temperature by putting it in a low temperature container and injecting a refrigerant, The normal state is changed to the superconducting state and the state becomes operable.

During cooling, when the SQUID is exposed to a magnetic field or exposed to strong magnetic noise in a cooled state, the magnetic flux may be confined in the superconducting thin film while interlinking (this is called “magnetic flux”). Called "trap"). When a magnetic flux trap is generated, the sensitivity of the magnetic flux-voltage conversion is reduced, and the trapped magnetic flux thermally fluctuates to generate noise, which is a major obstacle to weak magnetic field measurement.

The magnetic flux trap can be released by raising the temperature of the SQUID, temporarily changing it to normal conduction, and then cooling it again. However, temporarily removing the SQUID from the refrigerant is inefficient in working efficiency, not only costly but also dangerous. Therefore, a method of partially heating only the SQUID in the refrigerant using a heater has been proposed. There is also a method of installing a chip resistor near the SQUID substrate, but a thinner heater can be installed closer to the SQUID and can effectively heat.

Japanese Patent No. 2854663 (Prior Art 1) and Japanese Unexamined Patent Publication No. Hei 8 (1998) are known as prior arts using a thinned heater.
-78738 (Prior Art 2), IEICE Technical Report, 91, 176, pp. 43-48 (Prior Art 3) are known.

In the prior art 1, the heater is composed of a plurality of thin film resistance units, and the resistance unit is set so that the magnetic field acting on the superconducting circuit (corresponding to SQUID) by the current flowing through the plurality of resistance units becomes zero. They are close to each other.

In the prior art 2, a Josephson junction is provided in series with a feedback coil (feedback coil) which is a component of the SQUID, and the Josephson junction is used as a heater.

Prior art 3 discloses a structure in which a resistor (molybdenum) and a superconductor (Nb), which is a wiring layer having no resistance, form a two-layer film with an insulator interposed therebetween.

In prior art 2 and prior art 3, SQUID
And the heater are made of thin film on the same substrate.
The heating can be performed more efficiently than when D and the heater are formed on different substrates.

[0010]

If the heater for heating the SQUID is formed on the same substrate as the SQUID, the heating efficiency is the best. Also, considering the ease of manufacturing, SQU
It is desirable that it can be formed in the ID forming process. Further, the heater formed on the substrate is connected to the power supply of the heater installed at room temperature by the power supply line, but if the resistance of the heater is not sufficiently larger than the resistance of the power supply line, the power supply power is consumed in the power supply line. It is inefficient. In many cases, the power supply line is formed of a thin wire such as manganin and has a resistance of 10 Ω. Therefore, the resistance value of the heater needs to be about 100Ω, for example.

When the heater is the same substrate as the SQUID,
When formed in the vicinity of the UID, the wiring formed by a thin film in the substrate for connecting the heater to the power supply line and the magnetic field generated by the heater itself become a problem, and the wiring in the heater or the substrate (in the following description, There is a problem that when a wiring formed of a thin film in the substrate is simply referred to as “wiring”, it generates a magnetic field and causes a magnetic flux trap.

In a biomagnetism measuring device such as a magnetocardiography measuring device for measuring a magnetic field generated from a human heart and a magnetoencephalography measuring device for measuring a magnetic field generated from a brain, dozens to hundreds of SQUIDs are used. It will be installed. If all of the heaters installed integrally with these SQUIDs are connected to a power source at room temperature, the number of power source lines becomes enormous, and there is a problem that the heat inflow from the room temperature to the refrigerant becomes enormous. Also,
If the power supply for the heater is provided separately from the power supply for the drive circuit that drives the SQUID, the system configuration becomes complicated.

An object of the present invention is to provide an SQUID substrate having a heater having a resistance value of about 100Ω, which can be formed on the same substrate as the SQUID in the SQUID forming step, and by appropriately combining the heater and the wiring in the substrate. ，
It is an object to provide a heater module having a structure that does not generate a magnetic field, and to provide a magnetic field measuring device that has a small number of heater power supply lines and can share the power supply of a drive circuit for driving a SQUID and the power supply of a heater.

