JP2007047055A - Magnetic susceptibility measuring method, manufacturing method of scale for magnetic susceptibility measurement, magnetic susceptibility measurer, and magnetic susceptibility measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic susceptibility measuring method, a manufacturing method of a scale for magnetic susceptibility measurement, a magnetic susceptibility measurer having a simple constitution and capable of measuring the magnetic susceptibility of a diamagnetic material by easy operation, and a magnetic susceptibility measuring device. <P>SOLUTION: A plurality of kinds of diamagnetic materials having each ascertained magnetic susceptibility are floated one by one or simultaneously plurally in a vertical (direction) magnetic field having a gradient magnetic field. A relation between the magnetic susceptibility and a floating position of each diamagnetic material in the magnetic field is calculated from each position and each magnetic susceptibility of each floating diamagnetic material. A diamagnetic material whose magnetic susceptibility is not ascertained is floated in the magnetic field, and the floating position is specified, and the floating position is converted into the magnetic susceptibility by using the calculated relation between the magnetic susceptibility and the floating position. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for measuring a magnetic susceptibility of a diamagnetic material, a method for producing a scale for measuring a magnetic susceptibility, a magnetic susceptibility measuring device, and a magnetic susceptibility measuring device.

  Conventionally, a superconducting quantum interferometer (SQUID) has been used as a means for measuring magnetic properties such as magnetic susceptibility of magnetic materials. (For example, refer to Patent Document 1 below).

Japanese Patent Publication No. 2001-56316

  However, in SQUID, in general, since the magnetic susceptibility of a sample placed in a container is measured, there is an error due to the magnetic susceptibility of the container, and this needs to be corrected. In addition, since it cannot be sensed without using a certain amount of sample, naturally the magnetic susceptibility of a minute sample cannot be measured.

  The present invention has been made in view of the above problems, and a magnetic susceptibility measuring method capable of easily measuring the magnetic susceptibility of a diamagnetic material capable of magnetic levitation, a method for producing a magnetic susceptibility measuring scale, and an error. An object of the present invention is to provide a magnetic susceptibility measuring apparatus and a magnetic susceptibility measuring apparatus that can measure the magnetic susceptibility with little or a small amount of diamagnetic material.

Means and effects for solving the problems

  The magnetic susceptibility measuring method of the present invention includes a step of levitating a plurality of types of diamagnetic materials whose magnetic susceptibility is known one by one or a plurality simultaneously in a vertical magnetic field having a gradient magnetic field, and the levitated diamagnetic material The step of calculating the relationship between the magnetic susceptibility and the levitation position of the diamagnetic material in the magnetic field from the position and the magnetic susceptibility of the, and levitation of the diamagnetic material whose magnetic susceptibility is unknown in the magnetic field, Identifying the levitated position and converting the levitated position into a magnetic susceptibility using the calculated relationship between the magnetic susceptibility and the levitated position. As another aspect, the magnetic susceptibility measurement method of the present invention includes a step of levitating different types of diamagnetic materials in a vertical magnetic field having a gradient magnetic field, and a magnetic field and a magnetic field gradient at the levitation position of the diamagnetic material. A step of calculating by measurement or numerical calculation processing, and a step of calculating the magnetic susceptibility of the diamagnetic material using the measured or calculated magnetic field and magnetic field gradient.

  According to the said structure, the magnetic susceptibility of the diamagnetic material which can be magnetically levitated can be measured easily.

  The method for producing a susceptibility measurement scale according to the present invention includes a step of levitating a plurality of types of diamagnetic materials whose susceptibility is known one by one or simultaneously in a vertical magnetic field having a gradient magnetic field, Recording each position of the plurality of types of diamagnetic materials to make a scale, and dividing the scale so as to correspond to the product of a magnetic field and a gradient magnetic field to produce a small scale. is doing.

