A thermal-gradient approach to variable-temperature measurements resolved in space
Explore the source record for details and available documents.
99 GENERAL AND MISCELLANEOUS↗
SEARCH · Engineering Papers
Results for “WOUNDS”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Flux Switching Permanent Magnet Motor with Metal Amorphous Nanocomposite Soft Magnetic Material and Rare Earth Free Permanent Magnets
The power losses in high power-density motors due to high rotational speed and/or high pole counts may be reduced adopting metal amorphous nanocomposites (MANCs) featuring low power loss and a relatively high flux density (~1.3 T). We recently proposed a flux switching permanent magnet (FSPM) motor with a rating of 2.5 kW at 1400 Hz electrical speed by incorporating low loss (< 3 W/kg at 1 kHz) FeNi-based MANC material with projected iron loss of about 5 W. The motor design allows use of rare earth-free permanent magnets. For incorporation of MANC materials, an axial flux motor where the rotor and stator core are made from a wound ribbon core has been developed. We have performed a 3-d FEA to optimize the design and built and tested a prototype demonstrating that the low loss MANC material can be used for motor applications.
33 ADVANCED PROPULSION SYSTEMS↗
Polyphase Rotary Transformer for Field Excitation of Electric Machines
This paper presents the magnetic design of a high-frequency three-phase rotary transformer for Wound Rotor Synchronous Motors (WRSM). The traditional DC field excitation of the WRSM is highly challenging as it relies on the brushed connection. The brush/slipring-based connections need cooling, sealing and prone to wear and tear requiring regular maintenance. The proposed three-phase rotary transformer replaces the traditional brushed excitation by a high-power density polyphase wireless excitation. Furthermore, compared to a traditional single-phase rotary transformer, the proposed three-phase rotary transformer significantly enhances the power density, and reduces the eddy current losses and the output voltage ripples.
Aydin, Emrullah↗
High-Power Polyphase PCB-Type Inductive Coupler for Wireless Electric Vehicle Charging
The cost and manufacturing difficulty of traditionally wound coils for wireless charging of electric vehicles has led to the exploration of alternative manufacturing for scalable deployment at a range of rated powers. A rotating-field polyphase wireless coupler is developed with balanced fully pitched coils which are not possible with conventional Litz wire. The usage of printed circuit board (PCB) technology is proposed for the innovative construction at large dimensions due to reduced cost, increased ease of manufacturability, and potential geometric customization compared to would coils. Design considerations specific to PCBs are detailed for wireless power transfer coils including advantages such as the potential for many turns and transposition with planar interconnections. A design procedure is developed which may be used to investigate the frequency to power to dimension correlation and limits associated with PCB coils. Designs are simulated in 3D electromagnetic finite element analysis (FEA) for the polyphase coil to evaluate the coupling between coils with varying geometric parameters at 100mm and 500mm outer diameters. A discussion is included on methods to increase PCB power ratings through a mixture of layer stacking, connections, and material selection.