[0014]

A typical SQU of the present invention
In the ID board , the SQUID having the Josephson junction is formed on the board, and the heater is made of the superconductor which is superconducting at the operating temperature of the SQUID, and the heater is formed on the same board. Current is passed, the superconductor is transformed into normal conduction and heat is generated.
Release the magnetic flux trap. The superconductor forming the heater is made of the same material as the superconductor forming the SQUID , and the normal conductor forming the wiring is the SQUID formation process.
Since it is composed of the same material as the normal conductor used in
A heater module having a two-layer structure including a heater and wiring formed via an insulating layer can be easily formed on the substrate on which the SQUID is formed by using the manufacturing process of the QUID.

In the SQUID board of the present invention, the SQUID
A heater is formed on the same substrate as the superconducting thin film forming the SQUID. The thickness of the thin film is usually 1 μm or less.
The heater is composed of a superconducting thin film thin wire having a width of 5 μm or less, and a power source is connected to the heater to allow a current of a critical current value or more to flow, whereby the superconducting thin film thin wire is transformed into normal conduction and operates as a heater. If the SQUID superconductor is, for example, Nb, the resistance when Nb is transformed into the normal conductor is SQUI.
It is possible to realize a heater that has a larger resistance value than other metal materials used for D, for example, Al or Au. SQ
Since the manufacturing process of the UID includes the formation and processing of the superconducting thin film without exception, if the heater is manufactured using the manufacturing process of the SQUID, a high resistance heater can be realized without increasing the number of processes.

Prior art 3 discloses a configuration in which a current of a critical current value or more is passed through a Josephson junction to be used as a heater. Compared with using a point such as a Josephson junction (more precisely, a weakly coupled portion such as an oxide layer sandwiched between superconductors) as a heater, the superconducting thin film thin wire itself is used as a resistor. This has an advantage that a large resistance value can be easily realized.

In a heater module in which a heater made of a superconducting thin wire and a normal conductor wire have a two-layer structure with an insulating layer interposed therebetween, currents of opposite magnitudes and equal in magnitude flow in the heater and normal wire. Connect the heater and normal conductor wires to the power supply as shown. To make the structure simple, if at least one place is provided with a contact hole in the insulating layer and the heater and the wiring form a parallel reciprocal conducting wire in series,
When the heater and wiring are connected to the power supply, currents of equal magnitude flowing in opposite directions flow through the heater and wiring. Since the required heat is generated from the heater part, which is a superconducting thin film wire,
The wiring need not contribute to heat generation. Therefore, it is not necessary to use a high resistance material for the wiring, and it is sufficient to use an appropriate metal material used for SQUID, for example, Al or Au. Rather, it is better to make the line width of the wiring wider than that of the heater so as not to be melted by the heat generated by the heater.

The feature of the configuration of the present invention is that the superconducting thin film is used not as a wiring but as a heater.
Unlike the prior art 1, one of the two-layer structure is a wiring that does not contribute to heat generation. According to a feature of the configuration of the present invention, the wiring of the normal conductor need only be metal, and
There is no need to be limited to high resistance materials such as. SQUI
Since the step of forming D includes the steps of forming and processing a normal conductive metal without exception, a heater module that does not generate a magnetic field can be formed in the step of forming SQUID.

If the heater and the wiring have a two-layer structure, the heater portion and the wiring portion may have any individual structure, and it is not necessary to make the structure in which a magnetic field is small. It may be circular or linear, but it is practical if it is appropriately folded so that the heater module does not occupy an unnecessarily large area.

A typical magnetic field measuring apparatus of the present invention uses a plurality of SQUID substrates in which SQUIDs are formed on a substrate and a heater for transferring the SQUID to normal conduction is formed on the same substrate. However, two or more of the heaters of the plurality of SQUID boards are electrically connected in series or in parallel, and two or more heaters connected in series or in parallel form one set of wiring (one set of 2 Connected to the power supply via the power supply line of the book , the SQUID is driven by the same power supply, the superconductor that constitutes the heater is made of the same material as the superconductor that constitutes the SQUID, and the normal conduction that constitutes the wiring. The body is made of the same material as the normal conductor used in the SQUID formation process . The superconductor and the wiring that make up the heater are in electrical contact with each other at least at one point so that they are electrically in series when connected to the power source. Are equal to each other, a current exceeding the critical current value of the superconductor is passed, and SQU
The ID magnetic flux trap can be released.

