Methods and systems for enhancing superconductor manufacturing

Abstract

A metal organic chemical vapor deposition (MOCVD) device for manufacturing superconducting tapes and a method of fabricating superconducting tapes is disclosed. The device includes an ohmic heat terminal assembly to heat a superconductor substrate tape through ohmic heating. The assembly includes a first roller exterior to a housing and configured to heat multiple superconductor substrate tapes and guide the superconductor substrate tapes to multiple tape tracks and a second roller exterior to the housing and configured to heat the multiple superconductor substrate tapes and guide the heated superconductor substrate tapes out of the multiple tape tracks. Each of the multiple tape tracks includes a first precursor flow channel configured to supply longitudinal laminar precursor flow for deposition on one side of the superconductor substrate tape and a first wall shield flow channel configured to supply longitudinal shield gas flow on the one side of the superconductor substrate tape.

Description

Methods and Systems for Enhancing Superconductor ManufacturingGovernment Sponsorship;

[0001] Advanced Research Projects Agency-Energy (ARPA-E), award DE-AR0001374.U.S. Department of Energy Advanced Materials and Manufacturing Office award DE- EE0007869.Field of the Invention

[0002] The present invention is directed to methods and systems for fabricating superconducting tapes. More particularly, the present invention discloses methods and systems for fabricating superconducting tapes in high yields and efficiencies, with high critical current densities.Background

[0003] Superconductors are a unique system that provide potential solutions across a broad spectrum of energy’ problems. Superconductors may enable high efficiencies in generators, power transmission cables, motors, transformers, and energy storage. Superconductors are currently being used to make powerful magnets for applications such as magnetically confined fusion for energy7production. Further, superconductors may advance applications in medicine, particle physics, communications, and transportation. Superconducting tapes have come of age, enabled by approaches such as those herein for creating epitaxial, single-crystal- like thin films of RE-Ba-Cu-0 (REBCO, RE = rare earth) on polycrystalline substrates.

[0004] Superconducting films that are processed using REBCO growth techniques exhibit critical current densities comparable to that achieved in epitaxial films grown on single crystal substrates. Metal organic chemical vapor deposition (MOCVD) techniques have beenincorporated into the REBCO growth for the manufacturing of superconducting tapes.REBCO tapes are generally fabricated by a roll-to-roll process of deposition of several thin films in sequence on a flexible metal substrate. The superconductor films are ty pically about 2 pm thick.Summary

[0005] While superconducting tapes may be produced in long lengths, the cost of producing superconducting tapes is still high. For example, the cost of REBCO superconductor tape may be ~$200 / kA-m for a superconducting tape with a critical current at 77 K, 0 T. For many applications, a 5 to 10-fold decrease in the cost will be needed for the wide-spread use of superconductors. One avenue for reducing the cost is to increase the critical current. Approaches to increase the critical current include increasing the thickness of the superconductor film and introducing effective nanoscale defects in the superconductor film for enhanced flux pinning.

[0006] However, it has typically been found that the critical current density’ of REBCO tapes (critical current / cross sectional area) decreases with increasing film thickness. That is. the quality of the superconductor film can degrade with increasing thickness. One reason for this degradation is poor control of temperature of the tape (~800°C) during deposition.

[0007] The inventors have developed Advanced MOCVD methods to obtain a constant high critical cunent density in REBCO tapes with films as thick as 5 pm. In such methods, direct heating with an electric current is used to heat the tape to film growth temperature using the resistive substrate on which the films are grown. The temperature of the tape may be directly monitored using optical probes. As such, the deposition temperature is maintained constant within a narrow temperature window. Further, a laminar flow channel is employed in the Advanced MOCVD for the uniform delivery of chemical precursors. The uniform deliveryalso helps to maintain a uniform temperature and enables very' efficient conversion of the precursors into the REBCO film.

