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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.

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At least 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Pulsating Heat Pipes for Accelerator Magnets. Phase I Final Report

The primary objective of the Phase 1 award was to investigate the performance of cryogenic pulsating heat pipes (PHPs) and their use in practical large superconducting magnet systems. PHPs exhibit an effective thermal conductivity an order of magnitude and more over high purity metals such as copper and aluminum. They can therefore be utilized to reduce cold mass and effectively transfer heat from the magnet system components such as the coil pack, shields, or current leads to cryocoolers or cryogen reservoirs.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Parametric study and optimization trends for the Von-Kármán-sodium dynamo experiment

In this paper, we present magneto-hydrodynamic simulations of liquid sodium flow performed with the PLUTO compressible MHD code. We investigated the influence of the remanent magnetic field orientation and intensity, the impinging velocity field due to Ekman pumping as well as the impeller dimensions on the magnetic field collimation by helical flows in-between the impeller blades. For a simplified Cartesian geometry, we model the flow dynamics of a multi-blade impeller inspired by the Von-Kármán-Sodium experiment. This study shows that a remanent magnetic field oriented in the toroidal direction is the less efficient configuration to collimate the magnetic field, although if the radial or vertical components are not negligible, the collimation is significantly improved. As the intensity of the remanent magnetic field increases, the system magnetic energy becomes larger, but the magnetic field collimation efficiency remains the same, so the gain of magnetic energy is smaller as the remanent magnetic field intensity increases. The magnetic field collimation is modified if the impinging velocity field changes: the collimation is weaker if the impinging velocity increases from Γ = 0.8 to 0.9 and slightly larger if the impinging velocity decreases from Γ = 0.8 to 0.7. The analysis of the impeller dimensions points out that the most efficient configuration to collimate the magnetic field requires a ratio between the impeller blade height and the base longitude between 0.375 and 0.5. The largest enhancement of the hypothetical α 2 dynamo loop, compared to the hypothetical Ω-α dynamo loop, is observed for the model that mimics the TM 73 impeller configuration rotating in the unscooping direction with a remanent magnetic field of 10 –3 T orientated in the radial or vertical direction. Finally, the optimization trends obtained in the parametric analysis are also confirmed by simulations with a higher resolution and turbulence degree.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Implementation of a High-Speed Multichannel Data Acquisition System for Magnetic Diagnostics and Plasma Centroid Position Control in ISTTOK

In tokamak and other fusion devices, magnetic control is the main tool that allows to regulate the plasma current, position and shape; it is in charge of actuating the desired plasma current waveform, steering the plasma position to a given set point and maintain the plasma shape close to a prescribed plasma equilibrium. This work describes the application of several physics concepts and computational tools in order to obtain a novel optimal controller for the plasma centroid position, which has been implemented and tested in the real-time plasma control system at the ISTTOK tokamak. A key point for the development of the new control system was the installation of a recently upgraded hardware, that numerically integrates in real-time the magnetic probes signals.

poloidal field coils↗
DOE OSTI2016

Thermoelectricity in transition metal compounds: The role of spin disorder

Here, at room temperature and above, most magnetic materials adopt a spin-disordered (paramagnetic) state whose electronic properties can differ significantly from their low-temperature, spin-ordered counterparts. Yet computational searches for new functional materials usually assume some type of magnetic order. In the present work, we demonstrate a methodology to incorporate spin disorder in computational searches and predict the electronic properties of the paramagnetic phase. We implement this method in a high-throughput framework to assess the potential for thermoelectric performance of 1350 transition-metal sulfides and find that all magnetic systems we identify as promising in the spin-ordered ground state cease to be promising in the paramagnetic phase due to disorder-induced deterioration of the charge carrier transport properties. We also identify promising non-magnetic candidates that do not suffer from these spin disorder effects. In addition to identifying promising materials, our results offer insights into the apparent scarcity of magnetic systems among known thermoelectrics and highlight the importance of including spin disorder in computational searches.

