JPS61269005A - Displacement measuring apparatus for cryogenic ferromagnetic field - Google Patents

Abstract

PURPOSE:To measure the displacement of an object to be measured from a TV image, by a method wherein light containing no infrared ray is introduced into a cryogenic ferromagnetic field to irradiate an object to be measured and the image of the reflected light is transmitted outside to make the TV image through a photoelectric conversion. CONSTITUTION:A sample 13 with the known width of a cut P is mounted 14 to be irradiated at the tip 23 of a light guide 21 and the reflected light is received by an objective lens 24 of an image guide 22 to observe an image of an image receiver 33 through a TV camera 31. By so doing, the magnifying power is adjusted 32 and the position of the lens 24 is finely adjusted by considering the refractive index of a liquid He. Then, a sample 13 is arranged in an inner tank 2, after a lid 4 is set, a liquid He 7 is held therein and following the defoaming, the inner tank 2 is put under the atm. When a cryogenic superconductive coil 6 is excited, an expanded image of the part P when unloaded is obtained and when it is imparted 8 a tension to plot a load signal S0 and the mean of the expansion of the part P in the image of the image receiver 33, a rupture toughness test can be done in a cryogenic ferromagnetic field.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a displacement measuring device for cryogenic and strong magnetic fields that can satisfactorily measure displacement under special environments such as cryogenic temperatures and strong magnetic fields.

[Technical background of the invention and its problems]

Various materials are stored in cryogenic liquids such as liquid helium.
Moreover, when placed in a strong magnetic field, it is expected to exhibit mechanical properties different from those at room temperature. In this way, confirming the mechanical properties of various materials at extremely low temperatures and in strong magnetic fields has an important meaning in realizing nuclear fusion devices, which are seen as promising future energy sources.

Incidentally, the means for measuring the mechanical properties of various materials, such as the fracture toughness value, are determined in detail by JIS and the like. However, this method is based on the condition of room temperature, and it is often impossible to employ similar means under special environments such as extremely low temperatures and strong magnetic fields.

That is, the cryogenic field is created by containing a cryogenic liquid such as liquid helium in a cryostat, and the 9 strong magnetic field is created by the use of superconducting coils. Superconducting coils require cryogenic liquid as a refrigerant, so
Ultimately, by housing a cryogenic liquid and a superconducting coil within a cryostand, it is possible to create an extremely low wet field and a strong magnetic field within a closed chamber such as a cryostat. In this way, it is relatively easy to simultaneously create a cryogenic field and a strong magnetic field. but.

To perform a fracture toughness test in such a field, it is necessary to measure the displacement of the sample. Clip-on gauges and capacitance detectors are usually used to measure this displacement, but these cannot be used because they are affected by the magnetic field.

Therefore, the problem is how to measure the displacement of a sample located in a closed room without being affected by the magnetic field, and due to this problem, destruction in extremely low temperature strong magnetic fields is still difficult. The reality is that no toughness tests have been conducted.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to be able to satisfactorily measure mechanical displacement in an extremely low temperature strong magnetic field, thereby making it possible to conduct fracture toughness tests, etc. under the above environment. The object of the present invention is to provide a displacement measuring device for extremely low temperature and strong magnetic fields that can contribute to the present invention.

(Summary of the Invention) According to the present invention, there is provided a light source device that is placed outside a cryogenic strong magnetic field in which an object to be measured is placed and that emits illumination light that does not contain infrared rays; a light guide that guides illumination light into the cryogenic strong magnetic field and irradiates the displaced measurement object; an image guide that transmits a reflected light image from the displaced measurement object to the outside of the cryogenic strong magnetic field; a television camera that photoelectrically converts an image of the object to be displaced transmitted through an image guide; and a television receiver that displays an image of the object to be displaced by introducing a video signal sent from the television camera. equipped with a machine,
A displacement measuring device for a cryogenic strong magnetic field is provided, which measures the displacement of the object to be displaced from an image projected on the television receiver.

(Effects of the Invention) According to the present invention, the image of the object to be displaced is guided outside the ultra-low strong magnetic field using a transmission system such as a light guide and an image guide that is not affected by concentration and magnetic fields. projected onto a television receiver.

The displacement is measured from this projected image. Therefore; displacement can be measured without being affected by temperature or magnetic fields. Furthermore, since the image guided through the image guide is captured by a television camera, the 1 magnification can be set to a large degree, and as a result, highly accurate displacement measurement can be performed.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

Note that FIG. 2 shows an example in which the present invention is applied to a fracture toughness testing device.