[0008] Using the Advanced MOCVD method, REBCO tapes have been fabricated with films as thick as 5 pm. In addition, the Advanced MOCVD methods enable a tailoring of nanoscale defects in the superconductor that results in excellent flux pinning. As a result, the superconductor has superior critical current in high magnetic fields. For example, a superconductor tape made by Advanced MOCVD can exhibit about 4x higher critical current than the state-of-the-art superconductors. Consequently, 4x less superconductor can be used to obtain the same amperage. Additionally, the laminar flow geometry in the Advanced MOCVD process can result in an increase in the precursor-to-film conversion efficiency when compared to standard processes. The increase in the precursor-to-film conversion efficiency contributes to a significant reduction in the cost of manufacturing the tape.

[0009] In order to make long lengths of REBCO tape using the Advanced MOCVD, the throughput of the process is increased to include multi-track deposition with longitudinal laminar precursor flow and simultaneous coating of REBCO film on the top and bottom sides of the tape. The tape is heated using the direct heating described above, optionally combined with hot-walls in the Advanced MOCVD reactors. The multi-tracks may include a tapered reactor to facilitate the uniform growth rate along the length of the reactor. In addition to the above, a shield gas dispersed to flow' parallel to the precursor flow is used to prevent unw anted nucleation of film prior to the tape reaching the appropriate process conditions. A porous wall reactor may also be used to shield the gas flow near the reactor w alls. Shielding the precursor gas flow prevents parasitic film deposition on the reactor walls.

[0010] In one aspect, embodiments are directed to a MOCVD device for manufacturing superconducting tapes that includes an ohmic heat terminal assembly to heat asuperconductor substrate tape through ohmic heating. The assembly includes a first roller exterior to a housing and configured to heat multiple superconductor substrate tapes or multiple sections of one superconductor substrate tape and guide the heated superconductor substrate tapes or tape sections to multiple tape tracks at a first end of the housing and a second roller exterior to the housing and configured to heat the multiple superconductor substrate tapes or tape sections and guide the heated superconductor substrate tapes or tape sections out of the second end of the housing via the multiple tape tracks. The device may optionally include a top hot wall reactor with top wall flow channels to supply a first shield gas and a first heater array and a bottom hot wall reactor with bottom wall flow channels to supply a second shield gas and second heater array. Each tape track includes a first precursor flow channel configured to supply longitudinal laminar precursor flow for deposition on a one side of the superconductor substrate tape, and a first wall shield flow channel configured to supply longitudinal shield gas flow on the one side of the superconductor substrate tape.

[0011] In another aspect, embodiments are directed to a method of fabricating superconductor tapes that includes ohmic heating of superconductor substrate tapes using a first roller exterior to a housing configured to heat multiple superconductor substrate tapes or multiple sections of one superconductor substrate tape and guide the heated superconductor substrate tapes or tape sections to multiple tape tracks at a first end of the housing and a second roller exterior to the housing configured to heat the multiple superconductor substrate tapes or tape sections and guide the heated superconductor substrate tapes or tape sections out of the second end of the housing via the multiple tape tracks. The method may optionally include flowing a first shield gas via top wall flow channels of a top hot wall reactor comprising a first heater array and flowing a second shield gas via bottom wall flow channels of a bottom hot wall reactor comprising a second heater array. The method further includes supplying a longitudinal laminar precursor flow in a first precursor flow channel in each ofthe multiple tape tracks for deposition on a one side of the superconductor substrate tape and supplying a longitudinal shield gas flow in a first wall shield flow channel in each of the multiple tape tracks to supply longitudinal shield gas flow on the one side of the superconductor substrate tape.Brief Description of the Drawings

[0012] The foregoing summary, as well as the following detailed description, will be better understood when read in conjunction with the appended drawings. For the purpose of illustration only, there is shown in the drawings certain embodiments. It’s understood, however, that the inventive concepts disclosed herein are not limited to the precise arrangements and instrumentalities shown in the figures.

