Optical fiber quench detection

Abstract

A high temperature superconductor (HTS) cable includes at least one HTS tape stack extending along a length of the HTS cable and at least one optical fiber extending along the HTS cable, the at least one optical fiber having a plurality of gratings spaced apart from one another along a length of the HTS cable for detecting quenches of the at least one HTS tape stack.

Description

[Technical field]

[0001] Related Applications

[0001] This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63 / 230,302, entitled "Fiber Optic Quench Detection," filed on August 6, 2021, which is incorporated by reference in its entirety into this specification. [Background technology]

[0002]

[0002] A superconductor is a material that has no electrical resistance to electric current (is "superconductive") below a critical temperature. For many superconductors, the critical temperature is below 30 K, so that operation of these materials in the superconducting state is accomplished with significant refrigeration, such as can be achieved with liquid or supercritical helium. Summary of the Invention

[0003] Some embodiments are directed to a high temperature superconductor (HTS) cable comprising at least one HTS tape stack extending along a length of the HTS cable and at least one optical fiber extending along the HTS cable, the at least one optical fiber having a plurality of gratings spaced apart from one another along a length of the HTS cable for detecting a quench of the at least one HTS tape stack.

[0004] In some embodiments, the HTS cable comprises a jacket around at least one HTS tape stack, hi some embodiments, the jacket comprises copper.

[0005] In some embodiments, the HTS cable further includes at least one groove in the jacket, the at least one optical fiber being disposed in the at least one groove. In some embodiments, the at least one groove is in an outer surface of the jacket. In some embodiments, the HTS cable further includes an adhesive in the at least one groove, the adhesive securing the at least one optical fiber to the at least one groove.

[0006] In some embodiments, the HTS cable further comprises a former, and the at least one HTS tape stack is in a groove of the former. In some embodiments, the former comprises copper.

[0007] In some embodiments, the plurality of gratings are fiber Bragg gratings.

[0008]

[0008] In some embodiments, the gratings of the multiple gratings are spaced from one another by a distance suitable to detect a quench within a time short enough that current in the HTS cable can be reduced before damage occurs to the HTS cable.

[0009]

[0009] Some embodiments are directed to a cable comprising a former having an opening extending along its length and configured to receive an HTS material, an HTS material disposed in at least a portion of the opening in the former, and an optical fiber disposed about the former and extending along the length of the former in close proximity to at least a portion of the HTS material, the optical fiber having a plurality of gratings spaced apart from one another along the length of the former.

[0010]

[0010] In some embodiments, the openings in the former are provided as channels extending along the length of the former in the outer surface of the former, and the HTS material is provided as an HTS tape laminate disposed in at least a portion of the channel.

[0011] In some embodiments, the cable further includes an electrical conductor disposed about at least a portion of the HTS tape stack. In some embodiments, the electrical conductor includes copper. In some embodiments, the electrical conductor is provided with at least one groove disposed therein, and the optical fiber is disposed within the at least one groove.

[0012]

[0012] In some embodiments, the opening in the former is a first opening of multiple openings in the former, each opening extending along the length of the former and configured to receive the HTS material, the HTS material is disposed in at least a portion of the multiple openings in the former, the optical fiber is a first opening of multiple optical fibers disposed around the former and extending along the length of the former in proximity to at least a portion of the HTS material, and each of the multiple optical fibers has multiple gratings spaced apart from one another along the length of the former.

[0013]

[0013] In some embodiments, the openings in the former are provided as channels extending along the length of the former in the outer surface of the former, and the HTS material is provided as an HTS tape laminate disposed in at least a portion of the channel.

[0014] In some embodiments, the cable further includes an electrical conductor disposed about at least a portion of the HTS tape stack. In some embodiments, the electrical conductor includes copper.

[0015] In some embodiments, the cable further includes at least one optical fiber groove in the conductor, at least one of the plurality of optical fibers being disposed in the optical fiber groove.

[0016] In some embodiments, the electrical conductor further includes at least one optical fiber groove, and the at least one optical fiber is disposed within the at least one optical fiber groove.

[0017] In some embodiments, the electrical conductor is provided having a plurality of optical fiber grooves, and at least one optical fiber is disposed in each of the plurality of optical fiber grooves.

[0018] In some embodiments, the cable further includes an adhesive in the plurality of optical fiber grooves to secure the optical fibers.

[0019] In some embodiments, the plurality of gratings are fiber Bragg gratings.

[0020]

[0020] In some embodiments, the gratings are spaced apart a distance suitable to detect a quench within a time short enough that the current in the cable can be reduced before damage occurs to the cable.

[0021] In some embodiments, the cable is used in at least one of a fusion energy system, a magnetic resonance imaging system, a nuclear magnetic resonance system, a motor, a power transmission system, or a particle accelerator.

[0022]

[0022] Some embodiments are directed to a cable comprising an HTS material extending along a length of the cable and a plurality of optical fibers extending along the length of the cable, at least some of the optical fibers being proximate to the HTS material and at least some of the optical fibers having a plurality of gratings spaced apart from one another along their lengths.

[0023] In some embodiments, the cable further includes an electrical conductor disposed thereon, and the plurality of optical fibers are embedded in the electrical conductor. In some embodiments, the electrical conductor is provided with a plurality of grooves, and each of the plurality of optical fibers is disposed in a respective one of the grooves.

[0024] In some embodiments, the cable is used in at least one of a fusion energy system, a magnetic resonance imaging system, a nuclear magnetic resonance system, a motor, a power transmission system, or a particle accelerator.

[0025]

[0025] In some embodiments, the gratings are spaced apart a distance suitable to detect a quench within a time short enough that the current in the cable can be reduced before damage occurs to the cable.

