JPS59213110A - Magnetic field controlling device - Google Patents

Abstract

PURPOSE:To enable to generate a stabilized magnetic field on a wide area ranging from a weak magnetic field to a ferromagnetic field consuming a low electric power by a method wherein two superconductive coils and a high sensitivity magnetic field meter are provided. CONSTITUTION:First, an OFF position is given to superconductive switches 8 and 9, and superconductive coils 2 and 3 are excited by controlling the output current of constant current sources 12 and 13 in such a manner that the intensity of magnetic field will be brought to the desired value. Then, when an ON position is given to the superconductive switches 8 and 9, a superconductive closed circuit containing the superconductive coils 2 and 3 is formed. The value of current running on the respective superconductive closed circuit is maintained at the output current value of the constant current sources 12 and 13 which is set in such a manner that the prescribed magnetic field intensity will be given, and also the superconductive coils 2 and 3 function in such a manner that the fluctuations of the outer magnetic field will be completely cancelled in accordance with the magnetic flux retaining rule of the superconductive closed circuit. As a result, a highly accurate and stabilized magnetic field in wide area ranging from a weak magnetic field to a ferromagnetic field can be obtained.

Description

Detailed Description of the Invention (a1 Technical Field of the Invention) The present invention is directed to a magnetic field that is constant and variable in the range from an extremely weak magnetic field required as an operating environment for a superconducting circuit to a strong magnetic field required for magnetic susceptibility measurement. The present invention relates to a magnetic field control device that generates a magnetic field with a small amount of magnetic field.

(b) Background of the technology Since superconducting circuit elements malfunction due to the influence of extremely weak magnetic fields, the magnetic field in their operating environment should ideally be zero.
At least 1/1 millionth of geomagnetism (40,000γ)
It is said that it is desirable that the magnetic field strength is approximately Furthermore, in measurements of magnetic susceptibility, etc., a stable strong magnetic field of approximately several T (Tesla) is required.

(C1 Conventional technology and problems) Conventional magnetic field generators include a method using a Helmholtz coil for the purpose of magnetic shielding, and a method using a normal conduction electromagnet for the purpose of generating a strong magnetic field. However, the former has the disadvantage that it is difficult to effectively control the magnetic field strength to a constant value against transient external magnetic field fluctuations, and it is also difficult to apply a wide range of magnetic fields from very small to strong magnetic fields. However, the latter is unsuitable for anything other than applying a strong magnetic field, and has the drawback of high power consumption.

(d) Purpose of the Invention An object of the present invention is to provide a magnetic field control device that consumes low power and is capable of generating a stable magnetic field over a wide range from a weak magnetic field to a strong magnetic field.

(e) 8th Structure two superconducting switches connected by a wire; a constant current source for exciting the superconducting coil according to the output of the magnetometer;
It is characterized by comprising two superconducting coils, a nuclear agent-sensitive magnetometer, the two superconducting switches, and a cryogenic container for maintaining the superconducting wire at a cryogenic temperature.

(f) Examples of the invention Embodiments of the present invention will be described below with reference to the drawings.

The gist of the present invention is to utilize the zero electrical resistance property of superconductors to generate a strong magnetic field with low power consumption, and to utilize the so-called 5QUID (5QUID) which operates by the Josephson effect.
Superconducting Quantum I
A highly sensitive magnetic field meter using an inter-ference device (inter-ference device) is used to detect the magnetic field, and a weak magnetic field is provided by controlling the magnetic field. Magnetic field fluctuations are suppressed by using the law.

In other words, the superconducting coil can generate a strong magnetic field without energy loss, the 5QUID can detect a weak magnetic flux of about one flux quantum, and the superconducting closed circuit conserves the magnetic field. Two superconducting coils are placed inside the superconducting coil, and a probe of a magnetic field meter using the SO old is placed between the two superconducting coils, and the two superconducting coils are first connected to a constant current power source and excited. , the output of the magnetic field meter is fed back to the current control terminal of the constant current power supply to set the desired magnetic field strength between the two superconducting coils, and then each of the two superconducting coils is also heated to an extremely low temperature. By closing and short-circuiting a superconducting switch that is in a superconducting state within the container, the desired magnetic field strength is maintained and fluctuations in the external magnetic field are completely canceled out.

In the figure, Helmholtz-type superconducting coils 2 and 3 made of, for example, niobium-titanium alloy (Nb-Ti) wire are placed at a predetermined distance inside a container 1 maintained at an extremely low temperature. A magnetic field needle probe 4 using the 5QUID is placed near the center between the conduction coils 2 and 3. A test object 5 , such as a superconducting circuit element, to which a magnetic field is applied is placed near the magnetic field needle probe 4 .

The superconducting coils 2 and 3 are connected to superconducting switches 8 and 9 (switches whose electrical resistance is completely zero when closed) by superconducting wires 6 and 7, respectively. On the other hand, constant current sources 12 and 13 are connected to the superconducting switches 8 and 9 via normal conducting wires 10 and 11, respectively. The detection output of the magnetic field meter probe 4 is input to the control unit 14 via the magnetic field meter main body 15, and the output of the constant current sources 12 and 13 is controlled by the control unit 14 so that the detected magnetic field strength becomes a predetermined value. .

In the above configuration, first superconducting switches 8 and 9
The superconducting coils 2 and 13 are opened, and while measuring the magnetic field strength using the magnetometer probe 4 and the control unit 14, the output currents of the constant current sources 12 and 13 are controlled so that the magnetic field strength becomes a desired value. 3 is excited.

Then, when superconducting switches 8 and 9 are closed, a superconducting closed circuit including superconducting coils 2 and 3 is formed. In this case, the current value flowing through each superconducting closed circuit is
In the above, the output current values of the constant current sources 12 and 13 are set to provide a predetermined magnetic field strength, and the superconducting coils 2 and 3 completely eliminate fluctuations in the external magnetic field according to the law of conservation of magnetic flux of superconducting closed circuits. It acts to cancel out.

In the above magnetic field control device of the present invention, the superconducting coil 2
and 3, apply a magnetic field of arbitrary strength in the range of O to LOT in the coil axial direction with a high precision of 2 x 10 wb/s (where S is the cross-sectional area of superconducting coils 2 and 3, unit M). Moreover, it is possible to make the magnetic field fluctuation in the axial direction of the superconducting coil extremely small.

(Effects of the Invention According to the present invention, it is possible to provide a highly accurate and highly stable magnetic field over a wide range from a weak magnetic field to a strong magnetic field.
13110(3) This has the effect of making it possible to provide a magnetic field control device with low power consumption.

[Brief explanation of the drawing]

The figure is a diagram for explaining the principle of a magnetic field control device according to the present invention. In the figure, 1 is a cryogenic container, 2 and 3 are superconducting coils, 4 is a magnetometer probe, 5 is a test object, 6 and 7 are superconducting wires, 8 and 9 are superconducting switches, 10 and 1
1 is a normal conducting wire, 12 and 13 are constant current sources, 14 is a control section, and 15 is a main body of the magnetometer. Agent Patent attorney Weighing Koji% ▽35-

Claims (1)

[Claims] Two superconducting coils arranged at a predetermined interval, a highly sensitive magnetic field needle arranged between the superconducting coils, and two superconducting switches connected to each of the superconducting coils by a superconducting wire. , a constant current source for exciting the superconducting coil according to the output of the magnetometer, the two superconducting coils, the high-sensitivity magnetometer, the two superconducting switches, and the superconducting wire at an extremely low temperature. A magnetic field control device comprising: a cryogenic container for maintaining the temperature at a low temperature;