[0013] Figure 1 illustrates a schematic of an advanced MOCVD system, in accordance with one or more embodiments.

[0014] Figure 2 illustrates a schematic of a longitudinal laminar precursor flow Advanced MOCVD channel, in accordance with one or more embodiments.

[0015] Figure 3 illustrates a schematic of an Advanced MOCVD reactor showing shielded gas flows, in accordance with one or more embodiments.

[0016] Figure 4 illustrates a schematic of an Advanced MOCVD reactor showing the entries of the gas flows, in accordance with one or more embodiments.

[0017] Figure 5 illustrates the effect of wall flow shield gas velocity on containment of the precursor, according to some aspects.

[0018] Figure 6 illustrates the diffusivity of gas species, according to some aspects.

[0019] Figure 7 illustrates the effect of pressure on the deposition zone, according to some aspects.Detailed Description

[0020] Before explaining at least one embodiment in detail, it should be understood that the inventive concepts set forth herein are not limited in their application to the construction details or component arrangements set forth in the following description or illustrated in the drawings. It should also be understood that the phraseology and terminology employed herein are merely for descriptive purposes and should not be considered limiting.

[0021] It should further be understood that any one of the described features may be used separately or in combination with other features. Other invented systems, methods, features, and advantages will be or become apparent to one with skill in the art upon examining the drawings and the detailed description herein. It’s intended that all such additional systems, methods, features, and advantages be protected by the accompanying claims.

[0022] In order to make long lengths of REBCO tape by Advanced MOCVD, embodiments disclosed herein increase the throughput of the process, while maintaining a high critical current of the tape. Additionally, to reduce the cost of manufacturing tapes, embodiments disclosed herein increase the precursor-to-film conversion efficiency.

[0023] Embodiments provide for scaled-up, high-performance REBCO tapes using Advanced MOCVD devices and processes. More specifically, embodiments include a device with multi-track deposition using longitudinal laminar precursor flow. The Laminar precursor flow is longitudinally delivered along the tape length, rather than transverse across tape width. Embodiments may also include the use of a shield gas that flows parallel to theprecursor flow. The shield gas is provided to prevent unwanted nucleation of the film prior to the tape reaching the appropriate process conditions.

[0024] Embodiments may also include a tapered reactor enclosing the tape. That is, a tapered geometry of the reactor channel along the flow direction facilitates a uniform growth rate along length of the reactor in accordance with embodiments herein.

[0025] Embodiments may also include the simultaneous coating of a REBCO film on the top and bottom sides of tape within the device. Embodiments utilize direct Ohmic heating of the tapes as mentioned above, combined with a hot-wall approach. Embodiments may include a porous wall reactor that flows a shield gas near the reactor walls to prevent parasitic film deposition.

[0026] Figure 1 demonstrates a device of an Advanced MOCVD system in accordance with one or more embodiments herein. Tn the device 100 of Figure 1, a metal substrate tape 102 enters the device 100 into an ohmic heat terminal assembly 104. A tape direct ohmic heat terminal assembly 104 is located on two sides of the device 100. The device 100 includes multiple tape tracks 106 that allow the tape to undergo multiple passes through the device 100. The superconducting tape 108 may leave the device after a desired number of passes using the multiple tape tracks 106.

[0027] In embodiments, the substrate tape may contact a surface of a roller in the ohmic heat terminal assemble. The roller may be made of highly conductive metal such as copper, located outside the deposition zone. The metal roller heats the tape directly through an electric current flowing through the roller, i.e., ohmic heating. Direct ohmic heating provides a means for obtaining highly uniform temperature distribution across the length of the tape. Because the heating is not from an external heat source, the stability of the tape temperature may be maintained throughout the manufacturing processes.

