JP2008170164A - Magnetometric sensor - Google Patents

Magnetometric sensor Download PDF

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JP2008170164A
JP2008170164A JP2007001006A JP2007001006A JP2008170164A JP 2008170164 A JP2008170164 A JP 2008170164A JP 2007001006 A JP2007001006 A JP 2007001006A JP 2007001006 A JP2007001006 A JP 2007001006A JP 2008170164 A JP2008170164 A JP 2008170164A
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magnetic
squid
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Shinya Kuriki
栗城眞也
Mizufumi Matsuda
松田瑞史
Satoru Hirano
悟 平野
Shigetoshi Oshima
大嶋重利
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact superconducting quantum interference device (SQUID) magnetic sensor resistant to external magnetic noise which keeps a transmission efficiency of magnetic signals, heightened by making a signal transmission circuit include a magnetic substance having, such a structure as to form a closed magnetic path interlinked with an SQUID and prevents transmission efficiency from degrading, even if a magnetic shield is arranged close to the signal transmission circuit or integrated with the signal transmission circuit in a SQUID magnetic sensor circuit. <P>SOLUTION: The signal transmission circuit 5 includes a magnetic substance, having such a structure as to form a closed magnetic path interlinked with an SQUID 1, and part or the whole of its closed magnetic path structure is constituted, in such way as to form a magnetic shield 7. Since the closed magnetic path by magnetic signals is interlinked with the SQUID 1, the leakage of a signal magnetic flux is reduced to achieve a high signal transmission efficiency, and the capture of a magnetic flux to a superconducting membrane, constituting the SQUID 1, is prevented by the magnetic shield 7 to prevent sensitivity degradation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、超伝導量子干渉素子（ＳＱＵＩＤ）を用いた高感度測定機器に関するものである。   The present invention relates to a high sensitivity measuring instrument using a superconducting quantum interference device (SQUID).

図２は従来の超伝導量子干渉素子（Ｓｕｐｅｒｃｏｎｄｕｃｔｉｎｇ ＱＵａｎｔｕｍ Ｉｎｔｅｒｆｅｒｅｎｃｅ Ｄｅｖｉｃｅ， ＳＱＵＩＤ）を用いた磁気センサ回路を説明する模式図であり、例えば下記の非特許文献１に記載されている。図２の中で、１はＳＱＵＩＤを表す。 FIG. 2 is a schematic diagram for explaining a magnetic sensor circuit using a conventional superconducting quantum interference device (SQUID), which is described, for example, in Non-Patent Document 1 below. In FIG. 2, 1 represents a SQUID.

超伝導量子干渉素子（ＳＱＵＩＤ）１は、超伝導体からなるリングに一つまたは二つのジョセフソン接合を含み、リングに鎖交する磁束の大きさを電圧に変換する素子である。一般にＳＱＵＩＤの磁束−電圧変換係数は非線形であるので、図２が示すように、通常ＳＱＵＩＤをゼロ検出素子として用いたフィードバック・ループ（Ｆｌｕｘ−ｌｏｃｋｅｄ ｌｏｏｐ， ＦＬＬ回路）により線形応答する磁束計を構成する。２はＦＬＬ回路を表す。図２におけるＦＬＬ回路は変調型と呼ばれ、この他、非変調型のＦＬＬ回路もある。本発明の磁気センサにおけるＦＬＬ回路は、変調型・非変調型のいずれでもかまわない。 A superconducting quantum interference device (SQUID) 1 is an element that includes one or two Josephson junctions in a ring made of a superconductor, and converts the magnitude of magnetic flux linked to the ring into a voltage. Since the SQUID flux-voltage conversion coefficient is generally non-linear, as shown in FIG. 2, a magnetic flux meter that linearly responds is configured by a feedback loop (Flux-locked loop, FLL circuit) that normally uses a SQUID as a zero detection element. To do. 2 represents an FLL circuit. The FLL circuit in FIG. 2 is called a modulation type, and there are other non-modulation type FLL circuits. The FLL circuit in the magnetic sensor of the present invention may be either a modulation type or a non-modulation type.