Lewis, Donovin D.↗
Miniaturized Magnetoelastic Sensor System
This article describes the design, assembly, and implementation of a hand-held, magnetic-field-based sensor system that can be adapted for a variety of sensing applications. The miniaturized system is based on Chemical Identification by Magneto-Elastic Sensing (ChIMES) technology, which uses three concentric solenoid coils to wirelessly interrogate a sensor body comprised of a response material coupled to a magnetoelastic wire. The response material expands when it encounters a target, imposing mechanical stress on the wire and altering its magnetic permeability. The sensor bodies are passive, requiring no external power source, and they are small, measuring about 15 mm in length and 3.0 mm in diameter. Up to four sensor bodies can be configured as an evenly-spaced linear array. The sensor system operates by applying a low-frequency, current-stabilized, filtered triangle wave to a uniform-density excitation coil to switch the magnetic domains within the wire. Further, the responses from the sensors are picked up by a detection coil as stress-induced changes in the Faraday voltage, and the strong magnetic field induced by the excitation coil in the detection coil is nullified by a cancellation coil reverse-wound in series with the detection coil. The responses of the sensors in an array are separated in time by a linear gradient dc biasing coil. The sensors can be interrogated through metallic and nonmetallic barriers. The signals from the detection coil and the excitation coil are digitized by a pair of bipolar analog-to-digital converters (ADCs). A Raspberry Pi single-board computer (SBC) and associated software perform data acquisition and control all aspects of the sensor system hardware. The program allows the user to select the number of sensors in the array, the type of signal that is being collected, and the number of samples to take. The program also allows for signal processing of the sensor data, such as baseline correction. The program can differentiate sensor peaks from each other and calculate the magnitude of each sensor response with less than 1% error. The data are then displayed along with a graph of the signal.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
SuperCIC: Enhanced Winding Current Density for Hybrid Windings of Tokamaks
The design is presented for a new approach to cable-in-conduit (SuperCIC) for use in the high-field windings of tokamaks. Two layers of high-field superconductor wires are cabled onto a thin-wall perforated center tube. An overwrap is applied and the cable is inserted as a loose fit into a sheath tube. The sheath tube is drawn down onto the cable to compress the wires onto the center tube and immobilize them. The SuperCIC is then co-wound with a high-strength armor extrusion, which is kerf-cut so that the co-winding onto a coil mandrel can be made without deformation within the armor or the CIC. SuperCIC facilitates hybrid windings, in which subwindings of NbTi are used where B < 7 T, Nb 3 Sn where B < 14 T, and Bi-2212where B > 14 T to minimize superconductor cost. Demount-able splices are used to interconnect layers. A conceptual design has been prepared for a tokamak with aspect ratio A ~ 2.0, magnetic field of 17.4Tat the inner windings and 6.7 T at the plasma,and winding current density ~140 A/mm 2 -sufficient for optimizing the fusion power density in a compact spherical tokamak.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Sudden-Discharge Cycling Characteristics and Millisecond Dynamic Behaviors of a HTS Stainless-Steel Insulated Double-Pancake Coil With Thin Copper Plates
We have tested an intermediate-sized HTS stainless-steel (co-wound) insulated double pancake coil (~132 turns per coil) and discovered dynamic effects during sudden discharge on both millisecond and second scales. For soft break, the power supply is turned off suddenly but the shunt resistor (164 milliohm) is still connected; for hard break, a high voltage contactor is used to suddenly open the circuit so that the leads are completely open. Hard break is dangerous to traditionally insulated LTS magnets, but the SS-insulated HTS DPC retained integrity over ¡80 charge-discharge cycles. Voltage decay curves for soft and hard breaks are studied on short and long timescales. On long timescales, we observe the expected exponential decay and measure the time constant to calculate contact resistance. On short timescales, we observe highly dynamic effects: a hyper-exponential decay suggesting that the inductance or contact resistance is suddenly changing with time, likely an indication of the RL circuit forming. Moreover, peak voltage immediately (ms) after the sudden discharge were collected and compared. It is found that the peak voltage in soft-discharge is proportional to the applied current, while the those in hard-break has a unique pattern and tends to stay flat even though the applied current increases.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Distributed Fiber Optic Sensing to Identify Locations of Resistive Transitions in REBCO Conductors and Magnets