[0028] The device 100 may include a top hot wall reactor 110 with flow channels and a heater array 112. The device 100 also may include a similar bottom hot wall reactor 114. As can be seen on the bottom hot wall reactor 114 in Figure 1, the hot wall reactors may include a shield gas showerhead 116 to supply a shield gas, as will be explained further below. The device 100 includes optical temperature monitors 118 to directly monitor the temperature of tapes within the device. The device 100 also includes other thermocouple components (not show n) mounted within different zones of the hot wall reactor device 100 to monitor the temperature uniformity' within the device 100.

[0029] In accordance with embodiments, a longitudinal laminar flow of precursors is introduced into the chamber of the device 119. As such, the precursor is delivered along the length of the moving tape within the device and then any remaining precursor exits the chamber 120. In such an arrangement, the precursors are converted to a superconductor film over the entire deposition zone of 30 cm or longer.

[0030] In other embodiments, the device may include a tapering along the direction of the precursor flow. Figure 2 illustrates a schematic of a longitudinal laminar precursor How- Advanced MOCVD channel (shown without the gas inlets for clarity), in accordance with one or more embodiments. As shown in Figure 2, a tapering may be employed to consume the precursor more uniformly along the tape length. The tapering provides a decreasing height of the laminar flow channel in the direction of the tape 230 parallel to the direction of the precursor flow 232. Because the volume of the laminar flow channel decreases along the reactor length, the precursors are more effectively converted to form the superconducting film. This geometry helps to counteract the depletion of precursors during deposition. In accordance with embodiments, the taper may be a linear profile as shown in Figure 2 or mayinclude a curved profile. The profile may be designed for a near constant deposition rate along the reactor length of the device.

[0031] In other embodiments, a shield gas of nitrogen or argon flowing in channels around the tape may be employed. Such a shield gas may be applied above and / or below the channels used to deliver the precursor. For example, Figure 3 illustrates a schematic of an Advanced MOCVD reactor showing shielded gas flows, in accordance with one or more embodiments.

[0032] In the perspective of Figure 3. the tape 340 passes through the reactor 300 from left to right. The reactor 300 may include wall shield channels 342 for gas flow, similar to the flow channels shown in the bottom hot wall reactor 114 of Figure 1. Embodiments may also include a side shield channels 344. These channels allow a shield gas of argon or nitrogen to be delivered between a precursor delivery channel and the reactor wall. Such channels help prevent parasitic deposition of film on the reactor walls.

[0033] Embodiments disclosed herein may also include the use of a tape shield channel 346 as shown in Figure 3. The tape shield channel 346 is between the tape 340 and the precursor flow channel 348A, 348B. The ratio of tape shield gas flow to the precursor flow can range from 0.01 to 100. The purpose of this gas flow is to shield the tape 340 near the entry of the tape into the deposition zone. The tape shield channel 346 prevents backflow of precursor as well as premature coating of the tape near the tape entrance to the reaction chamber.

[0034] Metalorganic precursors that react to form the superconductor film on the tape 340 are introduced via the precursor flow channels 348A, 348B. The precursor flow channels 348A, 348B are designed to extended into the reactor such that the precursor begins to react on the tape surface at the optimum film nucleation temperature. The metalorganic precursors are converted to film along the tape as the precursors travel from the entrance to the exhaust. Thelength of the deposition zone may be tuned such to consume all the available precursor.Accordingly, -100% of the precursor may be converted into the superconducting film.

[0035] Embodiments may also include wall shield flow channels 350A, 350B. The wall shield flow channel 350A introduces an inert gas in a channel between the precursor flow channel 348A and the walls of the reactor. The wall shield flow channels 350A, 350B help contain precursor and prevent deposition on the reactor walls.

[0036] Figure 4 illustrates a schematic of an Advanced MOCVD reactor showing the entries of the gas flows, in accordance with one or more embodiments. As the gases enter the deposition chamber, the reactor 400 may include wall shield channels 442 and / or side shield channels 444 to help prevent deposition on the reactor walls. A tape shield channel 446 is between the tape 440 and a precursor flow channel 448A. 448B. This gas flow helps shield the tape 440 at the entrance of the deposition zone. Precursor flow channels 448A, 448B are provided on each side of the tape, between the tape shield channel 446 and the wall shield flow channels 450A, 450B. Also, Figure 4 includes wall shield flow channels 450A. 450B.

