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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Strongly enhanced vortex pinning from 4 to 77 K in magnetic fields up to 31 T in 15 mol.% Zr-added (Gd, Y)-Ba-Cu-O superconducting tapes

Applications of REBCO coated conductors are now being developed for a very wide range of temperatures and magnetic fields and it is not yet clear whether vortex pinning strategies aimed for high temperature, low field operation are equally valid at lower temperatures and higher fields. A detailed characterization of the superconducting properties of a 15 mol.% Zr-added REBCO thin film made by metal organic chemical vapor deposition, from 4.2 to 77 K under magnetic fields up to 31 T is presented in this article. Even at a such high level of Zr addition, T-c depression has been avoided (T-c = 91 K), while at the same time an exceptionally high irreversibility field H-irr approximate to 14.8 T at 77 K and a remarkably high vortex pinning force density F-p approximate to 1.7 TN/m(3) at 4.2 K have been achieved. We ascribe the excellent pinning performance at high temperatures to the high density (equivalent vortex matching field similar to 7 T) of self-assembled BZO nanorods, while the low temperature pinning force is enhanced by large additional pinning which we ascribe to strain-induced point defects induced in the REBCO matrix by the BZO nanorods. Our results suggest even more room for further performance enhancement of commercial REBCO coated conductors and point the way to REBCO coil applications at liquid nitrogen temperatures since the critical current density J(c)(H//c) characteristic at 77 K are now almost identical to those of fully optimized Nb-Ti at 4 K. (C) 2014 Author(s).

Xu, A↗
DOE OSTI2022

Rapid assessment of REBCO CC angular critical current density J c (B, T = 4.2 K, θ) using torque magnetometry up to at least 30 tesla

Abstract Detailed design of REBa 2 Cu 3 O 7 − x (REBCO)-based magnets ideally relies on knowledge of the full angular and wide temperature range characterization of the critical current I c of the REBCO coated conductors (CC) at high magnetic fields. In practice, however, obtaining I c ( B , T , θ ) data by the commonly used electrical transport technique is expensive, tedious, and difficult, due to high critical current values that exceed 2000 A for B | | a b -plane ( θ = 90 deg). The conductors are often damaged during angular transport measurements at angles approaching the ab -plane. Therefore, so far, REBCO magnets have been designed without full I c ( B , T , θ ) data sets. Here, we present J c ( B , T , θ ) results for more than twenty samples of CC all made to the same advanced pinning specification produced by SuperPower Inc. For this, we employed torque magnetometry, benchmarking the results to transport I c measurements mostly made away from ab -plane, finding good agreement with scaling factors ≈1–1.3. What is striking is the huge variety of properties exhibited by the samples, even for CC made recently. Given the huge attention now being paid to the effects of screening currents and to the torques generated by offsets between the tape plane and the local magnetic field vector, our data set suggests some caution in detailed design of such magnets without having data of the type presented here.

Physics↗
DOE OSTI2019

AMS-100: The next generation magnetic spectrometer in space – An international science platform for physics and astrophysics at Lagrange point 2

The next generation magnetic spectrometer in space, AMS-100, is designed to have a geometrical acceptance of 100 m 2 sr and to be operated for at least ten years at the Sun–Earth Lagrange Point 2. Compared to existing experiments, it will improve the sensitivity for the observation of new phenomena in cosmic rays, and in particular in cosmic antimatter, by at least a factor of 1000. The magnet design is based on high temperature superconductor tapes, which allow the construction of a thin solenoid with a homogeneous magnetic field of 1 Tesla inside. The inner volume is instrumented with a silicon tracker reaching a maximum detectable rigidity of 100 TV and a calorimeter system that is 70 radiation lengths deep, equivalent to four nuclear interaction lengths, which extends the energy reach for cosmic-ray nuclei up to the PeV scale, i.e. beyond the cosmic-ray knee. In conclusion, covering most of the sky continuously, AMS-100 will detect high-energy gamma-rays in the calorimeter system and by pair conversion in the thin solenoid, reconstructed with excellent angular resolution in the silicon tracker.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