36 MATERIALS SCIENCE↗
NASA NTRS2007

Magnet-Based System for Docking of Miniature Spacecraft

A prototype system for docking a miniature spacecraft with a larger spacecraft has been developed by engineers at the Johnson Space Center. Engineers working on Mini AERCam, a free-flying robotic camera, needed to find a way to successfully dock and undock their miniature spacecraft to refuel the propulsion and recharge the batteries. The subsystems developed (see figure) include (1) a docking port, designed for the larger spacecraft, which contains an electromagnet, a ball lock mechanism, and a service probe; and (2) a docking cluster, designed for the smaller spacecraft, which contains either a permanent magnet or an electromagnet. A typical docking operation begins with the docking spacecraft maneuvering into position near the docking port on the parent vehicle. The electromagnet( s) are then turned on, and, if necessary, the docking spacecraft is then maneuvered within the capture envelope of the docking port. The capture envelope for this system is approximated by a 5-in. (12.7-cm) cube centered on the front of the docking-port electromagnet and within an angular misalignment of <30 . Thereafter, the magnetic forces draw the smaller spacecraft toward the larger one and this brings the spacecraft into approximate alignment prior to contact. Mechanical alignment guides provide the final rotational alignment into one of 12 positions. Once the docking vehicle has been captured magnetically in the docking port, the ball-lock mechanism is activated, which locks the two spacecraft together. At this point the electromagnet( s) are turned off, and the service probe extended if recharge and refueling are to be performed. Additionally, during undocking, the polarity of one electromagnet can be reversed to provide a gentle push to separate the two spacecraft. This system is currently being incorporated into the design of Mini AERCam vehicle.

Howard, Nathan↗
DOE OSTI2016

The isothermal section of Gd–Ni–Si system at 1070 K

The Gd–Ni–Si system has been investigated at 1070 K by X-ray and microprobe analyses. The existence of the known compounds, i.e.: GdNi{sub 10}Si{sub 2}, GdNi{sub 8}Si{sub 3}, GdNi{sub 5}Si{sub 3}, GdNi{sub 7}Si{sub 6}, GdNi{sub 6}Si{sub 6}, GdNi{sub 4}Si, GdNi{sub 2}Si{sub 2}, GdNiSi{sub 3}, Gd{sub 3}Ni{sub 6}Si{sub 2}, GdNiSi, GdNiSi{sub 2}, GdNi{sub 0.4}Si{sub 1.6}, Gd{sub 2}Ni{sub 2.35}Si{sub 0.65}, Gd{sub 3}NiSi{sub 2}, Gd{sub 3}NiSi{sub 3} and Gd{sub 6}Ni{sub 1.67}Si{sub 3}, has been confirmed. Moreover, five new phases have been identified in this system. The crystal structure for four of them has been determined: Gd{sub 2}Ni{sub 16−12.8}Si{sub 1−4.2} (Th{sub 2}Zn{sub 17}-type), GdNi{sub 6.6}Si{sub 6} (GdNi{sub 7}Si{sub 6}-type), Gd{sub 3}Ni{sub 8}Si (Y{sub 3}Co{sub 8}Si-type) and Gd{sub 3}Ni{sub 11.5}Si{sub 4.2}(Gd{sub 3}Ru{sub 4}Ga{sub 12}-type). The compound with composition ~Gd{sub 2}Ni{sub 4}Si{sub 3} still remains with unknown structure. Quasi-binary phases, solid solutions, were detected at 1070 K to be formed by the binaries GdNi{sub 5}, GdNi{sub 3}, GdNi{sub 2}, GdNi, GdSi{sub 2} and GdSi{sub 1.67}; while no appreciable solubility was observed for the other binary compounds of the Gd–Ni–Si system. Magnetic properties of the GdNi{sub 6}Si{sub 6}, GdNi{sub 6.6}Si{sub 6} and Gd{sub 3}Ni{sub 11.5}Si{sub 4.2} compounds have also been investigated and are here reported. - Graphical abstract: The Gd–Ni–Si system has been investigated at 1070 K by X-ray and microprobe analyses. The known GdNi{sub 10}Si{sub 2}, GdNi{sub 8}Si{sub 3}, GdNi{sub 5}Si{sub 3}, GdNi{sub 7}Si{sub 6}, GdNi{sub 6}Si{sub 6}, GdNi{sub 4}Si, GdNi{sub 2}Si{sub 2}, GdNiSi{sub 3}, Gd{sub 3}Ni{sub 6}Si{sub 2}, GdNiSi, GdNiSi{sub 2}, GdNi{sub 0.4}Si{sub 1.6}, Gd{sub 2}Ni{sub 2.35}Si{sub 0.65}, Gd{sub 3}NiSi{sub 2}, Gd{sub 3}NiSi{sub 3} and Gd{sub 6}Ni{sub 1.67}Si{sub 3} compounds have been confirmed and five new ~Gd{sub 2}Ni{sub 4}Si{sub 3} (unknown type), Gd{sub 2}Ni{sub 16−12.8}Si{sub 1−4.2} (Th{sub 2}Zn{sub 17}-type), GdNi{sub 6.6}Si{sub 6} (GdNi{sub 7}Si{sub 6}-type), Gd{sub 3}Ni{sub 8}Si (Y{sub 3}Co{sub 8}Si-type) and Gd{sub 3}Ni{sub 11.5}Si{sub 4.2} (Gd{sub 3}Ru{sub 4}Ga{sub 12}-type) compounds have been detected in Gd–Ni–Si system at 1070 K. Quasi-binary phases, solid solutions, were detected at 1070 K to be formed by the binaries GdNi{sub 5}, GdNi{sub 3}, GdNi{sub 2}, GdNi, GdSi{sub 2} and GdSi{sub 1.67}; while no detectable solubility was observed for the other binary compounds of the Gd–Ni–Si system. Magnetic properties of the GdNi{sub 6}Si{sub 6}, GdNi{sub 6.6}Si{sub 6} and Gd{sub 3}Ni{sub 11.5}Si{sub 4.2} compounds have also been investigated and are here reported. - Highlights: • Gd–Ni–Si isothermal section was obtained at 1070 K. • Sixteen known ternary gadolinium nickel silicides were confirmed in Gd–Ni–Si. • Five new gadolinium nickel silicides were detected in Gd–Ni–Si. • GdNi{sub 6}Si{sub 6}, GdNi{sub 6.6}Si{sub 6} and Gd{sub 3}Ni{sub 11.5}Si{sub 4.2} show ferromagnetic-type ordering.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Modeling and design of compact, permanent-magnet transport systems for highly divergent, broad energy spread laser-driven proton beams