[0037] In the embodiments illustrated in Figures 3 and 4, the superconducting films may be formed on both sides of the tape during deposition; however, embodiments are not limited as such. For example, a single precursor flow channel on one side of the tape may be used for deposition on one side of a tape. The precursor flow channel may be accompanied by a combination of the tape shield channel, wall shield flow channel, wall shield channels and side shield channels in accordance with embodiments herein. Such embodiments may or may not include a second tape shield channel or second wall shield flow channel for deposition on the other side of the tape.

[0038] In addition to the reactor / devices described above, embodiments herein also include novel methods of manufacturing superconducting tapes. In embodiments, the tape is a metalsubstrate. For example, a tape made of Hastelloy C276, Inconel 625, stainless steel, or other similar materials with an electrical resistivity' of at least 50 p -cm may be used as the metal substrate tape. The high resistivity is required for directly heating tape with an electric current. The electric current may be AC, DC, or any applied in other waveforms. The electric current required to heat the tape depends on the dimensions of the tape (in addition to the tape material). For example, a tape may be 4 - 12 mm in width and 25 - 100 pm in thickness, and an electric current of up to 50 A may be used to the heat the tape. The tape is heated using the ohmic heat terminal assemblies, as described above. In some embodiments, the tape may be heated to approximately 700-850°C.

[0039] The temperature monitoring devices may be optical crystal probes. In some embodiments, the optical crystal probes are positioned beneath and in close proximity to the traveling tape to monitor the temperature of the surface of the tape. The probes may also be positioned outside of the reactor so as to not interfere with the gas flow during fabrication. In some embodiments, the temperature signal collected by a probe is fed back to the heating system in a closed PID loop to control the pow er of the heater system’s pow er supply to maintain a constant temperature. Because the thermal mass of the tape is substantially small, fluctuations in temperature can be immediately recognized by the optical probes achieving tight temperature control.

[0040] In accordance with embodiments, in addition to direct ohmic heating, the tape may also be indirectly heated using a hot-wall arrangement. The hot-wall arrangement (e g., see Figure 1) includes a fumace / oven that may be heated up to 1000°C. The fumace / oven may include multiple zones (3 or more) to monitor temperature uniformity. For example, the temperature uniformity may be less than a 5°C variance in the deposition zone. As describedabove, the temperature of the tape is directly monitored using optical probes. Thermocouples may be mounted in the various zones of the hot-wall reactor.

[0041] In accordance with some embodiments, the combined hot-wall heating and direct ohmic heating may facilitate a lower electrical current to directly heat the tape. The lower electrical current may reduce potential arcing at the electrical contacts. Such embodiments may also have a lower thermal load on the reactor. This may help maintain the mechanical integrity of components in the reactor.

[0042] In embodiments herein, the precursor is delivered in a longitudinal laminar flow along the length of the moving tape. As such, the precursors are converted to a superconductor film over the entire deposition zone (e.g.. 30 cm or longer) in the device. Accordingly, much more of the costly precursor is converted into the superconductor film when compared to a transverse flow. In a transverse flow, the precursor is converted to film only across the ~12- mm-width of the tape. Additionally, embodiments avoid misaligned grain growth near the tape edges when the precursor first contacts the tape, which may occur when using transverse flow.

[0043] In embodiments, the longitudinal precursor flow may allow for the precursor to be delivered simultaneously over multiple tapes, or multiple segments of the same tape, all moving in parallel in the same direction. Accordingly, the deposition areas are significantly increased, which increases the overall tape production throughput.

