JPS6325574A - Skid element for dc superconducting magnetometer - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to improvements in the skid element, that is, the detection section, of a DC superconducting magnetometer.

(b) Conventional technology In general, a DC superconducting magnetometer has one
Two Josephson coupling elements 42 and 43 are provided in each superconducting ring 41, and an external magnetic field φ is applied to this superconducting ring 41 from a coil 44 connected to a pink-up coil.
is given, the flowing current undergoes modulation, and the current flowing through the Josephson coupling element 42.43 becomes I C,=I C
, = T C, the maximum value of the modulating current is as follows, and as shown by A in FIG. 5, the current 1 m becomes a periodic function of the input magnetic flux φ. Therefore, the input magnetic flux φX can be detected by deriving the voltage ■ corresponding to the current 1 m.

(c) Problems to be solved by the invention In a DC superconducting magnetometer, in reality, there is a difference in the characteristics of the two Josephson coupling parts, and therefore lc+ ≠ Ic
, and the above equation (1) does not hold, and the relationship between the magnetic flux φ and the output current becomes the broken line B in FIG. 5, which is 1 m 2 , and the output of the magnetometer becomes small. Further, when focusing on the superconducting ring 41, the larger the inductance Ls of the ring, the smaller the modulation degree m becomes than 1, and the smaller the output of the magnetometer becomes. Therefore, from this point of view, it is desirable to reduce the inductance Ls of the superconducting ring 4I. However, on the other hand, it is necessary to introduce an external magnetic field into the superconducting ring 41, and when considering the conduction efficiency, there is a problem that the inductance Ls cannot be made very small.

In view of the above, it is an object of the present invention to provide a skid element for a DC superconductor 3Eff force meter that can bring the modulation degree m close to 1 and obtain a large output without reducing the transmission efficiency of the external magnetic field to the superconducting ring. The purpose is

(d) Means and operation for solving the problems The skid element of the DC superconducting magnetometer of the present invention is formed on a substrate (1) and includes two mutually symmetrical superconducting rings (7, 8). , a pair of Josephson coupling parts (11, 12) placed at the center of these two superconducting rings, and a multilayer thin film formed inside the superconducting rings, and vice versa, generates an I field. The superconducting coils (9, 10) are connected in this manner, and a DC driving current is caused to flow through the pair of Josephson coupling portions.

In this skid element, viewed from the Josephson junction,
Since two superconducting rings are inserted in parallel, the inductance Ls is equivalently reduced. Furthermore, since a reverse magnetic field is generated in the superconducting coil, the shielding current that flows is doubled.

(E) Examples The present invention will be explained in more detail with reference to Examples below.

FIG. 1 is a plan view of a skid element of a DC superconducting magnetometer showing an embodiment of the present invention. In the figure, a superconducting thin film pattern 2.3.4.5 made of niobium (Nb) or the like is formed on a substrate 1 made of a silicon wafer or the like. Bakun 2 is an electrode for flowing DC drive current 1d, pattern 3.4 is pink amplifier coil 6
This is an electrode for tlM. Superconducting rings 7.8 are formed symmetrically within the pattern 5, and superconducting coils 9.10 formed as a multilayer film of niobium are provided within these superconducting rings 7.8.

These superconducting coils 9.10 are connected in series and connected to the big amplifier coil 6 via the pattern 3.4.

The magnetic fields generated by the superconducting coils 9.10 are patterned in opposite directions.

In the central part of the pattern 5, ie between the superconducting rings 7 and 8, a pair of Josephson coupling parts 11, 12 are provided. The specific structure of the Josephson coupling portions 11 and 12 will be explained with reference to FIGS. 2 and 3.

Edges 5a and 5b of the pattern 5 are arranged on the substrate 1 in parallel to the superconducting a film layer 13 extending from the electrode pattern 2, and further in the direction in which the edge 5a and the superconducting thin film layer 12 extend. Insulating film layers 14 and 15 are stacked at right angles, and further insulating film layer 1
A superconducting thin film 16.17 is formed on the upper surface of 4.15. In particular, the superconducting thin film 13 and the edge 5a, and the superconducting thin film 13 and the edge 5 are coupled by a strip-shaped superconducting thin film 17, and Josephson coupling portions 11.12 are formed at the contact points. There is.

In the skid element of the above embodiment, when a magnetic field is applied to the pick amplifier coil 6 while a DC drive current 1d is flowing from the pattern electrode 2, the pickup coil 6
Current 11. , is induced. As this current 11n flows through the superconducting coils 9 and 10, a magnetic flux φ,n is generated in the superconducting coil 9, for example, from the front to the back of the paper, and conversely, in the superconducting coil 10, a magnetic flux flows from the back to the front. φ, 7 occurs, and as a result, a shielding current IS flows in the superconducting ring 7.8 in the direction of the arrow in FIG. Since the current flows through the circuit, a large change in the output (voltage ■) can be obtained. Further, when viewed from the Josephson coupling portions 11 and 12, the apparent inductance is Ls/2.

Also, the Josephson junction 11.12 is at the edge 5, the superconducting thin lI! Since the ii layer 13 is arranged at right angles to the edge 5b, the required bonding part can be created within a few μm, and the film pressure difference and IC adjustment error of the superconducting thin film depending on the position can be ignored, making it possible to create an element with uniform characteristics. can be created.

(f) Effects of the Invention According to this invention, two symmetrical
a pair of Josephson coupling portions placed at the center of the two superconducting rings, and a multilayer thin film formed within the superconducting rings to generate opposite magnetic fields. Since the superconducting coil is connected to a superconducting coil, a shielding current equivalent to the amount of two superconducting rings flows through the Josephson coupling portion, improving the efficiency of magnetic flux conversion from the pick amplifier coil. Additionally, compared to a device using a superconducting ring of the same area, the skid element has a smaller inductance and can provide greater output. Furthermore, it is possible to create two Josephson joints with the same characteristics, and in this sense, a large output can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view of a skid element of a DC superconducting magnetometer showing an embodiment of the present invention, FIG. 2 is an enlarged view of the Josephson coupling part of the same skid element, and FIG. line m
4 is a diagram for explaining the outline of a conventional DC superconducting magnetometer, and FIG. 5 is a diagram showing the relationship between the magnetic flux of the DCC superconducting magnetometer and the maximum current of the Josephson coupling part. FIG. 1: Substrate, 7.8: Superconducting ring, 9.10: Superconducting coil, 1].12: Josephson coupling part. Patent applicant: Shimadzu Corporation Agent
Patent Attorney Shigeru Nakamura Figure 2 Figure 4 d Figure 5

Claims (1)

[Claims] (1) Two superconducting rings formed on a substrate and symmetrical to each other, a pair of Josephson coupling portions placed at the center of these two superconducting rings, and a and a superconducting coil formed of a multilayer thin film and connected to generate a reverse magnetic field, the DC driving current being caused to flow through the pair of Josephson coupling parts.
Skid element of superconducting magnetometer.