ＳＱＵＩＤ１そのものを磁気信号検出素子として使用する場合もあるが、多くの場合、ＳＱＵＩＤ１の外部に磁気信号を検出する回路を設け、検出した磁気信号をＳＱＵＩＤ１に伝達する回路構成をとる。図３は、そのような回路構成を説明する模式図である。図３が示すように、通常、磁気信号を検出する回路（例えば、コイルや平面回路。以下、まとめて検出コイルという。３は検出コイルを表す）には、検出した磁気信号をＳＱＵＩＤ１に伝達する回路（例えば、コイルや平面回路。以下、まとめて入力コイルという。４は入力コイルを表す）が接続されている。検出コイル３と入力コイル４およびそれらを接続する導線をまとめて信号伝達回路という。５は信号伝達回路を表す。信号伝達回路５は、常伝導金属線または超伝導線で構成される。 In some cases, the SQUID 1 itself is used as a magnetic signal detection element. In many cases, a circuit for detecting a magnetic signal is provided outside the SQUID 1 and the detected magnetic signal is transmitted to the SQUID 1. FIG. 3 is a schematic diagram for explaining such a circuit configuration. As shown in FIG. 3, normally, a detected magnetic signal is transmitted to the SQUID 1 in a circuit that detects a magnetic signal (for example, a coil or a planar circuit; hereinafter collectively referred to as a detection coil. 3 represents a detection coil). A circuit (for example, a coil or a planar circuit. Hereinafter, collectively referred to as an input coil. 4 represents an input coil) is connected. The detection coil 3 and the input coil 4 and the conductive wires connecting them are collectively referred to as a signal transmission circuit. Reference numeral 5 denotes a signal transmission circuit. The signal transmission circuit 5 is composed of a normal metal wire or a superconductive wire.

入力コイル４とＳＱＵＩＤ１との間の相互インダクタンスＭの大きさが、磁気信号の伝達効率を決定する。伝達効率を大きくするためには、相互インダクタンスＭを出来るだけ大きくすることが必要である。そのためには、入力コイル４に生じる磁束のすべてがＳＱＵＩＤ１に鎖交し、磁束の漏洩が極力生じない構造をとることが望ましい。これは、入力コイル４に生じる磁力線がＳＱＵＩＤ１に鎖交し、かつ閉磁路となるように透磁率の大きな磁性体を配置することで解決される。 The magnitude of the mutual inductance M between the input coil 4 and SQUID 1 determines the transmission efficiency of the magnetic signal. In order to increase the transmission efficiency, it is necessary to increase the mutual inductance M as much as possible. For this purpose, it is desirable to adopt a structure in which all of the magnetic flux generated in the input coil 4 is linked to the SQUID 1 so that leakage of the magnetic flux does not occur as much as possible. This can be solved by arranging a magnetic material having a high magnetic permeability so that the magnetic field lines generated in the input coil 4 are linked to the SQUID 1 and become a closed magnetic path.

図４は、入力コイル４に生じる磁力線がＳＱＵＩＤ１に鎖交し、かつ閉磁路となるように透磁率の大きな磁性体６を配置した模式図である。ところが、図４に示すように、超伝導量子干渉素子（ＳＱＵＩＤ）１は、通常、高透磁率の磁性体から成る磁気遮蔽７を必要とし、磁気遮蔽７も高透磁率の磁性体であるが故に、磁気遮蔽７が入力コイル４近傍に設けられた場合、入力コイル４に生じる磁束の一部は、ＳＱＵＩＤ１に鎖交せず、磁気遮蔽７を構成する磁性体中に漏洩する結果となる。即ち、図４のような構成では、伝達効率の大きな信号伝達回路５と磁気遮蔽７とを、実用的寸法まで近接して配置することが出来ない。これは、磁気遮蔽７の大型化を意味し、小型ＳＱＵＩＤ磁気センサシステムの実現の大きな妨げとなる。 FIG. 4 is a schematic diagram in which the magnetic body 6 having a high magnetic permeability is arranged so that the magnetic field lines generated in the input coil 4 are linked to the SQUID 1 and become a closed magnetic circuit. However, as shown in FIG. 4, the superconducting quantum interference device (SQUID) 1 normally requires a magnetic shield 7 made of a high permeability magnetic material, and the magnetic shield 7 is also a high permeability magnetic material. Therefore, when the magnetic shield 7 is provided in the vicinity of the input coil 4, a part of the magnetic flux generated in the input coil 4 does not interlink with the SQUID 1 and leaks into the magnetic body constituting the magnetic shield 7. That is, in the configuration as shown in FIG. 4, the signal transmission circuit 5 and the magnetic shield 7 having high transmission efficiency cannot be arranged close to practical dimensions. This means an increase in the size of the magnetic shield 7, which greatly hinders the realization of a small SQUID magnetic sensor system.