[0044] In some embodiments, when multiple segments of a single tape are used (i.e., a single tape is passed through the multiple tracks in the deposition zone), the multiple segments are simultaneously coated. As a result, the tape may be moved faster through the deposition zone. In embodiments, the same segment of the tape may be coated sequentially multiple times as it passes through the deposition zone multiple times. Further, using the longitudinalprecursor flows herein, all tapes / tape segments will experience the same coating parameters.In contrast, in transverse precursor flow, coating multiple tapes results in depletion of precursor from the entry to exit. Thus, different tapes / tape segments will not experience the same deposition conditions.

[0045] In embodiments herein, the precursor will be depleted along the length of the tape from entry to exit in longitudinal precursor flow; however, it will not result in significant non-uniformity because of the motion of the tape along the direction of flow. This is further enhanced by those embodiments that include a tapered geometry in the device, as described in Figure 2.

[0046] Nucleation of the REBCO film at the optimum temperature is critical to assure growth of highly c-axis aligned film. If the nucleation occurs at a lower, sub-optimal temperature will cause growth of misaligned grains which will lower the critical current density of the tape. Embodiments disclosed herein also help to prevent nucleation of the film until the tape is at the optimum temperature. More specifically, there exists a temperature gradient in the tape as the tape enters the deposition zone. Because the precursor is delivered longitudinally along the tape length, embodiments include precautions to prevent premature nucleation of the film until the tape reaches the optimum temperature.

[0047] To that end, embodiments may include the use of a shield gas of nitrogen or argon that flows in a channel between the precursor and the tape. For example, the shield gas is supplied via the shield gas channels shown in Figures 3 and 4. The ratio of tape shield gas flow to the precursor flow may range from 0.01 to 100. A non-reacting gas, such as Argon or Nitrogen, is used in the tape shield channel to shield the tape near the entry of the deposition zone. The shield gas also prevents backflow of precursor in addition to preventing premature coating of the tape near the tape entrance of the reaction chamber.

[0048] In accordance with embodiments, the precursor is introduced via the precursor flow channels. The precursor gas include metalorganic precursors that react to form a superconductor fdm on the tape. The precursor flow channel extends into the reactor such that the precursor exiting the channel begins to react on the tape surface at the optimum film nucleation temperature. The metalorganic precursors are converted to film along the tape as the precursors travel from entrance to exhaust. As noted above, in some embodiments, the precursor may be introduced via a channel above and below the tape to coat superconducting films on both top and bottom sides of the tape.

[0049] In embodiments, before the precursor enters the reactor it can be vaporized from liquid to vapor by mixing with a hot argon carrier gas. In another embodiment, oxygen gas is injected into the precursor flow to assist the reaction kinetics. Once vaporized, the precursor is injected into the MOCVD system. The precursor flow channel may be maintained at a temperature between approximately 250 - 300°C to prevent the precursor from condensing on the channel walls. Because the tape is heated to a substantially higher temperature (e.g., ~700-850°C), the precursor can decompose thermally as it contacts the tape, depositing the carried metals (e.g., Y, Ba, Cu, etc.).

[0050] In embodiments, the length of the deposition zone may be engineered to consume all of the precursors during the deposition process. The ty pical precursor to film conversion efficiency in conventional MOCVD systems is about 10-15%. Embodiments herein may essentially convert 100% of precursor into the film.

[0051] Using a hot wall reactor can pose challenges with parasitic deposition of film on the reactor wall. As described above, in some embodiments, a shield gas of argon or nitrogen may be delivered through a wall flow shield channel located between the precursor channel(s) and the reactor wall(s). Embodiments of the reactor may also include shield gaschannels through a porous reactor wall, such as through the shield gas showerhead 116 ofFigure 1.

[0052] In embodiments, the shield gas may enter a housing through a gas inlet and leave the housing through a gas outlet. In some embodiments, as the wall shield gas enters the housing it may pass through an inlet pressure buffer chamber followed by an inlet dispersion plate. First, the gas may pass through the inlet pressure buffer chamber, which can have a large volume. Second, the gas may pass through the inlet dispersion plate that can include one or more substantially small holes (pores). The inlet dispersion plate may have a small conductance and can uniformly distribute the gas throughout the flow chamber. Such inlet designs can substantially absorb upstream pressure fluctuations (e.g., fluctuations caused by the precursor delivery7system). As a result, pressure fluctuations can be minimized at the tape.

