JPS63124975A - Stationary holding device for detection coil of magnetization measuring instrument - Google Patents

Abstract

PURPOSE:To prevent a noise signal from being generated owing to the movement of a detection coil by providing a conductor which has a small resistance value in an intense magnetic field and holding the detection coil at a fixed position with a force which operates on the conductor with an eddy current. CONSTITUTION:A supporter 18 is arranged fixedly in the intense magnetic field and ring-shaped detection coils 14 and 15 are fitted and fixed to the lower part. Further, a sample holder 16 where a sample 17 is set at the tip is inserted into the internal hole in a freely forward/backward movable state, and conductor rings 19 and 20 are embedded in the supporter 18. When vibration of the detection coils caused by the position shift of the sample 17 is transmitted to the fixed conductor rings 19 and 20, the eddy current is generated by the effect of the magnetic field, and consequently the strong stationary force operates on those rings 19 and 20. This force operates so as to fix the supporter 18, so the detection coils 14 and 15 united with the supporter 18 are held at constant positions.

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention is used in a magnetization measuring machine that measures the magnetization characteristics of a sample in a strong magnetic field, and the detection coil provided in the magnetization measuring machine is immobilized. The present invention relates to a stationary holding device.

``Conventional technology j'' There are so-called vibration-type measuring machines and pull-out type measuring machines that create a strong magnetic field using superconducting coils, normal-conducting coils, or hybrid coils that combine them, and measure magnetization within this strong magnetic field. Machines are known.

Both of these two types of measuring machines are equipped with a detection coil placed in a strong magnetic field, and the vibration type measuring machine makes the sample set in the sample holder undergo a simple vibration at the center of the detection coil, and the pull-out type measures The machine is configured to pull out the sample holder so that the sample passes through the detection coil.

The above-mentioned measuring device outputs the induced voltage generated in the detection coil as a sample magnetization signal.

FIG. 1 is a simplified diagram of this type of magnetization measuring device, and 12 is a strong magnetic field generating coil, which generates a strong magnetic field.

13 is a cylindrical support corresponding to a frame installed in a strong magnetic field, and a ring-shaped detection coil 14.1 is attached to this support 13.
5 is fitted and fixed. 16Lh A sample holder inserted into the support 13 so as to be able to move forward and backward.
7 is set.

"Problems to be Solved by the Invention" The magnetization measuring machine described above requires that the detection coils 14 and 15 are correctly fixed at a predetermined position within a strong magnetic field. .15 vibrates or moves to some extent, the induced voltage in the detection coils 14 and 15 due to such inadvertent dynamic causes appears as a noise signal.

This dynamic cause is mainly related to the following two points.

(1) Since the sample holder 16 is provided as a moving member, vibrations caused by the drive mechanism of the holder 16 are transmitted to the entire magnetization measuring device, resulting in vibrations of the detection coils 14 and 15.

(2) The effective inner diameter (space) in which a strong magnetic field is generated is designed to be within a few mm to be economically advantageous, and between the inner circumferential surface of the support 13 and the outer circumferential surface of the sample holder 16. becomes very narrow.

Furthermore, since the distance from the top of the strong magnetic field generator to the center of the magnetic field is often 1.5 m or more, the support 13 and sample holder 16 have an elongated rod shape.

For this reason, the sample holder 16 comes into contact with the support 13 during the vibration or withdrawal process, and this causes the detection coils 14, 15 to vibrate and move.

It is sufficient to make the sample holder 16 sufficiently thinner than the support 13, but as already mentioned, there is a limit to how thin it can be because of its long length.

Conventionally, the diameter is about several mm (for example, 5 mm),
A sample holder 16 with a length of 1.5 m or more is used, and if the length is made thinner, the curvature of this holder 16 becomes larger and contact with the support 13 increases.

The larger the movement of the detection coil 14.15, the more
As the strength of the strong magnetic field increases, the noise signal increases and the accuracy of magnetization measurement decreases.

"Means to solve problems" The present invention aims to solve the above-mentioned problems.

Therefore, in the present invention, in a magnetization measuring machine that changes the position of a sample in a strong magnetic field and outputs the induced voltage in a detection coil due to the change in the strong magnetic field as a magnetization measurement signal, a conductor with a small resistance value is installed in the strong magnetic field. The present invention proposes a device for holding a detection coil in place, characterized in that the detection coil is held in place by a force acting on the conductor by an eddy current.

"Operation" In the present invention described above, a strong force acts on the conductor due to the eddy current and strong magnetic field generated in the conductor, and the detection coil is immobilized by the force acting on the conductor.

In addition, the above-mentioned means for holding the detection coil in place increases the fixing force as the magnetic field becomes stronger, and when the temperature of the measurement condition is lowered, the resistance value of the conductor further decreases and the force acting on the conductor decreases. Because of this increase, the detection coil is more firmly held in place.

For this reason, it is particularly effective in magnetization measurements under extreme conditions of strong magnetic fields and extremely low temperatures.

``Example'' Next, an example of the present invention will be described with reference to the drawings.

FIG. 2 is a partially cutaway side view showing the support for the detection coil. This support 18 is a cylindrical body made of a synthetic resin material, and like the support 13 already mentioned, it is arranged so as to be fixed in a strong magnetic field, and a ring-shaped detection coil 14, 15 is attached to the lower part. are fitted and fixed, and a sample holder 16 for holding a sample 17 at its tip is inserted into the inner hole so as to be movable forward and backward.