超伝導量子干渉素子（ＳＱＵＩＤ）１が磁気遮蔽７を必要とする理由は、素子の冷却時に環境磁場による磁束が超伝導リングを構成する超伝導薄膜内に捕獲され、その捕獲された磁束のつくる磁場の影響でＳＱＵＩＤに含まれるジョセフソン接合の臨界電流が小さくなったり、超伝導リングを構成する超伝導薄膜内に捕獲された磁束量子の熱揺らぎ運動による低周波雑音が増加したりするためである。いずれの現象も、ＳＱＵＩＤの感度が劣化する原因となる。このような現象は、例えば下記の非特許文献２に記載されている。 The reason why the superconducting quantum interference device (SQUID) 1 requires the magnetic shield 7 is that when the device is cooled, the magnetic flux by the environmental magnetic field is captured in the superconducting thin film constituting the superconducting ring, and the captured magnetic flux is generated. This is because the critical current of the Josephson junction included in the SQUID is reduced due to the influence of the magnetic field, and the low frequency noise due to the thermal fluctuation motion of the flux quanta trapped in the superconducting thin film constituting the superconducting ring is increased. is there. Either phenomenon causes the sensitivity of the SQUID to deteriorate. Such a phenomenon is described in Non-Patent Document 2 below, for example.

超伝導量子干渉素子（ＳＱＵＩＤ）のなかには、システムの簡素化のために、磁気遮蔽７を配置することなく動作させるよう設計・製作されたものもある。そのようなタイプのＳＱＵＩＤ磁気センサは、例えば下記の非特許文献１に記載されている。しかし、磁気遮蔽７を施さない場合のＳＱＵＩＤ磁気センサは、一般に、磁気遮蔽７を施したものと比較して感度が悪く、また、ＳＱＵＩＤ磁気センサ出力に大きな磁気雑音成分を含み、信号との分離が困難になることが多い。従って、高感度磁気センサであるＳＱＵＩＤを応用する場合には、遮蔽効率が高くかつ簡素な構造の磁気遮蔽７を持つことが望ましい。 Some superconducting quantum interference devices (SQUIDs) are designed and manufactured to operate without the magnetic shield 7 in order to simplify the system. Such a type of SQUID magnetic sensor is described in Non-Patent Document 1, for example. However, the SQUID magnetic sensor without the magnetic shield 7 is generally less sensitive than the magnetic sensor with the magnetic shield 7, and the SQUID magnetic sensor output includes a large magnetic noise component and is separated from the signal. Is often difficult. Therefore, when applying a SQUID that is a high-sensitivity magnetic sensor, it is desirable to have a magnetic shield 7 with a high shielding efficiency and a simple structure.

結局、従来の技術によれば、伝達効率の大きな信号伝達回路を得るためにＳＱＵＩＤと鎖交する閉磁路を構成する構造と、ＳＱＵＩＤの高感度を維持するために必要な磁気遮蔽７とを、実用的寸法で近接して配置することが出来ない。このような問題から、これまで数多くの研究者達によって様々な試みがなされてきたにもかかわらず、小型で実用的な高感度ＳＱＵＩＤ磁気センサシステムの成功例は未だ報告されていないのが現状である。
Ｊ． Ｃｌａｒｋｅ ａｎｄ Ａ． Ｉ． Ｂｒａｇｉｎｓｋｉ ｅｄｓ．， Ｔｈｅ ＳＱＵＩＤ Ｈａｎｄｂｏｏｋ， Ｖｏｌ． １， Ｗｉｌｅｙ−ＶＣＨ， ２００４． Ｔ． Ｋｏｂａｙａｓｈｉ， Ｈ． Ｈａｙａｋａｗａ， Ｍ． Ｔｏｎｏｕｃｈｉ ｅｄｓ．， Ｖｏｒｔｅｘ Ｅｌｅｃｔｒｏｎｉｃｓ ａｎｄ ＳＱＵＩＤｓ， Ｓｐｒｉｎｇｅｒ， ２００３． Eventually, according to the prior art, a structure that forms a closed magnetic circuit interlinking with the SQUID to obtain a signal transmission circuit with high transmission efficiency, and a magnetic shield 7 that is necessary to maintain the high sensitivity of the SQUID, Cannot be placed close together with practical dimensions. Due to such problems, despite the many attempts made by many researchers so far, no successful examples of small and practical high-sensitivity SQUID magnetic sensor systems have yet been reported. is there.
J. et al. Clarke and A.C. I. Braginski eds. The SQUID Handbook, Vol. 1, Wiley-VCH, 2004. T.A. Kobayashi, H .; Hayagawa, M .; Tonouchi eds. , Vortex Electronics and SQUIDs, Springer, 2003.