[0026] In some embodiments, the HTS material includes at least one HTS tape stack.

[0027] In some embodiments, multiple gratings in multiple optical fibers are spaced apart from one another along the length of the cable to detect quenches in the HTS material.

[0028] In some embodiments, the plurality of gratings are fiber Bragg gratings.

[0029]

[0029] Some embodiments are directed to a cable comprising a plurality of HTS components, a plurality of conductive segments extending along the cable, each of the plurality of conductive segments including one of the plurality of HTS components, an electrically insulating material disposed between adjacent ones of the plurality of conductive segments and electrically insulating the plurality of conductive segments from one another, and at least one optical fiber extending along the length of the cable, the at least one optical fiber having a plurality of gratings spaced apart from one another along the length of the at least one optical fiber for detecting quench events in the cable.

[0030] In some embodiments, at least one optical fiber is disposed in one of the plurality of conductive segments.

[0031] In some embodiments, at least one optical fiber is disposed in two or more of the plurality of conductive segments.

[0032] In some embodiments, at least one optical fiber is disposed in each of the plurality of conductive segments.

[0033] In some embodiments, the at least one optical fiber includes a plurality of optical fibers disposed in one of the plurality of conductive segments.

[0034] In some embodiments, the at least one optical fiber includes a plurality of one optical fibers, and two or more of the plurality of conductive segments include at least two optical fibers.

[0035] In some embodiments, the at least one optical fiber includes a plurality of optical fibers, the plurality of optical fibers being disposed in each of the plurality of conductive segments.

[0036] In some embodiments, the cable further includes a conductor disposed over the plurality of conductive segments, and the at least one optical fiber is embedded in the conductor.

[0037]

[0037] In some embodiments, the at least one optical fiber corresponds to a plurality of optical fibers, and the cable is provided having a similar plurality of grooves, each of the plurality of optical fibers being positioned in a respective one of the plurality of grooves.

[0038] In some embodiments, the cable is used in at least one of a fusion energy system, a magnetic resonance imaging system, a nuclear magnetic resonance system, a motor, a power transmission system, and / or a particle accelerator.

[0039] Some embodiments are directed to a quench detection system for an HTS cable having at least one HTS tape stack extending along a length of the HTS cable, the quench detection system comprising at least one optical fiber extending along the HTS cable, the at least one optical fiber having a plurality of gratings spaced apart from one another along a length of the HTS cable for detecting a quench of the at least one HTS tape stack, a light source configured to illuminate the at least one optical fiber, a photodetector configured to detect light from the optical fiber, and circuitry configured to sense a temperature at one or more of the plurality of gratings using the light detected by the photodetector.

[0040]

[0040] Some embodiments are directed to a quench detection system for a high temperature superconductor (HTS) cable having at least one HTS tape stack extending along the length of the HTS cable, the quench detection system comprising at least one optical fiber extending along the HTS cable, the at least one optical fiber having a plurality of gratings spaced apart from one another along the length of the at least one optical fiber, a light source configured to illuminate the at least one optical fiber, a photodetector configured to detect light from the at least one optical fiber, and circuitry configured to sense temperature at one or more of the plurality of gratings using the light detected by the photodetector.

[0041] In some embodiments, the quench detection system is used in at least one of a fusion energy system, a magnetic resonance imaging system, a nuclear magnetic resonance system, a motor, a power transmission system, or a particle accelerator.

[0042]

[0042] Various aspects and embodiments are described with reference to the following drawings. It should be appreciated that the drawings are not necessarily drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various drawings is represented by the same numeral. For clarity, not every component is labeled in every drawing. [Brief description of the drawings]

[0043] [Figure 1] FIG. 1 is a schematic diagram of a system for detecting quench phenomena in a superconducting material according to some embodiments described herein. [Figure 2A]

[0044] FIG. 2A is a schematic diagram of a fiber Bragg grating (FBG) in an optical fiber according to some embodiments described herein. [Figure 2B]

[0045] FIG. 2B is a plot showing the shift in wavelength of light reflected from an FBG as a function of temperature according to certain embodiments described herein. [Figure 3A]

[0046] FIG. 3A is a schematic diagram of an optical fiber having multiple FBGs according to some embodiments described herein. [Figure 3B]

[0047] FIG. 3B is a plot showing a resolved reflectance spectrum from an optical fiber having multiple FBGs according to certain embodiments described herein. [Figure 3C]

[0048] FIG. 3C is a plot showing a combined reflectance spectrum from an optical fiber having multiple FBGs according to certain embodiments described herein. [Figure 4A]

[0049] FIG. 4A is a schematic diagram of a high temperature superconducting component experiencing a quench, including an optical fiber including a ULFBG, according to some embodiments described herein. [Figure 4B]

[0050] FIG. 4B illustrates incident and reflected spectra from FBGs located at different locations relative to the location of the quench in the high temperature superconducting component of FIG. 3A according to some embodiments described herein. [Figure 5A]

[0051] FIG. 5A is a diagram of a high temperature superconductor (HTS) cable according to some embodiments described herein. [Figure 5B] FIG. 5B is a diagram of a high temperature superconductor (HTS) cable according to some embodiments described herein. [Figure 6]

[0052] FIG. 2 is a perspective view of an HTS tape stack according to some embodiments described herein. [Figure 7]

[0053] FIG. 7A is a cross-sectional view of an HTS cable including an optical fiber for quench detection according to some embodiments described herein, and FIG. 7B is an enlarged view of the optical fiber of FIG. 5C according to some embodiments described herein. [Figure 8]

[0055] FIG. 11 is a plot showing FBG and ULFBG responses and voltage response to heating that induces a quench, according to certain embodiments described herein. [Figure 9]

[0056] FIG. 1 is a schematic diagram of an exemplary computing device in accordance with certain embodiments described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044]

[0057] Described herein are techniques for optically detecting quench events in superconductors. These techniques include using fiber optic thermometry to detect temperature changes in the superconductor indicative of quench events. The superconductor may be a high temperature superconductor (HTS) cable including an HTS material and one or more optical fibers extending along the length of the HTS cable. The optical fiber may include multiple Bragg gratings disposed along the length of the optical fiber. A light source may illuminate the optical fiber, and a photodetector may detect reflected or transmitted light from the optical fiber. Based on the spectrum of the detected light, a change in temperature at one or more of the Bragg gratings may be determined.

