KR20050010228A - High temperature superconductor junction methods to normal conductive parts for resistance-reducing of normal conductive parts in superconductivity system - Google Patents

Abstract

PURPOSE: A method of bonding a superconductor line to a normal conductive part existing in a superconductor system is provided to bond the superconductor line to the normal conductive part of the superconductor system to reduce the resistance of the superconductor system. CONSTITUTION: A plurality of long high-temperature superconductor lines(20) are bonded to a normal conductive part. The normal conductive part is a copper bar(10). A current path is formed using the copper bar having a large cross area since a superconductor system flows large current. The normal conductive part is heated to bond the superconductor lines to the normal conductive part. Otherwise, the superconductor lines are bonded onto a sheet having high thermal conductivity such as a copper sheet, and the sheet is bonded to the normal conductive part.

Description

HIGH TEMPERATURE SUPERCONDUCTOR JUNCTION METHODS TO NORMAL CONDUCTIVE PARTS FOR RESISTANCE-REDUCING OF NORMAL CONDUCTIVE PARTS IN SUPERCONDUCTIVITY SYSTEM}

The present invention relates to a method for reducing the resistance of the phase conduction portion existing in the superconducting system, and more particularly, to a method of simultaneously joining superconducting wire rods for bonding superconducting wires to the phase conduction portion and implementing the same. It is about.

In general, superconducting junctions are used when the wire length is insufficient when winding coils, when individual winding coils are connected in series, and when a superconducting permanent current switch for permanent current operation must be connected in parallel. The same operation as when all windings are made with one wire is to be performed. In this regard, in the method of joining a superconducting wire, Patent Publication No. 10-0380630 adds another superconducting wire to two strands of the superconducting wire to be joined for the purpose of improving the critical current characteristics of the superconducting junction and compresses the second superconducting wire. The present invention proposes a method of increasing the degree of joining of wires, and in Patent Application No. 10-0360292, 'Superconducting Bonding Method of High Temperature Superconducting Tape Wire', a multicore high temperature superconducting tape wire is cut at the same inclination angle and a single core superconducting wire is manufactured to manufacture the multicore high temperature superconducting tape. Wrap the area where the inclined surface of two multi-core high temperature superconducting tape wires to be joined by making a high temperature superconducting plate material having the same area as the inclined surface area of the wire rod with a certain material, and press the wrapped portion with a predetermined pressure to fix it Superconducting pillar by annealing the part at a certain temperature A method of improving the critical current of a superconducting junction by increasing the junction probability between the cements is proposed. In addition, Patent Application No. 10-2001-0084269 'Superconducting bonding method through the superconductor powder' bolts to block the entrance of the cup member filaments of the two superconducting wires to be joined by inserting the superconducting powder into the cup member with a thread inside Inserted through the hole of the type stopper member, and combined the cup member and the stopper member, and compresses only the portion where the superconductor powder and the superconducting filament are present together to increase the packing density of the superconductor in the form of powder, thereby superconducting the superconductor powder as a medium. Since it is connected to the filament of the wire rod, most of the current flowing in the superconducting wire rod is connected to the superconducting wire rod, thereby suggesting a method of reducing the drop in the critical current caused by the bonding.

However, the above contents are methods for reducing the drop in the critical current by the junction between the superconducting wires by increasing the contact probability between the superconducting wires, and the object of the present invention is to reduce the resistance of the phase conduction portion present in the superconducting system. It relates to a bonding method of the superconducting wire to the phase conducting portion for realizing this.

In general, since a superconducting system flows a large current, a phase conduction bar having a large cross-sectional area is used to configure a current path. Superconductors are materials with zero resistance, which makes them ideal for developing systems with no electrical resistance. However, in a real system, a phase conduction part such as an external current introduction part and a superconducting part, and a phase conduction part connecting the superconducting part and the superconducting part are included in the system, which causes an increase in the resistance value of the superconducting system. Here, the superconducting portion and the superconducting portion are not simply a junction between the superconducting wires, but a superconducting portion and a superconducting portion such as a connection of multiple superconducting solenoids. That is, by reducing the resistance value in the phase conduction part that is inevitably present, rather than the direct connection between the superconducting wires, the method of expecting the thermal safety of the superconducting system as well as the synergistic effect of the critical current should be sought.

The present invention has been made to solve the above problems by reducing the resistance of the phase conduction portion of the superconducting system, to reduce the resistance of the superconducting system by bonding the superconducting wire to the phase conduction portion existing in the superconducting system. It also included a method of joining several long wires at the same time. This joining method includes attaching to a round copper rod in addition to attaching multiple wire rods on a flat surface such as a bar. In particular, the method of joining round copper rods is also applied to joining high temperature superconducting multi-strand with copper rods.