高感度ＳＱＵＩＤ磁気センサにおいて、信号伝達回路５にＳＱＵＩＤと鎖交する閉磁路をつくる構造を含ませることで磁気信号の伝達効率を高め、かつ、磁気遮蔽７を信号伝達回路５の近傍に配置もしくは信号伝達回路５と一体としても伝達効率が劣化せず、外部磁気雑音に強く小型なＳＱＵＩＤ磁気センサを実現する。 In the high-sensitivity SQUID magnetic sensor, the signal transmission circuit 5 includes a structure that forms a closed magnetic circuit interlinking with the SQUID, thereby increasing the transmission efficiency of the magnetic signal, and the magnetic shield 7 is disposed in the vicinity of the signal transmission circuit 5 or Even if it is integrated with the signal transmission circuit 5, the transmission efficiency is not deteriorated, and a small SQUID magnetic sensor resistant to external magnetic noise is realized.

上記課題の解決は、信号伝達回路５にＳＱＵＩＤ１と鎖交する閉磁路をつくる構造をもつ磁性体を含み、その閉磁路構造の一部もしくは全部が磁気遮蔽７をなすことを特徴とするＳＱＵＩＤ磁気センサにより達成される。磁気信号による閉磁路がＳＱＵＩＤ１と鎖交するため、信号磁束の漏洩は抑制され、高い信号伝達効率が達成される。また、磁気遮蔽７によりＳＱＵＩＤ１の超伝導リングを構成する超伝導薄膜への磁束の捕獲が抑制され、感度の劣化は生じない。   A solution to the above problem is that the SQUID magnetism is characterized in that the signal transmission circuit 5 includes a magnetic body having a structure that forms a closed magnetic circuit interlinking with the SQUID 1, and a part or all of the closed magnetic circuit structure forms a magnetic shield 7. Achieved by sensor. Since the closed magnetic path by the magnetic signal is linked to SQUID1, leakage of the signal magnetic flux is suppressed, and high signal transmission efficiency is achieved. Further, the magnetic shielding 7 suppresses the trapping of the magnetic flux to the superconducting thin film constituting the superconducting ring of SQUID1, and the sensitivity does not deteriorate.

従来の技術において、磁気信号の伝達効率を高めるために高透磁率の磁性体を利用する信号入力方式が、磁気遮蔽７の近接配置を妨げていた根本原因は、信号伝達回路５において閉磁路を構成する磁性体と、磁気遮蔽７を構成する磁性体とが分離されているためであり、本発明は、閉磁路を構成する磁性体の一部もしくは全部を磁気遮蔽とすることで両者を一体とし、近接配置を妨げる根本原因を取り除く。これにより、小型で実用的な高感度ＳＱＵＩＤ磁気測定システムを実現することが可能となる。   In the prior art, a signal input method using a magnetic material having a high magnetic permeability in order to increase the transmission efficiency of a magnetic signal has hindered the close arrangement of the magnetic shield 7. This is because the constituting magnetic body and the magnetic body constituting the magnetic shield 7 are separated from each other, and the present invention integrates both by making a part or all of the magnetic body constituting the closed magnetic path a magnetic shield. And remove the root cause that hinders close placement. This makes it possible to realize a small and practical high-sensitivity SQUID magnetic measurement system.

