Processes, systems and devices for metal filling of high temperature superconductor cables

Abstract

SOLUTION: Techniques described herein relate to systems and methods for obtaining a high temperature superconducting (HTS) cable assembly and filling the HTS cable assembly with a molten metal, such as solder.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] One embodiment of the present invention relates to processes, systems, and devices for metal filling of, for example, high temperature superconductor cables. [Background technology]

[0002] High temperature superconductor (HTS) materials are capable of carrying large amounts of electrical current with low losses.

[0002] Some known HTS cables and magnets can be fabricated in a manner similar to that used for low temperature superconductor (LTS) cables, i.e., without using any solder around the HTS material. For example, if the HTS material is an HTS tape or a stack of HTS tapes, the HTS cable or magnet is fabricated without any solder around the HTS tape or HTS tape stack.

[0003]

[0003] Other HTS cables and magnets can be fabricated using a soldering process. Takayasu, for example, describes a soldering process technique for straight twisted laminated tape cables (TSTCs). The HTS tape stack is wrapped within a conductor, which is then manually threaded horizontally in its straight configuration through a 60% Sn-40% Pb molten bath. This technique requires bending the cable after soldering. However, such bending after soldering results in degradation of the superconducting properties of the HTS material (i.e., degradation of the superconducting properties of the HTS tape stack).

[0004]

[0004] One technique for solder-filling LTS cables having a so-called cable-in-conduit conductor (CICC) configuration is described by P. Bauer, P. Bruzzone et al. (Solder-Filling of a CICC cable) For The EFDA Dipole Magnet, AIP Conference Proceedings 986, 151 (2008); see https: / / doi.org / 10.1063 / 1.2900339. In this technique, a CICC with a low-temperature superconductor disposed therein is evacuated and the solder is pressurized with argon to initiate solder flow within the CICC. Summary of the Invention [Problem to be solved by the invention]

[0005] One embodiment of the present invention relates to processes, systems, and devices for metal filling of, for example, high temperature superconductor cables. [Means for solving the problem]

[0006]

[0005] According to one aspect of the concepts, processes, systems, devices, and techniques described herein, a method includes the steps of at least partially filling at least one channel of a high temperature superconductor (HTS) cable assembly with molten metal, the HTS cable assembly comprising an HTS and at least one channel, and operating one or more cooling devices to cool the molten metal in the at least one channel.

[0007] It should be understood that individual elements of different embodiments described herein may be combined to form other embodiments not specifically set forth above. Various embodiments described in the context of a single embodiment may also be provided separately or in any suitable subcombination. Other embodiments not specifically described herein may also be provided below. It is also understood that the present invention is within the scope of the following claims.

[0008]

[0007] The method has the following features: the HTS cable assembly includes a former in which at least one channel is disposed; the former includes four channels each including an HTS, and the method includes the step of at least partially filling the four channels of the former; the HTS cable assembly further includes a jacket disposed around the former; completely filling the at least one channel of the HTS cable assembly; the step of at least partially filling the at least one channel of the HTS cable assembly with molten metal includes heating the HTS cable assembly and applying pressure to the molten metal to force the molten metal through the at least one channel of the former; the molten metal is held by a container, and applying pressure to the molten metal The method may include, independently or in combination with one or more other features to be included, one or more of: applying pressure to the molten metal in the vessel; the HTS cable assembly comprising a tube having a wall defining at least one channel and at least partially filling the at least one channel of the tube with molten metal; the HTS cable assembly comprising a stack of HTS tapes; the molten metal comprising PbSn solder or a lead-tin solder alloy; depositing flux in the at least one channel before at least partially filling the at least one channel with molten metal; and the step of operating the one or more cooling devices comprises progressively cooling the HTS cable assembly towards the source of the molten metal.

[0009]

[0008] According to further aspects of the concepts, processes, systems, devices, and techniques described herein, there is provided a vacuum impregnation (VPI) station for filling a cable assembly including high temperature superconducting (HTS) material with molten metal, the VPI station comprising: (a) a can configured to hold a source of molten metal; (b) one or more heaters arranged to heat the HTS cable assembly, the HTS cable assembly comprising at least one of a tube or former having at least one channel formed therein or separately provided therein, the one or more heaters having HTS material disposed in at least one of the at least one channel of the tube or former; and (c) pressure applying means coupled to the can for applying pressure to the molten metal in the can to force the molten metal from the can through the at least one channel of the tube or former.

[0010]

[0009] The VPI station may include one or more of the following features, independently or in combination with one or more other features to be included: a siphon coupled to the can, positioned at a height greater than the height of the molten metal in the can, to inhibit the flow of molten metal from the can when the pressure application means is not acting; a plurality of contact sensors configured to monitor the flow of metal from the can into at least one channel of the tube or former, wherein one or more heaters are positioned in contact with the can; an outlet tube coupled to the can, wherein at least one of the one or more heaters is positioned adjacent to the outlet tube; a waste tank positioned to collect molten metal flowing through and exiting at least one channel of the tube or former; a U-bend coupled to the waste tank, which inhibits molten metal from flowing from the waste tank back into at least one channel of the tube or former.

[0011]

[0010] The concepts, processes, systems, devices, and techniques described herein According to yet a further aspect, a spreader for channeling molten metal into and / or out of an N-channel former, the spreader comprising an elongated member having a conical end, a smooth shank portion, and a helical groove portion having N grooves provided therein, the helical groove portion being a spiral groove. The spiral groove portion has a flared shape with a diameter that increases from a first end of the spiral groove portion toward a second end of the spiral groove portion, and the N grooves of the spiral groove portion are configured to direct molten metal into the channels of the N-channel former.

[0012] In an embodiment, the dispenser has the following features: the first end of the spiral groove portion is smooth The spiral groove portion may include, independently or in combination with one or more other features to be included, one or more of: a first end of the spiral groove portion having a diameter substantially corresponding to the diameter of one end of the shank portion; and a second end of the spiral groove portion having a diameter substantially corresponding to the diameter of the N-channel former.

[0013]

[0012] The concepts, processes, systems, devices, and techniques described herein According to yet another aspect, a method includes obtaining a high temperature superconducting (HTS) cable assembly, bending the HTS cable assembly, heating the HTS cable assembly, and filling the HTS cable assembly with molten metal.

[0014] In this particular arrangement, a method for manufacturing a high temperature superconducting (HTS) cable is provided. In an embodiment, the step of filling the HTS cable with molten metal includes using a vacuum impregnation (VPI) process to fill the HTS cable with molten metal.

[0015]

[0014] The concepts, processes, systems, devices, and techniques described herein According to another aspect, a method for filling a high temperature superconducting (HTS) cable with molten metal includes bending or otherwise forming an HTS cable assembly into a desired shape and filling the HTS cable assembly with molten metal.

[0016] In this particular arrangement, a cable containing superconducting material is filled with molten metal. A process for solder-filling HTS cables is provided. This technique allows the cable to be bent, wrapped, molded, formed, or otherwise fabricated into a desired shape (e.g., the final shape of a magnet, current lead, or other structure) prior to or simultaneously with solder filling of the cable. In embodiments, the HTS cable may be provided as a tape-in-conduit cable.

[0017]

[0016] The cable can be shaped before or during the solder filling process. This provides a robust cable suitable for many applications. Because the cable is shaped before or during the molten metal filling process, no deformation of the cable is required after the metal filling cools and solidifies. Therefore, degradation of the cable (and particularly of the HTS material within the cable) due to deformation of the cable after the metal filling process does not occur. This results in a robust cable.

[0018] In an embodiment, the molten metal is solder. , may be provided as a tin-lead solder. In an embodiment, the solder is Sn 60 Pb 40 It may be provided as a solder.

[0019] In an embodiment, the superconducting material is provided as a high temperature superconducting (HTS) tape. In embodiments, the HTS tape may be provided as a rare earth barium copper oxide (REBCO) tape. In embodiments, the HTS material may be provided as either a YBCO, BSCCO, or MgB2 tape.

[0020] In an embodiment, the cable is provided with one or more channels therein. The cable may include a former having channels with the HTS tape disposed within the channels. In embodiments, the channels have a helical shape (or helical pattern) along the length of the cable. In embodiments, the cable may include one or more cooling channels.

[0021]

[0020] The concepts, processes, systems, devices, and techniques described herein According to yet a further aspect, a vacuum impregnation (VPI) system for filling HTS cables with molten metal is described that includes an array of sensors to measure temperature at multiple points. Using these sensors for monitoring and control, a process is developed with a time-temperature profile that allows filling the HTS cable with molten metal without degrading the HTS material.

[0022]

[0021] The concepts, processes, systems, devices, and techniques described herein According to yet a further aspect, a method for filling an HTS cable with molten metal includes bending a cable assembly having an HTS material disposed therein and filling the cable assembly with molten metal. In an embodiment, the cable assembly may include a tube (or jacket) having one or more channels provided therein, and the HTS material may include an HTS tape. Thus, the cable assembly may have one or more HTS tapes disposed in corresponding ones of the additional channels of the tube before filling the cable assembly with molten metal. In an embodiment, the cable assembly may include a former having one or more channels provided therein, and the HTS material may include an HTS tape disposed in the channels of the former. Thus, one or more HTS tapes (e.g., an HTS tape stack) may be disposed in corresponding ones of the additional channels of the former.

[0023] In an embodiment, the cable assembly may be bent prior to filling. In embodiments in which the cable assembly includes one or more HTS tapes disposed in channels, the size and / or shape of the channels can be selected to allow each HTS tape to twist and redistribute within the channel in which it is disposed during the process of bending the cable assembly prior to filling the cable assembly with molten metal. The twisting and redistribution of the HTS tape within the channel in which it is disposed can be a result of the bending process. Thus, the manner in which the HTS tape twists and redistributes depends, at least in part, on the shape into which the cable is bent.

[0024] Therefore, in response to small bending operations of the cable assembly, the HTS tape In some cases, the HTS tapes may undergo only a small amount of twisting and redistribution within the channels (or even none at all). However, in response to a significant amount of bending of the cable assembly or portion of the cable assembly (e.g., into a generally circular or looped shape), the HTS tapes may undergo a relatively large amount of twisting and redistribution within the channels. Importantly, however, regardless of the amount of bending of the cable assembly, before the metal filling process begins, the HTS tapes are disposed in the channels with little or substantially no stress (e.g., the HTS tapes are not subjected to forces from the molten metal during the bending operation, and therefore the HTS tapes are not deformed by the liquid or solid metal during the bending operation). After the metal filling process and the subsequent cooling process (during which the metal changes phase from a liquid state to a solid state), the solid metal secures the one or more HTS tapes into each of the one or more channels of the former (i.e., the HTS tapes are mechanically secured within the channels by the solid metal).