1 is a block diagram for explaining a preferred embodiment of the present invention.

2 is a phase conductive conductor to which the high temperature superconducting wire according to the present invention is attached.

3 is a graph showing current-voltage characteristics according to the number of high temperature superconducting wires bonded to a copper bar.

4 is an explanatory diagram for showing the attachment state of the superconducting wire for the same resistance design.

Figure 5 is a block diagram for explaining a preferred embodiment of the present invention applied to a cylindrical phase conducting conductor.

FIG. 6 is a sectional view seen from the side of the bonding surface of FIG. 5; FIG.

<Description of Drawing>

10 copper bar 11: cylindrical phase conducting conductor

12: groove 13: solder

14 silver paste 15 current inlet

20: high temperature superconducting wire 21: strand type high temperature superconducting wire

30: heater 31: heater applied to the cylindrical phase conductor

40: Fixer 41: Fixer applied to cylindrical phase conductor

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, it should be noted that in the drawings, the same components or parts denote the same reference numerals as much as possible. In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the subject matter of the present invention.

1 is a view for explaining a bonding method in the case where the phase conduction portion is a bar form as a preferred embodiment of the present invention. An important point in the bonding of the present invention is to join several long high temperature superconducting wires 20 to the phase conducting portion at the same time. Here, the phase conduction part was used as the copper bar 10. In general, since a superconducting system flows a large current, a copper bar 10 having a thick cross section is used to configure a current path. In this case, the superconducting wire 20 may be bonded by heating the thick phase conductive parts at once, and another method may be to bond the superconducting wire 20 to a thin plate having good thermal conductivity, such as a copper sheet. It may be bonded to the bar 10. The reason for the bonding is that the current is concentrated in the portion where the resistance is the smallest in the current flow. In other words, in parallel circuits where the resistance difference is more than 100 times, the current flowing through the large resistance part can be ignored.

First of all, to join several long superconducting wires simultaneously to a flat part such as a copper bar 10

First, to provide a space to position the superconducting wire 20 in the copper bar (10). For the purpose of fixing the superconducting wire 20, it is possible to form grooves 12 on the copper bar 10 that match the width and thickness of the superconducting wire 20. However, provision of this space can be omitted in the joining method of the present invention.

Second, the solder 13 is applied to the portion to which the superconducting wire 20 is to be attached. However, it is preferable that the next step of the conductive bonding material is carefully applied so as not to interfere with the bonding of the portion to be attached, and the solder 13 is also melted at a sufficiently low temperature so as not to damage the conductive bonding material.

Third, conductive bonding materials such as silver paste 14 are applied to both ends of the superconducting wire 20 to be bonded to the copper surface. If necessary, the conductive bonding material can be applied to other portions to enhance the bonding strength.

Fourth, the solder 13 is melted so as not to damage the silver paste 14 by applying heat evenly to the copper bar 10 with the heater 30.

Fifth, the fixing is completed while fixing the superconducting wire 20 with a fixer 40 to complete the bonding.

To melt the right solder on thicker parts such as copper bars, a large heater capacity is required and the time required to melt the solder will also be large. In this case, after contacting the superconducting wire 20 to the copper sheet, it can be attached to a copper bar, etc. to reduce the effort required for bonding.

2 shows a phase conducting conductor in which a superconducting wire 20 is bonded to a copper bar 10 according to the method described above. The solder 13 should be applied so as not to interfere with the bonding by the silver paste 14.

3 is a graph showing the current-voltage characteristics measured while changing the number of superconducting wires 20 bonded to the copper bars 10 from 0 to 5. FIG. As the number of wire rods bonded to copper increases, the generated voltage according to the transmission current decreases. In other words, the resistance of the phase conduction portion is reduced. It can be seen that the resistance decreases significantly as the wire is attached. The decrease appears to show a tendency to saturate with more than 3 wire rods.

4 shows the attachment state of the superconducting wire 20 for the same resistance design. In the case where several superconducting wires 20 are joined at the same time, it is preferable that the phase conduction resistances from the current conducting portion 15 of the phase conducting portion to the superconducting wires 20 are the same to set the position at which the wires are to be joined. If the resistance of the phase-conducting part existing from the current induction part 15 to the superconducting wire is not the same, the current is concentrated to the smaller resistance part of the current, and the current to the superconducting wire 20 is not properly distributed, thereby reducing the resistance. Can be significantly reduced. If the resistance of the phase-conducting portion cannot be equal, the superconducting wire 20 in the portion having low resistance uses a significantly higher critical current than other wires or stacks two or more wires together. It may be.