  According to the above configuration, a small scale is produced by dividing the scale obtained from the levitation position of multiple types of diamagnetic materials with known magnetic susceptibility so as to correspond to the product value of the magnetic field and the gradient magnetic field. Therefore, it is possible to provide a method for producing a magnetic susceptibility measuring scale that can be used to measure the magnetic susceptibility of various diamagnetic materials capable of magnetic levitation.

  The method for producing a magnetic susceptibility measurement scale according to the present invention preferably includes a step of converting the values of the scale and the small scale into values of magnetic susceptibility corresponding to the scales. Thereby, since the scale is previously converted into magnetic susceptibility, it is not necessary to convert into magnetic susceptibility for every measurement. For example, if the value of the magnetic susceptibility is added to the scale itself, the measured magnetic susceptibility of the diamagnetic material can be read directly and easily.

  The susceptibility measuring instrument according to the present invention has a susceptibility scale for a diamagnetic material in a vertical magnetic field having a gradient magnetic field with a predetermined position as a reference, and the reference is moved from the predetermined position. The magnetic susceptibility is measured by reading from the scale the deviation width of the reference from the predetermined position when the height is adjusted to the height position of the levitated diamagnetic material in the vertical magnetic field having the predetermined intensity. . The susceptibility measuring apparatus according to the present invention includes the susceptibility measuring instrument, a superconducting magnet that generates a magnetic field in the vertical direction, and a gradient magnetic field generator that generates a gradient magnetic field.

  According to the above configuration, it is possible to provide a magnetic susceptibility measuring device and a magnetic susceptibility measuring device that can measure the magnetic susceptibility of a diamagnetic material with a simple operation while having a simple configuration.

  A magnetic susceptibility measuring device according to the present invention generates a magnetic field in a vertical direction and generates a gradient magnetic field, a levitation position detector that detects a levitation position of a diamagnetic material levitated in the magnetic field, Magnetic susceptibility calculating means for calculating the magnetic susceptibility of the levitation position measured by the levitation position detector. The magnetic susceptibility calculation means calculates the magnetic susceptibility of the diamagnetic material by calculating the magnetic susceptibility of the diamagnetic material from the magnetic field measuring device that measures the magnetic field and the gradient magnetic field at the levitation position, and the measured magnetic field and the gradient magnetic field. It is preferable to provide a container. The magnetic susceptibility calculating means calculates a magnetic field and a gradient magnetic field at the levitation position by numerical calculation processing, calculates a magnetic susceptibility of the diamagnetic material from the calculated magnetic field and the gradient magnetic field, and calculates the magnetic susceptibility. And a calculator.

  According to the above configuration, it is possible to provide a magnetic susceptibility measuring apparatus capable of measuring the magnetic susceptibility of a diamagnetic material with a simple operation while having a simple configuration.

  Hereinafter, embodiments of a magnetic susceptibility measuring apparatus including a magnetic susceptibility measuring device according to the present invention will be described. FIG. 1 is a schematic view of a magnetic susceptibility measuring apparatus including a magnetic susceptibility measuring device according to the present invention.

  The magnetic susceptibility measuring apparatus 10 includes a cylindrical superconducting magnet 1 composed of a superconducting coil, a magnetic susceptibility measuring device 2, a sample supply member 3, and a gradient that generates a gradient magnetic field in the magnetic field generated by the superconducting magnet 1. A magnetic field generator (not shown). The magnetic susceptibility measuring instrument 2 and the sample supply member 3 are made of a nonmagnetic material so as not to be affected by the superconducting magnet 1.

  The superconducting magnet 1 has a cylindrical shape made of a coil of superconducting wire, and is a so-called vertical superconducting magnet that generates a magnetic field in the vertical direction. Although not shown, it is housed in a cryostat and is cooled and excited by a cooler or liquid helium. Note that a gradient magnetic field generator, for example, is provided in the magnetic field generated by the superconducting magnet 1 to generate a gradient magnetic field whose magnetic field changes depending on the height in the vertical direction. This gradient magnetic field generator is a superconducting magnet. 1 and a reversing coil made of a superconducting wire housed in the cryostat, or a metal ring provided in a magnetic field. Alternatively, the magnetic field and the magnetic field gradient may be generated only by the superconducting magnet 1 without using the gradient magnetic field generator.