Laser-driven (LD) ion acceleration has been explored in a newly constructed short focal length laser beamline at the BELLA petawatt facility (interaction point 2, iP2). For applications utilizing such LD ion beams, a beam transport system is required, which for reasons of compactness be ideally contained within 3 m. While they are generated from a micron-scale source, large divergence and energy spread of LD ion beams present a unique challenge to transporting them compared to beams from conventional accelerators. This study gives an overview of proposed compact transport designs using permanent magnets satisfying different requirements depending on the application for the iP2 laser beamline such as radiation biology, material science, and high-energy density science. These designs are optimized for different parameters such as energy spread and peak proton density according to the application’s need. The various designs consist solely of permanent magnet elements, which can provide high magnetic field gradients on a small footprint. While the field strengths are fixed, we have shown that the beam size is able to be tuned effectively by varying the placement of the magnets. The performance of each design was evaluated based on high-order particle tracking simulations of typical LD proton beams. We also examine the ability of certain configurations to tune and select beam energies, critical for specific applications. A more detailed investigation was carried out for a design to deliver 10 MeV LD accelerated ions for radiation biology applications. With these transport system designs, the iP2 laser beamline is ready to house various application experiments.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Structural Analysis of Thermal Shields During a Quench of a Torus Magnet for the 12 GeV Upgrade

A toroidal magnet system consisting of six superconducting coils is being built for the Jefferson Lab 12- GeV accelerator upgrade project. This paper details the analysis of eddy current effects during a quench event on the aluminum thermal shield. The shield has been analyzed for mechanical stresses induced as a result of a coil quench as well as a fast discharge of the complete magnet system. The shield has been designed to reduce the eddy current effects and result in stresses within allowable limits.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Magneto-structural transformations via a solid-state nudged elastic band method: Application to iron under pressure