AC loss and contact resistance in REBCO CORC ® , Roebel, and stacked tape cables

Abstract Many high-temperature superconductor (HTS) applications require superconducting cables with high currents while operating in an alternating magnetic field. HTS cables should be composed of numerous superconducting tapes to achieve the required current capacity. Alternating current and magnetic fields cause AC losses in such cables and can provoke conductor instability. AC losses and contact resistances were measured of several cable designs based on commercially available REBCO tapes at the University of Twente. The AC loss was measured under identical conditions for eight REBCO conductors manufactured according to three types of cabling methods—CORC ® (Conductor on Round Core), Roebel, and stacked tape, including a full-size REBCO CICC (cable in conduit conductor). The measurements were done at T = 4.2 K without transport current in a sinusoidal AC magnetic field of 0.4 T amplitude and frequencies from 5 to 55 mHz. The AC loss was measured simultaneously by calibrated gas flow calorimeter utilizing the helium boil-off method and by the magnetization method using pick-up coils. Also, the AC loss of two CORC® conductors and a Roebel cable was measured at 77 K. Each conductor was measured with and without background field of 1 T. The measured AC coupling loss in the CORC ® and Roebel conductors is negligible at 4.2 K for the applied conditions while at 77 K coupling loss was observed for all conductors. The absence of coupling loss at 4.2 K can be explained by shielding of the conductor interior; this is confirmed with measurement and calculation of the penetration field of CORC ® and Roebel cables. The inter-tape contact resistance was measured for CORC ® and stacked tape samples at 4.2 and 77 K. It was demonstrated that a short heat treatment of CORC ® conductor with solder-coated tapes activates tape-to-tape soldering and decreases the contact resistance. The reduction of contact resistance by two orders in magnitude to tens of nΩm is comparable with the interstrand contact resistance in ITER Nb 3 Sn type conductors.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Forced flow cooling of high field, REBCO-based, fusion magnets using supercritical hydrogen, helium, and neon

Rare Earth Barium Copper Oxide (REBCO) High Temperature Superconductor (HTS) tapes are being considered for the Toroidal Field (TF) magnets of a highly compact, high field fusion reactor operating at magnetic fields as high as 21 T and operating temperatures in the range of 10–30 K. Due to the increase in range of operating conditions made available through HTS tapes, a new set of cryogenic fluids are being considered for forced flow cooling. The present study investigates helium, hydrogen, and neon as a forced flow coolant for REBCO HTS tapes used in a highly compact, high-field reactor design. Four design criteria are considered, including current sharing temperature, fluid inlet temperature, cable pressure drop (dP), and operating pressure. From these simulations, neon is removed from consideration due to its high required pressure drop and low temperature margins with respect to the current sharing limit. Helium and hydrogen are then compared, with hydrogen producing the highest overall heat transfer rate at its optimum operating condition (1.5 MPa/15 K). A compromise across inlet temperature, dP, and operating pressure is found when helium has a minimum initial temperature of 10 K and an inlet pressure of 2.0 MPa. For the current design, helium is selected as a coolant due its acceptable cable pressure drop, required cooling load, and system complexity inherent to a forced-flow cryogenic system.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2012

Apparatus and method for measuring critical current properties of a coated conductor

The transverse critical-current uniformity in a superconducting tape was determined using a magnetic knife apparatus. A critical current I.sub.c distribution and transverse critical current density J.sub.c distribution in YBCO coated conductors was measured nondestructively with high resolution using a magnetic knife apparatus. The method utilizes the strong depression of J.sub.c in applied magnetic fields. A narrow region of low, including zero, magnetic field in a surrounding higher field is moved transversely across a sample of coated conductor. This reveals the critical current density distribution. A Fourier series inversion process was used to determine the transverse J.sub.c distribution in the sample.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

Strain Distribution in REBCO-Coated Conductors Bent With the Constant-Perimeter Geometry