  The magnetic susceptibility measuring device 2 includes a bar member 2a and a CCD camera 2b for specifying the position of the sample 4 provided below the bar member 2a. A scale 2c for reading the magnetic susceptibility is formed on the upper portion of the bar member 2a. Furthermore, the central section in the vertical direction where the center of the lens of the CCD camera 2b exists is the reference 5 of the scale 2c. The magnetic susceptibility can be measured by making the reference 5 coincide with the floating position of the sample 4 and reading the deviation width of the reference 5 from the predetermined position from the scale. The predetermined position may be, for example, the position of the highest levitation of a plurality of diamagnetic materials whose magnetic susceptibility is known in advance, or conversely, the position of the lowest levitation. It is not restricted and may be determined appropriately. That is, the magnetic susceptibility can be measured simply by reading the deviation width from the initial position with the determined predetermined position as the initial position (reference point) of the reference 5 of the scale 2c.

  Here, the scale 2c is formed as follows. A plurality of diamagnetic materials (for example, diamagnetic materials mentioned in the sample 4 to be described later) that have been measured in advance with SQUID and whose magnetic susceptibility is known are placed one by one in a vertical magnetic field having a predetermined strength in the superconducting magnet 1. Alternatively, a plurality of floats are levitated simultaneously, and each position of the levitated diamagnetic material is recorded and used as a scale. At this time, the magnetic susceptibility values of a plurality of diamagnetic materials whose magnetic susceptibility values are known are directly recorded on a scale, and further, this scale is divided so as to correspond to the product value of the magnetic field and the gradient magnetic field. Form a minor tick. It should be noted that the magnetic susceptibility can be easily measured and determined by converting the scale value into a magnetic susceptibility value corresponding to each measured sample in advance. If the scale 2c is formed in this way, the magnetic susceptibility of various diamagnetic materials capable of magnetic levitation can be read directly and easily just by specifying the levitation position of the diamagnetic material and reading the deviation width of the scale. Can do.

  The sample supply member 3 includes a rod-shaped member and a bowl-shaped portion on which the sample 4 provided under the rod-shaped member can be placed. Sample 4 is a diamagnetic material capable of magnetic levitation, and examples thereof include polypropylene, polyethylene, polystyrene, polyamide, and polycarbonate. These samples are levitated in a magnetic field and used when the scale 2c is formed. The levitation position of the sample 4 is on the central axis of the superconducting magnet 1.

  According to the magnetic susceptibility measuring instrument 2 and the magnetic susceptibility measuring apparatus 10, since it has a scale of the magnetic susceptibility of the diamagnetic material, the magnetic susceptibility of the diamagnetic material can be measured with a simple operation while having a simple configuration. it can.

  Next, the scale in the magnetic susceptibility measuring device and the magnetic susceptibility measuring device according to the present invention will be described using examples.

The superconducting magnet in the magnetic susceptibility measuring apparatus having the same configuration as in FIG. 1 has a JMTD-LH15T40 (manufactured by Japan Superconductor Technology Co., Ltd.) that generates a magnetic field in the vertical direction. In a cylindrical space of φ40 mm as the axis, the product of the magnetic field and the magnetic field gradient can be 1500 T ² / m (the size of the superconducting magnet is φ800 mm × height 1800 mm). Samples include polyethylene (PE), polycarbonate (PC), polypropylene (PP), polystyrene (PS) (all manufactured by Sampratec Co., Ltd.), and a spherical polyamide of φ3.2 mm, each having a size of about 3 mm × 2 mm × 2 mm. (PA) (manufactured by ASONE Co., Ltd.) was used.

For each sample of PE, PC, PP, PS, and PA, B (z) dB (z) / dz required for each sample to be magnetically levitated using the magnetic susceptibility measuring device having the same configuration as FIG. The value was measured.
The values of B (z) dB (z) / dz of each sample are shown in Table 1 below together with the levitation position of each sample from the bottom of the superconducting magnet in this susceptibility measuring apparatus. At this time, the levitation position of each sample in the z-axis direction is recorded on the scale, and the small scale is formed as described in the above embodiment.