Since the heaters of a plurality of SQUID boards are electrically connected in series or in parallel to each other and connected to the power source,
Multiple SQUIDs can be heated at the same time. If necessary,
All SQUIDs may be divided into a plurality of groups, and the heaters of the SQUIDs in each group may be connected in series or in parallel so as to be energized simultaneously. At this time, the number of power supplies and power supply lines for the heaters is the same as the number of groups, and the number of power supplies and power supply lines for the heater can be greatly reduced.

Further, since the resistance value of each heater is determined by the line width and length of the superconducting thin film thin wire, the resistance value of each heater can be set appropriately, and the power supply voltage of the heater can be set to the power supply of the drive circuit for driving the SQUID. Even if it is shared with, it is possible to supply sufficient electric power to each heater. Details of specific power supply voltage values, resistance values, etc. will be described later. A magnetic field measuring device with a simple structure and a small heat inflow to the refrigerant by heating the heaters of a plurality of SQUID substrates with one power source and further sharing the power source of the heaters with the power source of the drive circuit for driving the SQUIDs. Can be realized.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. In addition, in order to prevent the drawing from becoming complicated, the parts other than those to be explained in the drawing are omitted as appropriate.

(Structure of Heater and Wiring) FIG. 1 is a view for explaining an example of a heater module according to an embodiment of the present invention, which is a top view showing a heater module formed of a thin film on a substrate and its peripheral portion, 2 is a sectional view of the heater module. FIG. 2 (a) is a sectional view taken along the line AA '(pad portion) shown in FIG. 1, and FIG. 2 (b) is a sectional view taken along the line B- shown in FIG.
FIG. 2C is a cross-sectional view taken along line B ′ (connecting portion) of FIG.
FIG. 9 is a cross-sectional view taken along line CC ′ (heater module portion) shown in FIG.

As shown in FIG. 2, by sandwiching the insulating layer 13,
A resistance layer 12 is formed as a lower layer, and an Nb layer (superconducting layer) 11 is formed as an upper layer. However, the resistance layer 12 and the superconducting layer 11 are in electrical contact with each other at the contact hole 3 shown in FIG. As shown in FIG. 1, in the heater module 5, the superconducting layer and the resistance layer, both of which have a narrow line width, have a bent portion. The superconducting layer 11 forms the heater 1 and the resistance layer 12 forms the wiring 2. When a power source is connected to the pads 4 and 4 ', the heater 1 and the wiring 2 form a series circuit connected by the contact hole 3 to form a parallel reciprocating conductor. Therefore, heater 1 and wiring 2
, A current flows in the same direction but in the opposite direction, and the magnetic field generated by the heater module 5 as a whole is so small that it can be ignored.

In the following, the numerical values will be specifically described.
The configuration of the present invention is not limited to this numerical value. In the heater module 5, the heater 1 is a Nb superconducting thin film thin wire having a thickness of 250 nm, a width of 3 μm, and a length of 600.
μm. When a current exceeding the critical current value is passed through the heater 1, the heater portion has a resistance value of about 100Ω. The wiring 2 is an Al thin film having a thickness of 100 nm, a width of 8 μm, and a length of 6
It is 00 μm. The resistance value of the wiring portion is 10Ω or less, which is smaller than the resistance value of the heater portion by one digit or more. Since the current values flowing through the heater 1 and the wiring 2 are the same, the heat generation amounts of the heater and the wiring also have a difference of one digit or more, and the heat generation is mainly performed by the heater. As shown in FIGS. 2 (b) and 2 (c), the connecting portion between the heater module 5 and the pads 4 and 4 ′ is the same as the heater module 5 and is made of Nb and Al.
Although it is a layer film, the line widths of Nb and Al between the heater module 5 and the pads 4 and 4'are arbitrary as long as they are wider than the line width of the heater module portion.

In the above description, Nb, which is a metallic superconducting material, is used as the superconducting thin film material.
The superconducting material that constitutes YBa ₂ Cu ₃ O _7-x , Bi ₂ S
In the case of oxide-based superconducting thin films such as r ₂ CaCu ₂ O ₈ and Tl ₂ Ba ₂ CaCu ₂ O ₈ , these oxide-based superconducting thin films are processed into a thin wire to form a metal-based superconducting material. The heater module can be constructed in the same manner as when it is used.

That is, the superconductor is a superconductor having a width of 5 μm or less and / or a thickness of 1 μm or less and containing any one of niobium, a niobium compound, yttrium, bismuth, and thallium (a metal-based superconducting thin film, or an oxide. (A superconducting thin film).