In the figure, 1 is a cryostat.

This cryostat 1 has an inner tank 2 and an outer tank 3.

It is comprised of a lid body 4 that selectively covers the upper opening of the inner tank 2. And between the inner tank 2 and the outer tank 3
The existing void 1I15 is evacuated and formed into a vacuum insulation layer.
) has been completed. Is there an external part (not shown) inside the inner tank 2? Superconducting coil 6 excited by l source □
is housed with its axis facing up and down, and liquid helium 7 is housed at a level where the superconducting coil 6 is sufficiently submerged.

A tensile force applying mechanism 8 is supported by a support column 9 above the cryostat 1, and is movable up and down along the support column 9 in the direction indicated by a solid line arrow 10. The tensile force applying mechanism 8 has a fixed rod 11 and a movable rod 12 that extend downward in parallel.1 A drive source (not shown) moves the movable rod 12.
It is configured to apply a tensile force by moving the member upward relative to the fixed rod 11. The fixed rod 11 and the movable rod 12 extend into the inner tank 2 through the lid 4 of the cryostat 1, and have their lower ends located within a portion surrounded by the superconducting coil 6. A sample holding mechanism 14 is provided between the lower end of the fixed rod 11 and the lower end of the movable rod 12 so as to face each other vertically. .

On the other hand, one end of the light guide 21 and one end of the image guide 22 are inserted into the inner tank 2 through the lid 4 of the cryostat 1. light guide 21
The end portion 23 located in the inner tank 2 is close to the notch P provided in the sample piece 13, and is arranged such that its optical axis faces the notch P at a predetermined angle. An objective lens 24 is attached to the end of the image guide 22 located inside the inner tank 2, and this objective lens 24
13(7)i;7J,)BMPIC! El! L, ka,
luster. 0,.

It is arranged so as to face the entrance P at a predetermined angle.

One end side of the light guide 21 and one end side of the image guide 22 arranged as described above are connected to the fixed rod 11.
They are supported by support members 25 and 26, respectively. The other end of the light guide 21 located outside the cryostat 1 is connected to a light source device 27. This light source device! 27 is a light source device main body 28 with a built-in lamp.
and a filter 29 that introduces into the light guide 21 light that cuts infrared rays out of the light sent out from the light source device main body 28 . An end of the image guide 22 located outside the cryostat 1 is connected via a connector 30 to a magnifying lens system of a television camera 31. The video signal sent from the television camera 31 is introduced into the television receiver 1!11133 via the camera controller 32.

Note that 34 in Figure 1 is a television camera 31. A magnetic shielding material that magnetically shields the camera controller 32 and the television receiver 33 is shown.

Further, 35 indicates pulp for introducing liquid helium.

36 and 37 indicate exhaust valves.

Next, an example of use of the fracture toughness testing apparatus configured as described above will be described.

First, loosen and remove the bolts tightening the lid 4 of the cryostat 1, and in this state, the tensile force applying mechanism 8
is raised along the support column 9 to a position where the sample holding mechanism 14 comes out of the cryostat 1. Next, the cut P
A sample piece 13 whose width is known is attached to the sample holding mechanism 14. next.

The light guide 21 is positioned so that the light emitted from the tip 23 of the light guide 21 is irradiated onto the notch P, and the image guide 22 is positioned so that the light reflected from the notch P can be received. The objective lens 24 is aligned. In this state, the image of the notch P actually projected on the image receiving Ia 33 is observed, and the camera controller 3
2 to set the magnification and receive the image Il! The position of the objective lens 24 is finely adjusted so that the image projected at 33 is in focus. Next, taking into consideration the distance from the notch P to the objective lens 24 and the refractive index of liquid helium, the objective is adjusted according to a predetermined calibration curve to avoid defocusing due to the influence of the refractive index of liquid helium. The position of the lens 24 is further finely adjusted. like this,
When the 11 adjustment is completed, the tensile force applying mechanism 8 is lowered to position the sample piece 13 in the inner tank 2 as shown in FIG. 2, and the lid 4 is set to its original state. Subsequently, the inside of the inner tank 2 is evacuated through the pulp 36, and once after exhausting.

The inner tank 2 is filled with helium gas, and then a predetermined amount of liquid helium 7 is stored in the inner tank 2 via the valve 35 while the helium gas is exhausted. Next, the inside of the inner tank 2 is again evacuated for a predetermined period of time to remove air bubbles existing in the inner tank t12, and then the pressure is brought to atmospheric pressure.

