JP5382616B2 - Superconducting critical current measuring device - Google Patents

Description

  The present invention relates to a superconducting critical current measuring apparatus capable of measuring a critical current value of a wire to be measured by bringing a wire to be measured supported by a cradle into contact with electrodes for measuring current and voltage.

  In recent years, thin film superconducting wires are being put into practical use in various fields as superconducting wires having superconductivity at the temperature of liquid nitrogen. This thin film superconducting wire is different from a normal copper core or aluminum core electric wire in that an orientation layer is formed on a tape-shaped metal substrate, and a superconducting layer made of a polycrystalline material is formed thereon, and A protective layer in which copper is thinly plated is formed thereon. On the other hand, for superconducting wires, critical current is measured at various positions as part of quality control.

  A device for measuring critical current in thin film superconducting wires (wires to be measured) is usually a direct conduction type superconducting critical current measuring device that measures superconducting critical current by direct current contact with electrodes on thin film superconducting wires. Is used (for example, Patent Document 1).

  Here, the configuration of a conventional superconducting critical current measuring apparatus will be described. FIG. 4 is a block diagram of a superconducting critical current measuring apparatus. In FIG. 4, 10 is a tape-shaped thin film superconducting wire, 21 is a feeding mechanism for the thin film superconducting wire, and 22 is a winding mechanism. Reference numeral 23 denotes a delivery side pulley, and 24 denotes a take-up side pulley. 60 is a liquid nitrogen reservoir, that is, a container, and 61 is liquid nitrogen stored in the liquid nitrogen reservoir 60.

  Reference numerals 70 and 72 denote current electrodes on the sending side and the winding side provided to be connected to a current source in order to pass a current through the thin film superconducting wire 10, and 71 and 73 are receiving electrodes corresponding to the respective current electrodes. It is a stand. Reference numerals 74 and 76 denote voltage electrodes on the sending side and the winding side provided in connection with an ammeter for measuring the resistance of the thin film superconducting wire 10, and 75 and 77 correspond to the respective voltage electrodes. It is a cradle. The feeding mechanism 21, the winding mechanism 22, the current source, and the voltmeter are connected to a PC (personal computer) via each I / F (interface).

  Under the above configuration, the thin film superconducting wire 10 unwound from the delivery mechanism 21 is immersed in the liquid nitrogen 61 of the liquid nitrogen reservoir 60 horizontally through the pulley 23, and the current electrodes 70 and 72, the voltage as it is. It passes between the electrodes 74, 76 and the respective pedestals 71, 73, 75, 77, rises vertically from the pulley 24, and is taken up by the take-up mechanism 22.

Next, a measuring method using the superconducting critical current measuring device will be described.
First, the delivery mechanism 21, the take-up mechanism 22, and further, the delivery-side pulley 23 and the take-up pulley 24 are rotated by a predetermined amount, and the measurement target portion of the thin film superconducting wire 10 is moved to the delivery-side current electrode 70, the take-up side. It is located below the current electrode 72 on the take-up side, the voltage electrode 74 on the send-out side, and the voltage electrode 76 on the take-up side.

  Thereafter, a pressure cylinder (not shown) that supports these four electrodes 70, 72, 74, 76 is lowered, and the thin film superconducting wire 10 is placed between the corresponding pedestals 71, 73, 75, 77. The protective layer (not shown) is sandwiched between the upper side (electrode side) and the substrate (not shown) on the lower side (cradle side).

  In this state, conduction between the thin film superconducting wire 10 and each of the electrodes 70, 74, 76, 72 is taken, and then the current is gradually increased to the set current value while controlling the current source with the PC. The voltage generated at the voltage electrodes 74 and 76 is monitored, the value is taken into the PC, and when the preset threshold is exceeded, the flow of current is stopped. Also, the critical current value is obtained from the generated voltage at the critical current defined in advance.

