JPS632068B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic flux detector, and more specifically, the present invention relates to a magnetic flux detector, and more specifically, a highly sensitive magnetic flux detector that applies the fact that a superconducting ring including a Josefson junction responds to changes in external magnetic flux using magnetic flux quanta as an operating unit. The present invention relates to a magnetic flux detector.

Fig. 1 is an explanatory diagram of the configuration of a conventional example of a magnetic flux detector, and Fig. 2 is an enlarged explanatory diagram of the vicinity of the input coil in Fig. 1. In the figure, 1 is a pickup coil made of superconducting wire; 2 is superconducting wire, 3
a, 3b are input coils made of superconducting wire; 4a, 4b are coil bobbins around which the input coils are wound; 5 is a two-hole superconducting block; 6a,
6b is two through holes provided in a two-hole superconducting block, 7 is a thin film SQUID, 8 is a buried plate, and 9 is a high frequency coil, all of which are placed in an extremely low temperature atmosphere. In the figure, the inductance Lp
When magnetic flux Φx from the outside tries to enter the pick-up coil 1 which has
The shielding current i flows through the input coils 3a and 3b, which constitute a magnetic flux transformer with the pick-up coil 1 and have an inductance Li, through the superconducting wire 2 to generate a magnetic flux Φs. acts on the thin film SQUID 7, and the signal from the input coil 3 is transmitted to the high frequency coil 9 and beyond. The two-hole superconducting block 5 functions as a completely diamagnetic material and focuses the magnetic flux Φs toward the thin film SQUID 7.

By the way, in the two-hole superconducting block 5,
Coil bobbins 4a, 4b wound with input coils 3a, 3b are inserted into through holes 6a, 6b. The inner diameter of holes 6a and 6b is 2.0 mm, and coil bobbin 4
The outer diameters of a and 4b are precisely cut to close dimensions of 1.8 mm. Here, as the outer diameter dimension of the coil bobbins 4a, 4b approaches the inner diameter dimension of the through holes 6a, 6b, the clearance between the coil bobbins 4a, 4b and the through holes 6a, 6b decreases, and the leakage magnetic flux passing therethrough decreases. As the magnetic flux acting on the thin film SQUID 7 increases, the input sensitivity of the signals from the input coils 3a, 3b increases, but on the other hand, when inserting the coil bobbins 4a, 4b into the through holes 6a, 6b, The wound input coils 3a, 3b are inserted into the through holes 6a, 6b.
This has the drawback that the risk of sliding on the inner wall surface of the pipe and being cut or short-circuited increases.

The present invention has been made in view of these drawbacks, and its purpose is to improve the degree of adhesion between the input coil and the superconducting block while maintaining electrical insulation in the vicinity of the input coil of a magnetic flux detector. The objective is to transmit signals from the input coil to the thin film SQUID with high sensitivity.

The feature of the present invention is to form a superconducting block in close contact with the coil bobbin by casting a low melting point superconductor around the coil bobbin around which the input coil is wound around the input coil of the magnetic flux detector. It is in.

Hereinafter, the present invention will be explained in detail using the drawings. FIG. 3 is a partially cutaway view of an embodiment of the present invention (hereinafter referred to as "Embodiment A"), in which 11 is a hollow cylinder made of, for example, SUS, 12 is a partition plate, and 13 is a hollow cylinder. It is a solidified low melting point superconductor.
In FIG. 3, the same symbols as in FIG. 2 are used with the same meanings, and the explanation here will be omitted. Also,
The tube 11 and the coil bobbins 4a, 4b are assembled by the method described below. That is,
The coil bobbins 4a, 4b around which the input coils 3a, 3b are wound, and the partition plate 12 are held at predetermined positions in the tube 11, and a low melting point superconductor (for example, low temperature solder) is filled into the gap in the tube 11. The coil bobbins 4a, 4b and the low melting point superconductor are brought into close contact with each other by pouring the low melting point superconductor into a liquid state and then cooling it to solidify the low melting point superconductor.

Further, FIG. 4 is a partially cutaway view of another embodiment of the present invention (hereinafter referred to as "Embodiment B"), and in the figure,
14 is a partition plate, 21 is an input coil, 22
is a U-shaped coil bobbin around which an input coil is wound. Incidentally, in FIG. 4, the same symbols as in FIG. 3 are used with the same meaning, and the explanation here will be omitted. Further, in the tube 11, the coil bobbin 22 and the partition plate 14 are held, and a liquid low melting point superconductor is poured into the cylinder 11, and is cooled and solidified so that the coil bobbins 4a, 4b and the low melting point superconductor are brought into close contact with each other. There is.

According to the embodiment of the present invention as described in detail above, since the coil bobbin and the partition plate are fixed in the hollow cylinder by the low melting point superconductor, the coil bobbin and the low melting point superconductor are The degree of adhesion is
This is significantly higher than that of the conventional example. Therefore, in combination with the fact that the low melting point superconductor functions as a perfect diamagnetic material, the magnetic flux from the input coil wound around the coil bobbin is more effective than in the case of the conventional example. It has the advantage that it is transmitted to the thin film SQUID. In addition, when producing the superconductor of the magnetic flux detector, unlike the conventional example, a coil bobbin with an inner diameter extremely close to the outer diameter of the coil bobbin is
This eliminates the difficult manufacturing process of cutting two through holes, making the overall manufacturing process easier.
The effect of implementing the present invention is also significant in manufacturing a magnetic flux detector at a high cost and at a low cost.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the configuration of a conventional example of a magnetic flux detector, Fig. 2 is an enlarged explanatory diagram of the vicinity of the input coil,
3 and 4 are partially cutaway views of an embodiment of the invention. 1...Pick-up coil, 2...Superconducting wire,
3a, 3b, 21...Input coil, 4a,
4b, 22... Coil bobbin, 5... 2-hole superconducting block, 6a, 6b... Through hole, 7... Thin film squid, 8... Buried plate, 9... High frequency coil, 1
1... Hollow cylinder, 12, 14... Shikiri plate, 13...
...Low melting point superconductor.

Claims (1)

[Claims] 1. In a magnetic flux detector that detects magnetic flux by utilizing the fact that a superconductor including a Josefson junction shows a response to external magnetic flux changes using magnetic flux quanta as a unit of operation, a pickup coil for detecting a magnetic flux transformer, an input coil that forms a magnetic flux transformer via the pickup coil and a superconducting wire, a coil bobbin around which the input coil is wound, a superconducting block that fixes the coil bobbin; It comprises a coil bobbin and a thin film SQUID which is magnetically coupled through the superconducting block and transmitting a signal from the input coil, and the superconducting block connects the coil bobbin to a low melting point superconductor in a hollow cylinder. A magnetic flux detector characterized by being fixed by casting. 2. The input coil includes first and second input coils, and the coil bobbin includes first and second coil bobbins around which the first and second input coils are respectively wound. The magnetic flux detector according to item 1.