[0045]

[0058] A superconductor is a material that has no electrical resistance to electric current (is "superconducting") below a critical temperature. Superconductors include low temperature superconductors (LTS), which usually have a critical temperature below 30 K and are cooled with liquid helium, and high temperature superconductors (HTS), which can have critical temperatures above 77 K and are cooled with liquid nitrogen. Both LTS and HTS materials have found applications in nuclear fusion energy, high efficiency motors, high efficiency power transmission, magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR), and high field particle accelerators.

[0046]

[0059] To maintain the superconducting state, a superconducting material must maintain its temperature below its critical temperature. However, localized energy dissipation (e.g., due to the flow of electrical current within the superconductor) can cause localized heating, which, if uncontrolled or undetected, can lead to a thermal runaway event that transitions the entire superconductor from the superconducting regime to the normal resistive regime ("quenches"). Quench events can not only lead to downtime of the superconducting device, but can also lead to damage to the superconducting device.

[0047]

[0060] To mitigate the risk of quenching, quench detection and protection systems are used to rapidly detect the quench event and prevent or mitigate damage by removing all of the current and stored energy from the superconductor. Conventional quench detection systems typically rely on the detection of localized voltage rises within the superconductor. However, such voltage-based quench detection systems are subject to noise due to electromagnetic induction, which can result in false detections and unnecessary dumping of stored energy from the superconductor, thereby increasing device downtime and / or the risk of damaging the device. Voltage-based quench detection systems are particularly challenging in environments that experience frequent electromagnetic interference due to their electromagnetic sensitivity. One example of such an environment is the Tokamak fusion environment, where surrounding magnets and plasma frequently produce large voltage signals that can interfere with voltage-based quench detection systems. In addition, voltage-based quench detection systems require multiple voltage taps that pass through high-voltage insulators to contact the superconductor. Therefore, each voltage tap introduces a break in the electrical insulation of the superconductor, increasing the risk of harmful electrical phenomena (e.g., arcing, short circuits).

[0048]

[0061] The inventors recognize and appreciate that optical systems are less susceptible to electromagnetic interference and can be used to develop more robust and accurate optical-based quench detection systems. Such optical-based quench detection systems can use fiber optic temperature measurements to measure the temperature and strain response of an optical fiber to detect a quench event by embedding a fiber optic cable in or adjacent to a superconductor. The optical fiber used in such optical-based quench detection systems can include multiple Bragg gratings (e.g., fiber Bragg gratings (FBGs), ultra-long fiber Bragg gratings (ULFBGs)), which are configured to reflect a portion of any light incident on the Bragg gratings. The spectrum of the reflected light can indicate the change in temperature and / or strain experienced by the Bragg gratings, such that a quench event can be detected by analyzing the spectrum of the reflected light.

[0049]

[0062] Accordingly, the inventors have developed a cable including a superconducting material and at least one optical fiber. In some embodiments, the superconducting material includes an HTS material extending along the length of the cable. In some embodiments, the HTS material is disposed in at least one HTS tape stack extending along the length of the cable. The HTS tape stack can include segments of HTS material and an electrically insulating material disposed between adjacent HTS segments to electrically insulate the HTS segments from one another.

[0050]

[0063] In some embodiments, a cable can include a former having an opening extending along the length of the cable. The HTS material can be disposed in at least a portion of the opening in the former. For example, an HTS tape laminate as described herein can be disposed in at least a portion of the opening in the former.

[0051]

[0064] In some embodiments, the cable can further include one or more optical fibers extending along the length of the cable. The optical fiber can include a plurality of gratings spaced apart from one another along the length of the cable. The optical fiber can be configured to detect a quench of the superconducting material in the cable. In some embodiments, the optical fiber can be positioned in proximity to the HTS material. In some embodiments, the optical fiber can be positioned around the former.

[0052]

[0065] The inventors have further developed a quench detection system for detecting quench events in a superconducting material. In some embodiments, the superconducting material is an HTS cable including at least one HTS tape stack extending along the length of the HTS cable. In some embodiments, the quench detection system includes at least one optical fiber extending along the length of the superconducting material, the at least one optical fiber including gratings (e.g., FBG, ULFBG) spaced apart from one another along the length of the superconductor.

[0053]

[0066] In some embodiments, the quench detection system further includes a light source configured to illuminate the optical fiber, a photodetector configured to detect light from the optical fiber, and circuitry configured to sense temperature at one or more of the gratings of the optical fiber using the light detected by the photodetector. In some embodiments, the light source, the photodetector, and / or the circuitry may be combined into a single device (e.g., disposed within a single housing).

[0054]

[0067] The following is a more detailed description of various concepts related to techniques for quench detection and embodiments thereof. It should be appreciated that the various aspects described herein can be implemented in any of numerous ways. Examples of specific implementations are provided herein for illustrative purposes only. In addition, the various aspects described in the following embodiments can be used alone or in any combination, and are not limited to the combinations expressly described herein.

