JPH01314957A - Method for detecting flaw of superconductor material current passage - Google Patents

Abstract

PURPOSE:To easily detect a quench part by heating a current passage constituted of a superconductor material to critical temp. or more and also allowing a current to flow through the current passage to detect the infrared rays corresponding to the temp. generated from the current passage. CONSTITUTION:A heating means 12 is used to heat a current passage 11 such as a coil constituted of a superconductor material to temp. higher than critical temp. Next, a DC power supply 13 is applied to both ends of the passage 11 and a required current is allowed to flow by a current variable part 14. As a result, a flaw part is increased in heat concn. quantity as compared with other part to increase the generation quantity of heat. Subsequently, an infrared camera 15 is used to detect the far infrared rays corresponding to the heat generation temp. of the passage 11 and said far infrared rays are converted to a electrical temp. video signal to be outputted. This temp. video signal is converted to digitial data having level gradation difference by an A/D converter circuit 16 to be stored in an image memory 17. The image data of the memory 17 is converted to appropriate data to be displayed on a CRT display part 18.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to defect detection of superconducting material current paths, which detects defective portions of various current paths such as coils and electric wires made of superconducting materials. In particular, the present invention relates to a method for detecting defects in current paths in a superconducting material, which effectively utilizes the critical temperature of the superconducting material to detect defective portions.

(Prior Art) In recent years, attempts have been made to develop various current paths 1 such as coils and electric wires using superconducting materials. The current path made of this superconducting material has the property of becoming zero resistance at a certain critical temperature, so there is a remarkable tendency to use it widely in various technical fields as a transmission path for large currents, and research and development is progressing. There is.

Incidentally, in this type of superconducting material current path, blockages may occur due to cracks or insulators being entangled due to the manufacturing process or manufacturing environment, but in such cases, a current exceeding the critical current density may flow. A quench phenomenon occurs that destroys the superconducting properties.

(Problem to be Solved by the Invention) Therefore, if a blockage occurs in a certain part of the current path in the superconducting material as described above, not only will the quench phenomenon greatly impair the superconducting function of the current path, but also the current path will be damaged. When a large current flows, the defective part, that is, the quench part, burns out and burns out as the discharge continues, making the current path unusable again.

The present invention has been made in view of the above-mentioned circumstances, and includes: ``Detection of defects in superconducting material current paths that enables reuse by quickly and appropriately repairing defective portions by accurately finding defective portions of current paths. The purpose is to provide a method.

[Structure of the Invention] (Means and Effects for Solving the Problems) In order to achieve the above object, the method for detecting defects in a current path in a superconducting material according to the present invention aims to detect a current path made of a superconducting material at a critical temperature that indicates superconductivity. The current path becomes quenched upon heating to a higher temperature than the current path. In this state, an infrared thermometer is used to detect the temperature state occurring in the current path, and a defective portion of the current path is detected by displaying the temperature in a color corresponding to the temperature.

(Example) Hereinafter, an example of an inspection system to which the method of the present invention is applied will be described with reference to FIG. In the same figure, reference numeral 11 denotes a current path such as a coil made of a superconducting material, and when detecting a defect in the current path 11, the current path 11 is used in a thermostat 12 (shown in the figure) as indicated by a dotted chain line, or in a burner (not shown), for example (hereinafter referred to as , these thermostats, burners, etc. as heating means 1
2).

Further, at both ends of this current path 11, a DC power source 12 and a current variable section 1 that changes the current to flow through the current path 11 are provided.
4 is provided.

Reference numeral 15 is an infrared camera that detects a temperature different from the normal object temperature, that is, a wavelength in the far infrared region. It is converted to digital data with gradation differences.

17 is an image memory for temporarily storing digital data; 18
is a CRT display unit that performs appropriate image processing on the image data stored in the image memory 17 and displays it.

Next, an example of detecting defects in a superconducting material current path using the above system will be described.

First, in this method, a current path 11 such as a coil is heated to a temperature higher than a critical temperature using a heating means 12 before installing it in an apparatus or a plant. As a result, current path 11
loses its superconducting properties and becomes a kind of electrical resistor.