[0025] The foregoing features can be more fully understood from the following description of the drawings. [Brief explanation of the drawings]

[0026] [Figure 1A]

[0025] FIG. 1B is a cross-sectional view taken across line AA of FIG. 1B of a metal-filled cable formed from a tube with high temperature superconducting (HTS) material disposed therein, according to concepts described herein. [Figure 1B]

[0026] FIG. 1 is an isometric view of a metal-filled cable formed from a tube with high temperature superconducting (HTS) material disposed therein, according to concepts described herein. [Figure 2]

[0027] FIG. 1 is a cross-sectional view of a cable including a four-channel former with HTS material disposed therein and a jacket disposed around the former. [Figure 3A]

[0028] FIG. 1 is a cross-sectional view of a cable with a four-channel former having HTS material disposed therein and a jacket disposed around the former. [Figure 3B]

[0029] FIG. 1 is a perspective view of a channeled former. [Figure 3C]

[0030] FIG. 1 is a side view of an HTS cable. [Figure 4A]

[0031] FIG. 1 is a flow diagram illustrating a process for filling an HTS cable with metal. [Figure 4B] FIG. 1 is a flow diagram illustrating a process for filling an HTS cable with metal. [Figure 5]

[0032] FIG. 4C is a schematic diagram of an illustrative processing station for performing a metal filling process that may be the same as or similar to the process described in conjunction with FIGS. 4A and 4B. [Figure 6A] [000213] FIG. 10 is a perspective view of a dispenser designed to channel solder into and out of a four-channel former. [Figure 6B] FIG. 6B is a side view of the dispenser of FIG. 6A. [Figure 6C] FIG. 6B is an end view of the dispenser of FIG. 6A. [Figure 6D]

[0022] FIG. 1 is a side view of a former with dispensers attached to each end. [Figure 7]

[0037] A schematic diagram of an exemplary processing station for performing a metal filling process on an HTS cable provided by forming a former having first and second spreaders coupled to opposite ends of the former. [Figure 8] 8 is a plot of former temperature versus time during a metal filling process using a system that may be the same as or similar to the processing station of FIG. 5 or FIG. 7. [Figure 9A]

[0023] FIG. 1 is a schematic diagram of a cooling system implemented with a single blower and heaters at both ends of the HTS cable. [Figure 9B]FIG. 9B is a plot of temperature versus axial position along the cable for the cooling system of FIG. 9A. [Figure 10A]

[0041] A bar graph illustrating a comparison of void distribution in two cables, a first cable produced using zone cooling as described above in conjunction with Figures 9A and 9B, and a second cable produced by uniformly cooling at least a portion of the cable (i.e., using a temperature gradient near zero). [Figure 10B] 9A and 9B , a bar graph illustrating a comparison of void distribution in two cables, a first cable produced using zone cooling as described above in conjunction with FIGS. 9A and 9B , and a second cable produced by uniformly cooling at least a portion of the cable (i.e., using a near-zero temperature gradient). [Figure 11]

[0042] A block diagram of a cooling system including one or more movable fans and one or more heaters having a first heater configured to be in thermal contact with a first end of an HTS cable and a second heater configured to be in thermal contact with a second, opposite end of the HTS cable. [Figure 12A]

[0024] FIG. 1 is a schematic diagram of a zone cooling system with movable baffles. [Figure 12B]

[0025] FIG. 1 is a diagram of a zone cooling system with movable baffles. [Figure 13]

[0026] A top view of a wound HTS cable that is metal-filled and has a central channel, and is configured to utilize one or more end heaters at a first end of the HTS cable and a cold fluid injection system configured to be coupled to a second end of the cable. DETAILED DESCRIPTION OF THE INVENTION

[0027]

[0027] Described are high temperature superconducting (HTS) cables (i.e., cables equipped with HTS materials). As used herein, the phrase "HTS material" or "HTS superconductor" refers to a superconducting material that has a critical temperature above 30°K in its own field.

[0028]

[0047] To facilitate clarity in this description, we sometimes refer to specific types of It should be understood that reference is made to the use of specific processes, systems, or devices with HTS cables. For example, the solder filling process is described as applied to a cable in which an HTS "tape" is disposed within the channels of a former. The HTS tape may comprise multiple layers, one of which comprises an HTS material. In one exemplary embodiment, the HTS tape may comprise a first stabilization layer (e.g., comprising copper), a first overlay layer (e.g., comprising silver), a substrate (e.g., having an electropolished surface), a buffer stack, an HTS material (e.g., comprising a rare-earth barium copper oxide superconductor (REBCO) such as yttrium barium copper oxide (YBCO)), a second cladding layer, and a second stabilization layer (e.g., comprising the same material as the first overlay and first stabilization layers, respectively). Other embodiments of HTS tapes having more, fewer, or different layers than the example described above are, of course, possible.

[0029] However, after reading the description provided herein, one skilled in the art will recognize that It is to be understood that the concepts, systems, processes, devices, and techniques described are not limited to use with cables having HTS tapes disposed within channels in a former, but rather the concepts, systems, processes, devices, and techniques described herein may be used to fill a variety of different types of HTS cables with any molten metal.

[0030] [000299] That is, the concepts, systems, processes, devices, and techniques described herein can be used with a variety of different types of HTS materials, different types of tubes and / or formers, and with different types or metals (including, for example, different types of solder). In general, it should be understood that the concepts, systems, processes, devices, and techniques described herein can be applied to any vacuum impregnation (VPI) metal filling of any tube having an HTS material disposed therein (e.g., solder filling of a tube having one or more HTS tapes disposed therein, as described below in conjunction with at least Figures 1-7, or solder filling of a channeled former having an HTS tape disposed therein, as described below in conjunction with at least Figures 2-7).

[0031]

[0050] We will now proceed to a description of some illustrative embodiments, and similar elements will be 1A and 1B, which are provided with similar reference labels, cable 10 includes a tube 12 (sometimes referred to as a "jacket") having a high-temperature superconductor (HTS) material 14 disposed therein. Tube 12 is filled with a metal (e.g., solder) 16 using a process that may be the same or similar to the process described below in conjunction with at least FIGS. 4A, 4B, 5, and 7. Tube 12 may comprise or consist of any other material having electrical or mechanical properties that meet the needs / requirements of the application in which the cable will be used. In embodiments, the tube may include or consist of, for example, copper. Similarly, the HTS material may comprise or consist of any HTS material having electrical, mechanical, and superconducting properties that meet the needs / requirements of the application in which the cable will be used.

[0032]

[0051] In the exemplary embodiment of FIG. 1, the HTS material 14 is disposed within a tube. The HTS tape stack 18 is provided as an HTS tape stack 18. The HTS tape stack 18 is formed from a plurality of individual tapes 20a-20N (i.e., layers of tape, such as a plurality of N tape layers, grouped, bonded, or otherwise combined to form a tape stack, where N is an integer greater than 1). In embodiments, each layer of HTS tape in the HTS tape stack 18 can comprise or consist of a single HTS material; thus, the HTS tape stack can be referred to as a single-material HTS tape stack.

[0033]

[0052] Also in this exemplary embodiment, the tube or jacket 12 (and The tube (and therefore the cable) is illustrated as having a circular cross-sectional shape. Of course, it should be understood that the tube (or cable) may be provided with any regular (e.g., rectangular, square, triangular) or irregular cross-sectional shape. Furthermore, depending on the application, different tubes / jackets / cables being used in the same application may not have the same cross-sectional shape. The particular cross-sectional shape of the tube / jacket / cable may be selected to suit the needs of the particular application in which the tube / jacket / cable will be used.

[0034] Regardless of the configuration and / or composition of the HTS materials, tubing, and cables, Rather, the process described herein for filling a tube with molten metal (e.g., solder) results in the metal being disposed around or substantially on all surfaces of the HTS material. Note also that in embodiments where the HTS material is provided as an HTS tape stack, the process also allows the molten metal to fill any spaces (i.e., interstitial spaces) that may exist between multiple layers of HTS tape forming the HTS tape stack. Thus, in embodiments, the metal may contact interstitial surfaces of the HTS tape layers.

[0035]

[0031] The processes, systems, devices, and techniques described herein therefore: For example, HTS materials can be used to fabricate or separately produce cables by placing or separately disposing them into conductive tubes of various sizes (e.g., placing a stack of HTS tapes inside a conductive tube as shown in FIG. 1A) to produce cables suitable for use as current leads or to be used in the fabrication of magnets.

[0036] In one embodiment, a 100 m long coil tube is The magnet is filled with molten metal using the processes, systems, devices, and techniques described herein without being disposed in a fusion reactor. This embodiment illustrates that the metal filling process described herein can be used to provide a field magnet (e.g., a toroidal or poloidal field magnet) suitable for use in fusion applications such as, for example, an Affordable, Rugged, and Compact (ARC) fusion reactor.

[0037]

[0033] It should be understood that the processes, systems, devices, and techniques described herein It is understood that the technology finds use in fusion applications, as well as any other application requiring HTS cables or magnets. Examples of such applications include, but are not limited to, nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI), magnetic material separation, accelerator / high energy physics (HEP) magnets, disposable mixing systems, generators and motors, fault current limiters, RF filtering, superconducting quantum interference device (SQUID) circuits, transmission lines, magnetic energy storage, transformers, and current leads for low temperature superconducting cables.

[0038]

[0034] Referring now to Figure 2, the cable 30 includes a plurality of channels 34, here Four channels 34a to 34d are provided, each containing a multi-stack HTS tape 36. 1, cable 30 includes a former 32 formed therein or separately provided, with a jacket 37 disposed about the former. Of course, it should be understood that any number of channels may be used, and that the particular number of channels to be used will be selected to meet the needs of the particular application in which cable 30 will be used.

[0039]

[0058] In this illustrative embodiment, each channel 34a-34d has a generally square cross section. However, it should be understood that the channels may be provided with any regular (e.g., rectangular, circular, triangular) or irregular cross-sectional shape. Furthermore, depending on the application, each channel may not have the same cross-sectional shape. The particular cross-sectional shape of the channel may be selected to meet the needs of the particular application in which the cable will be used.

[0040] [000359] Significantly, the metal filling process described herein can be used to fill the cable, and in particular any channels provided in the former, with molten metal. Thus, regardless of the configuration and / or composition of the HTS material, the configuration of the former, and / or the configuration of any channels provided in the former, the metal filling process described herein results in molten metal 38 being disposed around substantially all surfaces of the HTS material in the channels (and ideally, around all surfaces of the HTS material).

[0041]

[0060] Furthermore, when the HTS material is provided as a tape stack, the process This also results in the molten metal filling any spaces (i.e., interstitial spaces) that may exist between the multiple layers of HTS tape that form the HTS tape stack. Thus, the molten metal can contact the interstitial surfaces of the HTS tape layers. That is, the metal filling process described herein can fill the space around each HTS tape stack as well as any spaces between the HTS tape layers that comprise the stacked HTS tape. The metal filling process described herein can also fill metal (e.g., molten metal) into spaces that may exist between the surface of the former and the surface of the jacket. The metal is then cooled (e.g., using techniques described herein below) to a solid state, resulting in an HTS cable.

[0042]

[0061] The metal filling process described herein involves filling a tube (e.g., the tube illustrated in FIG. 1) with a metal. The present invention may be applied to any cable having a molten metal filling process (such as that shown in FIG. 2) and / or a former (such as that illustrated in FIG. 2). Furthermore, the metal filling process described herein may be readily used to fill molten metal into tubes or channels having arbitrary or complex cross-sectional shapes and arbitrary or complex patterns. Furthermore, the metal filling process described herein may be used to provide cables of any length. In embodiments, the metal filling process has been used to fill channels on formers greater than 11 meters (m) in length, although the process may be used with channeled formers or tubes having lengths of 100 m or more.

[0043]

[0062] Like elements are provided with like reference numerals throughout the several figures. 3A-3C, cable 42 includes a former 44 having a plurality of channels provided therein (and thus may be referred to as a "channeled former") (as can be seen most clearly in FIG. 3B). In this illustrative embodiment, cable 42 includes a former 44 having at least one channel 46 corresponding to a cooling channel. In this illustrative embodiment, former 44 includes a single cooling channel 46 provided along its central longitudinal axis 43. In this example, former's central longitudinal axis 43 is aligned with the central longitudinal axis 43 of the cable (FIG. 3C). In embodiments, the former's central longitudinal axis may not be aligned with the central longitudinal axis of the cable. In embodiments, the former may have multiple cooling channels provided therein. In some embodiments, one or more cooling channels may be disposed about the central longitudinal axis 43 .

[0044] The former 44 also has a plurality of channels 48 in which the HTS material 50 can be disposed. In this illustrative embodiment (and as can be seen more clearly in FIG. 3B ), the channels are provided in a twisted or spiral pattern along the surface of the former along the length of the former, with each channel having a generally square cross-sectional shape. In this illustrative embodiment, an HTS material 50 is disposed within each channel 48. In the illustrative embodiment of FIGS. 3A-3D , the HTS material 50 is shown as a multi-tape HTS stack disposed within each channel 48. Other configurations of the HTS material may, of course, also be used. A jacket 52 is disposed around the former.

[0045] 2, the particular number of channels, as well as the cross-sectional shape of the channels in former 44, are selected to meet the needs of the particular application in which the cable will be used. In the illustrative embodiment of FIGS. 3A-3C, each channel 50 is provided having a generally square cross-sectional shape and is formed or otherwise provided in a spiral pattern along the length of the former (as can be seen most clearly in FIG. 3B). However, as noted, channels may be provided in any pattern along the length of the former and with any complex shape or geometry (e.g., any regular or irregular cross-sectional shape and pattern).

