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NASA NTRS1996

YBCO High-Temperature Superconducting Filters on M-Plane Sapphire Substrates

Since the discovery of High Temperature Superconductors (HTS) in 1986, microwave circuits have been demonstrated using HTS films on various substrates. These HTS-based circuits have proven to operate with less power loss than their metallic film counterparts at 77 K. This translates into smaller and lighter microwave circuits for space communication systems such as multiplexer filter banks. High quality HTS films have conventionally been deposited on lanthanum aluminate (LaAlO3) substrates. However, LaAlO3 has a relative dielectric constant (epsilon(sub r)) of 24. With a epsilon(sub r) approx. 9.4-11.6, sapphire (Al2O3) would be a preferable substrate for the fabrication of HTS-based components since the lower dielectric constant would permit wider microstrip lines to be used in filter design, since the lower dielectric constant would permit wider microstrip lines to be used for a given characteristic impedance (Z(sub 0)), thus lowering the insertion losses and increasing the power handling capabilities of the devices. We report on the fabrication and characterization of YBa2Cu3O(7-delta) (YBCO) on M-plane sapphire bandpass filters at 4.0 GHz. For a YBCO 'hairpin' filter, a minimum insertion loss of 0.5 dB was measured at 77 K as compared with 1.4 dB for its gold counterpart. In an 'edge-coupled' configuration, the insertion loss went down from 0.9 dB for the gold film to 0.8 dB for the YBCO film at the same temperature.

Sabataitis, J. C.↗

NASA NTRS1982

Human Tissue Stimulator

Neurodyne Corporation Human Tissue Stimulator (HTS) is a totally implantable system used for treatment of chronic pain and involuntary motion disorders by electrical stimulation. It was developed by Pacesetter Systems, Inc. in cooperation with the Applied Physics Laboratory. HTS incorporates a nickel cadmium battery, telemetry and command systems technologies of the same type as those used in NASA's Small Astronomy Satellite-3 in microminiature proportions so that the implantable element is the size of a deck of cards. The stimulator includes a rechargeable battery, an antenna and electronics to receive and process commands and to report on its own condition via telemetry, a wireless process wherein instrument data is converted to electrical signals and sent to a receiver where signals are presented as usable information. The HTS is targeted to nerve centers or to particular areas of the brain to provide relief from intractable pain or arrest involuntary motion. The nickel cadmium battery can be recharged through the skin. The first two HTS units were implanted last year and have been successful. Extensive testing is required before HTS can be made available for general use.

Source record↗

NASA NTRS2001

A Cryogenic Magnetostrictive Actuator using a Persistent High Temperature Superconducting Magnet, Part 1: Concept and Design: Concept and Design - Part 1

Cryogenic magnetostrictive materials, such as rare earth zinc crystals, offer high strains and high forces with minimally applied magnetic fields, making the material ideally suited for deformable optics applications. For cryogenic temperature applications, such as Next Generation Space Telescope (NGST), the use of superconducting magnets offer the possibility of a persistent mode of operation, i.e., the magnetostrictive material will maintain a strain field without power. High temperature superconductors (HTS) are attractive options if the temperature of operation is higher than 10 degrees Kelvin (K) and below 77 K. However, HTS wires have constraints that limit the minimum radius of winding, and even if good wires can be produced, the technology for joining superconducting wires does not exist. In this paper, the design and capabilities of a rare earth zinc magnetostrictive actuator using bulk HTS is described. Bulk superconductors can be fabricated in the sizes required with excellent superconducting properties. Equivalent permanent magnets, made with this inexpensive material, are persistent, do not require a persistent switch as in HTS wires, and can be made very small. These devices are charged using a technique which is similar to the one used for charging permanent magnets, e.g., by driving them into saturation. A small normal conducting coil can be used for charging or discharging. Very fast charging and discharging of HTS tubes, as short as 100 microseconds, has been demonstrated. Because of the magnetic field capability of the superconductor material, a very small amount of superconducting magnet material is needed to actuate the rare earth zinc. In this paper, several designs of actuators using YBCO and BSCCO 2212 superconducting materials are presented. Designs that include magnetic shielding to prevent interaction between adjacent actuators will also be described. Preliminary experimental results and comparison with theory for BSSCO 2212 with a magnetostrictive element will be discussed.