We extend the solid-state nudged elastic band method to handle a non-conserved order parameter, in particular, magnetization, that couples to volume and leads to many observed effects in magnetic systems. We apply this formalism to the well-studied magneto-volume collapse during the pressure-induced transformation in iron—from ferromagnetic body-centered cubic (bcc) austenite to hexagonal close-packed (hcp) martensite. We find a bcc-hcp equilibrium coexistence pressure of 8.4 GPa, with the transition-state enthalpy of 156 meV/Fe at this pressure. A discontinuity in magnetization and coherent stress occurs at the transition state, which has a form of a cusp on the potential-energy surface (yet all the atomic and cell degrees of freedom are continuous); the calculated pressure jump of 25 GPa is related to the observed 25 GPa spread in measured coexistence pressures arising from martensitic and coherency stresses in samples. Our results agree with experiments, but necessarily differ from those arising from drag and restricted parametrization methods having improperly constrained or uncontrolled degrees of freedom.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Risk Assessment of EIC Central Detector (ePIC) Solenoid Magnet (MARCO)

As part of the BNL-JLab-CEA Electron Ion Collider (EIC) collaboration, the design of a 2 T, 2.8 m bore diameter, 3.8 m long conduction cooled superconducting detector magnet design is completed. Such magnet will be employed at the interaction region of ePIC for physics experiment. The magnet is a passive shielded solenoidal magnet system consisting of 3 coils wound with specially designed conductor using NbTi Rutherford type cable in copper stabilized channel. This paper describes the risk analysis as the part of Failure Modes and Effects Analysis (FMEA) that was carried out as a team to identify their various failure modes and risks associated with the magnets system. In conclusion, this FMEA is intended to become the content of the designed document as an integral part of the engineering assessment and the statement of work for the potential vendors towards design and built.

Ghoshal, Probir K. [Thomas Jefferson National Acce↗
DOE OSTI2017

Detection of the metal–insulator transition in disordered systems of magnetic nanoislands

We have studied the conductivity and permittivity of a series of nanoisland-type FeNi films with an effective thickness of up to 3.2 nm on different substrates. It has been observed that the quantity Re ε changes its sign at effective thickness d{sup *} ≈ 1.5–1.8 nm, because of the metal–insulator transition. Analysis of the temperature dependences of the conductivity has confirmed the existence of the metal–insulator transition at the same thickness d{sup *}. It has been concluded that the introduced effective permittivity can serve as a characteristic of island metal systems.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Long-range, non-local switching of spin textures in a frustrated antiferromagnet

Abstract Antiferromagnetic spintronics is an emerging area of quantum technologies that leverage the coupling between spin and orbital degrees of freedom in exotic materials. Spin-orbit interactions allow spin or angular momentum to be injected via electrical stimuli to manipulate the spin texture of a material, enabling the storage of information and energy. In general, the physical process is intrinsically local: spin is carried by an electrical current, imparted into the magnetic system, and the spin texture will then rotate in the region of current flow. In this study, we show that spin information can be transported and stored “non-locally" in the material Fe x NbS 2 . We propose that collective modes can manipulate the spin texture away from the flowing current, an effect amplified by strong magnetoelastic coupling of the ordered state. This suggests a novel way to store and transport spin information in strongly spin-orbit coupled magnetic systems.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Physics and Engineering Assessmetns of the K-DEMO Magnet Configuration