5 shows a preferred embodiment of the present invention applied to a cylindrical phase conducting conductor 11. The method of joining the cylindrical phase conducting conductor 11 such as a copper rod is as follows. In particular, in this method, if there is no bending of the copper rod, the superconducting wire 21 may be wound in the form of a multi-strand as shown in the following figure, and only the ends of the copper rod may be joined. In particular, this joining method also applies to joining high-temperature superconducting wires with phase-conducting parts when fabricating high-temperature superconducting multi-strands. The end portion refers to a portion where the superconducting wire and the multi-strand high temperature superconducting wire 21 are joined. As the material, a phase conducting metal such as oxygen free copper (OFC) is used. It is produced through the following steps.

First, grooves 12 are processed at a minimum machining interval of 0.5 mm or less between the ends of the strands (ex copper) to which the strand type superconducting wires 21 are joined. However, when the pitch and the fixed state of each strand can be maintained without groove processing, groove processing can be omitted.

Second, the junction length of the copper part is the length that can realize the minimum junction resistance in design. In general, the minimum resistance can be achieved if the junction more than 10cm. However, in special cases where the length of the joint cannot be extended, this clause may be omitted.

Third, a solder 13 such as PbSn, AgMn, or the like is applied to the groove 12. However, solder is not applied to the areas where the following conductive bonding materials will be attached. The solder uses a solder having a low melting point so that the bonding of the conductive bonding material is not damaged.

Fourth, the strand type superconducting wire 21 is placed in the phase conduction portion.

Fifth, the wire rod and the end portion are joined to a non-soldered groove 12 by a conductive bonding material such as silver-paste 14.

Sixth, the solder is melted by applying heat and cooled while the wire is fixed to complete the bonding. It is preferable that the wire rod is fixed with a fixer 41 manufactured to fix the wire rod during bonding, and the fixer 41 is made of a material having a very low thermal conductivity. Meanwhile, as shown in FIG. 5, the heat may be applied at the same time as a whole such that the heater enters into the copper rod.

FIG. 6: shows the cross section which looked at the joining method shown in FIG. 5 from the side. Strand-type high-temperature superconducting wire 21 can be seated in the groove 12, heat can be evenly transferred by the heater 31, and the fixer 41 reliably transfers the superconducting wire to the cylindrical phase-conducting conductor 11. Shows that it is fixed.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible within the scope without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

As described in detail above, when the superconducting wire is simultaneously bonded to the phase conducting portion existing inside the superconducting system, the resistance of the phase conducting portion is reduced, so that the thermal safety of the entire superconducting system as well as the synergistic effect of the critical current can be expected. . This joining method can be applied to places such as round copper bars in addition to attaching multiple wires to flat places, and in particular, the method of applying to places such as round copper bars can be applied to joining high temperature superconducting multi strands to copper bars.

Claims (6)

A method for reducing the resistance of a phase conducting portion present in a superconducting system, A first step of applying solder to a portion to which the high temperature superconducting wire is to be attached; Placing a high temperature superconducting wire in a solder-coated portion; Applying a conductive bonding material to both ends of the high temperature superconducting wire to bond the wire to the phase conducting portion; A fourth step of melting the solder by applying heat to the electric field of the phase conducting portion with a heater; And a fifth step of cooling and fixing the high temperature superconducting wire by means of a fixer to complete the joining. The method of claim 1, Bonding to the phase-conducting portion of the high-temperature superconducting wire, characterized in that the portion to which the high-temperature superconducting wire is attached in the first step is grooved. The method of claim 1, In the method of locating the high temperature superconducting wire of the second step, the distance from the current induction part to the high temperature superconducting wire is designed to be the same so that the phase conduction resistance from the current induction part of the phase conduction part to each of the high temperature superconducting wire is the same. A method of joining a high-temperature superconducting wire to a phase conducting portion of a high-temperature superconducting wire, wherein the high-temperature superconducting wire is bonded to the high-temperature superconducting wire by using a large critical current or by stacking two or more when the resistance from the current induction part to the high-temperature superconducting wire is small. The method according to any one of claims 1 to 3, And wherein said phase conductive portion is a copper bar or copper sheet and said conductive bonding material is a silver paste. A method for reducing the resistance of a phase conducting portion present in a superconducting system, A first step of forming a groove at a minimum machining interval between the portions of the strand to be joined to the cylindrical phase conducting metal to which the strand-type superconducting wire is joined; A second step of applying solder to the groove; A third step of positioning the strand-type superconducting wire in the groove position and adding the conductive bonding material to the end of the strand to fix the wire; A method of joining a superconducting wire to a cylindrical phase conducting conductor, characterized in that it comprises a fourth step of dissolving the solder by heating with a heater and cooling the superconducting wire with the fixer to complete the bonding. A phase conductive conductor to which a high-temperature superconducting wire manufactured by the method of any one of claims 1 to 5 is bonded.