Horner, Garnett C.↗

NASA NTRS2005

High-Power, High-Temperature Superconductor Technology Development

Since the first discovery of high-temperature superconductors (HTS) 10 years ago, the most promising areas for their applications in microwave systems have been as passive components for communication systems. Soon after the discovery, experiments showed that passive microwave circuits made from HTS material exceeded the performance of conventional devices for low-power applications and could be 10 times as small or smaller. However, for superconducting microwave components, high-power microwave applications have remained elusive until now. In 1996, DuPont and Com Dev Ltd. developed high-power superconducting materials and components for communication applications under a NASA Lewis Research Center cooperative agreement, NCC3-344 "High Power High Temperature Superconductor (HTS) Technology Development." The agreement was cost shared between the Defense Advanced Research Projects Agency's (DARPA) Technology Reinvestment Program Office and the two industrial partners. It has the following objectives: 1) Material development and characterization for high-power HTS applications; 2) Development and validation of generic high-power microwave components; 3) Development of a proof-of-concept model for a high-power six-channel HTS output multiplexer.

Bhasin, Kul B.↗

NASA NTRSDate not supplied

Helmholtz Motor: A Novel Electric Machine That Enables High Temperature Superconducting Armatures

Electrified aircraft are being developed to increase the efficiency and reduce the cost of operating subsonic transport aircraft. Achieving a substantial impact necessitates focusing on single- and twin-aisle aircraft which use propulsion systems with >20 MW ratings. For these aircraft, multi-MW superconducting electric machines are being developed due to their high specific power and high efficiency. Cryogenic electric machines are a promising technology for multi megawatt electric aircraft drivetrains. Second generation high temperature superconductors (HTS) are the ideal conductor for the field winding (typically the rotor) of superconducting machines, and they have attractive features for the armature winding (typically the stator) of these machines. However, their use in armature windings has been severely limited due to excessive AC losses in conventional electric machines. This presentation will present the working principle, design, and a performance trade study of a novel electric machine – termed a Helmholtz machine – that enables HTS armatures by significantly reducing AC losses. The working principle of the patent pending Helmholtz motor is to optimize the rotor-produced magnetic field (i.e., the field winding) so that it produces a magnetic field almost purely in the plane of the HTS. This is accomplished using 2 rotors that contain a set of matched Helmholtz coil pairs (or matched permanent magnet Halbach arrays). The armature (stator) HTS coils are positioned between the rotors and oriented to minimize the out of plane magnetic field. The armature HTS coils are also designed to minimize the out of plane component of their self field. The presentation will include the lessons learned in the sizing and design of this motor, including equations for how to match the magnet arrays. A performance trade study will be presented for a partially superconducting, radial flux version of the motor. The trade study involved an optimization of a motor design code based on analytical calculations (electromagnetic, AC loss, thermofluid, mechanical, and motor sizing) that determine the motor’s total efficiency and total specific power. The design code will be described in the presentation, with an emphasis on the calculation of magnetic fields, AC loss, and temperature distribution.

Superconducting electric machines↗

NASA NTRS1990

Microwave characterization of high-temperature superconducting thin films using stripline resonators

A method was derived for the extraction of the surface resistivity (Rs) of high-Tc superconducting (HTS) thin films at microwave frequencies, using a stripline resonator circuit. Surface resistivity values were calculated by measuring the difference in Q-values of a stripline resonator configuration when an HTS thin film was substituted for one of the metallic ground planes. Cryogenic tests were completed for several stripline resonator structures, yielding accurate predictions of the HTS thin-film performance at frequencies between 3 and 26 GHz (in harmonics of approximately 3 GHz). These results were then used to illustrate the dependence of HTS surface resistivity on frequency and temperature in the microwave frequency band.

Macdonald, Alan D.↗

NASA NTRS1990

Emerging applications of high temperature superconductors for space communications

Proposed space missions require longevity of communications system components, high input power levels, and high speed digital logic devices. The complexity of these missions calls for a high data bandwidth capacity. Incorporation of high temperature superconducting (HTS) thin films into some of these communications system components may provide a means of meeting these requirements. Space applications of superconducting technology has previously been limited by the requirement of cooling to near liquid helium temperatures. Development of HTS materials with transition temperatures above 77 K along with the natural cooling ability of space suggest that space applications may lead the way in the applications of high temperature superconductivity. In order for HTS materials to be incorporated into microwave and millimeter wave devices, the material properties such as electrical conductivity, current density, surface resistivity and others as a function of temperature and frequency must be well characterized and understood. The millimeter wave conductivity and surface resistivity were well characterized, and at 77 K are better than copper. Basic microwave circuits such as ring resonators were used to determine transmission line losses. Higher Q values than those of gold resonator circuits were observed below the transition temperature. Several key HTS circuits including filters, oscillators, phase shifters and phased array antenna feeds are feasible in the near future. For technology to improve further, good quality, large area films must be reproducibly grown on low dielectric constant, low loss microwave substrates.