[0055]

[0068] FIG. 1 is a schematic diagram of a system 100 for detecting a quench event in a superconducting material according to some embodiments described herein. In the illustrative example of FIG. 1, the system 100 includes a superconductor 110, an optical fiber 120, a light source 130, a photodetector 140, a circuit 150, a network 160, and a computing system 170. It should be appreciated that the system 100 is illustrative and the quench detection system may have one or more other components of any suitable type in addition to or instead of the components shown in FIG. 1. For example, there may be additional (e.g., two or more) computing systems in the quench detection system. As another example, in some embodiments, the light source 130, the photodetector 140, and / or the circuit 150 may be combined into a single device (e.g., disposed in a single housing).

[0056]

[0069] In some embodiments, the superconductor 110 can be any suitable superconducting material. For example, the superconductor 110 can include LTS and / or HTS materials. In some embodiments, the superconductor 110 can be arranged to form superconducting electromagnets and / or power lines, such as those used in motors, power transmission, MRI, NMR, particle accelerators, and / or fusion energy systems. In some embodiments, the superconductor 110 can include one or more HTS tape stacks, as described in more detail herein with respect to Figures 5A and 5B.

[0057]

[0070] In some embodiments, the optical fiber 120 may be in thermal contact with the superconductor 110. For example, the optical fiber 120 may be disposed proximate to the superconductor 110 and / or embedded within the superconductor 110. It should be appreciated that while the example of FIG. 1 shows a single optical fiber 120, aspects of the technology described herein are not limited in this respect. In some embodiments, there may be multiple optical fibers. For example, the number of optical fibers may be in the range of 2 to 50, 2 to 25, 2 to 10, or 2 to 7, or any range within these ranges.

[0058]

[0071] In some embodiments, the optical fiber 120 may include multiple gratings 122 arranged along the length of the optical fiber 120. The gratings may be diffraction gratings configured to reflect certain wavelengths of light and transmit other wavelengths of light. For example, the gratings 122 may be fiber Bragg gratings (FBGs) or ultra-long fiber Bragg gratings (ULFBGs). While the diagram of FIG. 1 shows four equally spaced gratings 122, it should be appreciated that there may be more than four gratings 122, which may be equally spaced or non-uniformly spaced, as aspects of the technology described herein are not limited with respect to the number of gratings 122 or their spacing. In some embodiments, the gratings 122 may be spaced apart by one or more distances suitable for detecting a quench event in a time short enough to remove stored energy in the superconductor 110 before damaging the superconductor 110 or other components of the device housing the superconductor 110.

[0059]

[0072] An illustrative example of an FBG is shown in Figure 2A. An optical fiber contains a Bragg grating, which is a periodic modulation of the refractive index of the optical fiber core over a length of the optical fiber. When broadband light is illuminated onto the Bragg grating, the grating selectively modulates a specific wavelength component λ B The reflected Bragg wavelength is given by λ B = 2Λn eff

[0060] where n eff is the effective refractive index of the core and Λ is the grating period in nanometers. FBGs are sensitive to both temperature and strain, and changes in these parameters affect both the effective refractive index and the grating period, resulting in a shift in the Bragg wavelength.

[0061]

[0073] 2B is a plot showing the shift in wavelength of light reflected from an FBG as a function of temperature according to some embodiments described herein. Curve 202 is the spectrum of reflected light from an optical fiber with an FBG at a temperature of about 10 K, and curve 214 is the spectrum of reflected light from the optical fiber at a temperature of about 273 K. Curves 204-212 are the spectra of reflected light of a single FBG as the temperature increases between the temperatures of curves 202 and 214. As can be seen from FIG. 2B, the peak wavelength reflected by the FBG of the optical fiber shifts with temperature from a longer value, as shown by curve 214, to a shorter value, as shown by curve 202.

[0062]

[0074] In some embodiments, multiple FBGs, or ULFBGs, may be disposed within the optical fiber 120. For example, the optical fiber 120 may include a ULFBG that includes a series of 9 millimeter long FBGs spaced with 1 mm gaps between the gratings such that the multiple FBGs act as one long FBG. Such a ULFBG may be used to monitor temperature changes in optical fibers many meters long.

[0063]

[0075] The reflection spectrum of a single FBG shows a single peak, but when combined into one ULFBG, the reflection spectrum may show more complex behavior. A simple example of an optical fiber containing a ULFBG with multiple FBGs is shown in Figure 3A. Part of the light incident on FBG1 is reflected and has a specific wavelength λ1. The remaining light is transmitted through FBG1 to FBG2. In FBG2, the temperature is increased so that FBG2 reflects light of a different specific wavelength λ2 ≠ λ1 and transmits the remaining light to FBG3. FBG3 is cooler than FBG2 and therefore reflects light of a third wavelength λ3 ≠ λ2 ≠ λ1. As a result, several wavelengths are reflected, possibly with different amplitudes. Thus, a change in temperature anywhere along the optical fiber produces at least two effects: (1) a change in the dominant reflection wavelength, which is a property of a conventional single FBG, and (2) a change in the shape of the entire reflection spectrum.

[0064]

[0076] While individual reflections from a ULFBG may exhibit well-defined peaks similar to conventional single FBGs, as shown diagrammatically in Figure 3B, the sum of these reflections may result in a combined, less well-defined spectrum, as shown in Figure 3C. This occurs because the reflectance spectrum of a ULFBG responds to all of the simultaneous temperature and strain changes along the length of the optical fiber, resulting in rapid detection of temperature fluctuations regardless of the location of the heat source along the optical fiber.

