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DOE OSTI2023

A Flexible Field Mapping System for Accelerator Magnets

Magnetic field mapping is a fundamental magnetic measurement method that typically uses Hall and NMR sensors. In magnet measurement facilities, such systems are likely used in various configurations suitable for a specific task at hand. To address this diversity, the authors developed a flexible field mapping system capable of being configured and tailored to each particular measurement case. Further, the system needs to address the variability introduced by differences in sensors and their readout systems, probe positioning systems, power supply systems, and required mapping geometry (mapping space and grid, measurement steps and sequences). Although the discussed field mapping systems range from a self-propelled multi-sensor mapper of a large detector magnet to a single 3D Hall sensor system to scan a small permanent magnet, they were all built with the same core mapping system. The variability present in field mapping systems, the measurement system architecture addressing this variability, as well as examples of several field mapping systems built in this architecture are presented.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2015

Highly efficient conductance control in a topological insulator based magnetoelectric transistor

The spin-momentum interlocked properties of the topological insulator (TI) surface states are exploited in a transistor-like structure for efficient conductance control in the TI-magnet system. Combined with the electrically induced magnetization rotation as part of the gate function, the proposed structure takes advantage of the magnetically modulated TI electronic band dispersion in addition to the conventional electrostatic barrier. The transport analysis coupled with the magnetic simulation predicts super-steep current-voltage characteristics near the threshold along with the GHz operating frequencies. Potential implementation to a complementary logic is also examined. The predicted characteristics are most suitable for applications requiring low power or those with small signals.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2023

Electronic signatures of successive itinerant, antiferromagnetic transitions in hexagonal La 2 Ni 7

We use high-resolution angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) calculations to study the electronic and magnetic properties of La 2 Ni 7 , an itinerant magnetic system with a series of three magnetic transition temperatures upon cooling, which end in a small moment antiferromagnetic (smAFM) ground state. Our APRES data reveal several electron and hole pockets that have hexagonal symmetry near the Γ point. We observe significant reconstruction of the band structure upon successive magnetic transitions at T 1 ~ 61 K, T 2 ~ 57 K and T 3 ~ 42 K. Several features observed in ARPES data were reasonably well reproduced by DFT calculations, while others were not. In particular, the flat band near E f predicted by DFT in AFM state, was seemingly absent in ARPES data. Our results detail the effects of magnetic ordering on the electronic structure in a Ni-based small moment antiferromagnet and highlight challenges of current computational methods.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2019

Local chiral interactions and magnetic structure of few-nucleon systems

The magnetic form factors of 2 H, 3 H, and 3 He, deuteron photodisintegration cross sections at low energies, and deuteron threshold electrodisintegration cross sections at backward angles in a wide range of momentum transfers are calculated with the chiral two-nucleon (and three-nucleon) interactions including Δ intermediate states that have recently been constructed in configuration space. The A=3 wave functions are obtained from hyperspherical-harmonics solutions of the Schrödinger equation. The electromagnetic current includes one- and two-body terms, the latter induced by one- and two-pion exchange (OPE and TPE, respectively) mechanisms and contact interactions. The contributions associated with Δ intermediate states are only retained at the OPE level and are neglected in TPE loop (tree-level) corrections to two-body (three-body) current operators. Expressions for these currents are derived and regularized in configuration space for consistency with the interactions. The low-energy constants that enter the contact currents are determined by reproducing the magnetic moments of these few-nucleon systems. The predicted form factors and deuteron electrodisintegration cross section are in excellent agreement with experiment for momentum transfers up to 2–3fm –1 . However, the experimental values for the deuteron photodisintegration cross section are consistently underestimated by theory, unless use is made of the Siegert form of the electric dipole transition operator. In conclusion, a complete analysis of the results is provided, including the clarification of the origin of the aforementioned discrepancy.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2017

Field Mapper for Superconducting Torus Magnet for the Jefferson Lab 12GeV Upgrade

As part of the Jefferson Lab 12 GeV upgrade, the Hall B magnet system requires two conduction cooled superconducting magnets ? a Torus and a Solenoid. The Torus consists of 6 trapezoidal coils connected in series with an operating current of 3770 A. During commissioning of the torus magnet, field mapping was carried out at different levels of operating current in order to determine the field profile and field error table. In order to meet the physics requirement of the field accuracy we need magnetic field strength measurements which are accurate at the 0.1% level, and we need to know radius and azimuth to 0.1 mm and z to 0.5 mm. The center line of the torus magnet is approximately 6 m from ground level and the overall height of the torus magnet is approximately 8.5 m. There is also limited space around the magnet and in between the coils. Field mapping had to be carried out along the Z axis (i.e. along the bore) and at 4 radial locations between each coil. These restrictions provided certain challenges for the magnetic field mapping task. The mapper prototype was built and tested prior to use on the Torus itself. In this presentation the field mapper design, prototyping and actual data collection procedure will be presented.