図１は、本発明の信号伝達回路５にＳＱＵＩＤ１と鎖交する閉磁路をつくる構造をもつ磁性体を含み、その閉磁路構造の一部もしくは全部が磁気遮蔽７をなすＳＱＵＩＤ磁気センサを説明する模式図である。検出コイル３によって検出された磁気信号は、信号伝達回路５によって入力コイル４に電流として伝達される。この電流によって入力コイル４に生じる磁場の磁力線は、ＳＱＵＩＤ１に鎖交しかつ閉磁路を形成するように配置された透磁率の大きな磁性体６によって、実用上漏洩なくＳＱＵＩＤ１に伝達される。図１から明らかなように、磁性体６は、入力コイル４のコアと閉磁路を形成する磁気回路８および磁気遮蔽７の機能を併せ持っている。従って、信号磁束の漏洩は抑制され、高い信号伝達効率が達成される。また、磁気遮蔽７によりＳＱＵＩＤ１を構成する超伝導薄膜への磁束の捕獲が抑制され、感度の劣化は生じない。   FIG. 1 illustrates a SQUID magnetic sensor in which the signal transmission circuit 5 of the present invention includes a magnetic body having a structure that forms a closed magnetic circuit that is linked to SQUID 1, and part or all of the closed magnetic circuit structure forms a magnetic shield 7. It is a schematic diagram. The magnetic signal detected by the detection coil 3 is transmitted as a current to the input coil 4 by the signal transmission circuit 5. The magnetic field lines generated in the input coil 4 by this current are transmitted to the SQUID 1 practically without leakage by the magnetic body 6 having a high magnetic permeability arranged so as to be linked to the SQUID 1 and form a closed magnetic circuit. As is clear from FIG. 1, the magnetic body 6 has the functions of a magnetic circuit 8 and a magnetic shield 7 that form a closed magnetic path with the core of the input coil 4. Therefore, leakage of signal magnetic flux is suppressed, and high signal transmission efficiency is achieved. Further, the magnetic shield 7 suppresses the trapping of the magnetic flux to the superconducting thin film constituting the SQUID 1, and the sensitivity does not deteriorate.

図１から明らかなように、入力コイル４のコアと閉磁路を形成する磁気回路８および磁気遮蔽７として働く磁性体６は、電子回路のインダクタ素子で使われる、いわゆるポット・コアと同様の形状をなしている。高透磁率の磁性体で作られたポット・コアの内部のコアの周りに入力コイル４が巻かれ、内部のコアのギャップの中にＳＱＵＩＤ１を配置することで閉磁路が形成され、また、ポット・コアの外側の磁性体が磁気遮蔽７を形成する。 As is apparent from FIG. 1, the magnetic circuit 8 that forms a closed magnetic circuit with the core of the input coil 4 and the magnetic body 6 that acts as the magnetic shield 7 have the same shape as a so-called pot core used in an inductor element of an electronic circuit. I am doing. An input coil 4 is wound around an inner core of a pot core made of a magnetic material having a high magnetic permeability, and a closed magnetic circuit is formed by disposing SQUID 1 in the gap of the inner core. The magnetic body outside the core forms the magnetic shield 7.

本発明における要点は、閉磁路を構成する磁性体の一部もしくは全部を磁気遮蔽とすることで両者を一体とし、近接配置を妨げる根本原因を取り除く点であるが、ここでいう一体とは、磁気回路を形成する上で一体といえる意味であり、強い磁気結合で単一の磁気回路を形成している限り、機械的に一体である必要はない。 The main point in the present invention is that the magnetic material constituting part of the closed magnetic circuit is partly or entirely magnetically shielded so that both are integrated, and the root cause that hinders proximity arrangement is removed. This means that the magnetic circuit is integrated, and as long as a single magnetic circuit is formed by strong magnetic coupling, it is not necessary to be mechanically integrated.

