JPS5917175A - Detecting element of magnetic field for extremely low temperature - Google Patents

Abstract

PURPOSE:To make possible a highly accurate and highly reliable measurement of an extrememly low temperature magnetic field, by utilizing magnetic flux current resistance phenomena of an amorphous super conductive alloy. CONSTITUTION:The variation of electric resistance value at the time of applying 0.06-110A/cm<2> electric current value and 0-70KOe magnetic field at 4.26 deg.K by using a sample of an amorphous super conductive alloy consisting of Mo77.5Si10 B12.5 which is manufactured by a liquid quenching method, is shown by the figure. A super conductive transition temperature of the alloy is 7.66 deg.K by a result of measurement and the electric resistance is changed suddenly at about 50KOe in the case where an electric current density JT is small (7, 8 in the figure) shown as the figure and the variation of its electric resistance for the magnetic field is increased nearly linear at about <=40KOe in the case where the JT is 20-50A/cm<2> (2, 3 in the figure) in opposition to the fact that the electric resistance is zero under the super conductive condition below the 50KOe and then, a magnetic flux current resistance is generated. Accordingly, the intensity of the magnetic field is measured by measuring the value of the electric resistance of the amorphous super conductive alloy.

Description

[Detailed description of the invention]

The non-invention relates to an element that detects a magnetic field at an extremely low temperature, mainly at the temperature of liquid helium.
, is used at extremely low temperatures such as superconducting magnets.
The strength of the magnetic field around the element can be measured by measuring the magnetic resistance. Conventionally, the strength of the magnetic field around the element can be measured.
Detection of 13i magnetic field of about KOθ2) For measurement,
Pole element - Is the detector used old or old?
A measuring instrument using a Hall element that can detect molten metal with a strength of several tens of KOe at extremely low temperatures is a semiconductor Ga-A
It is made using s (gallium-arsenide) and is vulnerable to thermal stress, so it lacks reliability and has a fatal drawback of not being able to withstand long-term use when repeatedly used at liquid helium temperatures and normal humidity. The present invention relates to a novel magnetic field detector that solves the drawbacks of the conventional products, and utilizes the magnetic flux flow resistance phenomenon that appears significantly in amorphous superconducting alloys when measuring high magnetic fields at extremely low temperatures. This aims to simplify the mechanism of the device, improve its reliability, and reduce its cost. Conventionally, it has been known that magnetic flux flow resistance appears in soft superconductors. was. However, although this change in magnetic flux flow resistance was extremely small, the present inventor found that a remarkable magnetic flux flow resistance phenomenon appeared during research on amorphous superconducting alloys, and found that γl. We have newly discovered that it is possible to measure magnetic fields at extremely low temperatures by utilizing this phenomenon. Next, the experimental result f'R' (
'Describe.・81 Figure 1 shows an amorphous superconducting alloy produced by the liquid quenching method.
(width 1all, thickness 25μm, length CV
10t'tN) Ite for F 4. At 26'K, current I1α sail 06~110A/c'IR2, magnetic field O~701 (Oθ) is shown. , Table 1 shows the current density JT'f corresponding to each curve in Figure 1:
show. Table 1 Superelectronic transition resistance of alloys (Measurement results 7, 6ft'
Nide I) Ivy. As shown in Figure 1, the current sound intensity J
If T is small (first meat 7 and 8), approximately 5 QKO
At e, electrical resistance &4 shows a rapid change, and at n and below, it becomes extremely
The electric resistance is 0 and the electric resistance is φ, whereas Jt
is 20 to 50 k/ax2 (11th J-2 & 8)