  Then, when the measurement of the part is completed, the pulley 23 on the sending side and the pulley 24 on the take-up side are rotated by a predetermined amount, the thin film superconducting wire 10 is sent out, and the same operation as above is performed at the next measurement target part. Repeat the measurement. Furthermore, the measurement can be automatically performed by inputting the moving distance of the thin film superconducting wire 10 and the number of times of measurement into the PC in advance.

Japanese Patent Application No. 2008-309669

  In the case of using the above apparatus, the thin film superconducting wire is immersed in the liquid nitrogen in the liquid nitrogen reservoir as described above and passes between the current and voltage measuring electrodes and the respective cradles. It is low temperature. For this reason, as shown in FIG. 5, although the moving thin film superconducting wire is not icing, ice S is icing on both sides of the thin film superconducting wire 10 at the cradle 71 facing the electrode 70, and the elapsed time of measurement is reached. I pile up with you. As a result, the electrode 70 hits the ice S and floats without coming into contact with the thin film superconducting wire 10 that should be in contact with the ice S, so that electrical connection cannot be obtained and measurement may be impossible.

  For this reason, when measuring the superconducting critical current of a thin film superconducting wire, there has been a demand for a superconducting critical current measuring apparatus capable of performing stable measurement without being affected by the occurrence of icing.

The present invention has been made for the purpose of solving the above problems. Hereinafter, techniques related to the present invention will be described.

The first technique related to the present invention is:
Directly measuring the superconducting critical current by having a cradle for supporting the wire to be measured, and flowing the current by directly pressing the measurement electrode which is a current electrode and a voltage electrode to the wire to be measured on the cradle. A current-carrying superconducting critical current measuring device,
A superconducting critical current measuring device comprising means for avoiding contact between the measuring electrode and the wire to be measured due to icing.

In this technology , by providing means to avoid contact between the measuring electrode and the wire to be measured due to icing, the superconducting critical current is reliably measured without being affected by icing. be able to.

The second technique related to the present invention is:
The superconducting criticality according to the first technique , wherein the means is formed by forming at least a peripheral part of a contact part of the cradle with the wire to be measured with a non-icing material. This is a current measuring device.

As described above, since icing occurs on both sides of the thin film superconducting wire on the cradle, in the present technology , the means to avoid is at least the periphery of the contact portion of the cradle with the wire to be measured. Since the portion is formed of a hard-to-ice material, the presence of the hard-to-ice material that will be located on the cradle corresponding to both sides of the thin film superconducting wire, It is possible to avoid icing on the periphery of the contact portion with the wire to be measured. As a result, the measurement electrode and the wire to be measured can be reliably brought into contact with each other, and accurate measurement can be performed.

The third technique related to the present invention is:
The means sets a width dimension of a contact portion with the wire to be measured in the cradle within a range of 50 to 100% of a width dimension of the wire to be measured, and does not contact the wire to be measured. The superconducting critical current measuring device according to the first technique or the second technique , wherein the position of the part is configured to be lower than the contact part.

In the present technology , the avoiding means is configured by setting a width dimension of a contact portion of the cradle with the wire to be measured in a range of 50 to 100% of a width dimension of the wire to be measured. Therefore, both sides of the wire to be measured do not come into contact with the cradle. As a result, even if icing occurs, the measurement electrode and the wire to be measured can be reliably brought into contact with each other.

  If it is less than 50%, the end of the wire to be measured hangs down, contact with the narrow wire to be measured becomes insufficient, or accurate measurement becomes difficult.

In addition, by using this technique together with the second technique , the measurement electrode and the wire to be measured can be brought into contact with each other more reliably.

The fourth technique related to the present invention is:
Said means comprises a first technique to a third technique, characterized in that it is constituted by setting the width of the measuring electrodes 50 to 100% of the width of the object to be measured for wire The superconducting critical current measuring device according to any one of the above.