Here, cable and magnet applications require bending REBa 2 Cu 3 O 7-δ (REBCO, RE = rare earth) tapes around a former to carry high current or generate specific magnetic fields. With a high aspect ratio, REBCO tapes favor the bending along their broad surfaces (easy way) than their thin edges (hard way). The easy-way bending forms can be effectively determined by the constant-perimeter method that was developed in the 1970s to fabricate accelerator magnets with flat thin conductors. The method, however, does not consider the strain distribution in the REBCO layer that can result from bending. Therefore, the REBCO layer can be overstrained and damaged even if it is bent in an easy way as determined by the constant-perimeter method. To address this issue, we developed a numerical approach to determine the strain in the REBCO layer using the local curvatures of the tape neutral plane. Two orthogonal strain components are determined: the axial component along the tape length and the transverse component along the tape width. These two components can be used to determine the conductor critical current after bending. The approach is demonstrated with four examples relevant for applications: a helical form for cables, forms for canted cos θ dipole and quadrupole magnets, and a form for the coil end design. The approach allows us to optimize the design of REBCO cables and magnets based on the constant-perimeter geometry and to reduce the strain-induced critical current degradation.

(REBCO RE = rare earth) coated conductors↗
DOE OSTI2024

Berkeley Lab Finite Element Framework (BELFEM) v0.1

The software program, referred to as BELFEM, is a specialized finite element code designed for the magnetodynamic modeling of high-temperature superconducting (HTS) tapes. It incorporates novel mixed finite element formulations, particularly the h-ϕ-formulation with thin-shell simplification, to efficiently simulate larger geometries. This methodology is extremely promising for predicting the electrodynamic performance of HTS tapes used in superconducting cables and magnets, offering the benefit of reduced computational cost. Compared to similar technologies like COMSOL Multiphysics and GetDP, BELFEM's performance benchmarking indicates superior efficiency in its thin-shell implementation. In the future, it will also support features like thermal coupling and inter-tape current sharing, enhancing its utility in research and development, particularly in nuclear fusion applications. The intent is to develop BELFEM as a robust and efficient tool for the HTS community, contributing to the analysis and design of superconducting cables and magnets.

Messe, Christian↗
DOE OSTI2025

Development of a second COMB dipole magnet with STAR wires

Rare-Earth Barium Copper Oxide (REBCO) coated conductors are an attractive option for application in high-field accelerator magnets due to their high critical field and the convenience of fabrication without heat treatment compared to some other superconductors. Fermilab plays a vital role in superconducting accelerator magnet R&D under the framework of the U.S. Magnet Development Program. An integral part of that program is the accelerator magnet development based on REBCO conductors to demonstrate self-fields of 5 T or greater compatible with operation in hybrid configurations to generate fields beyond 16 T for future High Energy Physics (HEP) applications. A small, two-layer REBCO dipole magnet based on the Conductor on Molded Barrel (COMB) magnet technology, developed at Fermilab with Symmetric Tape Round (STAR®) wires from AMPeers LLC was recently fabricated and tested in liquid helium, demonstrating the design feasibility. A second dipole magnet based on the same technology is currently under development at Fermilab. The coil has a 60-mm clear bore and a 120-mm OD and consists of six layers of STAR® conductor, which allows to significantly increase the magnetic field compared to the previous design, and potentially probe the 5 T self-field target. This presentation reports the progress in the magnet development.

Kashikhin, Vadim [Fermilab]↗
DOE OSTI2024

Conceptual Design of A 20 T Dipole Based on Hybrid REBCO/Nb 3 Sn Cos-theta Coil

This paper presents a design concept of an HTS/LTS hybrid dipole with 50 mm aperture and 20 T nominal field based on a cos-theta coil and a cold iron yoke. The HTS part of magnet coil uses REBCO Twisted Stacked Tape cable. The LTS part is graded and made of two Nb3Sn Rutherford cables. Due to high sensitivity of HTS/LTS coils to large stresses and strains at high fields, a Stress Management (SM) concept combined with the cos-theta coil geometry is used. The results of magnet magnetic analysis are presented and discussed.