(Structure of SQUID Substrate) FIG. 3 shows an SQUID board according to an embodiment of the present invention and an SQUID board equipped with a heater module.
FIG. 4 is a top view of the QUID board, and FIG. 4 is a view showing an outline of a cross section of the SQUID board. As shown in FIG. 4, SQUI
The layer 16 on which D and the heater module are formed is formed on the silicon substrate 15 via the insulating layer 14.

As shown in FIG. 3, the SQUID portion has a well-known structure and comprises a washer ring 21, a Josephson junction 22, an input coil 23, and a feedback coil 24. Figure 3
Are electrode pads 6 and 7 for supplying a bias current to the SQUID, electrode pads 6'for measuring the output voltage,
7 ', pads 8, 8'connecting the input coil 23 and the detection coil, and pads 9, 9'connecting the feedback coil 24 and a drive circuit for driving the SQUID.

FIG. 5 is a view for explaining the relationship between the superconducting layer and the resistance layer, and is a perspective view showing the structure of the SQUID substrate according to the embodiment of the present invention layer by layer. Actually, the SQUID is formed by a larger number of layers, but it is omitted in FIG. 5 as appropriate. The SQUID washer ring 21 and the Josephson junction 22 are formed in the superconducting layer 10. Superconducting layer 1
There is a resistance layer 12 on the surface of the heater module 0, and the wiring 2 of the heater module 5 is formed. Although it is not shown in FIG. 5 because it is small,
The resistance in the SQUID called shunt resistance or damping resistance is also formed by the resistance layer 12. On the resistance layer 12,
There is another superconducting layer 11 and the SQUID input coil 23
The heater 1 is formed together with the feedback coil 24. There is an insulating layer (not shown in FIG. 5) between the layers, and contact holes are opened in necessary portions. As is clear from the configuration of FIG. 5, the heater module 5 can be easily formed without increasing the number of SQUID manufacturing steps.

As shown in FIG. 3, the heater module 5 is arranged in the vicinity of the Josephson junction 22 for the following two reasons. The first reason is to efficiently heat the Josephson junction where the influence of the magnetic flux trap is greatest. The magnetic flux may be trapped anywhere in the superconducting thin film, but the most practical obstacle is SQ.
It is a trap to the Josephson junction that reduces the sensitivity of the UID's flux-voltage conversion. The second reason is that a temperature gradient is generated during recooling of the washer ring portion. It is well known in the related art 1, the related art 3 and the like that when the SQUID is heated to release the trap, it is particularly effective to cool the SQUID so as to have a temperature gradient during recooling.

FIG. 6 is a diagram showing measured values showing the relationship between the heating power and the inter-terminal resistance of the SQUID when the SQUID is heated using the heater module in the SQUID board having the structure shown in FIG. The results shown in FIG. 6 are obtained by applying a constant bias current using the SQUID electrode pads 6 and 7 shown in FIG. 3 and measuring the voltage between the electrode pads 6 ′ and 7 ′ for measuring the output voltage. However, this is the result obtained by applying a current to the heater module 5 to heat the SQUID. When the SQUID is heated and the temperature rises and the superconductivity is lost, the sensitivity disappears and the resistance between terminals increases, so the results shown in Fig. 6 indicate that the power required to eliminate the superconductivity of the SQUID Desired. From FIG. 6, the heating power that causes the loss of sensitivity and the increase in the inter-terminal resistance of the SQUID is 230 mW or more, and the heater module 5 has a minimum of 2
It can be seen that the superconductivity of SQUID disappears and the magnetic flux trap can be released by applying a heating power of 30 mW.

(Mounting of SQUID Substrate) FIG. 7 is a perspective view showing a configuration example of the SQUID magnetometer 50 of the embodiment of the present invention. The SQUID substrate 20 on which the heater module 5 is formed is connected to the detection coil 31. Detection coil 3
1 cut a groove in a resin bobbin 40 with a diameter of 18 mm,
The groove is formed by winding a Nb-Ti wire. SQ shown in FIG.
The configuration of the UID magnetometer 50 is a so-called gradiometer configuration for measuring a differential magnetic field in space in order to remove the environmental noise magnetic field, and the sensing coil 31a and the cancellation coil 31b are wound in opposite directions. . The SQUID board 20 is bonded to a mounting board 33 having a connector 34, and each pad of the SQUID board 20 is connected to an electrode of the mounting board 33 by wire bonding.