In the present technology , the avoiding means is configured by setting the width dimension of the measurement electrode in a range of 50 to 100% of the width dimension of the wire to be measured. Even if icing occurs on the cradle, the measurement electrode can reach the wire to be measured on the cradle by avoiding the icing part, and as a result, the measurement electrode and the wire to be measured can be securely connected. Can be contacted.

  If it is less than 50%, contact with the thin film superconducting wire becomes insufficient, and accurate measurement becomes difficult.

In addition, by using this technique together with the second technique and the third technique , the measurement electrode and the wire to be measured can be more reliably brought into contact with each other.

The present invention is based on the above technique, and the invention according to claim 1
Directly measuring the superconducting critical current by having a cradle for supporting the wire to be measured, and flowing the current by directly pressing the measurement electrode which is a current electrode and a voltage electrode to the wire to be measured on the cradle. A current-carrying superconducting critical current measuring device,
  Means for avoiding that the measurement electrode and the wire to be measured cannot be contacted due to icing,
The means sets a width dimension of a contact portion with the wire to be measured in the cradle within a range of 50 to 100% of a width dimension of the wire to be measured, and does not contact the wire to be measured. The superconducting critical current measuring device is characterized in that the position of the portion is lower than the contact portion.

The invention described in claim 2
Directly measuring the superconducting critical current by having a cradle for supporting the wire to be measured, and flowing the current by directly pressing the measurement electrode which is a current electrode and a voltage electrode to the wire to be measured on the cradle. A current-carrying superconducting critical current measuring device,
Means for avoiding that the measurement electrode and the wire to be measured cannot be contacted due to icing,
The means is a superconducting critical current measuring apparatus configured by setting the width dimension of the measurement electrode in a range of 50 to 100% of the width dimension of the wire to be measured.

The invention according to claim 3
The said means is comprised by forming the peripheral part of the contact part with the said to-be-measured wire rod among the said cradles with a hard-to-ice material. Is a superconducting critical current measuring device.

  In the present invention, when measuring the superconducting critical current of a thin film superconducting wire, the measurement can be performed stably without being affected by the occurrence of icing.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically the structure of the means which avoids the inability to contact the thin film superconducting wire and the electrode for a measurement in the superconducting critical current measuring apparatus of the 1st Embodiment of this invention, (a) is a thin film superconducting wire. (B) is sectional drawing of the direction orthogonal to the advancing direction of a thin film superconducting wire. It is a figure which shows typically the structure of the means which avoids the contact failure of the thin film superconducting wire and measurement electrode in the superconducting critical current measuring apparatus of the 2nd Embodiment of this invention, Comprising: (a) is a thin film superconducting wire. It is a side view in alignment with the advancing direction, (b) is a front view. It is a figure which shows typically the structure of the means which avoids the contact failure of the thin film superconducting wire and measuring electrode in the superconducting critical current measuring apparatus of the 3rd Embodiment of this invention, (a) is a thin film superconducting wire. It is a side view in alignment with the advancing direction, (b) is a front view. It is a figure which shows typically the structure of a superconducting critical current measuring apparatus. It is a figure which shows typically the non-contact state of the thin film superconducting wire and measuring electrode in the superconducting critical current measuring apparatus of a prior art.

  Hereinafter, the present invention will be described based on embodiments. Note that the present invention is not limited to the following embodiments. Various modifications can be made to the following embodiments within the same and equivalent scope as the present invention.

(First embodiment)
In the present embodiment, in the superconducting critical current measuring device conventionally used, the contact between the electrode and the wire is ensured by devising the cradle. Specifically, a portion that is likely to be iced by the cradle, that is, at least a peripheral portion corresponding to both sides of the wire is formed by using a material that is difficult to be iced (difficult icing material). It prevents icing on the table, avoids the inability to contact the electrode and the wire during electrode pressure contact, and enables stable measurement.