Rajput-Ghoshal, Renuka↗

NASA NTRS1974

The role of solar local time in polar cap magnetic variations

The role of the earth's main field in controlling the morphology of magnetic disturbance is usually accounted for by use of invariant latitude and MLT (magnetic local time) as a coordinate system. Magnetic disturbance from ionospheric currents is also controlled by ionospheric conductivity. At high latitudes, where SLT (solar local time) can be very different from MLT, the use of only MLT can give misleading results. In particular, those diurnal magnetic variations in the polar cap that change characteristics between interplanetary magnetic sectors have a tendency to peak near noon SLT rather than noon MLT at Alert, where noon MLT and noon SLT differ by more than 10 hours. Because of the sparsity of magnetic observatories it is not possible to completely separate SLT and MLT effects.

Langel, R. A.↗

NASA NTRS1986

Advances in cryogenic engineering. Volume 31; Proceedings of the Cryogenic Engineering Conference, MIT, Cambridge, MA, Aug. 12-16, 1985

The present conference on the applications of state-of-the-art cryogenic engineering technologies considers topics associated with the development status of the 'Superconducting SuperCollider', superconducting magnetic energy storage methods, large magnets for fusion and other physics researches, cryogenic hardware improvements, and phenomena and applications of superconducting magnet-employing acoustic emission test equipment. Also discussed are design criteria for superconducting magnet stability, heat exchangers and heat transfer to liquid He and N, heat and mass transfer characteristics of He II, refrigeration techniques for magnetic resonance imaging and other small systems, refrigeration for liquefaction and for superconducting fusion as well as for accelerator and generator systems, magnetic refrigeration, cryocooling and refrigeration for space applications, the storage and transfer of cryogenic fluids, the properties of cryogenic liquids, and air liquefaction equipment.

Fast, R. W.↗

NASA NTRS1994

Applications drivers for data parking on the Information Superhighway

As the cost of data storage continues to decline (currently about one-millionth of its cost four decades ago) entirely new applications areas become economically feasible. Many of these new areas involved the extraordinarily high data rates and universal connectivity soon to be provided by the National Information Infrastructure (NII). The commonly held belief is that the main driver for the NII will be entertainment applications. We believe that entertainment applications as currently touted (multi-media, 500 video channels, video-on-demand, etc.) will play an important but far from dominant role in the development of the NII and its data storage components. The most pervasively effective drivers will be medical applications such as telemedicine and remote diagnosis, education and environmental monitoring. These applications have a significant funding base and offer a clearly perceived opportunity to improve the nation's standard of living. The NII's wideband connectivity both nationwide and worldwide requires a broad spectrum of data storage devices with a wide-range of performance capabilities. These storage centers will be dispersed throughout the system. Magnetic recording devices will fill the majority of these new data storage requirements for at least the rest of this century. The storage needs of various application areas and their respective market sizes will be explored. The comparative performance of various magnetic technologies and competitive alternative storage systems will be discussed.

Johnson, Clark E., Jr.↗

DOE OSTI2023

Systems and methods for additive manufacturing magnetic solenoids

Systems and methods for forming a magnetically-enabled part via additive manufacturing. The method includes depositing a layer of additive manufacturing material on a build plate, melting or sintering the layer of additive manufacturing material, depositing additional layers of additive manufacturing material on previous layers of additive manufacturing material, the additive manufacturing material of at least some of the additional layers being magnetically permeable, and melting or sintering the additional layers of additive manufacturing material such that the magnetically-enabled part has a transition region including at least some of the magnetically permeable additive manufacturing material.