The pads 8 and 8'shown in FIG. 3 for connecting the input coil 23 and the detection coil 31 are Pb-In-Au.
Is superconductingly connected to the superconducting wire 17 of the detection coil 31 via the superconducting bonding wire, and the pads other than the pads 8 and 8'are connected to the connector 34 via the Al bonding wire and the electrode of the mounting substrate 33. It Since the heater module 5 is formed on the SQUID board 20, it is only necessary to bond the SQUID board 20 to the mounting board 33, and the SQUID magnetometer 50 can be manufactured with a simple configuration with a small number of parts.

(Arrangement of SQUID magnetometer and wiring of heater) FIG. 8 shows an arrangement example of the SQUID magnetometer 50 shown in FIG. 7 arranged at the bottom of the cryogenic container of the magnetocardiography device and an example of wiring to the heater. It is a figure explaining. With a magnetocardiography device,
The layout of the SQUID magnetometer is flat, for example, 8
They are arranged in a matrix of × 8 pieces and are installed at the bottom of a cryogenic container filled with a refrigerant to form an array of SQUID magnetometers (sensor array). 64 SQUIDs in total
The magnetometer is divided into eight groups, and the heaters in each group are wired so as to be electrically parallel to each other. In FIG. 8, only one group of wires is shown.

As shown in FIG. 8, is eight heaters two?
Ranaru a pair of power supply lines (set two power lines) 18
Is connected to the power supply 100 at room temperature via. The material of the power supply line 18 that connects between the room temperature and the refrigerant needs to be a metal having a small thermal conductivity, and in the example shown in FIG. 8, manganin wire is used. Manganin wire has a large electrical resistance and is 1m long
Is about 15Ω. Therefore, if the resistance of each heater is small, most of the electric power will be consumed by the manganin wire on the way, and the heat generation of the heater will be insufficient. However, if the heater module having the configuration shown in FIG.
Since it has a resistance of 00Ω, the current flowing through each heater is 55 mA and the amount of heat generated by each heater is 300 mW even when the power source (12 V power source) of the drive circuit that drives the SQUID is used as the power source. As shown in FIG. 6, the SQUID is sufficiently heated by the heating power of 300 mW, and the magnetic flux trap can be released.

Although not shown, the same effect can be expected if the heaters in the group are electrically connected in series. In this case, the number of SQUID magnetometers in one group is 16, and the resistance value of each heater is 80Ω.
To be Specifically, in the heater module shown in FIG. 1, the thickness and line width of the thin film of the heater and the wiring may be the same, and only the length may be 480 μm. The heater power supply voltage is set to 100 V, which is the same as the commercial power supply voltage. In this case, the current flowing through each heater is 55 mA, and the heating power for each heater is 240 mW. As shown in FIG. 6, the magnetic flux trap can be released even with the heat generation of 240 mW.

In the example described above, even if there is only one SQUID trapped by the magnetic flux, there are 8 or 16 SQUIDs.
The ID is heated, but there is no problem in practical use. Further, it is realistic that the switch 19 for heating is controlled to be opened and closed by a control computer.

(Cardiomagnetism measuring device, magnetoencephalography measuring device) FIG.
It is a figure which shows the structural example of a magnetocardiography measuring device as an example of the magnetic field measuring device which uses the SQUID magnetometer of the Example of this invention. The array (sensor array) of the SQUID magnetometer 50 shown in FIG. 8 is a cryogenic container 200 filled with liquid helium.
It is installed at the bottom of. The cryogenic container 200 is installed in the magnetically shielded room 160.
The inside of 60 is monitored by the camera 150. Outside the magnetically shielded room 160, a drive circuit 110 for driving the SQUID, a control / data collection computer (signal collection means) 130, and an analysis computer 140 are installed. An electrocardiograph 120 is also installed, and electrocardiographic data is collected by the control and data collecting computer 130 together with the measurement data of the cardiac magnetic field. The power source 100 that supplies power to the heater module is 12V, which is shared with the power source of the drive circuit that drives the SQUID. Power supply 100
From this, eight sets of 16 power supply lines 18 extend to the sensor array, and each power supply line shunts near the sensor array to supply power to eight heater modules connected in parallel. The power supply to the heater module is controlled by the control and data collection computer 130 for each sensor group.