Increased attention is being given now to studies of next-step fusion facilities with nuclear missions. Among these, South Korea's K DEMO is unique in its focus on a high toroidal magnetic field, large major radius, steady-state tokamak design for the core of a facility to test fusion nuclear components in Phase I and, after upgrades, produce 500 MW of electricity in a Phase II. Innovative features of the K DEMO magnet set include the use of two toroidal field (TF) coil winding packs with conductor grading and a machine configuration designed for vertical maintenance. The magnet arrangement features large TF coils and widely spaced poloidal field (PF) coils to accommodate removal of in-vessel components as large modules. Physics and engineering assessments of the pre-conceptual K-DEMO magnet configuration are reported, including: 1) design point and operating space assessment, 2) conductor assessment, and 3) structural assessment. It is found that a reference design point at 6.8 m major radius and 7.4 T toroidal field provides sufficient operating margins for the 500 MWe Phase II mission. Analyses of candidate cable-in-conduit conductors provide predictions of critical current degradation, both in the initial load cycle and an additionally with cyclic loading. A first-pass global analysis of the magnet system found minimal out-of-plane deformations of the TF coil, but an overstress condition in the inner leg of the TF coil. However an analysis taking into account elastic-plastic behavior, frictional sliding, and displacement shows that the structure can safely carry the load. Although the design evolution is still at an early stage, these assessments support the design point choices to date and the expectation that a feasible solution for the high-field K DEMO magnet system can be found.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Negative ion production in the RF multiaperture surface-plasma source

The experiments on negative hydrogen ion beam production in a multi-aperture long-pulse surface-plasma source are described. H- ions are produced on the surface of a plasma grid covered by cesium and illuminated by fast plasma particles. The source uses a radio-frequency driver to generate plasma. A composite magnet system made of external permanent magnets confines and filters electrons in the plasma region, and deflects them in the extraction area. A multiaperture, multi-electrode ion optical system is used for beam formation. The electrode heating and cooling during long pulses is accomplished by circulating a heat transfer fluid through channels drilled in the electrodes bodies. H- ions extraction through a single aperture and 21 apertures was performed and studied. A stable H- beam with the current up to 0.7 A, energy up to 74 kV, and pulse duration up to 7 s was routinely obtained.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

A Comparative Study of Fracture Toughness at Cryogenic Temperature of Austenitic Stainless Steel Welds

The ITER magnet system is based on the “cable-in-conduit” conductor (CICC) concept, which consists of stainless steel jackets filled with superconducting strands. The jackets provide high strength, limited fatigue crack growth rate and fracture toughness properties to counteract the high stress imposed by, among others, electromagnetic loads at cryogenic temperature. Austenitic nitrogen-strengthened stainless steels have been chosen as base material for the jackets of the central solenoid and the toroidal field system, for which an extensive set of cryogenic mechanical property data are readily available. However, little is published for their welded joints, and their specific performance when considering different combinations of parent and filler metals. Moreover, the impact of post-weld heat treatments that are required for Nb{sub 3}Sn formation is not extensively treated. Welds are frequently responsible for cracks initiated and propagated by fatigue during service, causing structural failure. It becomes thus essential to select the most suitable combination of parent and filler material and to assess their performance in terms of strength and crack propagation at operation conditions. An extensive test campaign has been conducted at 7 K comparing tungsten inert gas (TIG) welds using two fillers adapted to cryogenic service, EN 1.4453 and JK2LB, applied to two different base metals, AISI 316L and 316LN. A large set of fracture toughness data are presented, and the detrimental effect on fracture toughness of post-weld heat treatments (unavoidable for some of the components) is demonstrated. In this study, austenitic stainless steel TIG welds with various filler metals have undergone a comprehensive fracture mechanics characterization at 7 K. These results are directly exploitable and contribute to the cryogenic fracture mechanics properties database of the ITER magnet system. Additionally, a correlation between the impact in fracture toughness and microstructure resulting from the above treatment is provided.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Binding a hopfion in a chiral magnet nanodisk

Hopfions are three-dimensional (3D) topological textures characterized by the integer Hopf invariant $Q_H$. In this article, we present the realization of a zero-field, stable hopfion spin texture in a magnetic system consisting of a chiral magnet nanodisk sandwiched by two films with perpendicular magnetic anisotropy. The preimages of the spin texture and numerical calculations of $Q_H$ show that the hopfion has $Q_H$ = 1. Furthermore, another nontrivial state that includes a monopole-antimonopole pair (MAP) is also stabilized in this system. By applying an external magnetic field, hopfion and MAP states with the same polarization can be switched between each other. The topological transition between the hopfion and the MAP state involves a creation (annihilation) of the MAP and twist of the preimages. Our work paves the way to study nontrivial 3D topological spin textures and stimulates more investigations in the field of 3D spintronics.

36 MATERIALS SCIENCE↗