[0065]

[0077] Another example of the thermal response of an optical fiber with a ULFBG is shown in Figures 4A and 4B. Figure 4A is a schematic diagram of a superconductor 410 and an optical fiber 420 containing a ULFBG 422. The superconductor 410 is divided into sections I, II, III, and IV, with section III containing a hot spot 412 that increases the temperature of the superconductor 410. The thermal Q diss dissipates from the hot spot 412 into both sections II and IV.

[0066]

[0078] FIG. 4B shows the incident spectrum (top) and reflected spectrum (bottom) at each of sections I to IV of the optical fiber 420 of FIG. 4A. The original spectrum of the input light and the total reflected spectrum from the optical fiber 420 are shown on the left. As shown in FIG. 4B, the ULFBG in section I reflects light with wavelength λ1 and prevents it from transmitting to section II. Because section II is at approximately the same temperature as section I, no light is reflected from the ULFBG in section II and all light is transmitted to section III. Because section III contains a hot spot 412, it has a different effective refractive index, causing the ULFBG in section III to reflect light with wavelength λ2≠λ1 and prevents light with wavelength λ2 from transmitting to section IV. And again, because section IV is at approximately the same temperature as sections I and II, no light is reflected by the ULFBG in section IV. Thus, the reflected spectrum from the optical fiber includes light with wavelengths λ1 and λ2.

[0067]

[0079] Returning to FIG. 1, as shown in FIG. 1, the system 100 includes a light source 130 and a photodetector 140 optically coupled to the optical fiber 120. In some embodiments, the light source 130 may be a laser light source, a light emitting diode (LED) light source, or any other suitable type of light source. The light source 130 may be configured to generate an input light 132 that is provided to the optical fiber 120. For example, the light source 130 may be configured to generate an input light 132 having multiple wavelengths (e.g., broadband spectrum light). In some embodiments, the input light 132 may have multiple wavelengths near or close to the center of the Bragg wavelength of the optical fiber 120 at the operating temperature of the superconductor 110. In some embodiments, the light source 130 may be configured to generate a coherent input light 132.

[0068]

[0080] In some embodiments, the photodetector 140 may be configured to detect the received light 142 reflected or transmitted by the grating 122 of the optical fiber 120. For example, the photodetector 140 may be configured to detect a spectrum of the received light 142 and / or determine a peak wavelength of the received light 142. In some embodiments, the photodetector 140 may be an optical spectrum analyzer (OSA), an integrating sphere detector, a wavemeter, or any other suitable photodetector.

[0069]

[0081] In some embodiments, the photodetector 140 may be coupled to a circuit 150. The circuit 150 may be configured to determine a temperature of the superconductor 110 based on an output of the photodetector 140. For example, the circuit 150 may be configured to receive an optical spectrum from the photodetector 140, determine a peak wavelength of the received optical spectrum, and determine a temperature corresponding to the peak wavelength. The circuit 150 may be implemented using any suitable electronic circuitry, including, but not limited to, an FPGA, an ASIC, a microcontroller, and / or other microprocessing technology.

[0070]

[0082] In some embodiments, system 100 includes a computing system 170 communicatively coupled to circuit 150. Computing system 170 may be any suitable electronic device configured to receive information from circuit 150 and / or process information received from circuit 150. In some embodiments, computing system 170 may be a fixed electronic device, such as a desktop computer, a rack-mounted computer, or any other suitable fixed electronic device. Alternatively, computing system 170 may be a portable device, such as a laptop computer, a smartphone, a tablet computer, or any other portable device that may be configured to receive information from circuit 150 and / or process information received from circuit 150.

[0071]

[0083] In some embodiments, the circuit 150 and the computing system 170 may be communicatively connected by an optional network 160. The network 160 may be or may include one or more local and / or wide area, wired and / or wireless networks, including local or wide area enterprise networks and / or the Internet. Thus, the network 160 may be, for example, a hardwired network (e.g., a local area network within one facility), a wireless network (e.g., connected via Wi-Fi and / or cellular networks), a cloud-based computing network, or any combination thereof. For example, in some embodiments, the superconductor 110, the optical fiber 120, the light source 130, the photodetector 140, and the circuit 150 may be located in the same facility and connected to each other directly or via the network 160, while the computing system 170 may be located in a remote facility and connected to the circuit 150 via the network 160. However, it should be appreciated that in some embodiments, computing system 170 may be connected directly to circuitry 150 rather than being connected by network 160, as the aspects of the technology described herein are not limited in this respect.

[0072]

[0084] In some embodiments, computing system 170 may include a quench detection facility 172. Quench detection facility 172 may be configured to analyze data obtained by photodetector 140 and processed by circuit 150. Quench detection facility 172 may be configured, for example, to analyze temperature data output by circuit 150 to determine whether a quench event is imminent and / or currently occurring in superconductor 110. For example, quench detection facility 172 may be configured to determine whether the temperature data output by circuit 150 is greater than a threshold temperature value and / or may be configured to fit a function to the temperature data over time to determine whether a thermal runaway event is imminent and / or currently occurring.

[0073]

[0085] In some embodiments, computing system 170 may further include a quench mitigation facility 174. In response to a determination of a quench event by quench detection facility 172, quench mitigation facility 174 may be configured to generate instructions to cause energy to be removed from superconductor 110. For example, quench mitigation facility 174 may be configured to generate instructions to cause current flow through superconductor 110 to be removed (e.g., to shunt or otherwise short superconductor 110) to remove energy stored in superconductor 110.