  Hereinafter, the present embodiment will be described with reference to FIG. In addition, since the relationship between each measurement electrode and the corresponding cradle in the superconducting critical current measuring apparatus can be regarded as the same, in the following description, the current electrode 70 and the cradle 71 will be described. Moreover, in FIG. 1, in order to make an understanding of invention easy, the dimension of each part is changed suitably. These also apply to FIGS.

  FIG. 1 is a diagram schematically showing a structure of a means for avoiding inability to contact a thin film superconducting wire and a measuring electrode in the superconducting critical current measuring apparatus according to the present embodiment, and (a) shows the progress of the thin film superconducting wire. It is sectional drawing which follows a direction, (b) is sectional drawing of the direction orthogonal to the advancing direction of a thin film superconducting wire.

  The current electrode 70 has a size of, for example, 15 mm width × 45 mm length × 10 mm thickness, and, as shown in FIG. 1A, on the side facing the thin film superconducting wire 10, front and rear ends in the traveling direction of the thin film superconducting wire 10 These corners are chamfered (R is attached), and the contact portion length with the thin film superconducting wire 10 is 40 mm.

  The cradle 71 is formed, for example, 50 mm square × 15 mm thick and sufficiently larger than the size of the current electrode 70, and the portion to which the thin film superconducting wire 10 is pressed is 30 mm wide × 50 mm long × 1 mm thick, An ice icing portion 71 a that is slightly larger than the width of the thin film superconducting wire 10 is provided.

  As the material constituting the difficult-to-ice part 71a, a material that is excellent in electrical insulation and does not deform during pressure contact is preferable. Specifically, for example, fluorocarbon, monofluorinated phosphoric acid on the surface of anodized aluminum A treated member, a material provided with an alkyl ketene dimer, or the like is preferably used. In consideration of the occurrence of icing at the periphery of the portion where the thin film superconducting wire 10 is pressed, it is sufficient to form a pair of difficultly icing portions 71a only at the periphery. However, providing a pair of such small ice-free portions is more costly than providing one large ice-free portion, so in FIG. 1 it is slightly more than the width of the thin film superconducting wire 10. A large difficult icing portion 71a is provided.

  In addition, as a material which comprises the receiving stand 71, the material excellent in electrical insulation and mechanical strength is preferable, and, specifically, fiber reinforced plastics (FRP), such as a glass fiber reinforced epoxy resin, is used preferably, for example.

  Providing the difficult icing portion 71a makes it difficult for the peripheral portion of the portion where the wire 10 on the pedestal 71 is pressed to come into contact with the ice, so that the current electrode 70 and the thin film superconducting wire 10 due to icing are prevented from being inaccessible. And stable measurement can be performed.

(Second Embodiment)
This embodiment also ensures the contact between the electrode and the wire by devising the structure of the cradle in the superconducting critical current measuring device. Specifically, a portion that is likely to be iced by the cradle, that is, a peripheral portion of a portion corresponding to both sides of the wire is cut out, and the size of the cradle body is set to be equal to or smaller than the wire width. It prevents icing on the main body, avoids the inability to contact the electrode and the wire during electrode pressure welding, and enables stable measurement.

  Hereinafter, the present embodiment will be described with reference to FIG. FIG. 2 is a diagram schematically showing a structure of means for avoiding inability to contact the thin film superconducting wire and the measurement electrode in the superconducting critical current measuring apparatus of the present embodiment, and (a) shows the progress of the thin film superconducting wire. It is a side view along a direction, and (b) is a front view.

  As shown in FIG. 2, the cradle 71 includes a cradle body 81 having a width W0 that is equal to or smaller than the width of the thin film superconducting wire 10 and a support portion 82 provided at a lower stage by a step 71b. Here, the height of the step 71 b is set sufficiently large so that the icing generated on the support portion 82 does not come into contact with the current electrode 70.