[0046] Significantly, the metal filling process described herein The metal filling process described herein can be used to fill channels (e.g., channels in a spiral pattern) with molten metal, such as solder. Thus, regardless of the configuration and / or composition of the HTS material, the configuration of the former, the configuration of any channels provided within the former (including, but not limited to, the cross-sectional shape and pattern of the channels), and the configuration of the jacket, the metal filling process described herein results in molten metal being disposed around substantially all surfaces of the HTS material within the channels. Furthermore, when the HTS material is provided as a tape stack, the process can also result in molten metal filling any spaces (i.e., interstitial spaces) that may exist between multiple layers of HTS tape forming the HTS tape stack, such that the molten metal contacts the interstitial surfaces of the HTS tape layers.

[0047] 4A and 4B are illustrations of a metal filling process according to the concepts described herein. In the drawings, flow diagrams are formed that comprise a series of process operations that form a typical embodiment. Unless expressly stated, it should be understood that the process operations within a flow diagram are not ordered, implying that the process operations listed within the flow diagram can be performed in any convenient order.

[0048]

[0067] 4A and 4B, an HTS cable (e.g., An illustrative process for filling any of the cables described in begins by cleaning 62 the components (e.g., tubing, formers, HTS materials, jackets, fittings, etc.) that will be used in the cable that will undergo the metal filling process. In an embodiment, the cable components may be cleaned using a process that involves flushing with an acidic solution followed by rinsing with water or other liquid. Details of such a process related to one particular embodiment are described below.

[0049]

[0040] One non-limiting cleaning example is a mixture of water and a cleaning solution (e.g., Citron A reservoir containing a mixture of cleaning solution (e.g., acidic cleaner) may be coupled to the cable former, and the mixture is pumped or otherwise delivered from the reservoir through the cable former. A rinse fluid (e.g., clean water) may then be pumped through the cable former to rinse the cleaning solution from the cable former. In some cases, the cleaning mixture and / or the rinsing fluid may be pumped through the cable former to rinse the cleaning solution from the cable former. The solution may be heated above room temperature (eg, to 60° C. (140° F.)).

[0050]

[0069] Once the components are cleaned, the HTS material is placed in a tube (e.g., the The HTS material may be disposed within a cable or a channel of a channeled former (e.g., as illustrated in Figures 2-3B) (64). In embodiments, the HTS material may be provided as an HTS tape stack. In embodiments, the HTS tape stack may be pre-tinned to ensure good adhesion between the tapes (e.g., adhesion that securely bonds the tapes to one another). In one embodiment, the HTS tape stack may be pre-tinned with the metal to be used to fill the cable. In one embodiment, the HTS tape is pre-plated with lead-tin (PbSn) solder (or a lead-tin solder alloy).

[0051]

[0070] Then, the "loose HTS cable assembly" (or more simply, "HT An HTS cable assembly ("HTS cable assembly") is formed (65). HTS cable assemblies are sometimes referred to as "loose cable assemblies" because at least the HTS material (and possibly other components) is not structurally secured to a tube or channeled former or other structure that forms part of the HTS cable. As used herein, "HTS cable assembly" or "loose HTS cable assembly" can refer to any tube comprising HTS material (e.g., HTS tape), examples of which are provided herein. For example, one type of HTS cable assembly can be formed by disposing HTS material in a tube (e.g., as shown in FIG. 1 ) and optionally adding fittings and the like, as needed. In an actual embodiment, the tape can be disposed on the bottom of the tube. In this illustrative embodiment, the tube is shown having a circular cross-sectional shape, but in other embodiments, the tube can be provided with a different cross-sectional shape (e.g., an oval cross-sectional shape, a rectangular cross-sectional shape, a square cross-sectional shape, or any regular or irregular geometric cross-sectional shape).

[0052]

[0071] As another example, HTS cable assemblies may be constructed such that the HTS material is embedded in a channel (e.g. , as shown in FIGS. 2-3B ), and optionally adding fittings and the like, as needed. Other types of HTS cable assemblies may be envisioned, and the techniques applied thereto for filling metal into HTS cable assemblies may be used for all such HTS cable assemblies. For example, it may be used with an HTS cross conductor cable arrangement (CroCo HTS), in which tapes of different widths are arranged in the shape of a cross.

[0053]

[0072] Before or after the HTS material is disposed in the HTS cable assembly (e.g., At any point after the HTS material has been disposed in the openings of the tubes, the channels of the tubes, or the channels of a former or other structure, the HTS cable assembly can be bent into a desired shape (e.g., a circle, loop, or multi-loop shape as illustrated in Figures 12A, 12B, and 13).

[0054]

[0073] Returning now to FIG. 4A, as shown in processing element 66, the flux is A liquid flux may be applied (as needed) to some or all of the HTS materials and / or cable components forming the HTS cable to remove any oxidation that may occur. The HTS cable assembly may then be evacuated (e.g., via a vacuum process) and purged with a gas, which may be an inert gas (68). In embodiments, the liquid flux may be applied immediately prior to soldering. Ideally, the flux penetrates all surfaces of the cable components that will be exposed to the molten metal, in a manner similar to the subsequent flow of molten metal to be described. In embodiments, it has been found that application of the liquid flux allows for good wetting of the solder to the tape and cable. In embodiments, the RM A-5 liquid flux (Indium Corp) may be used, however, it should be understood that other liquid fluxes having the same or similar properties as RMA-5 liquid flux may also be used.

[0055] [000414] Excess flux (i.e., flux that does not adhere to the HTS materials or components) is evacuated from the assembly as a result of vacuuming (68). However, it has been found that any remaining flux can be effectively washed away by a heavier stream of molten metal solder (to be described in conjunction with 78). As such, an explicit step of evacuating excess flux may not be required, depending on how much flux remains in the assembly. In embodiments with long and complex cable geometries, pressure may be used to evacuate excess flux. If fluxing is used, after fluxing, the cable assembly is again evacuated and purged with an inert gas to remove oxygen, if present, which interferes with the effective action of the flux when it is heated.

[0056] [000425] The HTS cable assembly is heated to a temperature below that which would cause the metal (e.g., solder) to melt (74). In embodiments, an oven, such as a convection oven, may be used to control the temperature of the cable and any associated fittings and tubing during the metal filling process. This provides uniformity with reduced (and ideally minimal) external temperature control required, and importantly, reduces (and ideally avoids) the risk that the HTS tape temperature will exceed the oven setpoint, causing degradation to that portion of the HTS tape (and therefore that portion of the cable) due to exposure to undesired temperatures.

[0057] [000436] Either before, after, or simultaneously with heating the cable assembly (74), the metal to be loaded into the HTS cable assembly is melted to a liquid state (75). The metal may be melted, for example, using a temperature-controlled heater in a container (sometimes referred to herein as a can or crucible). Thermocouples inside and / or outside the can may be used to determine when melting is complete and the temperature of the molten metal before flowing. In some embodiments, the metal may be melted inside the oven in which the cable is located, while in other embodiments, the metal may be melted separately (i.e., outside the oven). The HTS cable assembly is then heated to a temperature at which the metal will flow (76).

[0058] [000447] One aspect of the metal loading process that proved important was obtaining a desired time-temperature profile. The temperature needed to be high enough to make the metal a low viscosity fluid, but result in low enough exposure to avoid thermal degradation and degradation due to chemical effects of the metal on the HTS material (e.g., REBCO tape stack).

[0059]

[0078] HTS cable with HTS tape stack with layers of REBCO tape For solder filling, and in one embodiment for using tin-lead (PbSn) solder, two steps may be used. First, an oven may be set to a temperature that warms the HTS cable assembly but does not degrade the HTS tape. In an embodiment, the oven may be set to a temperature below the melting point of the solder on the HTS tape (e.g., 185°C for PbSn solder), thereby greatly reducing, and ideally avoiding, degradation of the HTS tape stack, and the temperature of the entire cable (or more appropriately, cable assembly) is allowed to equilibrate. The cable assembly is held at this temperature until the solder supply (e.g., the supply of solder in a can) is fully melted and equilibrated to the process temperature of approximately 200°C. Second, the oven temperature is then set to a temperature that achieves the desired flow temperature of the solder. In embodiments utilizing PbSn solder, the oven temperature may be set to a temperature of approximately 205°C, with a waiting period occurring until all points on the cable and any associated tubing required for the metal filling process (as described in conjunction with FIG. 5) have achieved the desired flow temperature (e.g., a flow temperature of approximately 200°C for PbSn solder), with temperature monitoring being performed to ensure that no points exceed a temperature of approximately 202°C. This approach reduces, and ideally avoids, degradation of the superconducting properties of the HTS tape stack. Once these temperature conditions are met, the metal flow process (78) may begin (and preferably begins immediately so as to reduce, and ideally minimize, the amount of time the HTS tape stack is exposed to such relatively high temperatures (e.g., above or about 200°C)).

[0060] [000459] The application and monitoring of multiple temperature monitoring devices (e.g., thermocouples) within the metal filling processing station (an example of which is described below in conjunction with FIG. 5) and at multiple points on the cable can be important to this process because degradation of some HTS materials (e.g., REBCO) increases exponentially at temperatures above 200°C. The location of the temperature monitoring devices is selected for each cable geometry. Considerations include the size and expected thermal uniformity of the cable, as well as the local measurements needed to guide the planned cooling process. Temperatures can be adjusted for different solders or different types of HTS materials. Such optimized time-temperature profiles for solder filling (or more generally, metal filling) of HTS cables are unique to the process described herein and are suitable for solder filling of HTS cables, such as Sn, whose melting temperatures are high enough to potentially damage the HTS. 60 Pb 40 This is one factor that leads to the success of the described technique, even when solders such as .alpha.

[0061]

[0080] Alternative solder alloys that reduce degradation may also be used. The choice of solder will depend on the properties required for the cable application, including but not limited to mechanical, thermal, and electrical properties.

[0062]

[0081] The processing elements 78, 80 allow the molten metal to flow through the entire cable assembly ( 78). In embodiments, the flow of molten metal through the entire cable assembly may be achieved at least in part by gravity (i.e., air pressure), by a positive displacement pump, or using vacuum pressure techniques. One example of vacuum pressure technique is described below in conjunction with FIG. 5.

[0063]

[0082] At decision block 80, sufficient molten metal is present in the case in which the HTS material is disposed. Once a determination is made that the molten metal has flowed through a portion (or portions) of the cable assembly, the flow of molten metal is stopped (82), the molten metal and HTS cable assembly are allowed to cool (84), and after cooling is complete, a solder-filled (or more generally, metal-filled) HTS cable results. Note that in embodiments, the flow of molten metal (e.g., solder in a liquid state) does not stop as soon as the metal passes through the cable. Rather, the metal flow is not stopped until a predetermined amount of metal has passed through the cable and reached a disposal location. Flowing additional metal beyond simply filling the cable can be beneficial to remove flux from the cable and / or reduce porosity within the metal-filled cable when the metal returns to a solid state.

[0064]

[0083] In the exemplary method shown in FIGS. 4A and 4B, the HTS cable It should be understood that not all of the processes shown in Figures 4A and 4B may be performed and / or in the particular order presented. Furthermore, in at least some cases, some portions of the method may be performed simultaneously. As one non-limiting example, in some cases, application of flux at (68) may be performed after evacuating the HTS cable assembly at (66). As another non-limiting example, in some cases, application of flux at (68) may be performed after evacuating the HTS cable assembly at (66). In some cases, melting of the HTS cable assembly (74) and the metal (75) may be performed simultaneously, or either step may be initiated or even completed before the other. In some cases, steps (and / or portions of steps) of the illustrative method shown in Figures 4A and 4B may be omitted entirely. For example, in some embodiments, step (68), in which flux is applied to the HTS material and evacuated, may be omitted. In some embodiments, the purging aspect of step (66) may be omitted, but the vacuum aspect of step (66) may be performed.