[0074]

[0086] Quench detection facility 172 and / or quench mitigation facility 174 may be implemented as hardware, software, or any suitable combination of hardware and software, as aspects of the technology described herein are not limited in this respect. As shown in FIG. 1, quench detection facility 172 and quench mitigation facility 174 may be implemented by computing system 170, such as by being implemented in software (e.g., executable instructions) executed by one or more processors of computing system 170. However, in other embodiments, quench detection facility 172 and / or quench mitigation facility 174 may additionally or alternatively be implemented in one or more other elements of system 100. For example, quench detection facility 172 and / or quench mitigation facility 174 may be implemented in circuit 150. In other embodiments, the quench detection facility 172 and / or the quench mitigation facility 174 may be implemented in or with another device, such as a computing device that is located remotely from the system 100 and receives data via the network 160.

[0075]

[0087] In the example of FIG. 1, the superconductor 110 may correspond to an HTS cable. As can be seen in FIGS. 5A and 5B, the HTS cable 500 includes a former 516 having an HTS tape stack 518 disposed in a channel provided on the outer surface of the former 516 and extending along its length. The HTS tape stack 518 is held in its respective channel using solder 519. An inner jacket 520 (e.g., a copper jacket) may be disposed around the former 516 and the HTS tape stack 518, and a plating 522 (e.g., a silver plating) may be disposed on the inner jacket 520. The entire surface of the inner jacket 520 may be plated, but in some embodiments, only a portion of the inner jacket 520 may be plated. Thus, as shown in FIG. 5A, only about half of the surface of the inner jacket 520 has the plating 522 disposed thereon. An outer jacket 524 (e.g., a steel or stainless steel jacket) is disposed around the inner jacket 520.

[0076]

[0088] In this exemplary embodiment, cable 500 has multiple channels in a conductive (e.g., copper) former surrounded by one or more jackets. Each channel has an HTS tape stack and is filled with a metal (e.g., solder). Cable 500 also includes optional cooling channels 529.

[0077]

[0089] 5B, an exemplary channel width is W1, the former 516 has a diameter D1, the inner jacket 520 has a diameter D2, and the outer jacket 524 has a diameter D3. In some embodiments, the inner jacket 520 may be made of copper and the outer jacket 524 may be made of stainless steel. However, this is merely an example and other suitable materials for the jackets and formers may be used.

[0078]

[0090] 6, an exemplary HTS tape stack 600 includes a first layer 602 corresponding to a first stabilization layer (here, the stabilization layer 602 includes copper). An overlay layer 604 (here, the overlay 602 includes silver) is disposed on the layer 602. A substrate 606 is disposed on the layer 604. In this example, the substrate 606 may be prepared from any suitable material and is provided with an electropolished surface. A buffer stack 608 is disposed on the substrate 606. In this example, the buffer stack 608 may include one or more materials disposed using magnetron sputtering techniques. An HTS material 610 is disposed on the buffer stack 608. In this exemplary embodiment, the HTS material may include a rare earth barium copper oxide superconductor (REBCO), such as yttrium barium copper oxide (YBCO). Disposed on the HTS material layer 610 is an overlayer 612, and disposed on the overlay 612 is a second stabilization layer 614. Overlayer 612 and stabilizing layer 614 may be made of the same materials as overlay 604 and stabilizing layer 602, respectively, as described above.

[0079]

[0091] 7A and 7B, an HTS cable 700 can include one or more grooves 710 configured to receive an optical fiber 712. As shown in Figures 7A and 7B, the grooves 710 can be disposed on an outer surface of the inner jacket 520 of the HTS cable 700. In some embodiments, the grooves 710 can be disposed on other surfaces of the HTS cable 700 (e.g., an inner surface of the inner jacket 520, an inner surface of the cooling channel 529).

[0080]

[0092] The grooves 710, in some embodiments, can extend along the length of the HTS cable 700. The grooves can be located on one side of the HTS cable 700, as shown in the example of Figure 7A. In some embodiments, the grooves 710 and optical fibers 712 can be located around a smaller or larger portion of the circumference of the cable 700, including the entire circumference.

[0081]

[0093] In some embodiments, the optical fiber 712 can be secured in the groove 710 using an adhesive. For example, the optical fiber 712 can be secured in the groove 710 using a thermally conductive adhesive (e.g., a silver adhesive) to ensure thermal bonding between the optical fiber 712, the former 516, and the HTS tape stack 518.

[0082]

[0094] The optical fiber 712 may be disposed anywhere within or near the HTS cable 700. In some embodiments, the optical fiber 712 may be disposed on a surface of the HTS cable 700 rather than being disposed within a groove (e.g., groove 710). For example, the optical fiber 712 may be adhered to any suitable surface of the HTS cable 700 (e.g., the exterior or interior surface of the inner jacket 520, the interior surface of the cooling channel 529) using an adhesive (e.g., a thermally conductive adhesive).

[0083]

[0095] Referring now to FIG. 8, data collected from an experiment comparing optical and voltage-based quench detection systems are shown. Curve 802 shows the application of a heat pulse to a superconductor by a heater. The vertical dashed lines indicate the start of the heat pulse application (left) and the end of the heat pulse application (right). Curve 804 shows the measured temperature at the site of the heat pulse application. Curves 806 and 808 show signals determined using an optical fiber with a ULFBG and an FBG, respectively, while curves 810 and 812 are electrical measurements taken at different nodes of the superconductor. As can be seen from FIG. 8, curves 806 and 808 show almost the same time response as the electrical measurement of curve 810, indicating that optical quench detection is a robust and accurate technique for detecting quenching events in superconducting materials.

[0084]

[0096] In some embodiments, the techniques described herein may be embodied in computer-executable instructions implemented in software, including application software, system software, firmware, middleware, embedded code, or any other suitable type of computer code. Such computer-executable instructions may be written using any of a number of suitable programming languages ​​and / or programming or scripting tools, and may also be compiled as executable machine code or intermediate code that runs on a framework or virtual machine.