High-temperature superconductors such as REBa 2 Cu 3 O 7-x (REBCO, RE = rare earth) can generate strong magnetic fields that are promising for applications in particle accelerators and compact fusion reactors. Traditionally, voltage taps are installed in superconducting magnets to measure the voltage signals due to resistive transitions. The voltage-tap-based diagnostics is important for the development of magnet technology as it can help pinpoint the locations in the magnet windings that limit the magnet performance. The architecture of the multi-tape REBCO cable such as CORC wires, however, makes it difficult to apply the voltage-tap-based diagnostics to identify the locations of resistive transitions. Distributed fiber optic sensing (DFOS) has the potential to address this issue. In this paper, we report the measurements of thermal strain along a CORC wire based on optical frequency domain reflectometry with a maximum spatial resolution of 0.65 mm and a temporal resolution of 10 Hz. The optical fiber is co-wound with the CORC wire that is epoxy impregnated. During the test, current was increased until a resistive transition occurred in the conductor. The spectrum shift of the reflected light along the fiber was recorded. The results suggested that with proper thermal isolation from the cryogen, DFOS can be used to identify the locations of resistive transitions in CORC wires and magnets. In conclusion, the results will allow a better understanding of the causes of resistive transitions in REBCO conductors and magnets, which will help improve the REBCO magnet technology.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Design, Fabrication, and Testing of a 1.9 m Long, 16.5 mm Period NbTi Superconducting Undulator for the Advanced Photon Source Upgrade
Superconducting undulator (SCU) technology has been in use at the Advanced Photon Source since 2013. Due to the successful and reliable operation of the existing SCUs, the Advanced Photon Source upgrade project has decided to expand the use of NbTi-based SCUs. The first new magnets to be designed and fabricated are 1.9 m long with a period length of 16.5 mm. NbTi superconductor is used for coil winding and there are four separate coils wound on the mandrel to produce the main undulator field along with end compensation and distributed dipole compensation. The magnetic design, fabrication details, assembly, and testing are described in detail.
NbTi.↗
Simulation for the fault current limiting operation of REBCO CORC superconducting cables with different core materials
With high power density and low loss, CORC superconducting cables composed of RE- Ba 2 Cu 3 O 7–δ (REBCO) coated conductors are of great interest for power transmission applications. They can also effectively be designed to serve as fault current limiters, thanks to their sharp superconducting-to-normal transition. Coupled electromagnetic-thermal finite element (FE) simulations implemented in COMSOL Multiphysics were developed and validated against the published results for the fault current limiting performance of two CORC cables of REBCO coasted conductors wound on either copper or stainless steel cores. For improved accuracy, temperature dependencies of electrical and thermal properties of all component materials were considered in the simulations. The simulations were performed in the cross-sections of the cables for every individual layer of each REBCO tape to deliver comprehensive understanding of evolution of the current distribution and temperature rise in those layers. Furthermore, the studies can suggest approaches to optimize cable design for fault current limiting (FCL) applications by assessing the role of individual components. In the paper, possible computational errors, challenges and improvements are also discussed.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Critical Current Densities and n-Values of MgB 2 Conductors for SMES, MRI, and Low AC Loss Applications
Multifilamentary MgB 2 strands (filament numbers 36 to 114) prepared by the in-situ power-in-tube (PIT) route with carbon doping contents of 0, 2, and 3.2% were wound on barrels for transport J c and n -value measurement at 4.2 K in fields of up to 12 T. The strand and gauge lengths were 1 m and 0.5 m. Heat treatments at 675 °C and 650 °C centered around the melting point of Mg (650 °C) and both utilized the liquid-solid reaction. A pair of strands, with and without 2% C doping exhibited the J c (B) crossover effect. Here studied were the dependencies of J c on field strength, dopant concentration, and cabling and the dependence of n -value on field strength.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Design of an Emittance Compensation Superconducting Magnet Package for LCLS-II-HE's SRF Photo-Injector