[0065]

[0084] Referring now to FIG. 5, the same process as described in conjunction with FIGS. 4A and 4B is Processing station 90, which may be used to perform the same or similar metal filling process, includes an oven sized to accommodate HTS cable assembly 94, the resulting HTS cable (not shown in FIG. 5 ), and optionally a vessel 96 (e.g., a crucible) for holding molten metal and associated inlet and outlet tubes generally designated 97. A gas source 95 is coupled to an input 96a of vessel 96 through one or more valves V4, V5 and a flow controller 99 that limits the gas flow rate and hence the initial viscosity of the solder flow.

[0066]

[0085] The container 96 (sometimes referred to herein as a "can") holds the cable assembly. The container 90, crucible, is arranged to hold a quantity of metal (e.g., solder) sufficient to fill the crucible 94 and may be located inside or outside the oven 92. In embodiments, the container may be provided having a cylindrical shape of a length and diameter sufficient to hold the metal (e.g., solder). In embodiments, the container may comprise a cylindrical stainless steel (SS) tube of approximately 3.5 inches outer diameter configured to hold up to 30 pounds of metal (e.g., up to 30 pounds of solder bar). Of course, other shapes may also be used. In general, however, the container 90, crucible, should be sized to hold at least a quantity of molten metal sufficient to fill an HTS cable of known size according to the concepts and processes described herein, and ideally some additional metal to flow through the cable to fill all voids and flush out any impurities. After reading the description provided herein, one skilled in the art will understand how to select the appropriate amount of metal and therefore the container shape and size (e.g., volume) for a particular application.

[0067] [000466] A plurality of heaters 98 are disposed around the vessel 96 (e.g., on the interior or exterior surface of the vessel 96) and configured to heat the vessel in a desired manner. The heaters may be coupled to one or more controllers 100 that control the heaters. In one embodiment, three 650 W, 120 VAC heaters are thermally coupled to the vessel and controlled by one or more proportional-integral-derivative (PID) processors (not shown in FIG. 5). In an embodiment, the controller may be provided as a Solo SL4848-VV series controller from Automation Direct. In this embodiment, the output of the controller 100 is a voltage pulse that operates a relay, which then gates duty-cycle-controlled 120 VAC power to the heaters. Other means for heating the vessel 90 (or for melting the metal inside the vessel) may, of course, be used.

[0068]

[0087] A plurality of thermocouples 102 on the outside of the vessel 96 and at different levels inside the vessel 96 Two thermocouples 103 (disposed in a tube, such as a stainless steel tube, of known thickness selected so as not to interfere with the operation of the thermocouples) at the top of the vessel 90 can be used to control the melting process and establish when melting of the metal inside the vessel is complete. Multiple heaters 99 (two heaters 99 are shown in FIG. 5) proximate the outlet of the vessel 90 are controlled cooperatively using a single outer thermocouple (TC) 101, and an upper heater 98 (maximum 650 W) is controlled separately from the heaters 99. Details of the thermocouples and other equipment are provided in the accompanying drawings. This may vary depending on the size and geometry of the cable being filled (i.e., the cable to be filled).

[0069]

[0088] After reading the description provided herein, one skilled in the art will be able to determine the needs of a particular application. The user shall understand how to select the appropriate number, size (wattage), and placement (i.e., physical location) of heaters, and the number, characteristics, and placement (i.e., physical location) of thermocouples to meet the requirements.

[0070]

[0089] Siphon 104 has a first end coupled to output 96 b of vessel 96 . The siphon is provided with a height greater than the height of the molten metal in the vessel so that flow cannot occur without pressurization. In an embodiment, the siphon 104 may comprise a tube having a 0.5 inch inner diameter.

[0071]

[0090] A plurality of contact sensors 108 are used to monitor both the melting and flow of the metal. The contact sensors 108 may be disposed at various points within the processing station 90. In an embodiment, the contact sensors may be provided as commercially available single-conductor vacuum feedthrough sensors. In an embodiment, the contact sensors have pins. In an embodiment, the pins may be part of a coaxial structure with a center pin, a ceramic insulator, and a stainless steel outer housing. In one embodiment, the feedthroughs are brazed or otherwise secured to fittings (e.g., threaded end caps) that may be connected to mating fittings on various devices (e.g., siphons, connecting tubes, and waste tanks) that are part of the processing station. Several sensors 108 may be disposed near the expected level of liquid solder in the vessel, and sensor 109 may be disposed at different levels or heights (either internal or external) within or above waste tank 110. In this exemplary embodiment of FIG. 5, a set of three sensors is disposed at different heights within the waste tank. Such sensor placement may be useful in monitoring the metal filling process and stopping at a desired amount of solder or other metal.

[0072]

[0091] In one embodiment, the center pin of the sensor is The is connected to a DC power source (e.g., 5 to 24 volts DC) through a light-emitting diode (LED) lamp and a current-limiting resistor. The tank and pipe are connected to a reference potential (e.g., electrical earth or 0 VDC) and the voltage relative to the center pin is recorded.

[0073]

[0092] In this embodiment, if no solder is present, the center pin of the sensor and the reference voltage When solder is present, the center pin is connected to ground; the LED is energized and the recorded voltage is LOW (e.g., a voltage level corresponding to a logic LOW value). Such an electronic device provides both a visual indication of solder flow, which is very useful for immediate manual control of the process, and an electronic record and inlet that is useful for post-process interpretation and can be used for process automation (e.g., using a programmable logic controller).

[0074]

[0093] The HTS cable assembly 94 is disposed in contact with the former. In embodiments with a jacket (e.g., as shown in FIG. 3A), the jacket extends beyond the end of the HTS cable assembly 94, as indicated by reference numerals 112a, 112b in FIG. 5. The extensions 112a, 112b allow for a smooth transition from the inlet tube 114 for the metal flow (e.g., solder flow) to the cable assembly (e.g., former and jacket) and at the outlet tube 115 leading to the waste tank 110. If it is desired or necessary to bend the extension, the extension is preferably provided with a smooth bend.

[0075]

[0094] The heaters 116a and 116b heat the solder in the cable assembly 94 until it is solidified. Heaters are disposed adjacent to or otherwise coupled to extensions 112a, 112b and thermal extensions to maintain the liquid solder within these extensions until the liquid solder is released. In embodiments, heaters may be located on either side of each bend in the inlet and outlet tubes 114, 115, or even at each end of the cable assembly. As explained below, the heaters serve to avoid voids that might otherwise occur as a result of cooling of the molten metal within the cable assembly.

[0076]

[0095] The tube 115 at the inlet 110a of the waste tank 110 is connected to a second "U-bend" The cable assembly is provided with a "gate" 140 which prevents the original solder and flux that flowed through the cable to be filled and into the waste tank from flowing back into the cable assembly.

[0077]

[0096] The waste tank holds excess molten metal after it flows through the cable assembly. As noted, contact sensors 109 at various heights indicate how much molten metal has reached the waste tank. A variable flow valve (99) adjusts the amount of gas flow (e.g., inert gas flow) and pressure buildup. In an embodiment, an inert gas such as argon may be used, although other inert gases may be used. In an embodiment, the waste tank may comprise a stainless steel tube having a diameter of approximately 4 inches with an inlet from the top and may be sized to hold approximately 10 pounds of excess molten metal (e.g., excess solder). Those skilled in the art will understand how to size a waste tank to meet the needs of a particular application.

[0078]

[0097] Containers and waste tanks must be evacuated (typically 250mT The gas supply system 99 is coupled to (i.e., in fluid communication with) a vacuum system 122 and a gas system 124 that allow the gas supply system 99 to be either pressurized with an inert gas such as argon or to a pressure of 100 psi (up to 100 psi). Variable flow valve 99 can be used to regulate gas flow and pressure buildup. Valve V4 is an open / close valve, and valve 99 is a flow regulator / valve.

[0079]

[0098] Thermocouples are measured at various points in the system (e.g., on cans, pipes, ovens, etc.). ) and can be monitored in real time (e.g., by a monitor), including thermocouples 130a along the cable 94 to be filled. In an embodiment, in a cable assembly having a length of about 10 meters, up to 18 thermocouples can be monitored in real time by two 16-channel Agilent 34972A scanners, typically at a rate of 1 second. Such a monitor can also store and display contact sensor status (converted to DC voltage as described above) and pressure gauge analog output. The spacing of the thermocouples will depend on the cable length, geometry, expected thermal uniformity, and planned cooling method.

[0080]

[0099] The processing station also includes an entrance area and solder can for the cable assembly, and a vacuum and pressure system 131 comprising a vacuum pump 133 and a plurality of valves 134 and tubing 136 that allows the exit area and solder waste 110 of the cable assembly 94 to be independently evacuated, pumped, or pressurized. It should thus be understood that the cable assembly 94 is coupled to associated tubing, fittings, sensors, heaters, thermocouples in a manner that forms a closed system, thereby allowing the various components (including the cable assembly) to be evacuated and / or pressurized.

[0081]

[0100] Before filling the HTS cable with metal, bypass valve V2 94. This, along with the siphon area 104 between the container 104 and the cable assembly 94, ensures that all components are at the target temperature. This prevents premature solder flow before the solder is fully heated. Once both the metal and the cable in the vessel are at their respective target temperatures, metal flow is initiated. In one embodiment, metal flow may be initiated by setting the gas pressure for the gas source 95 to the target pressure.

[0082]

[0101] To allow the metal to flow, bypass valve V2 is closed and cable assembly end 94 At this point, outlet 96b of vessel 96 is blocked by the molten metal, and pressure from gas source 95 forces the metal from vessel 96 through extension 112a, through tube and siphon 104, and into cable assembly 94.

[0083]

[0102] In an embodiment, pressurized inert gas from source 95 (e.g., valve V4 , is applied to the vessel by opening V5, thereby pushing the molten metal down and over the inlet siphon 104 into the cable assembly. The molten metal flow continues through the cable assembly, penetrating all vacuum gaps, including any space between and around the HTS material. Because the molten metal is heavier than the flux, it pushes any remaining lighter flux in front of it. In this manner, a vacuum impregnation (VPI) process is provided for filling a cable assembly (e.g., comprising a tube or jacketed former) containing high temperature superconducting material with molten metal.

[0084]

[0103] The second inverted tube ("siphon") 139 has a similar height to the inlet siphon 104. The vertical sections 104a, 104b, and 139a are used between the cable assembly outlet 94b and the waste tank inlet 110a. This prevents the molten metal from flowing out under gravity. The molten metal remaining in each vertical section 104a, 104b, and 139a creates pressure on the metal-filled cable assembly after flowing.

[0085]

[0104] In an embodiment, contact sensors 108, 109 are used to monitor the molten metal flow. , and may be used at multiple points within the system to help control this. For example, contact sensors may be placed internally and / or externally to the can, at the container outlet, in the inlet siphon, at the cable inlet and / or outlet, and at multiple levels within the waste tank. In embodiments, the contact sensor includes a pin, which must be inside the can and contact the solder. In embodiments, one or more sensors may be disposed in the wall of the can using a fixture that penetrates the wall where the sensor pin is disposed (so that the pin can contact the solder when the solder (or another molten metal) reaches the level of the sensor pin). In embodiments, one or more sensors may be disposed within the can's internal tube. Contact sensors at the cable outlet and inside the waste section may be used to monitor the flow of molten metal. The use of sensors at multiple levels inside the waste tank allows for setting a predetermined amount of molten metal flowing through the cable to optimize filling and flux washout.

[0086]

[0105] In one embodiment, typically 2.2680 to 4.5359 kg (5 to 10 100 pounds of molten metal is present in the outlet pipe and waste tank, which is sufficient for a cable having a length of approximately 3 meters. Once the target level is reached, bypass valve V2 is opened, which again equalizes the pressure between the first and second ends of the cable assembly, thereby stopping the flow and ensuring that the inlet pipe of the cable assembly is not emptied.

[0087] In an embodiment, the contact sensors 108, 109 may be provided as commercially available single conductor vacuum feedthroughs having a coaxial structure with a center pin, ceramic insulator, and stainless steel outer housing. In this application, the feedthroughs may be brazed to threaded end caps that may be coupled to mating fixtures on the equipment.