[0085]

[0097] When the techniques described herein are embodied as computer-executable instructions, these computer-executable instructions can be implemented in any suitable manner, such as as multiple functional facilities, each of which performs one or more operations to complete the execution of an algorithm operating according to these techniques. A "functional facility" is a structural component of a computing system, however instantiated, that is integrated with one or more computers and, when executed by the one or more computers, causes the one or more computers to perform a particular operational role. A functional facility may be a part of a software element or may be an entire software element. For example, a functional facility may be implemented as a function of a process, or as a discrete process, or as any other suitable processing unit. When the techniques described herein are implemented as multiple functional facilities, each functional facility may be implemented in a unique manner and need not all be implemented in the same manner. In addition, these functional facilities may be executed in parallel and / or sequentially, as appropriate, and may pass information between each other using shared memory on the computer on which they are executing, using a message passing protocol, or in any other suitable manner.

[0086]

[0098] Generally, functional facilities include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically, the functionality of the functional facilities may be combined or distributed as desired in the systems in which they operate. In some implementations, one or more functional facilities that perform the techniques herein may together form a complete software package. These functional facilities may be adapted in alternative embodiments to interact with other unrelated functional facilities and / or processes to implement a software program application, e.g., as a software program application such as a fetal heart analysis facility.

[0087]

[0099] In the present specification, several exemplary functional facilities for accomplishing one or more tasks have been described. However, it should be appreciated that the described functional facilities and division of tasks are merely illustrative of the types of functional facilities that may implement the exemplary techniques described herein, and that the embodiments are not limited to being implemented with a particular number, division, or type of functional facilities. In some implementations, all functions may be implemented in a single functional facility. It should also be appreciated that in some implementations, some of the functional facilities described herein may be implemented together with others or separately from others (i.e., as a single unit or as separate units), or some of these functional facilities may not be implemented.

[0088]

[0100] Computer-executable instructions implementing the techniques described herein (whether implemented as one or more functional facilities or in any other manner) may, in some embodiments, be encoded on one or more computer-readable media to provide functionality to the media. Computer-readable media may include magnetic media such as hard disk drives, optical media such as compact disks (CDs) or digital versatile disks (DVDs), persistent or non-persistent solid-state memory (e.g., flash memory, magnetic RAM, etc.), or any other suitable storage media. Such computer-readable media may be implemented in any suitable manner, including as computer-readable storage medium 906 of FIG. 9 described below (i.e., as part of computing device 900) or as a standalone separate storage medium. As used herein, a "computer-readable medium" (also referred to as a "computer-readable storage medium") refers to a tangible storage medium. A tangible storage medium is non-transitory and has at least one physical, structural component. As used herein, in a "computer-readable medium," at least one physical, structural component has at least one physical property that can be altered in some way during the process of creating the medium in which information is embedded, recording information thereon, or any other process of encoding the medium with information. For example, the magnetization state of a portion of the physical structure of the computer-readable medium can be altered during the recording process.

[0089]

[0101] In some, but not all, implementations in which the techniques may be embodied as computer-executable instructions, these instructions may be executed on one or more suitable computing devices operating in any suitable computer system, including the example computer system of Figure 9, or one or more computing devices (or one or more processors of the one or more computing devices) may be programmed to execute the computer-executable instructions. A computing device or processor may be programmed to execute the instructions if the instructions are stored in a manner accessible to the computing device or processor, such as in a data store (e.g., an on-chip cache or instruction register, a computer-readable storage medium accessible via a bus, a computer-readable storage medium accessible via one or more networks and accessible by the device / processor, etc.). The functional facility containing these computer-executable instructions may be integrated with and direct the operation of a single general-purpose programmable digital computing device, a cooperative system of two or more general-purpose computing devices that share processing power and jointly perform the techniques described herein, a single computing device or a cooperative system of computing devices (either co-located or geographically distributed) dedicated to performing the techniques described herein, one or more field programmable gate arrays (FPGAs) for performing the techniques described herein, or any other suitable system.

[0090]

[0102] 9 illustrates one exemplary implementation of a computing device in the form of a computing device 900 that may be used in a system implementing the techniques described herein, although other implementations are possible. It should be appreciated that FIG. 9 is not intended to be a depiction or comprehensive depiction of the components necessary for a computing system to operate as a quench detection system and / or quench mitigation system in accordance with the principles described herein.

[0091]

[0103] The computing device 900 may include at least one processor 902, a network adapter 904, and a computer-readable storage medium 906. The computing device 900 may be, for example, a desktop or laptop personal computer, a personal digital assistant (PDA), a smart mobile phone, or any other suitable computing device. The network adapter 904 may be any suitable hardware and / or software that enables the computing device 900 to communicate wired and / or wirelessly with any other suitable computing devices over any suitable computing network. The computing network may include any suitable wired and / or wireless communication medium for exchanging data between two or more computers, including wireless access points, switches, routers, gateways, and / or other network equipment, as well as the Internet. The computer-readable medium 906 may be adapted to store data to be processed and / or instructions to be executed by the processor 902. The processor 902 enables the processing of data and the execution of instructions. The data and instructions may be stored in the computer-readable storage medium 906.

[0092]

[0104] The data and instructions stored in the computer-readable storage medium 906 may include computer-executable instructions implementing techniques that operate according to the principles described herein. In the example of Fig. 9, the computer-readable storage medium 906 stores computer-executable instructions implementing various facilities and storing various information, as described above. The computer-readable storage medium 906 may store a quench detection facility 908 configured to derive information indicative of a quench event from the optical fiber temperature measurement data and / or a quench mitigation facility 910 configured to cause stored energy to be removed from the superconducting material if a quench event is detected.