本発明における、磁性体６がＳＱＵＩＤ１を囲んでいるという特徴は、ＳＱＵＩＤ磁気センサとして機能させる上で、ＳＱＵＩＤ１だけでなく磁性体６も冷却しなければならないという制約が課される場合もあり得ることを意味する。このような場合には、例えばクライオパームのような、ＳＱＵＩＤが動作する極低温環境でも高い透磁率を示す磁性材料を、磁性体6に使用する必要がある。しかし、このことは、本発明におけるＳＱＵＩＤ磁気センサの実用上の性能や製造の容易さ、取り扱いの簡便さなどを低下させる要因とはならない。図１が示唆するように、磁性体６はＳＱＵＩＤ１と入力コイル４のみを取り囲む大きさがあれば十分であるため、従来の磁気遮蔽と比較して極めて小さな構造とすることが出来、また、ＳＱＵＩＤ１を取り囲む磁気遮蔽７は、磁性体６をクライオパームのような金属磁性体とすることで、磁束捕獲による磁束雑音の抑制だけでなく、電磁波(いわゆるラジオ波)の遮蔽にも有効であり、環境雑音に対する耐性が強い高感度計測システムとなることを意味する。なお、以下の実施例２が示すように、上記制約が限定的に課されるだけの場合もあり、磁性体６と磁気遮蔽７の配置の仕方によって本発明の特徴を損なうことなく実用的な構造を設計することが出来る。 In the present invention, the feature that the magnetic body 6 surrounds the SQUID 1 may impose a restriction that not only the SQUID 1 but also the magnetic body 6 must be cooled in order to function as a SQUID magnetic sensor. Means. In such a case, it is necessary to use, for the magnetic body 6, a magnetic material that exhibits high permeability even in a cryogenic environment where the SQUID operates, such as cryopalm. However, this does not cause a decrease in practical performance, ease of manufacture, ease of handling, and the like of the SQUID magnetic sensor of the present invention. As suggested by FIG. 1, since it is sufficient that the magnetic body 6 has a size that surrounds only the SQUID 1 and the input coil 4, it can have a very small structure as compared with the conventional magnetic shield, and the SQUID 1 The magnetic shield 7 that surrounds the magnetic body 6 is effective not only for suppressing magnetic flux noise due to magnetic flux trapping but also for shielding electromagnetic waves (so-called radio waves) by making the magnetic body 6 a metal magnetic body such as cryopalm. This means a highly sensitive measurement system with high resistance to noise. In addition, as the following Example 2 shows, the said restrictions may only be imposed limitedly, and it is practical without impairing the features of the present invention depending on the arrangement of the magnetic body 6 and the magnetic shield 7. The structure can be designed.

図５は本発明の信号伝達回路５にＳＱＵＩＤ１と鎖交する閉磁路をつくる構造をもつ磁性体を含み、その閉磁路構造の一部もしくは全部が磁気遮蔽７をなすＳＱＵＩＤ磁気センサの一実施例を説明する模式図である。図５は、ＦＬＬ回路を用いた線形応答するＳＱＵＩＤ磁気センサシステムである。 FIG. 5 shows an embodiment of the SQUID magnetic sensor in which the signal transmission circuit 5 of the present invention includes a magnetic body having a structure that forms a closed magnetic circuit that is linked to SQUID 1, and part or all of the closed magnetic circuit structure forms a magnetic shield 7. FIG. FIG. 5 shows a SQUID magnetic sensor system that performs linear response using an FLL circuit.

図５における信号伝達回路５の材料は、所望のＳＱＵＩＤ磁気センサシステムの測定原理に応じて、常伝導金属線であっても、または超伝導線であってもよい。検出コイル３が単純なコイルである場合には、常伝導線の場合、検出コイル３に鎖交する磁束の時間変化に比例した出力が得られ、超電導線の場合には、検出コイル３に鎖交する磁束に比例した出力が得られる。その他、検出コイル３を差動型コイルにするなど、所望の測定原理に応じて様々な構成をとり得るが、本発明のＳＱＵＩＤ磁気センサを使用することで、磁気信号の伝達効率が高い、磁気遮蔽が小型である、磁気遮蔽・電磁遮蔽の効率が高い、などの特徴を持たせることが出来る。 The material of the signal transmission circuit 5 in FIG. 5 may be a normal metal wire or a superconductive wire depending on the measurement principle of the desired SQUID magnetic sensor system. When the detection coil 3 is a simple coil, an output proportional to the time change of the magnetic flux linked to the detection coil 3 is obtained in the case of a normal conducting wire, and in the case of a superconducting wire, a chain is connected to the detection coil 3. An output proportional to the intersecting magnetic flux is obtained. In addition, various configurations such as a detection coil 3 as a differential coil can be used depending on a desired measurement principle. However, by using the SQUID magnetic sensor of the present invention, magnetic signal transmission efficiency is high. Features such as small shielding and high magnetic shielding / electromagnetic shielding efficiency can be provided.