Where χ is the mass magnetic susceptibility of the sample, μ ₀ is the magnetic permeability of the vacuum, B (z) is the magnetic flux density at the position z in the vertical direction, dB (z) / dz is the gradient of the magnetic flux density, and m is the single grain of the sample. If the mass and g of gravitational acceleration are
(Mχ / μ ₀ ) B (z) dB (z) / dz = mg (1)
It can be expressed as.

  Therefore, χ of each sample can be obtained from the above equation (1). The calculation results are also shown in Table 1 above.

  Further, the magnetic susceptibility of each sample was also measured by SQUID. The results are also shown in Table 1 above.

  It can be seen from Table 1 that there is a difference between the magnetic susceptibility measured by the SQUID and the magnetic susceptibility measured by the magnetic susceptibility measuring apparatus according to the present embodiment. This is considered to be caused by an error due to the measurement accuracy of the levitation position z or the measurement accuracy of B (z) dB (z) / dz. Therefore, it is necessary to correct the value to the magnetic susceptibility measured by SQUID. For example, a straight line in the proportional relationship between the levitation position of each sample and the magnetic susceptibility measured by the SQUID corresponding to each sample may be created by the least square method, and the value of each scale may be determined using this straight line. . By doing so, a magnetic susceptibility measuring device and a magnetic susceptibility measuring device having a susceptibility scale close to an accurate or accurate value are obtained.

  The present invention can be changed in design without departing from the scope of the claims, and is not limited to the above-described embodiments and examples. For example, with the CCD camera facing down, the sample is projected through an inclined reflector, the floating position of the sample is measured with a laser beam, and a scale used in a susceptibility measuring instrument and susceptibility measuring device is formed. Also good.

  Further, if a microscope or the like is used instead of the CCD camera, or the magnetic field strength or magnetic field gradient is changed, the magnetic susceptibility can be measured even with a cell level.

  Further, the magnetic susceptibility of each sample may be obtained by the above equation (1) from the measured values of magnetic field and magnetic field gradient (measured by a magnetic field measuring device such as a Gauss meter) at the floating position of the sample whose magnetic susceptibility is to be measured. The magnetic susceptibility of each sample may be obtained by the above equation (1) from the calculated value (calculated by a simulator or the like) of the magnetic field and magnetic field gradient at the floating position of the sample whose rate is to be measured. Note that these magnetic susceptibility values may be obtained by calculation using a computer from the levitation position, magnetic field, and magnetic field gradient value of the found diamagnetic material.

  There are various methods for detecting the levitation position of the diamagnetic material, but the following method may be used. For example, like the magnetic susceptibility measuring apparatus 20 shown in FIG. 2, a sample that is a diamagnetic material that floats in the magnetic field of the superconducting magnet 11 by moving the reflecting mirror 13 while observing the image of the reflecting mirror 13 with the CCD camera 12. A position where the side surface of 14 is projected at a predetermined position of the reflecting mirror 13 is detected as a floating position. Other methods include the following. Like the magnetic susceptibility measuring apparatus 30 shown in FIG. 3, the laser beam is incident on the reflecting mirror 23b in the magnetic field from the upper part of the superconducting magnet 21, and the reflecting mirror 23a and the image of the reflecting mirror 23a are observed with the CCD camera 22. The reflecting mirror 23b is moved in the vertical direction and in parallel by the same distance. Then, the laser beam strikes the side surface of the sample 24, which is a diamagnetic material levitating in the magnetic field of the superconducting magnet 21, and the position where the laser beam intensity is weakened is captured by the reflecting mirror 23a. And detect the position as the floating position. The reflecting mirrors 13, 23a, 23b may be simple mirrors or prisms.