FIG. 10 is a diagram showing a configuration example of a magnetoencephalography measuring apparatus as an example of a magnetic field measuring apparatus using the SQUID magnetometer of the embodiment of the present invention.

In the magnetoencephalography apparatus, an array (sensor array) of SQUID magnetometers 50 shown in FIG. 8 is arranged in a spherical shape in accordance with the shape of the skull. There are many SQUID magnetometers 50, and 128 of them are installed. An electroencephalograph 170 is installed instead of the electrocardiograph shown in FIG. Although it is necessary to give a stimulus to a subject in the brain magnetic field measurement, a small speaker 190 and an acoustic device 180 for auditory stimulation are illustrated here. The configuration other than this is the same as that of the magnetocardiography device shown in FIG. 9, and 16 sets of 32 power supply lines 18 extend from the power supply 100 supplying power to the heater module to the sensor array, and each power supply line is a sensor. The current is divided near the array and power is supplied to eight heater modules connected in parallel.

In the above-described magnetocardiography and magnetoencephalography measurement apparatus, it is not necessary to newly provide a power source for supplying power to the heater module, and the SQUID magnetic flux trap can be released with a simple structure. Is. Further, the number of power supply lines is only 1/8 of the case where electric power is supplied to each SQUID magnetometer, and the thermal evaporation amount of the refrigerant can be suppressed.

[0044]

According to the present invention, a SQUID capable of releasing a magnetic flux trap and an SQUID magnetometer using the same can be realized without increasing the number of manufacturing steps.
Using a magnetometer, it is possible to realize a magnetic field measurement device that can release the magnetic flux trap without increasing the new power supply.

[Brief description of drawings]

FIG. 1 is a top view showing an example of a heater module according to an embodiment of the present invention and its peripheral portion.

2 is a cross-sectional view of a heater module of an embodiment of the present invention, (a) is a cross-sectional view taken along the line AA ′ shown in FIG.
1B is a sectional view taken along the line BB 'shown in FIG. 1, and FIG. 1C is a sectional view taken along the line CC' shown in FIG.

FIG. 3 is a top view of an SQUID board on which an SQUID and a heater module according to an embodiment of the present invention are mounted.

FIG. 4 is a diagram schematically showing a cross section of an SQUID board according to an embodiment of the present invention.

FIG. 5 is a perspective view showing the layers of the SQUID substrate according to the embodiment of the present invention.

FIG. 6 is a diagram showing measured values showing a relationship between heating power and inter-terminal resistance of SQUID when the SQUID is heated using a heater module in the SQUID board having the configuration shown in FIG.

FIG. 7 is a perspective view showing a configuration example of an SQUID magnetometer according to an embodiment of the present invention.

FIG. 8 is a diagram illustrating an arrangement example of SQUID magnetometers arranged at the bottom of a cryogenic container and an example of wiring to a heater in a magnetocardiographic apparatus using the SQUID magnetometer of FIG. 7.

FIG. 9 is a diagram showing a configuration example of a magnetocardiography measuring apparatus according to an embodiment of the present invention.

FIG. 10 is a diagram showing a configuration example of a magnetoencephalography measuring apparatus according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Heater, 2 ... Wiring, 3 ... Contact hole, 4, 4
... Heater module electrode pad, 5 ... Heater module, 6,6 ... SQUID electrode pad, 7,7 ... SQU
ID electrode pad, 8, 8 ... Input coil pad, 9,
9 ... Feedback coil pad, 10 ... Superconducting layer, 11 ... Superconducting layer, 12 ... Resistive layer, 13 ... Insulating layer, 14 ... Insulating layer, 1
5 ... Silicon substrate, 16 ... SQUID, and layer on which heater module is formed, 17 ... Superconducting wire, 18 ... Power line, 19 ... Switch, 20 ... SQUID substrate, 2
1 ... Washer ring, 22 ... Josephson junction, 23 ...
Input coil, 24 ... Feedback coil, 31 ... Detection coil, 3
1a ... Sensing coil, 31b ... Cancellation coil, 33 ... Mounting board, 34 ... Connector, 40 ... Bobbin, 50 ... Sensor, 100 ... Heater and drive circuit power supply, 110 ... Drive circuit, 120 ... Electrocardiograph, 130 ... Computer for control and data collection, 140 ... Analysis computer, 150 ... Monitor camera, 160 ... Shield room, 170 ... EEG, 180 ... Acoustic device, 190 ... Speaker, 200 ... Cryogenic container.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiichi Ukai 882 Ichige, Hitachinaka-shi, Ibaraki Hitachi Ltd. Measuring Instruments Group (56) Reference JP-A-8-51237 (JP, A) JP 6-5932 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 33/035 ZAA H01L 39/22 ZAA