43 PARTICLE ACCELERATORS↗
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↗
DOE OSTI2013

Electromagnetic Properties of (Gd, Y)Ba2Cu3Ox Superconducting Tapes With High Levels of Zr Addition

The dependence of the critical current density (J(c)) on the orientation of applied magnetic fields was studied in Zr-doped (Gd, Y)Ba2Cu3Ox tapes fabricated by metal organic chemical vapor deposition. The in-field performance of J(c) of (Gd, Y)Ba2Cu3Ox tapes with Zr-doping levels of 7.5-30 at.% was investigated up to 5 T over a temperature range of 40-77 K. The highest critical currents (I-c) at H parallel to c and the highest values of minimum Ic in angular dependence measurements were achieved in the tapes with 20% Zr doping over a broad range of temperature and magnetic field conditions measured. The electromagnetic properties have been related to the changes in BaZrO3 content and microstructure.

Liu, Y↗
DOE OSTI2023

Business models to assure availability of advanced superconductors for the accelerator sector and promote stewardship of superconducting magnet technology for the US economy

Stakeholders representing concerns of national and global leadership, industries that use superconducting magnets in products, manufacturers of superconducting wires and tapes that supply to industries, and innovation generators from small businesses and universities came together to address stewardship of superconducting magnet technology and assurance of supply of advanced superconductors to the accelerator sector. This report outlines potential public-private partnerships that develop and enhance domestic capabilities to meet the needs of science facilities in the accelerator systems sector and in the broader commercial ecosystem.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

High-current density CORC® wires for use in accelerator magnets

Next generation accelerator magnets capable of generating magnetic fields in excess of 16 T require high-temperature superconductors (HTS) such as Conductor on Round Core (CORC®) cables and wires, wound from RE-Ba 2 Ca 3 O 7-δ (ReBCO, Re = rare earth) coated conductor tapes.1 The severe operating requirements of an engineering current density (J e ) of at least 400 Amm -2 at 4.2 K and 20 T, high operating currents of 5-20 kA, tolerance to Lorentz stresses in excess of 150 MPa, and in many cases cable bending diameters as small as 30 mm, make accelerator magnets one of the most challenging applications for any HTS material. Advanced Conductor Technologies (ACT) has been developing CORC® cables and wires wound from ReBCO tapes containing substrates of 30-50 µm thickness to meet these requirements. Although these requirements could each be met separately with current CORC® technology, meeting the requirements at the same time requires thinner, more powerful CORC® wires wound from tapes with even thinner substrates. The purpose of this Phase I SBIR program was to determine the feasibility to develop ReBCO tapes containing 25 µm thick substrates on an industrial scale and wind thinner CORC® wires from these tapes that could eventually meet the stringent performance specifications for accelerator magnets. The results of the Phase I program clearly demonstrated the feasibility of developing thinner, more powerful CORC® wires using ReBCO tapes with 25 µm substrate that would likely meet the stringent requirements for use in accelerator magnet by the end of the potential Phase II program. SuperPower Inc., as the subcontractor on the Phase I program, was successful in developing tapes with 25 µm substrate at minimum piece lengths of 30-40 m with a clear path towards industrial production. A total length exceeding 350 meters of 2 mm wide ReBCO tape with critical current (I c ) of between 45 and 65 A at 77 K was delivered to ACT during the Phase I program. The thinner tapes allowed us to reduce the CORC® core (former) from 2.5 mm to 2.0 mm, resulting in a higher current density conductor with enhanced flexibility. Several CORC® wires were manufactured to reach the Phase I goal of a Je of at least 300-400 Amm -2 at 20 T at a minimum bending diameter to less than 50 mm. Several CORC® wires were wound and analyzed after bending by identifying the location of peak stresses and causes of tape damage. Data was compared to 3D finite element models that included parametric studies to identify key parameters leading to the observed tape failure modes. The models suggest that flexibility is heavily dependent on the friction coefficient between tapes in a CORC® wire and the width of the tapes used. These studies provide a clear and straightforward path to improve conductor flexibility within the proposed Phase II program to reach our goal of minimum bending diameters below 30 mm with minimal I c reduction. We were successful in developing a flexible, 3.3 mm thick, high-J e CORC® wire containing 30 ReBCO tapes that carried > 80 % of its original I c after bending to diameters down to 44 mm. The CORC® wires showed no cyclic degradation due to in-field testing up to 57 stress cycles at 12 T. Another CORC® wire of 3.4 mm thickness had a J e as high as 451 Amm -2 when extrapolated to 20 T at a bending diameter of 63 mm, which is a new high-field performance record. We were also able to design a CORC® wire with increased tensile strength of 240 MPa at 76 K. The results of the Phase I program allow us to propose a very strong Phase II program with a high likelihood of reaching the ultimate goal of CORC® accelerator magnets wires with I c exceeding 8-10 kA and J e exceeding 600 Amm -2 at 20 T while bent to a 30 mm diameter.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Analysis of Screening Current Effects in a Hybrid Nb$_{3}$Sn/REBCO Superconducting Accelerator Magnet Using a T - A Formulation