An SRF photo-injector (low frequency, quarter-wave resonator plus emittance compensation magnet) is planned for LCLS-II-HE as it can provide a higher cathode gradient and better electron beam quality than other types of CW electron guns. The magnet package is located immediately downstream of the SRF cavity, and incorporates a solenoid doublet, bucking coils for reduction of the fringe field, normal/skew quadrupoles and horizontal/vertical dipoles. All the magnets are wound of NbTi wire and operate in liquid helium environment. The solenoid package is located inside the SRF gun cryomodule. Design considerations include space limitations, optimal emittance compensation, the magnetic field limits in the superconducting wire and quench protection. The solenoid coils must provide a peak excitation > 25 kgauss 2 ·cm, a fringe field < 20 gauss at the wall of the SRF cavity, an integrated dipole field < 90 gauss·cm and an integrated quadrupole field < 10 gauss. As a result, a genetic algorithm was used to optimize the solenoid design. Correction dipoles and quadrupoles were designed using coil dominated Walstrom style coils.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
The B1APF Large Aperture Interaction Region Dipole
Brookhaven National Laboratory is hosting the Electron Ion Collider (EIC). B1APF dipole is the last magnet near the interaction point #6. The longitudinal geometrical space available for this magnet is 1.5 m. The diameter of the coil mandrel is 370 mm. The 3-dimensional coil ends design is particularly challenging because of this large aspect ratio. The coil operating current and operating temperature are 12600 A and 1.9 K respectively. It produces an integrated dipole field of 4.05 Tm. The coil is wound with a NbTi Rutherford cable which is 15.1 mm wide and 1.8 mm thick. The parameters for the 3D end design optimization are obtained after a series of winding tests on a real mandrel with the given cable. In conclusion, this study discusses the latest design based on 1) sensitivity studies on variations in wedge thicknesses and variations in B-H data, and 2) experimental data from the winding trials, analysis and its implementation in the 3D design of this magnet.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Metal-Insulation REBCO Pancake Coil With Solder Surface Shunt: Testing and Modeling
Rare-earth barium copper oxide (REBCO) high-temperature superconducting (HTS) magnets can generate very high magnetic fields with superior engineering current density and robust mechanical integrity. The no-insulation (NI) winding technique, including its metal-insulation (MI) variant, enables “self-protection” against localized overheating through inter-turn current sharing, improving defect tolerance and allowing temporary current overloads. In REBCO pancake coils, the current-sharing path is predominantly confined to the edges of the REBCO tapes due to insulating buffer layers. Applying a surface shunt using solder can effectively enhance current sharing in NI/MI coils via the REBCO tape edges. Here, in this paper, we present both experimental and numerical research on the current distribution in surface-shunt metal-insulation (SSMI) REBCO pancake coils. We tested a stainless steel co-wound MI REBCO double-pancake coil, before and after applying a soldered surface shunt, in a saturated liquid nitrogen bath. The SSMI coil was modeled using the H-formulation and rotated anisotropic resistivity to study its dynamic behavior, including inter-turn current sharing and intra-turn screening currents. Benchmarked by experimental data, the numerical model is able to study the defect tolerance of the SSMI coil during energization.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Voltage-Current Behavior of a Superconducting STAR ® Wire in a 6-Around-1 Cable Configuration
A 6-around-1 transposed cable using superconducting STAR® wires can be useful for future circular collider applications. We made three cable samples using single STAR® wires with a diameter of 1.3 mm. The first two samples, made with a cabling machine, used STAR® wires consisting of a 0.7 mm diameter Nb-Ti core. The third cable sample was manually wound and used a STAR® wire made with a 0.81 mm diameter Cu core. The first sample showed severe degradation after the cable was bent to a 75 mm radius. The current-carrying capability of the innermost and outermost REBCO tapes in the STAR® wire degraded by 42% to 98% and the middle REBCO tapes remained intact. This was also the case for the second and straight cable sample. After fabrication of the third cable sample, we observed only about 5% reduction in the current along the wire, measured at different locations inside the terminations. Finally, the results indicate that the differences in architecture or fabrication of the STAR® wires could have caused differences in critical current retention after cabling.