[0088]

[0487] In an embodiment, all tanks, pipes, and fittings are made of conductive copper or The cable may comprise or consist of stainless steel or stainless steel and may be disposed in an oven to ensure uniform temperature. In embodiments, a vacuum level of several hundred mTorr is typically achieved before flux application, and one to several Torr is typically achieved after flux application. After reading the disclosure provided herein, one of ordinary skill in the art will understand how to select a vacuum level for a particular application. The vacuum ensures an oxygen-free environment prior to heating and good impregnation of the metal (e.g., solder) into all parts of the cable, between and around the tapes, and even into the gaps between the surface of the former and the jacket.

[0089] Following solder flow, one or more air movers (e.g., blowers) can be used to direct air preferentially to selected zones on the cable to control the cooling profile of the cable. Specific techniques for cooling metal-filled cables are selected according to the cable's geometry, as discussed below in conjunction with FIGS. 7-11. In HTS cables bent into a generally circular or looped shape, movable baffles can be utilized to localize cooling to specific portions of the loop. One illustrative embodiment is described below in conjunction with FIGS. 10A-10B.

[0090]

[0509] This may be implemented using a system that may be the same as or similar to the system of FIG. A process that allows for metal filling of an HTS cable will now be described. The following process is described for an HTS cable comprising a channeled former with one or more HTS tape stacks disposed within the channels and a jacket disposed over the former. The process begins with cable fabrication and preparation prior to the actual metal filling process. Cable Preparation and Handling

[0110] In an embodiment, one or more HTS tape stacks are channeled. Before inserting the former into the assembled former and adding a jacket (e.g., a copper or steel or stainless steel jacket, and / or in some cases an outer stainless steel jacket), the former and jacket may be cleaned with a solution of an acidic cleaner. In embodiments, a cleaner provided by Citronox may be used.

[0091]

[0111] In one exemplary embodiment for cleaning cables, a cleaning solution reservoir is filled with approximately 7 gallons of hot water (140°F (60°C)) to 10 ounces of acid cleaner. The channeled former or jacketed channeled former (i.e., a channeled former with a jacket as discussed) is inserted into a pipe (e.g., PVC pipe) and connected to a pump and reservoir. The diameter of the pipe is selected to accommodate the channeled former (or jacketed channeled former).

[0092]

[0112] The cleaning solution was applied at 124.1 kPa (18 psi) and 75.7 liters for 30 minutes. The cable to be filled is pumped at 20 gpm onto the cable to be filled. This is followed by a two-minute rinse cycle in clean hot water. The cable to be filled is drained and dried (ideally, immediately drained and dried). Ideally, the cable to be filled should have a shiny appearance, with oil and light water stains removed. This process is repeated on the jacket, with the addition of scrubbing the holes with Scotch Brite or other suitable cleaner, and wiping with ethanol and a cloth wipe until the wipe is clean. Regardless of the particular cleaning method, the cable to be filled must be cleaned.

[0093]

[0113] In one embodiment, a REBCO tape (e.g., pre-plated with solder) ) is disposed within the channels of the former. Preferably, the pre-plated solder is of the same type as that used to fill the cable. Several different manufacturers HTS tapes from manufacturers such as SuperPower, Super Ox, Shanghai can be used.

[0094]

[0514] The dispenser, which will be discussed in conjunction with FIGS. 6A-6D, optionally includes a It can be added to the former before the packet is applied.

[0525] The cable jacket is optionally configured to protect the molten metal from the flow of heat into and out of the former. The tube may be provided having a length longer than the cable length (e.g., longer than the former to form a so-called extension) to provide a smooth flow of molten metal through the tube. In embodiments, a cable without an extension may be soldered. In such embodiments, the tube may be bonded directly to the cable jacket such that the tube serves the same purpose / function as an extension. It should also be understood that the jacket need not be highly conductive.

[0095]

[0116] The cable is then subjected to the following process after jacketing and before the metal filling process or At times, the cable can be bent into a desired shape. The ability to bend the cable before the metal filling process is one advantage of the solder filling processes and structures described herein for making complex cables or multi-turn magnets. That is, the metal filling process described herein allows the cable to be bent before or during the metal filling process.

[0096]

[0537] Cable components (e.g., fittings) and cable assemblies must be The solder is kept in an inert gas until soldering to reduce (ideally minimize) the amount of oxidation. In an embodiment, the gas can be nitrogen (N) or argon (Ar). Flux application

[0118] In an embodiment, prior to soldering, oxides are removed to ensure good wetting and soldering. Flux is applied to the cable to ensure adhesion. In an embodiment, the cable is fluxed using Indium Corp. 5RMA-RC flux. Other types of commercially available fluxes may, of course, also be used. If a liquid flux is used (e.g., Indium Corp. 5RMA-RC flux), the flux is provided or separately applied to the surface of the former and / or the surface of the HTS material, allowed to sit for an appropriate amount of time (e.g., several minutes to tens of minutes for Indium Corp. 5RMA-RC flux), and then drained. For a substantially straight cable, the draining process may be accomplished by gravity. For long, spiral, or other complex-shaped cables or formers, pressurization with an inert gas may be used to fill and drain the flux. Vacuum Pump and Purge

[0549] In embodiments, after completing the fluxing process (and ideally , immediately after flux application), the HTS cable may be coupled to a solder station and a vacuum may be pulled on the cable (i.e., the HTS cable is evacuated (or "pumped down") to remove O2). The vacuum extends to a container that may be pre-filled with solid metal (e.g., a bar of solder) that will eventually be melted and used for the solder filling process.

[0097]

[0120] In embodiments, multiple pump and purge cycles with an inert gas are used. In some embodiments, argon (Ar) may be used.

[0098] [0012155] Depending on the process timing, the cable may be purged for approximately 2 hours or Backfill with an active gas and release for a period of time sufficient to remove O2 from the cable atmosphere and much of the alcohol in the flux (e.g., in the range of about 8 to about 24 hours). Either it can be placed

[0099]

[0122] A processing system that may be the same as or similar to the processing system described above in conjunction with FIG. The stem is placed under vacuum before beginning the metal filling process. A bypass valve (e.g., valve V2 in FIG. 5) remains open to ensure substantially equal pressure at both ends of the cable assembly to be filled with metal (i.e., the HTS cable assembly) and to prevent premature solder flow. Solder melting

[0123] In an embodiment, a heater on the vessel (e.g., heater 98 in FIG. 5) The temperature can be controlled using a PID algorithm via a thermocouple (e.g., thermocouple 102 in FIG. 5) external to the solder, and used to melt the metal and bring it to a target temperature T. The specific target temperature depends on the metal. If the metal is lead-tin solder (e.g., Sn 60 Pb 40 In one embodiment, a heater on the vessel can be controlled using a PID algorithm via a thermocouple on the outside of the vessel, and the heater is controlled to melt the solder and bring it to a target temperature T of 200°C. In other embodiments, a slightly lower temperature can be used as long as it is above the solder liquidus temperature. A heater in the vessel's outlet tube (e.g., heater 112 in FIG. 5) can be used to ensure that the solder remains liquidus in the inlet siphon. Internal thermocouples and contact sensors inside the vessel (e.g., thermocouple 103 and sensor 108 in FIG. 5) and a contact sensor in the inlet siphon (e.g., sensor 109) can be used to determine when the solder is fully melted. One indication that the metal is fully melted is a rapid rise above the liquidus temperature of the metal used to fill the HTS cable. Cable temperature rise

[0124] In an embodiment, oven convection is used to heat the cable to a target temperature T. The target temperature for cables is below the melting point of the metal being used to fill the cable, but is a temperature that speeds up the overall metal filling process. Also, if the process is being used to fill HTS cables, the target temperature is also selected to reduce (and ideally) avoid) the risk of HTS degradation due to exposure of the HTS material to relatively high temperatures for relatively long periods of time. The specific temperatures and time periods that may result in HTS degradation depend on the particular HTS material.

[0100]

[0125] For example, if the HTS material is a REBCO multilayer tape stack, and Sn 60 Pb4 If 0 is used, oven convection can be used to heat the cable to a temperature below the solder melting point (e.g., about 182°C) while the solder in the can is raised to a temperature above the solder melting point so that the solder in the can is melted. This approach not only speeds up the overall process but also avoids the risk of HTS degradation.

[0101]

[0126] Once the metal in the vessel is melted, the cable temperature can be increased to ensure uniformity. The HTS cable with REBCO multilayer tape stack and Sn can be carefully monitored with multiple thermocouples to avoid either cold spots that could impede metal flow or hot spots that could degrade the HTS. 60 Pb 40 If solder is used, a typical oven set point is about 205°C and the process temperature can be about 200°C ± 2°C. Of course, other heating methods can also be used as long as they achieve the same or similar heating uniformity as can be achieved by convection heating. Embodiments can include covering with resistive heater tape, a jacket with a heated liquid, or Joule heating where an electric current is passed through a cable. Solder flow

[0127] In embodiments, both the metal (e.g., solder) in the container and the cable Once their respective target temperatures are reached, solder flow can be initiated. In one embodiment, solder flow can be initiated by setting the gas pressure (e.g., via gas source 140) to the target pressure. ) may be initiated.

[0102]

[0128] In one embodiment, the system utilizes argon gas, typically at a pressure of A target pressure is typically set in the range of about 34.5 to about 206.8 kPa (gauge pressure) (about 5 to about 30 psig). The appropriate pressure can be calculated based on the liquid metal pressure drop for the length and diameter of the empty cable channel and the target fill time.

[0103]

[0129] Higher pressures can be achieved in cable assemblies with proper design of the components. This technique may be desirable when filling cable assemblies having lengths that may result in flow times that may be damaging to the HTS (e.g., due to exposure of the HTS to temperature and time combinations that may result in damage / degradation of the superconducting and / or mechanical properties of the HTS).

[0104]

[0130] The bypass valve (e.g., bypass valve V2 in FIG. 5) can then be closed, preventing An active gas valve (e.g., valve V4 in FIG. 5) can then be opened, thereby applying pressure to the vessel while the waste tank (e.g., waste tank 110 in FIG. 5) and cable assembly (e.g., cable assembly 94 in FIG. 5) remain under vacuum.

[0105]

[0131] In an embodiment, a contact sensor may be used to monitor the solder flow. During solder flow, the solder can quickly reach the cable inlet sensor and then the outlet sensor, typically in 10 to 30 seconds for a cable having a length of a few meters (e.g., 2 to 3 meters).

[0106]

[0132] The flow is controlled by a predetermined level in the waste tank (indicated by multiple internal contact sensors). This results in the washing away of any remaining flux and filling of voids.

[0107]

[0133] To stop the flow, the pump valve (e.g., pump valve V1 in Figure 5) is closed. The bypass valve is opened. Once the system pressure equalizes to more than one atmosphere, the gas valve (e.g., inert gas valve V4 in Figure 5) is closed. This, in combination with the weight of the solder in the inlet and outlet siphons, keeps both ends of the cable under pressure during cooling to reduce voids. cooling

[0134] According to the concepts described herein, the cable filling process One solder (i.e., Sn 60 Pb 40 It has been found that the heat-resistant properties of HTS cables (solder) have a shrinkage of approximately 4% during solidification. If not properly controlled, this can result in large voids, especially in the areas that cool last. Such large voids can compromise the mechanical, electrical, and thermal properties of HTS cables. Therefore, the following general methods and principles can be used to reduce, and ideally minimize, voids during solidification.

[0108] 1. Ensuring that a supply of molten metal (e.g., liquid solder) is maintained at one or both ends of the cable until the metal within the cable solidifies. In embodiments, the cable may be provided with an extension region ("extension"), and heaters may be used on the cable extension at the inlet and / or outlet. Such heaters may be enabled before cooling and temperature controlled (e.g., raised, lowered, held, maintained, managed, or otherwise controlled) to a temperature that ensures the supply of molten metal fills the reduced void.

[0109] 2. Maintaining the molten metal under pressure (e.g., both ends of the cable) reduces air gaps, and and ideally may be pressurized during cooling to minimize 3. Cool progressively toward the metal source so that the voids can always be filled with a supply of molten metal (e.g., start cooling the cable at the end of the cable farthest from the source of liquid metal, or start in the middle and progress toward the two ends).