図６は、上記制約が限定的に課されるだけの場合であり、本発明のＳＱＵＩＤ磁気センサの第二の実施例を示す。図のように、磁気遮蔽７と閉磁路をつくる磁性体６の一部がそれぞれ機械的に分離しており、ＳＱＵＩＤを設置する部分と機械的に一体となる磁性体など、磁気遮蔽７と閉磁路をつくる磁性体６の一部のみを冷却すればよい構造となっている。この場合も、機械的に分離したそれぞれの磁性体を、強い磁気結合で単一の磁気回路を形成するように配置する。なお、図６では、図５と同様のＦＬＬ回路とＳＱＵＩＤとを接続する配線などは省略してある。 FIG. 6 shows a second embodiment of the SQUID magnetic sensor according to the present invention, which is a case where the above-mentioned restrictions are imposed only to a limited extent. As shown in the figure, the magnetic shield 7 and a part of the magnetic body 6 forming the closed magnetic path are mechanically separated from each other, and the magnetic shield 7 and the closed magnetic field, such as a magnetic body mechanically integrated with the portion where the SQUID is installed, are shown. Only a part of the magnetic body 6 forming the path needs to be cooled. Also in this case, the magnetic materials separated mechanically are arranged so as to form a single magnetic circuit with strong magnetic coupling. In FIG. 6, wirings for connecting the FLL circuit and the SQUID similar to those in FIG. 5 are omitted.

以上詳細に説明したように本発明によれば、磁気信号の伝達効率が高く、磁気遮蔽が小型で済み、磁気遮蔽・電磁遮蔽の効率が高く外部雑音に強い、などの特徴を持つ実用性の高い小型で高感度なＳＱＵＩＤ磁気センサを実現することが可能となる。 As described above in detail, according to the present invention, the practicality of the magnetic signal transmission efficiency is high, the magnetic shielding is small, the magnetic shielding / electromagnetic shielding efficiency is high, and it is resistant to external noise. It is possible to realize a highly compact and highly sensitive SQUID magnetic sensor.

従来の技術において、高磁気信号伝達効率と高磁気遮蔽率の両立を達成することは困難であったが、本発明は、その根本原因を取り除くことで、小型で実用的な高感度ＳＱＵＩＤ磁気測定システムの開発を促進するものである。 In the prior art, it has been difficult to achieve both high magnetic signal transmission efficiency and high magnetic shielding ratio. However, the present invention eliminates the root cause, thereby reducing the size and practical high-sensitivity SQUID magnetic measurement. It promotes system development.

本発明の信号伝達回路にＳＱＵＩＤと鎖交する閉磁路をつくる構造をもつ磁性体を含み、かつ、その閉磁路構造の一部もしくは全部が磁気遮蔽をなすＳＱＵＩＤ磁気センサを説明する模式図である。FIG. 4 is a schematic diagram for explaining a SQUID magnetic sensor that includes a magnetic body having a structure that forms a closed magnetic circuit linked to a SQUID in the signal transmission circuit of the present invention, and a part or all of the closed magnetic circuit structure forms a magnetic shield. . 従来の、ＳＱＵＩＤを用いた磁気センサ回路を説明する模式図である。It is a schematic diagram explaining the conventional magnetic sensor circuit using SQUID. 従来の、ＳＱＵＩＤの外部に設けた磁気信号検出回路と、検出した磁気信号をＳＱＵＩＤに伝達する回路の構成を説明する模式図である。It is a schematic diagram explaining the structure of the conventional magnetic signal detection circuit provided in the exterior of SQUID, and the circuit which transmits the detected magnetic signal to SQUID. 従来の、透磁率の大きな磁性体を用いて入力コイルに生じる磁力線がＳＱＵＩＤに鎖交し、かつ閉磁路となるように配置する回路構成を説明する模式図である。It is a schematic diagram explaining the circuit structure arrange | positioned so that the magnetic force line which arises in an input coil using the magnetic body with a large magnetic permeability may be linked to SQUID, and becomes a closed magnetic circuit. 本発明の信号伝達回路にＳＱＵＩＤと鎖交する閉磁路をつくる構造をもつ磁性体を含み、かつ、その閉磁路構造の一部もしくは全部が磁気遮蔽をなす構造をもつＳＱＵＩＤ磁気センサの一実施例を説明する模式図である。（実施例１）An embodiment of a SQUID magnetic sensor including a magnetic body having a structure that forms a closed magnetic circuit linked to a SQUID in the signal transmission circuit of the present invention, and a part or all of the closed magnetic circuit structure forms a magnetic shield. FIG. (Example 1) 本発明のＳＱＵＩＤ磁気センサの第二の実施例で、磁気遮蔽と閉磁路をつくる磁性体の一部のみを冷却すればよい構造を説明する模式図である。（実施例２）It is a schematic diagram explaining the structure which should cool only a part of magnetic body which makes a magnetic shielding and a closed magnetic circuit in the 2nd Example of the SQUID magnetic sensor of this invention. (Example 2)