Thereafter, a predetermined DC power source 13 is applied to both ends of the current path 11, and the current is varied by the current variable section 14 to flow a required current. As a result, the amount of heat concentrated in the defective portion is greater than in other portions, resulting in a greater amount of heat generation. Note that although the heating means 12 was used to heat the current path 11, conversely, after passing the required current through the current path 11, the heating means 1
2 may be used for heating. In this case, only the part to be inspected is heated and quenched, and after this quenching, the inspection can be performed by heating the current, so the external heating may be turned off.

Further, after setting the above state, the infrared camera 15 is used to detect far-infrared rays corresponding to the heat generation temperature of the current path 11, convert it into an electrical temperature video signal, and output it. This temperature video signal is converted into digital data having a level gradation difference in an A/D conversion circuit 16, and then sequentially stored in an image memory 17 in a predetermined order. Then, by converting the image data in the image memory 17 into appropriate data and displaying it on the CRT display section 18, a temperature distribution image having the same shape as the current path 11 can be displayed on the CRT display section 18. , and the current path 11 can be displayed in a color corresponding to its temperature, including a particularly large central portion of the heat flux.

Therefore, according to the method of the embodiment described above, the current path 11 made of a superconducting material is heated to a temperature higher than the critical temperature before it is installed in a device or plant that requires the current path 11. By making it a normal electrical resistor and passing the necessary current through this resistor, a high temperature part different from other parts is created, especially in the part corresponding to the quench.

Then, the far infrared rays generated from the current path 11 according to the temperature are imaged by the infrared camera 15, and the imaged result is
Since the information is displayed on the RT or the like, defective portions of the current path 11 made of superconducting material can be indirectly detected. Furthermore, by displaying colors on the CRT display section 18 in accordance with the respective temperatures of the current path 11, it is possible to know the state of the superconducting properties of the entire current path 11 from the color state, and of course, it is possible to accurately identify defective parts. The defect location can be recognized from the image.

Incidentally, regarding whether the defective portion experimentally found in the current path 11 using the above method matches the quenched portion when an overcurrent is passed through the current path 11 which is in a superconducting state below the critical temperature, Repeated examinations of various defective parts revealed that the parts were almost identical. Moreover, if the defect detection method described above is applied before being incorporated into a device or the like, defects can be reliably detected at low cost, making it very effective.

In addition, in the embodiment described in 2, the current path 11 is relatively compact.
For example, as shown in FIG. 2, the heating wire 21 is placed in advance in parallel with the current path 11 or in necessary locations or surrounding the current path, and the heating wire 21 is placed only when a defect is detected. By energizing the wire 21 with the heater power source 22, it is possible to heat the wire 21 to a temperature higher than the critical temperature regardless of the size of the current path 11. Furthermore, although the CRT display section 18 displays the temperature in a color corresponding to the temperature of the current path 11, since the temperature is already digital data corresponding to the gradation difference, the temperature can also be displayed in text at the corresponding location. In addition, the present invention can be implemented with various modifications without departing from the gist thereof.

[Advantageous Effects of the Invention 1] As detailed above, according to the present invention, a current path made of a superconducting material is heated to a temperature higher than the critical temperature and a current is passed through the current path, and at this time, the temperature generated from the current path is We developed a method for detecting defects in superconducting material current paths that can easily detect quenched portions of current paths, quickly and reliably repair the quenched portions, and install them in equipment, etc. Can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an inspection system to which the method for detecting defects in superconducting material current paths according to the present invention is applied, and FIG. 2 is a block diagram illustrating another embodiment of the method of the present invention. 11... Current path, 12... Heating means, 13...
DC power supply, 14... Current variable section, 15... Infrared camera, 16... A/D conversion circuit, 17... Image memory, 18... CRT display section, 21... Heating line . Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] At least the part of the current path to be inspected, including coils, wires, etc. made of superconducting material, is heated to a temperature higher than the critical temperature that indicates superconductivity, and a current is passed through the current path to create a quench state, and at this time, the 1. A method for detecting defects in a superconducting material current path, comprising: detecting a defective portion of the current path by imaging the temperature generated from the current path with an infrared camera.