[0093]

[0105] Although not shown in FIG. 9, a computing device may further have one or more components and peripherals, including input and output devices. These devices may be used, among other things, to present a user interface. Examples of output devices that may be used to provide a user interface include a printer or display screen for visual presentation of output, and a speaker or other sound generating device for audible presentation of output. Examples of input devices that may be used for a user interface include a keyboard and a pointing device, such as a mouse, touchpad, digitizing tablet, etc. As another example, a computing device may receive input information via voice recognition or other audible format.

[0094]

[0106] Having thus described several aspects of at least one embodiment of the technology, it will be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art.

[0095]

[0107] Various aspects of the technology described herein may be used alone, in combination, or in various arrangements not specifically described in the embodiments described above, and thus are not limited in application to the details of the components and arrangements set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments.

[0096]

[0108] The use of ordinal numbers such as "first," "second," and "third" in the claims to modify claim elements does not, per se, imply priority, precedence, or ordering of one claim element relative to other claim elements, or the temporal order in which acts of a method are performed, but is merely used as a label to distinguish one claim element having a certain name from another element having the same name (but using an ordinal number) to distinguish among the claim elements.

[0097]

[0109] Also, the words and terms used herein are for purposes of description and should not be regarded as limiting. As used herein, the use of "including," "comprising," "having," "containing," "involving," and variations thereof, is meant to encompass the items listed thereafter and equivalents thereof, as well as additional items.

[0098]

[0110] The terms "approximately" and "about" can be used to mean, in some embodiments, within ±20% of a target value, in some embodiments, within ±10% of a target value, in some embodiments, within ±5% of a target value, and in some embodiments, within ±2% of a target value. The terms "approximately" and "about" can include the target value.

Claims

1. 1. A high temperature superconducting (HTS) cable, comprising: at least one HTS tape stack extending along the length of the HTS cable; at least one optical fiber extending along the HTS cable; 1. A high temperature superconducting (HTS) cable, wherein the at least one optical fiber has a plurality of gratings spaced apart from one another along the length of the HTS cable for detecting quenches of the at least one HTS tape stack.

2. 10. The HTS cable of claim 1, wherein the HTS cable comprises a jacket around the at least one HTS tape stack.

3. 3. The HTS cable of claim 2, wherein the jacket comprises copper.

4. 3. The HTS cable of claim 2, further comprising at least one groove in said jacket, said at least one optical fiber disposed within said at least one groove.

5. 5. The HTS cable of claim 4, wherein said at least one groove is in an outer surface of said jacket.

6. 5. The HTS cable of claim 4, further comprising an adhesive in said at least one groove, said adhesive securing said at least one optical fiber in said at least one groove.

7. 7. The HTS cable of claim 1, further comprising a former, wherein the at least one HTS tape stack is in a groove of the former.

8. 8. The HTS cable of claim 7, wherein the former comprises copper.

9. 7. The HTS cable of claim 1, wherein the plurality of gratings are fiber Bragg gratings.

10. 7. The HTS cable of claim 1, wherein the gratings of the plurality of gratings are spaced apart a distance suitable to detect a quench in a time short enough that current in the HTS cable can be reduced before damage occurs to the HTS cable.

11. An HTS cable as described in any one of claims 1 to 6, wherein the at least one optical fiber having the plurality of gratings is configured to generate a combined reflection spectrum in response to input light for detecting quenches.

12. The method of claim 1, further comprising: forming a former extending along the length of the HTS cable and having an opening; the opening in the former is provided as a channel extending along the length of the former in an outer surface of the former; 7. The cable of claim 1, wherein the at least one HTS tape stack comprises a high temperature superconducting (HTS) material and is disposed in at least a portion of the channel.

13. 13. The cable of claim 12, further comprising an electrical conductor disposed around at least a portion of the HTS tape stack.

14. The method of claim 1, further comprising: forming a former extending along the length of the HTS cable and having a plurality of openings; each opening of the plurality of openings extending along a length of the former and configured to receive high temperature superconducting (HTS) material; the HTS material is disposed in at least some of the openings in the former; 7. The cable of claim 1, wherein the at least one optical fiber is disposed about the former and extends along a length of the former proximate at least a portion of the HTS material, the at least one optical fiber having a plurality of gratings spaced apart from one another along the length of the former.

15. the opening in the former is provided as a channel extending along the length of the former in an outer surface of the former; 15. The cable of claim 14, wherein said at least one HTS tape stack comprises said HTS material and is disposed in at least a portion of said channel.

16. 7. The cable of any one of claims 1 to 6 for use in at least one of a fusion energy system, a magnetic resonance imaging system, a nuclear magnetic resonance system, a motor, a power transmission system, or a particle accelerator.

17. 1. A quench detection system for a high temperature superconductor (HTS) cable having at least one HTS tape stack extending along a length of the HTS cable, comprising: the quench detection system comprising: at least one optical fiber extending along the HTS cable, the at least one optical fiber having a plurality of gratings spaced apart from one another along the length of the at least one optical fiber; a light source configured to illuminate the at least one optical fiber; a photodetector configured to detect light from the at least one optical fiber; a circuit configured to sense temperature at one or more of the plurality of gratings using light detected by the photodetector; and A quench detection system comprising:

18. 20. The quench detection system of claim 17 for use in at least one of a fusion energy system, a magnetic resonance imaging system, a nuclear magnetic resonance system, a motor, a power transmission system, or a particle accelerator.

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