Hatch, Jonathan Douglas↗

DOE OSTI2024

Systems and methods for additive manufacturing magnetic solenoids

Hatch, Jonathan Douglas↗

DOE OSTI2023

A Flexible Field Mapping System for Accelerator Magnets

Magnetic field mapping is a fundamental magnetic measurement method that typically uses Hall and NMR sensors. In magnet measurement facilities, such systems are likely used in various configurations suitable for a specific task at hand. To address this diversity, the authors developed a flexible field mapping system capable of being configured and tailored to each particular measurement case. The system needs to address the variability introduced by differences in sensors and their readout systems, probe positioning systems, power supply systems and in required mapping geometry (mapping space and grid, measurement steps and sequences). Although the discussed field mapping systems range from a self-propelled, multi-sensor mapper of a large detector magnet to a single 3D Hall sensor system to scan a small permanent magnet, they were all built with the same core mapping system. The variability present in field mapping systems and the measurement system architecture addressing this variability, as well as examples of several field mapping systems built in this architecture are presented.

43 PARTICLE ACCELERATORS↗

NASA NTRS1995

Dynamic modelling and response characteristics of a magnetic bearing rotor system with auxiliary bearings

Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotordynamic model which describes the dynamic behavior of a flexible rotor system with magnetic bearings including auxiliary bearings. The model is based upon an experimental test facility. Some simulation studies are presented to illustrate the behavior of the model. In particular, the effects of introducing sideloading from the magnetic bearing when one coil fails is studied.

Free, April M.↗

DOE OSTI2026

Quantum critical point followed by Kondo-like behavior due to Cu substitution in the itinerant antiferromagnet La 2 ⁢(Cu 𝑥 ⁢Ni 1−𝑥 ) 7

La 2 ⁢Ni 7 is an itinerant magnetic system with a small ordered moment of ∼ 0.1⁢µ 𝐵 /Ni and a series of antiferromagnetic (AFM) transitions at 𝑇 1 = 61.0K, 𝑇 2 = 56.5K, and 𝑇 3 = 42.2K. 𝑀 ⁡(𝐻), and 𝜌 ⁡(𝐻) isotherms as well as constant field 𝑀⁡ (𝑇) and 𝜌 ⁡(𝑇) measurements on single-crystalline samples manifest a complex, anisotropic 𝐻−𝑇 phase diagram with multiple phase lines. Here, in this study, we present the growth and characterization of single crystals of the La 2 ⁢(Cu 𝑥 ⁢Ni 1−𝑥 ) 7 series for 0 ≤ 𝑥 ≤ 0.181. We measured powder x-ray diffraction and composition, as well as anisotropic temperature- and field-dependent resistivity, temperature- and field-dependent magnetization, and temperature-dependent heat capacity on these single crystals. Using the measured data we infer a transition temperature-composition (𝑇−𝑥) phase diagram for this system to study the evolution of the AFM ordering upon Cu substitution. For 0 ≤ 𝑥 ≤ 0.097, the system remains magnetically ordered at base temperature with 𝑥 ≤ 0.012, showing signs of multiple AFM ordering temperatures. For the higher substitution levels 0.125 ≤ 𝑥 ≤ 0.181, there are no signatures of magnetic ordering, but anomalous features in resistance and heat capacity data are observed which are consistent with the Kondo effect in this system. The intermediate 𝑥 = 0.105 sample lies between the magnetic ordered and the Kondo regime and is in the vicinity of the AFM quantum critical point (QCP). Thus, La 2⁢ (Cu 𝑥 ⁢Ni 1−𝑥 ) 7 is an example of a small moment system that can be tuned through a QCP. Given these data combined with the fact that the La 2⁢ Ni 7 structure has kagomelike, Ni sublattices running perpendicular to the crystallographic 𝑐 axis, and a predicted 3⁢𝑑-electron flat band that contributes to the density of states near the Fermi energy, La 2 ⁢(Cu 𝑥 ⁢Ni 1−𝑥 ) 7 becomes a promising system to host and study exotic physics.

Das, Atreyee [Ames Laboratory, and Iowa State Univ↗

DOE OSTI2022

A Quench Detection and Monitoring System for Superconducting Magnets at Fermilab

A quench detection system was developed for protecting and monitoring the superconducting solenoids for the Muon-to-Electron Conversion Experiment (Mu2e) at Fermilab. The quench system was designed for a high level of dependability and long-term continuous operation. It is based on three tiers: Tier-I, FPGA-based Digital Quench Detection (DQD); Tier-II, Analog Quench Detection (AQD); and Tier-3, the quench controls and data management system. The Tier-I and Tier-II are completely independent and fully redundant systems. The Tier-3 system is based on National Instruments (NI) C-RIO and provides the user interface for quench controls and data management. It is independent from Tiers I & II. The DQD provides both quench detection and quench characterization (monitoring) capability. Both DQD and AQD have built-in high voltage isolation and user programmable gains and attenuations. The DQD and AQD also includes user configured current dependent thresholding and validation times. A 1 st article of the three-tier system was fully implemented on the new Fermilab magnet test stand for the HL-LHC Accelerator Up-grade Project (AUP). It successfully provided quench protection and monitoring (QPM) for a cold superconducting bus test in November 2020. The Mu2e quench detection design has since been implemented for production testing of the AUP magnets. A detailed description of the system along with results from the AUP superconducting bus test will be presented.