Heinen, Vernon O.↗

NASA NTRS1991

High temperature superconductor analog electronics for millimeter-wavelength communications

The performance of high temperature superconductor (HTS) passive microwave circuits up to X-band was encouraging when compared to their metallic counterparts. The extremely low surface resistance of HTS films up to about 10 GHz enables a reduction in loss by as much as 100 times compared to copper when both materials are kept at about 77 K. However, a superconductor's surface resistance varies in proportion to the frequency squared. Consequently, the potential benefit of HTS materials to millimeter-wave communications requires careful analysis. A simple ring resonator was used to evaluate microstrip losses at Ka-band. Additional promising components were investigated such as antennas and phase shifters. Prospects for HTS to favorable impact millimeter-wave communications systems are discussed.

Romanofsky, R. R.↗

NASA NTRS1991

High temperature superconductor analog electronics for millimeter-wavelength communications

Romanofsky, R. R.↗

NASA NTRS1992

Glass precursor approach to high-temperature superconductors

The available studies on the synthesis of high T sub c superconductors (HTS) via the glass precursor approach were reviewed. Melts of the Bi-Sr-Ca-Cu-O system as well as those doped with oxides of some other elements (Pb, Al, V, Te, Nb, etc.) could be quenched into glasses which, on further heat treatments under appropriate conditions, crystallized into the superconducting phase(s). The nature of the HTS phase(s) formed depends on the annealing temperature, time, atmosphere, and the cooling rate and also on the glass composition. Long term annealing was needed to obtain a large fraction of the 110 K phase. The high T sub c phase did not crystallize out directly from the glass matrix, but was preceded by the precipitation of other phases. The 110 K HTS was produced at high temperatures by reaction between the phases formed at lower temperatures resulting in multiphase material. The presence of a glass former such as B2O3 was necessary for the Y-Ba-Cu-O melt to form a glass on fast cooling. A discontinuous YBa2Cu3O(7-delta) HTS phase crystallized out on heat treatment of this glass. Attempts to prepare Tl-Ba-Ca-Cu-O system in the glassy state were not successful.

Bansal, Narottam P.↗

NASA NTRS1993

An experimental investigation of high temperature superconducting microstrip antennas at K- and Ka-band frequencies

The recent discovery of high temperature superconductors (HTS) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS results in narrow bandwidths and high patch edge impedances of such antennas. To investigate the performance of superconducting microstrip antennas, three antenna architectures at K and Ka-band frequencies are examined. Superconducting microstrip antennas that are directly coupled, gap coupled, and electromagnetically coupled to a microstrip transmission line were designed and fabricated on lanthanum aluminate substrates using YBa2Cu3O7 superconducting thin films. For each architecture, a single patch antenna and a four element array were fabricated. Measurements from these antennas, including input impedance, bandwidth, patterns, efficiency, and gain are presented. The measured results show usable antennas can be constructed using any of the architectures. All architectures show excellent gain characteristics, with less than 2 dB of total loss in the four element arrays. Although the direct and gap coupled antennas are the simplest antennas to design and fabricate, they suffer from narrow bandwidths. The electromagnetically coupled antenna, on the other hand, allows the flexibility of using a low permittivity substrate for the patch radiator, while using HTS for the feed network, thus increasing the bandwidth while effectively utilizing the low loss properties of HTS. Each antenna investigated in this research is the first of its kind reported.