6-around-1 cable↗
Suppressing Screening-Current-Induced Strain in a 72-mm-Bore REBCO Insert for a 20-T Magnet: A Numerical Study
Rare-earth barium copper oxide (REBCO) high-temperature superconducting (HTS) magnets are considered a game changer for the capability of generating magnetic fields exceeding 20 T at or above liquid helium temperature, combined with the potential for substantially reduced manufacturing and operational costs. Princeton Plasma Physics Laboratory is dedicated to developing large-bore high-field superconducting magnet systems to support forefront physics research. Here, our current project focuses on a φ72-mm cold-bore REBCO insert comprising 21 dry-wound double-pancake coils, designed to generate at least 8 T when nested within a 12-T outsert magnet. A significant challenge for high-field REBCO magnets is the time-varying-magnetic-field-induced screening currents (SC) in the REBCO conductors, which can cause localized strain and stress concentrations. This paper presents a numerical study of the SC-induced strain in the REBCO insert magnet, confirming that the SC-induced strain can be substantially suppressed by energizing the REBCO insert before the outsert magnets. We discuss and reveal the mechanism behind this reduction. By applying this strategy, we expect to unleash the potential of the REBCO insert magnet to generate up to 12 T in a 12-T background field.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Fabrication of a Nb-Ti Superconducting Closed-Loop Coil for the Next-Generation 45 GHz ECR Ion Source MARS-D
Electron Cyclotron Resonance Ion Sources (ECRISs) that utilize Nb-Ti superconducting coils for 28 GHz frequencies have been operating effectively for over twenty years. However, transitioning to higher frequencies demands stronger magnetic fields, and the conventional racetrack-and-solenoid ECRIS structures have reached their maximum capability with Nb-Ti. To address this, a Mixed Axial and Radial field System Demonstrator (MARS-D) is being developed at Lawrence Berkeley National Laboratory (LBNL). This system features an innovative Closed-Loop Coil (CLC) design that optimizes the use of the conductor fields, enabling the application of Nb-Ti in the next-generation 45 GHz ECRISs. The fabrication of the hexagonal CLC is particularly challenging due to its complex winding path and shape, the stiffness of the Nb-Ti superconducting wire, and the small bending radius. Here, to address these challenges, a series of unique fixtures and tools, as well as a pre-over-bending method, were developed for winding the CLC. To validate the winding fixtures, tools, procedures, and materials used in the coil assembly, a 4-layer practice CLC was wound, epoxy-impregnated, and then cold-tested using liquid nitrogen. The full-size MARS-D CLC is in the process of winding. This paper presents the structure of the MARS-D CLC, the winding fixtures and tools, the winding procedures, the quality control, the impregnation, the test results, and the potential future improvements.
ECR ion sources↗
Fabrication and Test of C3a: A Six-Layer Subscale Canted $\cos \theta$ Dipole Magnet Using High-Temperature Superconducting corc Wires
REBCO coated conductors have a strong potential for high-field magnet applications. The REBCO technology, however, is still in its infancy for accelerator magnet applications. As part of the U.S. Magnet Development Program (MDP), we developed a six-layer canted cos θ dipole magnet, C3a, using CORC® wires developed by Advanced Conductor Technologies LLC. All the layers were wound using a semi-automated winding machine. Three layers of the magnet used CORC® wires containing the SuperPower “AP” REBCO tapes and the remaining layers used the wires containing the “HM” tapes. At 77 K, both kinds of CORC® wires showed 5% to 10% degradation, after bending to a minimum bend radius of 30 or 35 mm, with respect to the self-field critical current measured before winding. At 4.2 K, the magnet reached 9.5 kA at a ramp rate of 9 A s -1 and generated a dipole field of 1.4 T. Further, the critical current of one layer degraded by 4% after a current transient up to 10.5 kA ramped in an averaged rate of 175 kA s -1 or 20 T s -1 . We confirmed the HM CORC® wire can carry a higher current than the AP CORC® wire at 4.2 K. The test results of the C3a magnet showed that the fabrication and assembly procedure can be used for the upcoming full-scale C3 magnet.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