[0053] In some embodiments, as the shield gas exits the housing it may pass through an outlet dispersion plate followed by an outlet pressure buffer chamber. First, the gas may pass through an outlet dispersion plate that can include one or more substantially small holes. Second, the gas may pass through the outlet pressure buffer chamber , which can have a large volume. This outlet design can substantially absorb downstream pressure fluctuations caused by the downstream pump and valves. Again, as a result, pressure fluctuations can be minimized at the substrate tape site so that the tape is fabricated at a substantially constant and optimum temperature.

[0054] Embodiments herein can adjust the tape shield gas flow, precursor flow, and different wall flows to obtain an optimum flow pattern for deposition of the precursor onto the tape. For example. Figure 5 illustrates the effect of wall flow shield gas velocity on containment of the precursor, according to some aspects. The panels illustrate the concentration of precursorusing different velocities of wall flow shield gas. In Figure 5. the velocity of the wall flow shield gas relative to precursor velocity7is increasing in panels A-B-C. At the slowest velocity7of wall flow shield gas in panel A, the precursor concentration indicates precursor can drift from the tape and approach the reactor walls. At the greatest velocity in panel C, the concentration of precursor remains in proximity of the tape. In embodiments herein, the ratio of the flow of the wall flow shield gas to the precursor may range from 0.01 to 100.

[0055] In addition to wall flow shield gas delivery7longitudinally along the tape length, embodiments may also include a porous reactor wall for delivery of shield gas perpendicular the tape length and along the tape face from the sides of the reactor, as demonstrated in Figures 3 and 4. The porous reactor w all includes an array of holes in a regular or random pattern to deliver the w all shield gases. Figure 6 illustrates the diffusivity7of gas species, according to some aspects. The wall shield gas enters from pores at the top of Figure 6. The ratio of the flow7of w all shield gas to the precursor may range from 0.01 to 100. As can be seen, the wall shield gas prevents deposition of precursors on the porous wall during deposition.

[0056] In accordance with embodiments, the reactor pressure, precursor flow rate and precursor molarity is optimized to control the deposition rate and, thus, the length of the deposition zone. Figure 7 illustrates the effect of pressure on the deposition zone, according to some aspects. Figure 7 shows the effect of pressure on the length of the deposition zone ranging from a lowest pressure Panel A to a highest pressure Panel C. The panels illustrate the concentration of precursor at the different pressures. Figure 7 demonstrates that a precursor is distributed more homogeneously over the length of the deposition zone at a higher pressures. The nominal reactor pressure may range from 2 to 10 Torr, with most embodiments using a reactor pressure of 4 to 6 Torr.

[0057] It’s understood that the above description is intended to be illustrative, and not restrictive. The material has been presented to enable any person skilled in the art to make and use the inventive concepts described herein, and is provided in the context of particular embodiments, variations of which will be readily apparent to those skilled in the art (e.g., some of the disclosed embodiments may be used in combination with each other). Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention therefore should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms "including" and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.”

Claims

What is Claimed is:

1. A metal organic chemical vapor deposition (MOCVD) device for manufacturing superconducting tapes, the device comprising: an ohmic heat terminal assembly to heat a superconductor substrate tape through ohmic heating, the assembly comprising: a first roller exterior to a housing and configured to heat multiple superconductor substrate tapes and guide the heated superconductor substrate tapes to multiple tape tracks at a first end of the housing; a second roller exterior to the housing and configured to heat the multiple superconductor substrate tapes and guide the heated superconductor substrate tapes out of a second end of the housing via the multiple tape tracks; wherein each of the multiple tape tracks comprises: a first precursor flow channel configured to supply longitudinal laminar precursor flow for deposition on a one side of the superconductor substrate tape.