monitoring↗

NASA NTRS1992

Recent progress towards developing a high field, high-T(sub c) superconducting magnet for magnetic suspension and balance systems

This paper reviews superconducting magnets and high T(sub c) superconducting oxide ceramic materials technology to identify areas of fundamental impasse to the fabrication of components and devices that tap what are believed to be the true potential of these new materials. High T(sub c) ceramics pose problems in fundamentally different areas which need to be solved unlike low T(sub c) materials. The authors map out an experimental plan designed to research process technologies which, if suitably implemented, should allow these deficiencies to be solved. Finally, assessments are made of where and on what regimes magnetic system designers should focus their attention to advance the practical development of systems based on these new materials.

Derochemont, L. Pierre↗

DOE OSTI2018

Spontaneous Hall effects in the electron system at the SmTiO 3 /EuTiO 3 interface

Magnetotransport and magnetism of epitaxial SmTiO 3 /EuTiO 3 heterostructures grown by molecular beam epitaxy are investigated. It is shown that the polar discontinuity at the interface introduces ~3.9 × 10 14 cm -2 carriers into the EuTiO 3 . The itinerant carriers exhibit two distinct contributions to the spontaneous Hall effect. The anomalous Hall effect appears despite a very small magnetization, indicating a non-collinear spin structure, and the second contribution resembles a topological Hall effect. Qualitative differences exist in the temperature dependence of both Hall effects when compared to uniformly doped EuTiO 3 . In particular, the topological Hall effect contribution appears at higher temperatures and the anomalous Hall effect shows a sign change with temperature. The results suggest that interfaces can be used to tune topological phenomena in itinerant magnetic systems.

36 MATERIALS SCIENCE↗

NASA NTRS1991

The relict magnetism of meteorites

Meteorite paleomagnetic studies are reviewed and evaluated. Possible mechanisms for producing early solar system magnetic fields that could have been responsible for the magnetization of some or all meteorite classes are explored. A detailed review of paleointensity results derived from the various classes of meteorites is given, and the likelihood that the results might related to solar or nebulawide magnetic fields is considered. The implications of meteorite magnetism for early solar system evolution are discussed.

Cisowski, S. M.↗

DOE OSTI2022

Exchange bias and interface-related effects in two-dimensional van der Waals magnetic heterostructures: Open questions and perspectives

The exchange bias (EB) effect is known as a fundamentally and technologically important magnetic property of a magnetic bilayer film. It is manifested as a horizontal shift in a magnetic hysteresis loop of a film subject to cooling in the presence of a magnetic field. The EB effect in van der Waals (vdW) heterostructures offers a novel approach for tuning the magnetic properties of the newly discovered single-layer magnets, as well as adds a new impetus to magnetic vdW heterostructures. Indeed, intriguing EB effects have recently been reported in a variety of low-dimensional vdW magnetic systems ranging from a weakly interlayer-coupled vdW magnet (e.g., Fe 3 GeTe 2 ) to a bilayer composed of two different magnetic vdW materials (e.g., Fe 3 GeTe 2 /CrCl 3 , Fe 3 GeTe 2 /FePS 3 , Fe 3 GeTe 2 /MnPS 3 , Fe 3 GeTe 2 /CrSe, Fe 3 GeTe 2 /CrOCl, Fe 3 GeTe 2 /CoPc, Fe 5 GeTe 2 /FePS 3 ), to bilayers of two different vdW defective magnets (e.g., VSe 2 /MoS 2 ), or to metallic ferromagnet/vdW defective magnet interfaces (e.g., Fe/MoS 2 ). Despite their huge potential in spintronic device applications, the physical origins of the observed EB effects have remained elusive to researchers. Here, we present here a critical review of the EB effect and associated phenomena such as magnetic proximity (MP) in various vdW heterostructure systems and propose approaches to addressing some of the emerging fundamental questions.

2D magnets↗