[0135] The cooling principles and methods described above reduce the reduced voids that may occur within the cable. This provides controlled, gradual cooling to reduce, and ideally avoid, cooling. For a nearly straight cable, it may be desirable to first cool the cable from the middle (e.g., with a fan) while simultaneously heating both ends. A temperature measurement device (e.g., a thermocouple disposed thereon) on or near the cable can be used to monitor when the molten metal in each section of the cable becomes solid, at which point a cooling device (e.g., a fan) is moved or otherwise directed to another cable section. This prevents having an area with molten metal between two solid areas, which could result in a shrinking void as it cools. The method of actively controlling cooling spatially while providing a strong temperature gradient is unique, and its usefulness is evident from the fewer, larger voids with this method versus uniform cooling (see Figures 8A, 8B).

[0110]

[0136] It is recommended to use a former such that it may be most useful for fusion and other magnets. In a long helical cable, only one end of the cable is heated and channels (or holes) in the cable for cryogenic cooling can be used to gradually cool the cable from the other end.

[0111]

[0137] The cooling method is optimized for different cable lengths and geometries. Methods have been developed and demonstrated to put these principles into practice, and examples illustrating these general concepts are described herein in conjunction with at least Figures 7-11. Of course, it should be understood that variations of these methods may be used for different cable geometries and / or lengths.

[0112]

[0138] However, while the cooling methods described herein may be preferred, The cable could also be filled and cooled using more uniform cooling (e.g., by simply turning off the oven and allowing the cable to be disposed therein (i.e., metal-filled HTS cables), and the results would be acceptable for at least some (and possibly many) applications and HTS cables utilized. Cable removal

[0139] Once the metal filling and cooling processes are complete, the jacket of the HTS cable is The tubing (i.e., the extended region of the cable assembly) can be simply cut past the former with the HTS and the cable removed. The connecting tubes (e.g., between the can, siphon, cable to be filled, and waste tank) can be replaced for subsequent processes. Also, the metal (e.g., solder) can be removed from the container and waste tank (e.g., by melting the metal out of the container and waste tank) so that the container and waste tank can be reused in a subsequent metal filling process.

[0113]

[0140] 6A-6C, first and second ends 150a, 150b The flow diffuser 150 (or, more simply, the "diffuser") having a diameter of 150 mm comprises a central member 152 having a first tapered end 152 a (shown here tapered to a tip) that transitions to a smooth shank section 152 b and then to a channel section 152 c having a channel 154 formed therein.

[0114]

[0141] 6A-6C, in which like elements are provided with like reference labels. In an embodiment, the dispenser is designed to interface with a cable having four angled channels. One example of such a cable is shown in Figures 3A and 3B in conjunction with Figure 3B. As described above, dispenser 150 thus includes four channels 154 configured to channel solder into and out of a cable having four channels, such as a cable with a four-channel former (e.g., as illustrated in FIGS. 3A and 3B).

[0115]

[0142] Of course, the size and number of channels in the dispenser 150 may vary depending on the size and number of other cables or It should be understood that the dispenser channel section may be readily adaptable to any cable or former geometry, i.e., the dispenser channel section comprises four angled square channels having a configuration (e.g., size, shape, and pattern) selected to mate with channels in the cable or former.

[0116]

[0143] The flow distributor 150 distributes the flow of molten metal through channels provided within the cable. It should be understood that the mechanical characteristics of the dispenser (including, but not limited to, the number of dispenser channels, the shape of the dispenser channels, the pattern of the dispenser channels, and other channel characteristics) are therefore selected for operation with a particular former or a particular tube.

[0117]

[0144] As illustrated, the dispenser has a tapered end 152a to reduce turbulence. The distributor section 152a is shaped to gradually transition the flow of molten metal from a single circular channel (such as might be present in the tube 114 in the system of FIG. 5) to multiple angled channels in the former or tube to reduce (and ideally eliminate) the number of voids that may occur in the metal at the inlet and outlet of the former or tube. In the illustrative embodiment of FIGS. 6A-6C, the distributor section 152a tapers toward its tip to gradually transition the flow of molten metal from a single circular channel to four angled channels in the former to reduce turbulence and thus reduce (and ideally eliminate) the number of voids that may occur in the metal at the inlet and outlet of a four-channel former such as that shown in FIGS. 2-3B. The former channels have a rectangular cross-sectional shape, and therefore the distributor channels also have a rectangular cross-sectional shape. The distributor end 150 is configured to couple or join to a channeled former or channeled tube. Therefore, ideally, the channels at the dispenser end 150b have a size, shape, and configuration selected to substantially match the size, shape, and configuration of the former (including the channels within the former) to which the dispenser will be coupled (i.e., the dimensions and configuration of the channels at the dispenser end 150b substantially match the dimensions and configuration of the former at the interface between the dispenser and the former).

[0118]

[0145] Referring now to FIG. 6D, the dispenser described above in conjunction with FIGS. 6A-6C A first conical twisted spreader 158a, which may be the same as or similar to spreader 150, is coupled to a first end of former 160, and a second conical twisted spreader 158b, which may be the same as or similar to spreader 158a, is coupled to a second, opposite end of former 160. Former 160 has a plurality of channels 48' arranged in a helical configuration, and thus the former is sometimes referred to herein as a "twisted" former. Spreader 150 likewise has channels in a helical configuration. As noted above, the size (i.e., dimensions), shape (e.g., cross-sectional shape), and configuration of the spreader channels are selected to substantially match the size, shape, and configuration of the former channels.

[0119]

[0146] The dispenser smoothly directs the solder flow into and out of the channels of the twist former. As noted in, the dispenser geometry can be adapted to substantially match the former geometry. The dispenser reduces the amount of turbulence in the molten metal flow (compared to the amount of turbulence that would occur in the absence of the dispenser), thus reducing the risk of voids existing near the entrance and exit of the molten metal to and from the former.

[0120]

[0147] Reference is now made to FIG. 7, in which like elements to FIG. 5 are provided with like reference labels. 5 operates to metal fill a cable assembly 94′ (which may be the same as or similar to the cable assembly 94 described above in conjunction with FIG. 5) having a channeled former 170 with a dispenser 172 disposed at each end.

[0121]

[0148] Former 170 and the HTS material (not visible in FIG. 7) disposed within its channels. 1-6D), the filling process may be the same as or similar to the filling process described above in conjunction with at least FIGS. 1-5 (e.g., using SnPb solder), and the system for heating and filling the former may be the same as or similar to that described for the processing station of FIG. 5. The temperature of the former illustrated in FIG. 8 may be measured or otherwise determined, for example, using one or more thermocouples as described in conjunction with FIG. 5.

[0122]

[0149] Significantly, the exemplary time-temperature exposure profile illustrated in Figure 8 This results in a metal-filled HTS cable while reducing (and ideally minimizing) HTS tape degradation (e.g., the superconducting properties of the HTS tape are not degraded as a result of exposure to temperatures during the metal-filling process). Ideally, the superconducting properties of the HTS tape are not degraded at all, and at most, the superconducting properties of the HTS tape are degraded by an amount that does not prevent the HTS tape from maintaining its superconducting properties.

[0123]

[0150] Referring now to FIG. 9A, a cable assembly 100 including a former 170 is shown. 80, having spreaders 172 coupled to first and second opposing ends thereof, is cooled using a cooling system 182 and zone cooling techniques. The zone cooling begins in a central region 184 of the metal-filled cable 180 (and ideally in the middle of the metal-filled cable). One or more temperature measurement devices (e.g., thermocouples) TC8, TC10, TC11, TC13, TC14, TC16 are coupled to various regions of the cable assembly 180 and optionally in extension regions.

[0124]

[0151] The metal source 190 is connected to the cable assembly 180 through a first siphon 192. The first end of the cable assembly 180 is coupled to a waste tank 194 through a second siphon section 196. The second end of the cable assembly 180 is coupled to a waste tank 194 through a second siphon section 196. In embodiments, the cooling system may include one or more fans or blowers. In other embodiments, the cooling system may include a jacket disposed around (or wrapped around) one, some, or all of the smallest portions of the solder-filled cable, the jacket having a cooling liquid therein, such that application of the jacket cools the solder-filled cable in a controlled and desired manner. Alternatively, the solder-filled cable may still be cooled by direct application of a liquid (e.g., a cooling liquid) to one, some, or all of the portions of the solder-filled cable.

[0125] In one method suitable for a substantially straight cable, both ends 180a, 180b of the cable 180 are kept liquid using heaters 186 attached to or directed at short extensions (e.g., jacket extensions) of the cable assembly 180. If the ends (and indeed the solder-filled cable portion up to the solidifying area) are not kept liquid, the molten metal may not be able to reach and fill the voids. The oven (not shown in FIG. 9A) is turned off and opened to ambient room temperature air after metal flow. Convection is directed toward the central portion of the cable via a cooling system 182 (FIG. 9A). This creates a temperature gradient along the cable, as illustrated in FIG. 9B. After the molten metal areas near the ends of the cable have solidified, the end heaters 186 (e.g., heaters in or around the extensions) are turned off, and the cable assembly 180 is allowed to cool to ambient room temperature. To be fooled.

[0126]

[0153] 10A and 10B show the cable ( 7A and 7B ) (e.g., as described above in conjunction with FIGS. 7A and 7B ) but allowing the remainder of the cable to cool uniformly, i.e., near zero temperature gradient. The voids were determined from computed tomography (CT) scans of the central region of each cable.

[0127]

[0154] The bar graph in Figure 10A shows the results based on all air gaps for both cables (i.e. The cables produced using the zone cooling method and the cables produced using the uniform cooling method had a similar number of small voids (i.e., voids with a volume of 1 mm 3 These small voids were likely due to processes other than shrinkage, such as slight flux inclusions, and did not affect cable performance.

[0128]

[0155] However, the bar graph in FIG. 10B shows a higher number of large voids (i.e., approximately 2 mm 3 10A and 10B reveal that m more voids (m larger voids) are present in cables produced using a uniform cooling process compared to the number of large voids present in cables produced using a zone cooling method. Such large voids are likely due to shrinkage. Thus, FIGS. 10A and 10B confirm the effectiveness of the zone cooling method in reducing the number of large voids (compared to the number or large voids that occur when a uniform cooling method is used).

[0129]

[0156] The zone cooling method described above is suitable for cables up to a length of at least about 2 m. Although this technique has proven effective for cables with lengths greater than 2 m, it can also be applied to cables with lengths greater than 2 m. The length of cable that can be cooled using this technique is determined by how quickly the cable cools by natural convection. To obtain the benefits provided by this technique, it is preferable that the entire cable not cool by natural convection before the cooling system takes effect.

[0130]

[0157] In an embodiment, an oven or other cable heating device that is still on Different cooling methods comparable to the above arrangement can be used, which allows for cooling of cables longer than 2 m. Of course, there is a trade-off between cable length and oven temperature, so the longer the cable, the slower the cooling process.

[0131]

[0158] The cooling zones are placed in all areas of the cable so that they (i.e., It has been recognized that it is desirable to reach the maximum temperature (the upper limit of the cable length) before the cable is solidified by natural convection. Therefore, a variation of the above method was developed using a cooling system capable of cooling multiple cable sections simultaneously, as described below in conjunction with FIG. 11.

[0132]

[0159] Referring now to FIG. 11, a cooling system 200 includes one or more movable 11, the cooling system 200 includes two movable blowers (or fans) and a pair of heaters. The cooling system is thermally coupled to a cable assembly 206, which may or may not include extensions. One or more end heaters 204 may be thermally coupled to opposite ends of the HTS cable, while the two blowers 204 are thermally coupled to the HTS cable 106 but are movable relative to the HTS cable.

[0133]

[0160] The cooling is performed in a first region 208a or zone (see FIG. 11) of the HTS cable. Starting with the first and second cooling elements, identified by the number "1" and hereafter referred to as "Zone 1" or "Region 1"), a thermocouple (designated TC11 in FIG. 11) is oriented toward the is disposed in or adjacent to Zone 1 of the cable. A thermocouple (designated TC10 or TC12 in FIG. 11 ) is disposed in or adjacent to Zone 2 of the cable. When thermocouples TC10, TC11, and TC12 indicate that the liquid metal in and adjacent to this zone (i.e., Zones 1 and 2) has solidified, cooling elements are moved or otherwise directed to one or more zones of the cable assembly adjacent Zone 1. In this example, cooling elements are moved to two zones adjacent to Zone 1, each designated as Zone 2 (identified by the reference numeral “2” in FIG. 11 and hereafter referred to as “Zone 2” or Region 2). The minimum zone width is set by the length affected by the cooling element. When thermocouples TC9 and TC13 indicate that the molten metal in the next zone (i.e., Zone 3) is solid, cooling elements are moved to Zone 3, then Zone 4, and so on, and the process is repeated for each zone. In some embodiments, it may be preferable to position the thermocouple substantially in the middle of the zone, although the thermocouple may be placed in other parts of the zone.