  Furthermore, in each method of detecting the levitation position of the diamagnetic material, the image captured by the CCD camera 12 or the CCD camera 22 is taken out of the superconducting magnet and recorded by a video recorder to confirm the levitation position of the diamagnetic material. It is good to do.

It is the schematic of the magnetic susceptibility measuring apparatus containing the magnetic susceptibility measuring device which concerns on this invention. It is the schematic of the magnetic susceptibility measuring apparatus for demonstrating the modification of the detection method of the levitation position of a diamagnetic material. It is the schematic of the magnetic susceptibility measuring apparatus for demonstrating another modification of the detection method of the levitation position of a diamagnetic material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 11, 21 Superconducting magnet 2 Magnetic susceptibility measuring device 2a Bar member 2b, 12, 22 CCD camera 2c Scale 3 Sample supply member 4, 14, 24 Sample 5 (Scale 2c) standard 10, 20, 30 Magnetic susceptibility measurement Device 13, 23a, 23b Reflector

Claims (9)

Levitation of a plurality of types of diamagnetic materials with known magnetic susceptibility, one by one or several simultaneously in a vertical magnetic field having a gradient magnetic field;
Calculating the relationship between the susceptibility and the levitation position of the diamagnetic material in the magnetic field from each position and each susceptibility of the levitated diamagnetic material;
A diamagnetic material whose magnetic susceptibility is unknown is levitated in the magnetic field, the levitated position is specified, and the levitated position is converted into a magnetic susceptibility using the calculated relationship between the magnetic susceptibility and the levitated position. And measuring the magnetic susceptibility. Levitating different types of diamagnetic materials in a vertical magnetic field with a gradient magnetic field;
Calculating the magnetic field and magnetic field gradient at the levitation position of the diamagnetic material by measurement or numerical calculation processing;
And a step of calculating a magnetic susceptibility of the diamagnetic material using the measured or calculated magnetic field and the magnetic field gradient. Levitation of a plurality of types of diamagnetic materials with known magnetic susceptibility, one by one or several simultaneously in a vertical magnetic field having a gradient magnetic field;
Recording each position of the levitated diamagnetic material to make a scale;
A method for producing a susceptibility measurement scale, comprising the step of dividing the scale so as to correspond to a product value of a magnetic field and a gradient magnetic field to produce a small scale.   4. The method for producing a susceptibility measuring scale according to claim 3, further comprising a step of converting the scale and the small scale values into corresponding susceptibility values. It has a scale of magnetic susceptibility for diamagnetic material in a vertical magnetic field with a gradient magnetic field with respect to a predetermined position,
When the reference is moved from the predetermined position and adjusted to the height position of the levitated diamagnetic material in the vertical magnetic field having the predetermined intensity, the deviation width of the reference from the predetermined position is read from the scale. Magnetic susceptibility measuring instrument that can measure magnetic susceptibility.   6. A magnetic susceptibility measuring apparatus comprising: the magnetic susceptibility measuring apparatus according to claim 5; a superconducting magnet that generates a magnetic field in a vertical direction; and a gradient magnetic field generator that generates a gradient magnetic field. A superconducting magnet that generates a magnetic field in the vertical direction and a gradient magnetic field;
A levitation position detector for detecting a levitation position of a diamagnetic material levitated in the magnetic field;
A magnetic susceptibility measuring device comprising: a magnetic susceptibility calculating means for calculating a magnetic susceptibility at the floating position measured by the floating position detector.   The magnetic susceptibility calculation means calculates and calculates the magnetic susceptibility of the diamagnetic material from the magnetic field measuring device that measures the magnetic field and the gradient magnetic field at the levitation position, and the measured magnetic field and the gradient magnetic field. The magnetic susceptibility measuring apparatus according to claim 7, further comprising:   The magnetic susceptibility calculator calculates the magnetic susceptibility of the diamagnetic material from the magnetic field and the gradient magnetic field calculated by the magnetic susceptibility calculating means by calculating the magnetic field and the gradient magnetic field at the levitation position by a numerical calculation process. The magnetic susceptibility measuring device according to claim 7, comprising:

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