2. The MOCVD device of claim 1, further comprising: a top hot wall reactor comprising top wall flow channels to supply a first shield gas and a first heater array; and a bottom hot wall reactor comprising bottom wall flow channels to supply a second shield gas and second heater array, wherein each of the multiple tape tracks further comprises: a first wall shield flow channel configured to supply longitudinal shield gas flow on the one side of the superconductor substrate tape.

3. The MOCVD device of claim 1, wherein each of the multiple tape tracks further comprises: a second precursor flow channel configured to supply longitudinal laminar precursor flow for deposition on the other side of the superconductor substrate tape.

4. The MOCVD device of claim 3, wherein each of the multiple tape tracks further comprises: a second wall shield flow channel configured to supply longitudinal shield gas flow on the other side of the superconductor substrate tape.

5. The MOCVD device of claim 1, wherein at least one of the multiple tape tracks is tapered to decrease a height of the first precursor flow channel parallel to the direction of the precursor flow.

6. The MOCVD device of claim 1, wherein the multiple tape tracks allow a single superconductor substrate tape to undergo multiple passes through the housing.

7. The MOCVD device of claim 1, further comprising: multiple optical temperature monitors to directly monitor the temperature of superconductor substrate tapes within the device.

8. The MOCVD device of claim 1, further comprising: multiple thermocouple components mounted within different zones to monitor temperature uniformity within the device.

9. The MOCVD device of claim 1, wherein the first shield gas, the second shield gas, and the longitudinal shield gas are selected from nitrogen, argon, or combinations thereof.

10. The MOCVD device of claim 1, wherein a nominal pressure of the device may range from 2 to 10 Torr.

11. A method for fabricating superconductor tapes, the method comprising: ohmic heating of superconductor substrate tapes using: a first roller exterior to a housing configured to heat multiple superconductor substrate tapes and guide the heated superconductor substrate tapes to multiple tape tracks at a first end of the housing; a second roller exterior to the housing configured to heat the multiple superconductor substrate tapes and guide the heated superconductor substrate tapes out of the second end of the housing via the multiple tape tracks; and supplying a longitudinal laminar precursor flow in a first precursor flow channel in each of the multiple tape tracks for deposition on a one side of the superconductor substrate tape.

12. The method of claim 1 1, the method further comprising: flowing a first shield gas via top wall flow channels of a top hot wall reactor comprising a first heater array; flowing a second shield gas via bottom wall flow channels of a bottom hot wall reactor comprising a second heater array; and supplying a longitudinal shield gas flow in a first wall shield flow channel in each of the multiple tape tracks to supply longitudinal shield gas flow on the one side of the superconductor substrate tape.

13. The method of claim 1 1. the method further comprising: supplying longitudinal laminar precursor flow in a second precursor flow channel in each of the multiple tape tracks for deposition on the other side of the superconductor substrate tape.

14. The method of claim 13, the method further comprising: supplying longitudinal shield gas flow in a second wall shield flow channel in each of the multiple tape tracks on the other side of the superconductor substrate tape.

15. The method of claim 11, wherein at least one of the multiple tape tracks is tapered to decrease a height of the first precursor flow channel parallel to the direction of the precursor flow.

16. The method of claim 1 1, w herein the multiple tape tracks allow a single superconductor substrate tape to undergo multiple passes through the housing.

17. The method of claim 1 1, further comprising: monitoring a temperature of superconductor substrate tapes within the device using multiple optical temperature monitors.

18. The method of claim 11, further comprising: monitoring a temperature uniformity of the device using multiple thermocouple components located in different zones within the device.

19. The method of claim 11, wherein the shield gas and the longitudinal shield gas are selected from nitrogen, argon, or combinations thereof.

20. The method of claim 11. wherein a nominal pressure of the device may range from 2 to 10 Ton.

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