[0134]

[0161] During operation, the cooling element first cools the cable in the middle (and ideally, The temperature along the cable is monitored (e.g., via thermocouples or any other suitable means for monitoring temperature) and a cooling element is moved to that section (or sections) of the cable to cool that section more quickly, creating a gradient toward the next. Thus, as illustrated in FIG. 11 , both cooling elements 201 a, 201 b are first directed toward Zone 1 (i.e., TC11), then toward Zone 2 (e.g., one cooling element is moved to Zone 2 208 b and the other to Zone 2 208 c), then Zone 3 208 d, 208 d, and so on, until each cable section has been cooled. The number of sections used in this process can be adapted to the length of the cable. This approach avoids the risk of “trapping” liquid by waiting until one section is solid before cooling an adjacent section.

[0135]

[0162] The cooling system and process described in conjunction with FIG. 11 may be used for cooling water over a surface area greater than about 2 m. This method may be suitable for cables having long lengths. This method has been successfully applied to cables up to about 3 m in length, and favorable mechanical and electrical performance has been demonstrated in tests at high magnetic fields. The upper cable length limit for this method may be set by natural convection cooling, which may be increased by increasing the ambient temperature around the cable 206.

[0136]

[0163] 12A and 12B, a single Another cooling method is described called central zone cooling using fans.

[0164] In a cable assembly 220 filled with molten metal and having a nonlinear geometry, Cooling systems that include air movement devices (e.g., fans, blowers, or other devices capable of generating airflow; all such devices are collectively referred to as air movers) that direct air toward only one cable assembly section can cause earlier sections along the cable assembly to solidify prematurely, thereby trapping liquid and creating voids.

[0137]

[0165] Therefore, cable assemblies filled with molten metal and having nonlinear geometries (e.g. For cooling of a cable assembly (such as cable assembly 220 shown in FIG. 12A having a circular or loop geometry), an air flow directing device capable of generating a directed air flow 221 (e.g., using specific air directing structures) can be used to localize the convection currents (i.e., localize the air flow to a specific portion or region of the cable assembly). For the circular (or loop) cable assembly configuration of FIG. 12A, region 222 is cooled first, followed by region 224, then region 226.

[0138]

[0166] An example of a device for progressive cooling of a cable having a single loop is shown in FIG. 12B. An air-moving device 230 (illustrated in FIG. 12B as a blower) directs air toward specific regions or zones 232a-232c of a metal-filled cable assembly 234. In the illustrative embodiment of FIG. 12B, three regions are shown (labeled Zone 1 232a, Zone 2 232b, and Zone 3 232c). Those skilled in the art will understand that in other embodiments, more or less than three regions may be used.

[0139]

[0167] In an embodiment, the air mover 230 directs the airflow toward different zones. Thus, it may be movable (eg, tiltable in the elevation plane).

[0168] In embodiments, one or more air directing devices (or baffles) ) 240 may be disposed in the path of the air flow between air mover 230 and cable 234 (for clarity, only one baffle 240 is illustrated in FIG. 12B). The one or more baffles are configured to direct the air toward different zones.

[0140]

[0169] In an embodiment, the baffle 240 has a plurality of different positions 242a-242N. In operation, the baffle 240 first aims to direct cooling to the bottom of the cable (including the bottom of the loop) (i.e., oriented to cool Zone 1 232a) and is progressively raised to cool the zones including the ends of the cable loop. That is, Zone 1 is cooled first, then Zone 2, then Zone 3. The baffle may help focus the airflow so that the cable loop 234 is cooled in a progressive manner (i.e., different portions of the cable loop in each of the aforementioned zones are cooled over time, rather than the entire cable loop being cooled simultaneously).

[0141]

[0170] In an embodiment, the baffles 240 are arranged to separate the cables within each desired cooling zone. The width of the cable loop may be approximately the same as the cable loop diameter D1 so as to direct the airflow over a portion of the cable loop.

[0142]

[0171] Other airflow directing structures may, of course, be used. Any structure or device capable of cooling the cable over time (and ideally cooling a localized region of the cable over time) may be used. In an embodiment, the blower may be coupled to a movable frame and tilted slightly downward in height, and the baffle may be movably coupled to the movable frame (e.g., by a hinge).

[0143]

[0172] Referring now to FIG. 13, a spiral, which is a common configuration for fusion and other magnets, 2 shows a cable 250 wound into a helix. In this example, the helix lies in a single plane. Cooling such a cable configuration with a fan is impractical because such an approach would likely cool multiple turns, thereby trapping liquid volume. Therefore, for cables having a central cooling hole (e.g., used for cryogenic cooling during HTS cable operation) and wound into a helical shape, a cooling method has been developed and demonstrated that utilizes a central cooling hole in the cable. Thus, the method applies to cooling a wound cable having a cooling channel (e.g., a central cooling channel such as channel 46 described above in conjunction with at least FIGS. 3A-3C ).

[0144]

[0173] This technique precludes the use of diffusers at the inlet and outlet. In the method, the jacket area is relied upon to smooth and direct the metal flow (eg, solder flow) into the channel.

[0145]

[0174] This method utilizes an end heater at only one end of the cable. The cable is made of metal (e.g. The metal is placed in an oven maintained at a temperature above the liquidus of the metal (e.g., solder). Fluid at temperature is injected from the end of the cable away from the heater, causing the solder to gradually cool and solidify along the cable from the first end (where the cold fluid is injected) to the second end (where the heater is located).

[0146]

[0175] Once it is determined that the molten metal in the cable has solidified (e.g., the If the thermocouple is not on the heater, the end heater is turned off and the oven temperature is reduced to allow the cable to cool completely.

[0147]

[0176] In a proof of principle embodiment, this technology uses room temperature air cooling to It has been demonstrated for an 11 meter cable with windings. For faster cooling (which may be desirable for cables greater than 2 meters in length), a closed-loop fluid cooling system may be used. In such a system, the fluid may be at any temperature below the solder liquidus. In embodiments (e.g., during magnet manufacturing), a liquid cooling system may be used.

[0148]

[0177] For cables without a central cooling channel, or for faster cooling, alternatives The first method is to add a cooling jacket to the outside of the cable (i.e., a method for cooling a cable using an external jacket). A cold fluid is then applied to the end of the cable opposite the heater, with a similar effect on the central fluid.

[0149]

[0178] In the foregoing detailed description, various concepts, systems, devices and techniques have been described. Features may be grouped together in one or more individual embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed concepts require more features than are expressly recited in each claim. Rather, inventive aspects may lies in less than all features of each disclosed embodiment.

[0150]

[0179] Examples that serve to illustrate various concepts, structures, and techniques that are the subject of this disclosure. Although implementations have been described, it will now become apparent to those skilled in the art that other implementations incorporating these concepts, structures, and techniques may be used.

[0151]

[0180] For example, in an alternative embodiment, instead of zoned cooling, External or Joule heating may be used. This represents an alternative heating method to an oven, which is perhaps more practical for very large magnets. Disadvantages or concerns include the need for more active control and monitoring and the risk of temperature non-uniformity. Fluid jackets, as described in the method for cooling cables using an external jacket, may also be used to heat cables instead of or as a supplement to an oven. Furthermore, it should be noted that it may be possible to fill with HTS cables at ambient pressure rather than solder under vacuum and at high pressure. It is recognized that such an approach may result in increased air or flux entrapment in tight spaces and, therefore, more voids. Furthermore, oxidation during heating may occur in such an approach.

[0152]

[0181] Still further, the metal crucible described herein above can be used outside the oven. The solder can be placed in a hot oven, with the solder melted before heating the cable. This can reduce (and ideally minimize) the time-temperature exposure of the cable, thereby reducing (and ideally minimizing) the risk of waiting for the HTS at elevated temperature for metal melting to complete, or for the cable to cool in the event of excessive temperatures after melting. The disadvantages of this approach are that more heater power is required in a room temperature ambient environment compared to a hot oven, and all tubing between the can and the cable must also be temperature controlled at the process temperature. It may be what needs to be.

[0153]

[0182] As used herein, HTS cables, HTS cable assemblies, or "Filling" a cable, cable assembly, or open channel with molten material refers to the introduction of material into the cable, cable assembly, or channel and does not necessarily imply that all available space in the cable, cable assembly, or channel is replaced with material. For example, "filling" a channel of a former as described above may involve directing molten metal into the channel and subsequently cooling the metal with the goal of preventing the formation of any voids in the channel. Nevertheless, in some cases, the channel may not contain only metal due to at least one void forming in the channel. In such cases, it is fully consistent with this disclosure that the channel is nevertheless "filled" with molten metal. In some embodiments, "filling" a cable, cable assembly, or channel with molten metal may include depositing metal such that at least 90%, at least 95%, at least 98%, at least 99%, or at least 99.9% of the initially open volume of the cable, cable assembly, or channel contains metal. It should be noted that in HTS cable embodiments with channeled formers, much (or even most) of the cable may be comprised of formers and tape, and the void volume to be filled with molten metal (e.g., solder) may be relatively small compared to the total volume of the cable.

[0154]

[0183] The concepts, systems, devices, structures and technologies sought to be protected Various embodiments are described herein with reference to the associated drawings. Alternate embodiments may be devised without departing from the scope of the concepts, systems, devices, structures, and techniques described herein. It should be noted that various connections and relationships (e.g., above, below, adjacent, etc.) are specified between elements in the above description and drawings. These connections and / or relationships may be direct or indirect unless otherwise stated, and the described concepts, systems, devices, structures, and techniques are not intended to be limiting in this respect. Thus, coupling of entities can refer to either direct or indirect coupling, and relationships between entities may be direct or indirect relationships.

[0155]

[0184] An example of an indirect positional relationship is placing element "A" relative to element "B." References in this description to being positioned or otherwise include situations where one or more intermediate elements (e.g., element "C") are between element "A" and element "B" as long as the relative features and functionality of elements "A" and "B" are not substantially changed by the intermediate elements.

[0156]

[0185] Additionally, the following definitions and abbreviations are used for interpretation of the claims and the specification: As used herein, the terms "comprise," "comprises," "comprising," "include," "includes," "including," "has," or "contains," or any variation thereof, are intended to cover non-exclusive inclusions. For example, a device, method, composition, mixture, or article that includes a list of elements is not necessarily limited to only those elements and may include other elements not expressly listed or inherent in such device, method, composition, mixture, or article.

[0157]

[0186] Additionally, the word "exemplary" means serving as an example, instance, or illustration. As used herein, the term "exemplary" refers to any embodiment or design described herein as "exemplary." Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The terms "one or more" and "one or more" are understood to include any integer greater than or equal to one, i.e., 1, 2, 3, 4, etc. The term "plurality" is understood to include any integer greater than or equal to 2, i.e., 2, 3, 4, 5, etc. The term "connected" can include an indirect "connected" and a direct "connected."

[0158]

[0577] "embodiment," "one embodiment," "one embodiment," "example embodiment" References herein to "a" or "an" indicate that the described embodiment may include a particular feature, structure, or characteristic, but all embodiments may or may not include that particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with one embodiment, it is understood that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described.

[0159]

[0588] Hereinafter, for purposes of explanation, but not limitation, the terms "upper" and "lower" will be used interchangeably. Relative or positional terms, including "side," "right," "left," "vertical," "horizontal," "top," "bottom," and derivatives thereof, refer to the described structures and methods as oriented in the drawings. The terms "overlay," "top," "on top," "positioned above," or "top-most" mean that a first element, such as a first structure, is above a second element, such as a second structure, and intervening elements, such as interface structures, may be present between the first and second elements. The term "direct contact" means that a first element, such as a first structure, and a second element, such as a second structure, are connected without any intermediate elements.