Richard, Mark A.↗

NASA NTRS1996

A Magnetic Bumper-Tether System Using ZFC Y123

We consider the use of magnetic forces in a bumper system, to soften docking procedures. We investigate a system which exhibits no magnetic field except during the docking process, which, if desired, can automatically tether two craft together, and which provides lateral stability during docking. A system composed of zero field cooled Y(1.7)Ba2Cu3O(7-delta) (Y123) tiles and electromagnets is proposed. The Y123 high temperature superconductor (HTS) is mounted on one craft, and the electromagnet on the other. Results of small prototype laboratory experiments are reported. The electromagnet has, for convenience, been replaced by a permanent SmCo ferromagnet in these measurements. When the two craft approach, a mirror image of the ferromagnet is induced in the Y123, and a repulsive bumper force, F(sub B), results. F(sub B) is velocity dependent, and increases with v. For presently available HTS materials, bumper pressure of approx. 3.7 N/cm(exp 2) is achieved using SmCo. This extrapolates to approx. 18 N/cm(exp 2) for an electromagnet, or a force of up to 20 tons for a 1 m(exp 2) system. After reaching a minimum distance of approach, the two colliding craft begin to separate. However, the consequent change of SmCo magnetic field at the Y123 results in a reversal of current in the Y123 so that the Y123 is attractive to the SmCo. The attractive (tether) force, F(sub T), is a function of R = B(sub Fe)/B(sub t, max), where B(sub Fe) is the field at the surface of the ferromagnet, and B(sub t, max) is the maximum trapped field of the Y123, i.e., the trapped field in the so-called critical state. For R greater than or equal to 2, F(sub T) saturates at a value comparable to F(sub B). For a range of initial approach velocities the two craft are tethered following the bumper sequence. Most of the kinetic energy of the collision is first converted to magnetic field energy in the Y123, and then into heat via the creep mechanism. About 15% of the work done against magnetic forces during collision remains stored as magnetic energy after 1 hour. Experiments have also been conducted on the spatial range of the bumper force for arrays of HTS tiles. For a single HTS tile approx. 2 cm in diameter, the range of F(sub B) is approx. l cm. For a l m(exp 2) array the range of F(sub B) will be circa 50 cm.

Weinstein, Roy↗

NASA NTRS1996

Characterization of Hybrid Ferroelectric/HTS Thin Films for Tunable Microwave Components

Since the discovery of High-Temperature-Superconductors (HTS) in 1986, a diversity of HTS-based microwave components has been demonstrated. Because of their low conductor losses, HTS-based components are very attractive for integration into microwave circuits for space communication systems. Recent advancements have made deposition of ferroelectric thin films onto HTS thin films possible. Due to the sensitivity of the ferroelectric's dielectric constant (epsilon(sub r)) to an externally applied electric field (E), ferroelectric/superconducting structures could be used in the fabrication of low loss, tunable microwave components. In this paper, we report on our study of Ba(0.5)Sr(0.5)TiO3/YBa2Cu3O(7-delta) and Ba(0.08)Sr(0.92)TiO3/YBa2Cu3O(7-delta) ferroelectric/superconducting thin films on lanthanum aluminate (LaAlO3) substrates. For the (Ba:Sr, 0.50:0.50) epitaxial sample, a epsilon(sub r) of 425 and a loss tangent (tan delta) of 0.040 were measured at 298 K, 1.0 MHz, and zero applied E. For the same sample, a epsilon(sub r) of 360 and tan delta of 0.036 were obtained at 77 K, 1.0 MHz, and zero applied E. Variations in epsilon(sub r) from 180 to 360 were observed over an applied E range of 0V/cm less than or equal to E less than or equal to 5.62 x 10(exp 4) V/cm with little change in tan delta. However, the range of epsilon(sub r) variation for the polycrystalline (Ba:Sr, 0.08:0.92) sample over 0V/cm less than or equal to E less than or equal to 4.00 x 10(exp 4) V/cm was only 3.6 percent while tan delta increased markedly. These results indicate that a lack of epitaxy between the ferroelectric and superconducting layers decreases tuning and increases microwave losses.

Winters, M. D.↗

NASA NTRS2000

A Cryogenic Magnetostrictive Actuator Using a Persistent High Temperature Superconducting Magnet: Concept and Design - Part 1

Cryogenic magnetostrictive materials, such as rare earth zinc crystals, offer high strains and high forces with minimally applied magnetic fields, making the material ideally suited for deformable optics applications. For cryogenic temperature applications the use of superconducting magnets offer the possibility of a persistent mode of operation, i.e., the magnetostrictive material will maintain a strain field without power. High temperature superconductors (HTS) are attractive options if the temperature of operation is higher than 10 degrees Kelvin (K) and below 77 K. However, HTS wires have constraints that limit the minimum radius of winding, and even if good wires can be produced, the technology for joining superconducting wires does not exist. In this paper, the design and capabilities of a rare earth zinc magnetostrictive actuator using bulk HTS is described. Bulk superconductors can be fabricated in the sizes required with excellent superconducting properties. Equivalent permanent magnets, made with this inexpensive material, are persistent, do not require a persistent switch as in HTS wires, and can be made very small. These devices are charged using a technique which is similar to the one used for charging permanent magnets, e.g., by driving them into saturation. A small normal conducting coil can be used for charging or discharging. Because of the magnetic field capability of the superconductor material, a very small amount of superconducting magnet material is needed to actuate the rare earth zinc. In this paper, several designs of actuators using YBCO and BSCCO 2212 superconducting materials are presented. Designs that include magnetic shielding to prevent interaction between adjacent actuators will also be described. Preliminary experimental results and comparison with theory for BSCCO 2212 with a magnetostrictive element will be discussed.