符号の説明Explanation of symbols

１ ＳＱＵＩＤ
２ ＦＬＬ回路
３ 検出コイル
４ 入力コイル
５ 信号伝達回路
６ 入力コイルのコアと閉磁路を形成する磁気回路および磁気遮蔽の機能を併せ持つ透磁率の大きな磁性体
７ 磁気遮蔽
８ 閉磁路を形成する磁気回路 1 SQUID
2 FLL circuit 3 Detection coil 4 Input coil 5 Signal transmission circuit 6 Magnetic circuit that forms a closed magnetic circuit with a core of the input coil and a magnetic material having a high magnetic permeability having a function of magnetic shielding 7 Magnetic shielding 8 Magnetic circuit that forms a closed magnetic circuit

Claims (3)

超伝導量子干渉素子（Ｓｕｐｅｒｃｏｎｄｕｃｔｉｎｇ ＱＵａｎｔｕｍ Ｉｎｔｅｒｆｅｒｅｎｃｅ Ｄｅｖｉｃｅ， ＳＱＵＩＤ）を用いた磁気センサにおいて、信号伝達回路にＳＱＵＩＤと鎖交する閉磁路をつくる構造をもつ磁性体を含み、その閉磁路構造の一部もしくは全部がＳＱＵＩＤを囲む磁気遮蔽をなすことを特徴とする磁気センサ。 In a magnetic sensor using a superconducting quantum interference device (SQUID), the signal transmission circuit includes a magnetic body having a structure that forms a closed magnetic circuit interlinking with the SQUID, and part or all of the closed magnetic circuit structure Makes a magnetic shield surrounding the SQUID. ＳＱＵＩＤを囲む磁気遮蔽の内部に、ＳＱＵＩＤへ磁気信号を伝達するコイルのコアを設け、そのコイルの作る磁力線が磁気遮蔽を通って閉磁路を形成することを特徴とする請求項１記載の磁気センサ。   2. A magnetic sensor according to claim 1, wherein a core of a coil for transmitting a magnetic signal to the SQUID is provided inside a magnetic shield surrounding the SQUID, and a magnetic line generated by the coil forms a closed magnetic circuit through the magnetic shield. . 請求項１記載の磁気センサを備える測定機器。 A measuring instrument comprising the magnetic sensor according to claim 1.
JP2007001006A 2007-01-09 2007-01-09 Magnetometric sensor Pending JP2008170164A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104569868A (en) * 2015-02-11 2015-04-29 中国科学院上海微***与信息技术研究所 Superconducting quantum interference device
CN105738838A (en) * 2016-04-14 2016-07-06 中国科学院上海微***与信息技术研究所 Superconducting quantum interference device gradiometer and height-balanced magnetic field detection method

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07318591A (en) * 1994-05-25 1995-12-08 Toyo Commun Equip Co Ltd Current detector

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07318591A (en) * 1994-05-25 1995-12-08 Toyo Commun Equip Co Ltd Current detector

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104569868A (en) * 2015-02-11 2015-04-29 中国科学院上海微***与信息技术研究所 Superconducting quantum interference device
CN105738838A (en) * 2016-04-14 2016-07-06 中国科学院上海微***与信息技术研究所 Superconducting quantum interference device gradiometer and height-balanced magnetic field detection method

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