On the other hand, the support 18 has its lower end and the detection coil 1
A conductor ring 19, 20 as shown in FIG.

These conductive rings 19, 20 preferably have as small an electrical resistance value as possible, and are made of non-magnetic materials such as copper, aluminum, gold, and silver.

Further, as shown in FIG.
is buried in the support 18. Note that the conductor ring 19.
20, their shape and attachment can be determined by the most appropriate means, such as wrapping a band-shaped conductor around the concave portion along the circumference of the support 18 and then integrally fixing the ends of the conductor. should be adopted.

In the stationary holding device configured in this way, vibrations of the detection coil caused by positional fluctuations of the sample 17 are transmitted to the conductor rings 19 and 20 fixed thereto, causing eddy currents due to the effect of the magnetic field, and as a result, these rings 19.
20 exerts a strong static force.

This force acts to fix the support 18, so
A detection coil 14,15 integral with the support 18 is held in a fixed position.

As a result, vibration or movement of the detection coils 14.15 is effectively prevented and noise signals due to dynamic causes of these coils 14.15 are significantly reduced.

Let's think about it using mathematical formulas. The force F acting on the conductor ring 19.20 is F ■ r2 × 12 × H2 × v (1) “: Radius of the conductor ring l: Width of the conductor ring H: Strength of the strong magnetic field V: The induced voltage (noise signal) Vn due to the movement of the conductor ring moving speed detection coil 14.15 is proportional to the following: Vn=HXv (2).

Therefore, from the above equations (1) and (2), we get this (
3) The noise signal can be reduced in proportion to Eq.

Next, the experimental results will be explained.

An experiment was conducted using a conductive ring 19.20 with a diameter 2r = 1.5 cm and a ring width # = 1 cm, and a sufficient effect was obtained when the strength H of the strong magnetic field was set to 27 (20 KOe) or more.

For magnetization measurements of l emu, conductor ring 19.2
When 0 is not provided, the S/N ratio is at the limit of about I x 10-2.

However, by providing the conductor ring 19.20, a result was obtained in which the S/N ratio was approximately 1×10 2 .

Furthermore, the S/N ratio improved in proportion to the magnetic field.

From the results of this experiment, it has been found that according to the present invention, the noise signal is reduced as much as possible by a unit of 10<-2 >compared to the conventional magnetization measuring device.

Although one embodiment of the present invention has been described above, the present invention can be implemented in the following manner.

(1) Even if the sample holder 16 comes into contact with the support 18, the detection coils 14 and 15 do not vibrate or move.
It is advantageous that the diameter of the support 18 can be reduced.

In particular, when measuring magnetization in a direction intermediate between the easy magnetization direction and the difficult magnetization direction of a ferromagnetic material with a large magnetic anisotropy constant, the sample 17 is attracted to the strong magnetic field generating coil, causing the sample holder 16 to bend and the support 18 However, even in such magnetization measurement, the detection coils 14 and 15 are fixed, allowing highly accurate magnetization measurement.

(2) Detection coil 14, 15 and conductor ring 19
．． The number of conductive rings 19 and 20 can be increased or decreased as desired, and in particular, the shape, structure, etc. of the conductive rings 19 and 20 may be determined as necessary.

(3) The support 18 does not necessarily have to be cylindrical; it may also be a rectangular cylindrical frame.

"Effects of the Invention" As described above, the present invention has a configuration in which a conductor with a low electrical resistance value is placed in a strong magnetic field, and the detection coil is immobilized by using the force action of the eddy current of this conductor. The detection coil will not vibrate or move due to inadvertent dynamic causes such as vibration of the measuring machine or moving force applied when the sample holder contacts the detection coil support frame.

Therefore, it is possible to provide a highly accurate magnetization measuring device that effectively prevents the generation of noise signals due to the movement of the detection coil.

[Brief explanation of the drawing]

Fig. 1 is a simplified diagram showing a conventional magnetization measuring device, Fig. 2 is a vertical cross-sectional side view showing a support for a detection coil according to an embodiment of the present invention, and Fig. 3 is a conductor ring provided on the support. FIG. 14.15...Detection coil 16...Sample holder 17...Sample 18...Support 19.20...Conductor ring Patent applicant Yoshiyu Kido Patent applicant Toei Kogyo Co., Ltd. Figure 1 Figure 2 Figure 3

Claims (3)

[Claims] (1) In a magnetization measuring machine that changes the position of a sample in a strong magnetic field and outputs the voltage induced in the detection coil due to the change in the strong magnetic field as a magnetization measurement signal, a conductor with a small resistance value is installed in the strong magnetic field, and the eddy current A device for holding a detection coil in place, characterized in that the detection coil is held in place by a force acting on the conductor. (2) A slender frame into which a sample holding member is movably inserted is placed in a strong magnetic field, and the detection coil and the conductor are integrally fixed to the frame. A device for holding the detection coil in place as described in scope (1). (3) The device for holding a detection coil in place as set forth in claim (1), wherein the conductor is made of a non-magnetic material such as copper, aluminum, gold, or silver that has a low electrical resistance value.