Horner, Garnett↗

NASA NTRS1999

Superconductor-Magnet Bearings With Inherent Stability and Velocity-Independent Drag Torque

A hybrid superconductor magnet bearing system has been developed based on passive magnetic levitation and the flux pinning effect of high-temperature superconductivity. The rationale lies in the unique capability of a high-temperature superconductor (HTS) to enhance system stability passively without power consumption. Characterization experiments have been conducted to understand its dynamic behavior and to estimate the required motor torque for its driving system design. These experiments show that the hybrid HTS-magnet bearing system has a periodic oscillation of drag torque due mainly to the nonuniform magnetic field density of permanent magnets. Furthermore, such a system also suffers from a small superimposed periodic oscillation introduced by the use of multiple HTS disks rather than a uniform annulus of HTS material. The magnitude of drag torque is velocity independent and very small. These results make this bearing system appealing for high-speed application. Finally, design guidelines for superconducting bearing systems are suggested based on these experimental results.

Lee, Eun-Jeong↗

NASA NTRS2019

High Temperature Superconductor Lead Assemblies for XRISM

The RESOLVE instrument on the upcoming XRISM mission is a rebuild of the SXS instrument that successfully demonstrated high resolution X-ray spectroscopy on the Hitomi mission using a microcalorimeter array at 50 mK. As with SXS, the RESOLVE instrument requires High Temperature Superconductor (HTS) lead assemblies to carry high current to the Adiabatic Demagnetization Refrigerator (ADR) while meeting a very stringent heat conductance budget. For the RESOLVE HTS lead assemblies, we have used new materials and processes to improve the stability and consistency of solder joints to the HTS material. We have also designed a new thermal strap that eliminates stress concentrations on the HTS tapes. We present the results of testing on the engineering model and flight model units, as well as the results of long term testing on prototype solder joints.

Canavan, Edgar R.↗

DOE OSTI2024

Quench protection for high-temperature superconductor cables using active control of current distribution

Superconducting magnets of future fusion reactors are expected to rely on composite high-temperature superconductor (HTS) cable conductors. In presently used HTS cables, current sharing between components is limited due to poorly defined contact resistances between superconducting tapes or by design. The interplay between contact and termination resistances is the defining factor for power dissipation in these cables and ultimately defines their safe operational margins. However, the current distribution between components along the composite conductor and inside its terminations is a priori unknown, and presently, no means are available to actively tune current flow distribution in real-time to improve margins of quench protection. Also, the lack of ability to electrically probe individual components makes it impossible to identify conductor damage locations within the cable. In this work, we address both problems by introducing active current control of current distribution between components using cryogenically operated metal-oxide-semiconductor-field-effect transistors (MOSFETs). We demonstrate through simulation and experiments how real-time current controls can help to drastically reduce heat dissipation in a developing hot spot in a two-conductor model system and help identify critical current degradation of individual cable components. Finally, prospects of other potential uses of MOSFET devices for improved voltage detection, AC loss-driven active quench protection, and remnant magnetization reduction in HTS magnets are also discussed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2024

Advanced silver sheathed 2212/Ag wire for high field magnets

Commercial High Temperature Superconductors (HTS) are all tape shaped (widths > 10 times thickness), because achieving useful current densities required them to be processed into this form, even though this also makes it more problematic to use them in some important coil types. Our product is based on 2212 (Bi2Sr2CaCu2O8) and it is the only HTS that can be processed into high current density wire forms that are similar to proven low temperature superconductors (LTS), while surpassing them in field generating and operating temperature capability. Required now are higher current density, lower cost and longer length 2212 wires to enable broad utilization where HTS tape usage is problematic. In Phase II we developed vital cost-lowering process technology elements and we test-processed longer wires with the standard commercial design as baseline and benchmark for our lower cost, higher quality and longer piece length wire advances. By initial application of Jc-boosting wire features, these wires exhibited significant performance increases. This Phase IIA program has now developed and qualified these technologies for lower cost, higher quality and longer piece length manufacturing in combination with current density-boosting wire features, paving the way to manufacturing capability that is essential for cost-effective commercial utilization of 2212 wire. Technical areas included automated, high uniformity powder packing, advanced drawing, annealing, lubricant cleaning and filament bundling, followed by integration of higher current density wire features and process variations.

17 WIND ENERGY↗