To explore the feasibility of using high-temperature superconducting (HTS) REBCO coated conductors in future accelerator magnets, two REBCO flat racetrack coils were fabricated using 4-mm wide EuBCO tapes at the High Energy Accelerator Research Organization (KEK). These coils were tested as an insert inside a Nb$_{3}$Sn common-coil dipole magnet, which provides a background field of up to $\sim$ 9.5T, at the Brookhaven National Laboratory (BNL). REBCO tapes offer exceptionally high critical current density under strong magnetic fields; however, they also exhibit significant magnetization due to screening currents, leading to magnetic field errors. Here, this study presents a 2D finite element model of screening current-induced fields (SCIF) in REBCO coils using the T-A formulation, along with the results obtained. Simulations were then performed for two KEK test cases: one where the REBCO conductors were oriented with the HTS tapes parallel to the background field, and another where the tapes were perpendicular to it. Since screening currents also influence the stress distribution and increase the peak stress in the coils, the mechanical effects of these currents were analyzed. The implications of these simulation and test results for the design of Nb$_{3}$Sn/REBCO superconducting accelerator magnets are discussed.

Accelerator magnets↗
DOE OSTI2025

A round bobbin critical current measurement and thermal runaway simulation of REBCO coated conductors

A round bobbin test has been widely used to measure critical current Ic of practical superconductors including Nb–Ti, Nb3Sn, and Bi-2212 round strands at 4.2 K and in high magnetic fields but rarely used for rare earth-barium-copper-oxide (REBCO) coated conductor tapes. Here, we applies this method to REBCO tapes and test their Ic at 77 K, self-field, and 4.2 K with a magnetic field of 14 T applied parallel to the tape. The sample carries very high current densities; it is 1.3 m long and has a dense array of voltage taps that allows probing localized thermal runaways and correlation with Ic variations along the length. At 77 K, the Ic values of all sections were measured and found to be rather uniform. However, at 4.2 K, we found that a 3 cm section has 90% of the overall voltage drop and it went into thermal runaways upon further increasing current. Thus, at 4.2 K, we were prevented by localized thermal runaways and unable to determine Ic of most of the REBCO conductor sections; this behavior is different from Bi-2212 and Bi-2223 for which Ic of all turns of a round barrel sample can be determined. We simulate REBCO tapes during current ramping to a thermal runaway and analyze impacts of various factors including cooling, conductor n-values, and thickness of stabilizer on the thermal runaway current Iq. The combined experiments and simulations identify n-value as a crucial factor that leads to the observed differences between Bi-2212 and REBCO. Together with cooling and the standard deviation of Ic variations along the length, the n-value determines whether Iq is above or below the average Ic of a long piece of conductor and their ratio Iq/Ic,ave, greatly affecting quench detection and thermal runaway prevention strategies of Bi-2212 and REBCO magnets.

Mosat, Marek↗