[4. Below about 40 KOe, the magnetic field of its electrical resistance [
The difference between the two is ha! The magnetic flux flow resistance increases linearly. Therefore, by utilizing this property and measuring the electrical resistance value of the amorphous superconducting alloy, the strength of the magnetic field can be measured. A feature of this case is that the current flowing through the device is as small as 20 to 50 mA, which means that it does not increase the temperature of the device or cause the evaporation of liquid helium for cooling. The present invention, which is extremely advantageous in this respect, utilizes the change in magnetic flux flow resistance described above. An element made of an amorphous superconducting alloy is installed at the location where the magnetic field is to be measured at an extremely low temperature, and four The strength of the magnetic field near the element can be determined by constantly passing a DC current υ1i' through the current terminal of the main lead wire, connecting it to a voltmeter to measure the voltage, and measuring the magnetic flux flow resistance obtained from both. It can be easily measured. Table 2 shows examples of types of amorphous superconducting alloys that can be used in the device of the present invention. The range of alloys that can be effectively used as elements has been experimentally confirmed by various researchers, and is not limited to the alloys shown in Table 2. In addition, these alloys can be used as the element, either in the form of a ribbon made by a liquid quenching method or in the form of a thin film formed on a glass or other ceramic substrate by a vapor deposition method such as sputtering. I can do it. Table 2 Lists the advantages of the magnetic field detection element for extremely low temperatures using the amorphous superconducting alloy described above. (1) Due to the high electrical resistance, the change in magnetic flux flow resistance is large; Highly accurate measurements are possible. (2) Due to its high strength and ductility, it is an extremely strong element against external forces such as impact resistance, and due to its low thermal IA (F tensile coefficient), thermal shock and thermal stress occur when transitioning from room temperature to cryogenic temperature. It is an extremely reliable element that can be used for a long period of time without problems such as performance change, deterioration, or breakage. (3) Magnetic flux flow resistance is more likely to occur than other crystalline superconducting alloys. Since the device can be used with a small amount of current, there is no increase in the humidity of the device, and it is possible to suppress the evaporation of liquid helium used for cooling due to a rise in temperature around the device. (4) Since the mechanism is a newly developed one, it can be manufactured at a lower cost than other detection elements such as conventional Hall elements. There are advantages such as Examples will be described below. FIG. 2 shows an example of a device manufactured by the liquid quenching method. Figure 2 G Kogoke 2.1 i11 Element of the present invention, 2 is its composition Iv1077-5 S inn B12.5
A joint venture crystalline superconducting alloy, 3a to 3dii steam stones, 21 silver electrodes, 4 a support made of a substrate, 5 lead wires, 6 low temperature solder, 5a and 5b current terminals, 5 b
* 50c: a % Ik terminal, 7 (J adhesive. In this case, the shape of the amorphous superconducting alloy is 10μ thick
m, [[]41RN, length 44 ho. This element 100・
Figure 3 shows the results obtained using the following methods. In Figure 8, 1 is the result at 4.26°, 2 is the result at 8.51°, and at 4.26°, up to about 40 KOe, 3.5
At 1°, the resistivity changes in a straight line up to about 50KOθ. When we used this result to determine the magnetic field, we found that at 4.26°: 60 KOe, 3.
510K ``i:'' is 4J: i It was possible to measure the magnetic field with an accuracy of ±2 KOe up to 70 KOe. In this way, the present invention
The present invention provides an innovative magnetic field detection element that is highly accurate and highly reliable for measuring strong magnetic fields.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the current density dependence of magnetic flux flow resistance, which is the principle of the present invention, and Fig. 2 is a diagram showing one of the elements based on the present invention.
This is an example, (a) is a sketch of the entire device, (b) is an AA
' is a cross-sectional view taken in the direction of arrows. FIG. 8G: ↑The result of the example shown in FIG. 2 shows the magnetic flux flow resistance value as a function of the strength of the field. l...Magnetic field detection element, 2...Amorphous superconducting alloy, 3
a-3d... Electrode, 4... Support Patent applicant Aisin Seiki Co., Ltd. Representative Reio Nakai Masu Ken Moto

Claims (1)

[Claims] Transferring to superconductivity at an absolute temperature of 10° above the helium wetting temperature of the tη body and below 13) A thin plate-like or linear superconducting alloy of 50 It m or less consisting of an amorphous phase is fixed to a support made of an insulator. Magnetic field at cryogenic temperatures] A magnetic field detection element for cryogenic temperatures that is installed at the location to be measured to measure the strength of the magnetic field.