[0160]

[0189] Use of "first," "second," and "third" in a claim to modify a claim element The use of ordinal terms such as "of three" does not, in and of itself, imply any priority, precedence, or ordering of one claim element over another, or the temporal order in which the acts of a method are performed, but is merely used as a label to distinguish one claim element having a particular name from another element having the same name (however, due to the use of ordinal terms) in order to distinguish between claim elements.

[0161]

[0190] The terms "approximately" and "about" in some embodiments refer to a range of values ​​within ±100 of a target value. The term "substantially equal" can be used to mean within ±20% of each other, in some embodiments within ±10% of a target value, in some embodiments within ±5% of a target value, and even in some embodiments within ±2% of a target value. The terms "approximately" and "about" can include the target value. The term "substantially equal" can be used in some embodiments to refer to values ​​that are within ±20% of each other, in some embodiments within ±10% of each other, in some embodiments within ±5% of each other, and even in some embodiments within ±2% of each other.

[0162]

[0191] The term "substantially" in some embodiments refers to a range of ±20% or more of the comparative measurement. In some embodiments, "substantially" perpendicular to a second direction may be used to refer to a value that is within ±20% of making a 90° angle with the second direction, in some embodiments, within ±10% of making a 90° angle with the second direction, in some embodiments, within ±5% of making a 90° angle with the second direction, and even in some embodiments, within ±2% of making a 90° angle with the second direction. For example, a first direction that is "substantially" perpendicular to a second direction may in some embodiments refer to a first direction that is within ±20% of making a 90° angle with the second direction, in some embodiments, within ±10% of making a 90° angle with the second direction, in some embodiments, within ±5% of making a 90° angle with the second direction, and even in some embodiments, within ±2% of making a 90° angle with the second direction.

[0163]

[0192] The disclosed subject matter, in its application, may be any of the components set forth in the following description or illustrated in the drawings. It is understood that no limitation is intended to the details of construction and arrangement of components illustrated. The described subject matter is susceptible to other embodiments and to being practiced or carried out in various ways.

[0164]

[0193] Also, the phraseology and terminology used herein is for the purpose of description and not limitation. It should be understood that the present disclosure is not to be construed as limiting the scope of the present disclosure. As such, those skilled in the art will appreciate that the conception on which this disclosure is based may readily be utilized as a basis for the design of other structures, methods, and systems for carrying out some of the purposes of the disclosed subject matter. The claims should therefore be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the disclosed subject matter.

[0165]

[0194] The disclosed subject matter has been described and illustrated in the foregoing exemplary embodiments. It should be understood, however, that the present disclosure has been made by way of example only, and that numerous changes in the details of the implementation of the disclosed subject matter may be made without departing from the spirit and scope of the disclosed subject matter.

[0166]

[0195] Therefore, the scope of this patent should not be limited to the described implementations. , should be limited only by the spirit and scope of the following claims.

[0059] All publications and references cited herein are expressly incorporated herein by reference in their entirety.

Claims

1. at least partially filling at least one channel of a high temperature superconductor (HTS) cable assembly with molten metal, the HTS cable assembly comprising an HTS and the at least one channel; operating one or more cooling devices to cool the molten metal in the at least one channel; A method comprising:

2. The method of claim 1 , wherein the HTS cable assembly comprises a former in which the at least one channel is disposed.

3. 3. The method of claim 2, wherein the former comprises four channels each comprising an HTS, the method including at least partially filling the four channels of the former.

4. The method of claim 3 , wherein the HTS cable assembly further comprises a jacket disposed around the former.

5. The method of claim 1 , comprising completely filling the at least one channel of the HTS cable assembly.

6. At least partially filling the at least one channel of the HTS cable assembly with molten metal includes: heating the HTS cable assembly; and The method of claim 1 , comprising applying pressure to the molten metal to force the molten metal through the at least one channel of the former.

7. The method of claim 6 , wherein the molten metal is held by a vessel, and applying pressure to the molten metal comprises applying pressure to the molten metal within the vessel.

8. The HTS cable assembly comprises: a tube having a wall defining the at least one channel; and The method of claim 1 , comprising at least partially filling the at least one channel of the tube with the molten metal.

9. The method of claim 1 , wherein the HTS cable assembly comprises a stack of HTS tapes.

10. The method of claim 1 , wherein the molten metal comprises PbSn solder.

11. The method of claim 1 , further comprising the step of depositing a flux within said at least one channel prior to at least partially filling said at least one channel with said molten metal.

12. 10. The method of claim 1, wherein operating the one or more cooling devices comprises progressively cooling the HTS cable assembly toward a source of the molten metal.

13. Vacuum for filling molten metal into cable assemblies containing high temperature superconducting (HTS) materials 1. A VPI station comprising: a) a can configured to hold a source of molten metal; b) one or more heaters positioned to heat an HTS cable assembly, the HTS cable assembly comprising at least one of a tube or former having at least one channel formed therein or otherwise provided therein, and having an HTS material disposed in at least one of the at least one channel of the tube or former; and c) A vacuum impregnation (VPI) station comprising pressure applying means coupled to the can for applying pressure to the molten metal in the can so as to force the molten metal from the can through the at least one channel of the tube or former.

14. 14. The VPI station of claim 13, further comprising a siphon coupled to the can positioned at a height greater than the height of the molten metal in the can to inhibit flow of the molten metal from the can when the pressure applying means is not activated.

15. The VPI station of claim 13 , further comprising a plurality of contact sensors configured to monitor the flow of the metal from the can into the at least one channel of the tube or former.

16. The VPI station of claim 13 , wherein the one or more heaters are positioned in contact with the can.

17. The VPI station of claim 13 , further comprising an outlet tube coupled to the can, wherein at least one of the one or more heaters is disposed adjacent to the outlet tube.

18. 14. The VPI station of claim 13, further comprising a waste tank positioned to collect molten metal flowing through and exiting said at least one channel of said tube or former.

19. 20. The VPI station of claim 18, further comprising a U-bend coupled to the waste tank that inhibits the molten metal from flowing from the waste tank back into the at least one channel of the tube or former.

20. A dispenser for channeling molten metal into and / or out of an N-channel former, comprising: A spreader comprising an elongated member having a cone-shaped end, a smooth shank portion, and a helical groove portion having N grooves provided therein, the helical groove portion having a flared shape with a diameter increasing from a first end of the helical groove portion toward a second end of the helical groove portion, the N grooves of the helical groove portion being configured to direct molten metal into channels of the N-channel former.

21. 21. The device of claim 20, wherein the first end of the spiral groove portion has a diameter that substantially matches the diameter of one end of the smooth shank portion, and the second end of the spiral groove portion substantially matches the diameter of the N-channel former.

22. obtaining an HTS cable assembly; bending the HTS cable assembly; filling the bent HTS cable assembly with molten metal; A method comprising:

23. The step of obtaining a high temperature superconductor (HTS) cable assembly includes obtaining a former having at least one channel; and 23. The method of claim 22, including at least partially filling the at least one channel of the former with the molten metal.

24. The step of obtaining a high temperature superconductor (HTS) cable assembly includes obtaining a former having at least one channel; and 24. The method of claim 23, including completely filling the at least one channel of the former with the molten metal.

25. At least partially filling the at least one channel of the former with molten metal comprises: obtaining a source of said molten metal; heating the HTS cable assembly to a temperature that allows the molten metal to flow through the at least one channel of the former; and 24. The method of claim 23, comprising applying pressure to the molten metal to force the molten metal from the source through the at least one channel of the former.

26. The step of obtaining a high temperature superconductor (HTS) cable assembly includes: obtaining a tube having a wall defining at least one channel; and The method of claim 22, comprising at least partially filling the at least one channel of the tube with the molten metal.

27. The step of obtaining a high temperature superconductor (HTS) cable assembly includes: obtaining a tube having a wall defining at least one channel; and 27. The method of claim 26, including completely filling the at least one channel of the tube with the molten metal.

28. At least partially filling the at least one channel of the tube with molten metal comprises: obtaining a source of said molten metal; heating the HTS cable assembly to a temperature that allows the molten metal to flow through the at least one channel of the tube; and 27. The method of claim 26, comprising applying pressure to the molten metal to force the molten metal from the source through the at least one channel of the tube.

29. 1. A vacuum impregnation (VPI) station for filling a cable assembly including high temperature superconducting (HTS) material with molten metal, comprising: a) a can configured to hold a source of molten metal; b) means for heating an HTS cable assembly, the HTS cable assembly comprising at least one of a tube or former having at least one channel formed therein or otherwise provided therein, and having an HTS material disposed in at least one of the at least one channel of the tube or former; and c) A vacuum impregnation (VPI) station comprising pressure applying means coupled to the can for applying pressure to the molten metal in the can so as to force the molten metal from the can through the at least one channel of the tube or former.

30. An outlet siphon and waste configured to couple to one end of an HTS cable assembly 30. The VPI station of claim 29, further comprising an outlet siphon and disposal section configured to allow excess solder to flow through the HTS cable assembly, flushing away flux and completely filling the HTS cable assembly with molten metal from the can, such that an end of a cable remains pressurized by molten metal and impurities cannot return to the HTS cable assembly.

31. A method comprising at least partially filling at least one channel of a high temperature superconductor (HTS) cable assembly with molten metal, said HTS cable assembly comprising an HTS and said at least one channel.

32. 32. The method of claim 31 , wherein the HTS cable assembly comprises a former in which the at least one channel is disposed.

33. 33. The method of claim 32, wherein the former comprises four channels each comprising an HTS, the method including at least partially filling the four channels of the former.

34. 34. The method of claim 33, wherein the HTS cable assembly further comprises a jacket disposed around the former.

35. 32. The method of claim 31, comprising completely filling the at least one channel of the HTS cable assembly.

36. At least partially filling the at least one channel of the HTS cable assembly with molten metal includes: heating the HTS cable assembly; and 33. The method of claim 32, comprising applying pressure to the molten metal to force the molten metal through the at least one channel of the former.

37. 37. The method of claim 36, wherein the molten metal is held by a vessel, and applying pressure to the molten metal comprises applying pressure to the molten metal within the vessel.

38. The HTS cable assembly comprises: a tube having a wall defining the at least one channel; and 32. The method of claim 31, comprising at least partially filling the at least one channel of the tube with the molten metal.

39. 32. The method of claim 31 , wherein the HTS cable assembly comprises a stack of HTS tapes.

40. 32. The method of claim 31 , wherein the molten metal comprises PbSn solder.

41. 32. The method of claim 31 , further comprising depositing a flux in said at least one channel prior to at least partially filling said at least one channel with said molten metal.

42. 32. The method of claim 31 , further comprising, following the step of at least partially filling the at least one channel with the molten metal, progressively cooling the HTS cable assembly toward a source of the molten metal.

43. 1. A method for filling an HTS cable with molten metal, the method comprising heating at least a portion of the HTS cable comprising an HTS tape using a time-temperature exposure profile that does not degrade HTS tape properties by more than 5%.

44. 1. A method for filling an HTS cable, comprising: Bending a cable assembly having an HTS material disposed therein; filling the cable assembly with molten metal after bending the cable assembly; A method comprising:

45. 45. The method of claim 44, wherein bending the cable assembly having the HTS material disposed therein comprises bending the cable assembly to form at least one partial loop.

46. The step of filling the cable assembly with molten metal comprises: heating the HTS cable assembly including the HTS material; and heating the HTS cable assembly; and 46. ​​The method of claim 45, comprising applying pressure to the molten metal to force the molten metal through the cable assembly to form at least one partial loop.

47. 46. ​​The method of claim 45, wherein bending the cable assembly having the HTS material disposed therein comprises bending the cable assembly to form at least one loop.

48. 48. The method of claim 47, wherein the HTS material comprises at least an HTS tape, and wherein bending the HTS cable assembly includes twisting the HTS tape and allowing the HTS tape to redistribute during bending such that the HTS tape is substantially stress-free prior to filling the cable assembly with molten metal.

49. 49. The method of claim 48, further comprising cooling the molten metal within the cable assembly to fix the position of the HTS tape within the cable assembly.

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