  Since the width of the cradle body 81 is set to be equal to or smaller than the width of the thin film superconducting wire 10, there is no possibility that the cradle body 81 is iced. Further, the icing generated on the support portion 82 is not in contact with the current electrode 70 because the step 71b is sufficiently provided. For this reason, it is possible to prevent contact between the current electrode 70 and the thin film superconducting wire 10 due to icing, and stable measurement can be performed regardless of the presence or absence of icing.

  If the width W0 of the cradle body 81 is too narrow with respect to the width of the thin film superconducting wire 10, the thin film superconducting wire 10 and the current electrode 70 may not be brought into sufficient contact. For this reason, the width W0 of the cradle body 81 is preferably 50 to 100% of the width of the thin film superconducting wire 10.

(Third embodiment)
In the present embodiment, in the superconducting critical current measuring apparatus, the contact between the electrode and the wire is ensured by devising the shape of the electrode. Specifically, by making the size of the electrode equal to or less than the wire width, it ensures contact between the electrode and the wire during electrode pressure contact regardless of icing that has occurred on the cradle, enabling stable measurement. Is.

  Hereinafter, the present embodiment will be described with reference to FIG. FIG. 3 is a diagram schematically showing a structure of means for avoiding inability to contact the thin film superconducting wire and the measurement electrode in the superconducting critical current measuring apparatus of the present embodiment. FIG. 3A shows the progress of the thin film superconducting wire. It is a side view along a direction, and (b) is a front view.

  As shown in FIG. 3, the width W <b> 1 of the current electrode 70 is set to be equal to or smaller than the width of the thin film superconducting wire 10. Thereby, even when the icing S occurs on the cradle 71, the current electrode 70 can be reliably brought into pressure contact with the thin film superconducting wire 10. For this reason, it is possible to prevent contact between the current electrode 70 and the thin film superconducting wire 10 due to icing, and stable measurement can be performed regardless of the presence or absence of icing.

  If the width W1 of the current electrode 70 is too narrow relative to the width of the thin film superconducting wire 10, there is a risk that the thin film superconducting wire 10 and the current electrode 70 cannot be brought into sufficient contact. For this reason, the width W1 of the current electrode 70 is preferably 50 to 100% of the width of the thin film superconducting wire 10.

DESCRIPTION OF SYMBOLS 10 Thin film superconducting wire 21 Sending mechanism 22 Winding mechanism 23, 24 Pulley 60 Liquid nitrogen reservoir 61 Liquid nitrogen 70, 72 Current electrodes 71, 73, 75, 77 Receiving base 71a Anti-icing part 71b Step 74, 76 Voltage electrode 81 Receiving Base unit 82 Support unit S Icing

Claims (3)

Directly measuring the superconducting critical current by having a cradle for supporting the wire to be measured, and flowing the current by directly pressing the measurement electrode which is a current electrode and a voltage electrode to the wire to be measured on the cradle. A current-carrying superconducting critical current measuring device,
Means for avoiding that the measurement electrode and the wire to be measured cannot be contacted due to icing ,
The means sets a width dimension of a contact portion with the wire to be measured in the cradle within a range of 50 to 100% of a width dimension of the wire to be measured, and does not contact the wire to be measured. superconducting critical current measurement apparatus position of the part, it characterized that you have been configured by less than the contact portion. Directly measuring the superconducting critical current by having a cradle for supporting the wire to be measured, and flowing the current by directly pressing the measurement electrode which is a current electrode and a voltage electrode to the wire to be measured on the cradle. A current-carrying superconducting critical current measuring device,
Means for avoiding that the measurement electrode and the wire to be measured cannot be contacted due to icing,
The said means is comprised by setting the width dimension of the said electrode for a measurement to the range of 50 to 100% of the width dimension of the said to-be-measured wire, The superconducting critical current measuring apparatus characterized by the above-mentioned. Said means, according to claim 1 or claim 2, characterized in that at least the peripheral portion of the contact portion between the measuring wire of said cradle is constituted by forming flame icing material Superconducting critical current measuring device.

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