When liquid helium 7 is introduced into the inner tank 2 as described above,
The wire constituting the superconducting coil 6 is cooled to an extremely low temperature and becomes a superconducting wire. Further, the sample piece 13 is also cooled to an extremely low temperature. Next, the superconducting coil 6 is excited by an external power source (not shown). This excitation places the sample piece 13 in a strong magnetic field. Note that, of course, the strength of the ll field is detected by a sensor (not shown). Further, at this time, the portion of the notch P is displayed on the receiver 33.

This projected image is in focus because the position of the objective lens 24 is set taking into consideration the refractive index of the liquid helium 7 as described above. Moreover, since no load is applied to the sample piece 13 at this point, the brass portion of the notch P projected on the receptacle 133 is an enlarged image of the actual portion of the notch P.

Since the actual dimensions are known, the magnification can be immediately determined. Therefore, from now on, the tensile force applying mechanism 8 is operated, and the load signal So at this time.

By plotting the average value of the spread distance of the cut P projected on the image receiver 33, a fracture toughness test in a cryogenic strong magnetic field can be performed.

In this case, the light guide 21 and the image guide 22 are used to take out the image of the sample piece 13 outside the low-temperature strong magnetic field, and the image is received! 133, and the displacement of the sample piece 13 is measured from the projected image, so that the displacement can be measured without being affected by extremely low temperatures and strong magnetic fields.

In addition, the sample piece 1 transmitted via the image guide 22
Photograph the image of 3 with television camera 31.

This is projected onto the receiver 33.

Since the magnification can be freely set and, as a result, the measurement accuracy can be increased, the above-mentioned effects can be achieved after all.

Furthermore, according to this embodiment, since the light source device 27 is equipped with a filter 29 that cuts infrared rays, it is possible to prevent helium bubbles from being generated at the light transmission end of the light guide 21, and to achieve more accurate can contribute to measurements. In addition, since the objective lens position of the image guide 22 is set taking into account the refractive index of liquid helium, the image of the sample piece 13 projected on the image receiver 33 is
□The contour can be made clearer, contributing to even more accurate measurement. Furthermore, with the magnetic shielding material 34.

Television camera 31. Camera controller 32. Receiver 3
Because the 3rd class is magnetically shielded.

There is no risk that these will be affected by magnetism, and they can be operated stably.

Note that the present invention is not limited to the embodiments described above. That is, the above-mentioned embodiment is an example in which the present invention is applied to the fracture toughness test V&T.

The present invention is not limited to this, but can of course be applied to displacement measurements in general at extremely low temperatures and in strong magnetic fields. Furthermore, a mechanism may be provided that allows the position of the tip of the light guide and the position of the objective lens of the image guide to be adjusted from the outside. Also.

The light guide and the image guide may be integrated.

In this case, if the optical axis on the light transmitting side and the optical axis on the light receiving side are set so that a certain angle exists, a clear image can be transmitted.

[Brief explanation of the drawing]

The figure is a schematic configuration diagram of an example in which the present invention is applied to a fracture toughness testing device. 1... Cryostat, 6... Superconducting coil. 7...Liquid helium, 8...Tensile force imparting mechanism. 13... Sample piece, 21... Light guide, 22...
- Image guide, 27... Light source device, 31... Television camera, 33... Television receiver.

Claims (3)

[Claims] (1) A light source device that is placed outside the extremely low temperature strong magnetic field in which the object to be measured is placed and that emits illumination light that does not contain infrared rays; a light guide that guides the object to be displaced and irradiates it to the object to be measured; an image guide that transmits a reflected light image from the object to be measured to the outside of the cryogenic strong magnetic field; The television camera is equipped with a television camera that photoelectrically converts an image of the object to be displaced, and a television receiver that receives a video signal sent from the television camera and projects an image of the object to be displaced. A displacement measuring device for a cryogenic strong magnetic field, characterized in that the displacement of the object to be displaced is measured from an image projected on a receiver. (2) The displacement measuring device for a cryogenic strong magnetic field according to claim 1, wherein each element placed outside the cryogenic strong magnetic field is magnetically shielded. (3) The displacement measuring device for cryogenic strong magnetic fields according to claim 1, wherein the image guide is configured such that the position of the objective lens is set in consideration of the refractive index of the cryogenic coolant. .