Claims (11)

(57) [Claims] 1. A SQUID having a Josephson junction,
Superconductivity that becomes superconductivity at the operating temperature of the SQUID
It consists of a body, a heater to transfer at least a portion of the SQUID in the normal conducting when current flows, the superconducting
A plurality of SQUID boards each having a body and a wiring composed of a normal conductor via an insulator, and two or more of the heaters of the plurality of SQUID boards are electrically connected in series or in parallel, and are connected in series. or two or more of the heaters connected in parallel have a a power supply connected through a pair of power line consisting of two, each other the wire and the superconductor
A magnetic field measuring device characterized in that currents of the same magnitude are applied in opposite directions . 2. The magnetic field measuring device according to claim 1, wherein:
A magnetic field measuring apparatus characterized in that the width of the wiring is wider than the line width of the superconductor . 3. The magnetic field measuring device according to claim 1, wherein:
The superconductor forming the heater is the SQUID.
Is composed of the same material as the superconductor that constitutes
The normal conductor constituting the SQUID is formed in the step of forming the SQUID.
A magnetic field measuring device characterized by being made of the same material as the normal conductor used . 4. A SQUID having a Josephson junction,
Superconductivity that becomes superconductivity at the operating temperature of the SQUID
It is composed of the body, and the SQUID is
A heater for converting at least a part of the superconductivity
Body and wiring composed of normal conductor through insulator
A plurality of SQUID boards and the plurality of SQUID groups
Two or more of the plate heaters are electrically in series or parallel
Two or more fronts connected in series and connected in series or parallel
Connected via a pair of power lines consisting of two heaters
Connected to the power source and the superconductor and the wiring.
At least one place so that it will be electrically connected in series when continued
A magnetic field measuring device characterized by being in electrical contact . 5. The magnetic field measuring device according to claim 4,
A magnetic field measuring apparatus characterized in that the width of the wiring is wider than the line width of the superconductor . 6. The magnetic field measuring device according to claim 4,
The superconductor forming the heater is the SQUID.
Is composed of the same material as the superconductor that constitutes
The normal conductor constituting the SQUID is formed in the step of forming the SQUID.
A magnetic field measuring device characterized by being made of the same material as the normal conductor used . 7. A SQUID having a Josephson junction,
Superconductivity that becomes superconductivity at the operating temperature of the SQUID
Through a heater composed of a body and the superconductor and insulator
SQUID group having wiring composed of a normal conductor
Multiple equipped with a plate to detect the magnetic field generated from the inspection object
Cool the SQUID magnetometer and the SQUID magnetometer
Cryogenic container and drive circuit for driving the SQUID magnetometer
And a power supply connected to the drive circuit and the heater
And the superconductor forming the heater is
Made of the same material as the superconductor that makes up the QUID,
The normal conductor forming the wiring is in the form of the SQUID.
It is composed of the same material as the normal conductor used in the formation process,
The superconductor and the wiring that compose the heater are the power source.
At least one so that it is electrically connected in series when connected to
That are in electrical contact with the
The superconductor and the wiring are in opposite directions and have the same size,
A current greater than the critical current value of the superconductor is applied, and the S
A magnetic field measuring device characterized by releasing a magnetic flux trap of a QUID . 8. The magnetic field measuring device according to claim 7,
The superconductor has a width of 5 μm or less and / or a thickness of 1 μm or less.
Below, niobium, niobium compounds, yttrium, bis
Formed by thin wire of superconductor containing either mass or thallium
A magnetic field measuring device characterized by being formed. 9. The magnetic field measuring apparatus according to claim 7,
The width of the wiring is different from that of the superconductor that constitutes the heater.
A magnetic field measuring device characterized by being wider than the line width . 10. The magnetic field measuring apparatus according to claim 7.
And the SQUID is driven by the power source . 11. The magnetic field measuring device according to claim 7.
A magnetic field measuring device , wherein the voltage of the power supply is the same as the commercial power supply voltage .