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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Influence of the neutron-skin effect on nuclear isobar collisions at energies available at the BNL Relativistic Heavy Ion Collider

The unambiguous observation of a Chiral Magnetic Effect (CME)-driven charge separation is the core aim of the isobar program at RHIC consisting of $96\atop{40}$Zr+$96\atop{40}$Zr and $96\atop{44}$Ru+$96\atop{44}$Ru collisions at √s NN = 200 GeV. We quantify the role of the spatial distributions of the nucleons in the isobars on both eccentricity and magnetic field strength within a relativistic hadronic transport approach (SMASH, Simulating Many Accelerated Strongly-interacting Hadrons). In particular, we introduce isospin-dependent nucleon-nucleon spatial correlations in the geometric description of both nuclei, deformation for $96\atop{44}$Ru and the so-called neutron skin effect for the neutron-rich isobar i.e. $96\atop{40}$Zr. The main result of this study is a reduction of the magnetic field strength difference between $96\atop{44}$Ru+$96\atop{44}$Ru and $96\atop{40}$Zr+$96\atop{40}$Zr by a factor of 2, from 10% to 5% in peripheral collisions when the neutron-skin effect is included. Further, we find an increase of the eccentricity ratio between the isobars by up to 10% in ultra-central collisions as due to the deformation of $96\atop{44}$Ru while neither the neutron skin effect nor the nucleon-nucleon correlations result into a significant modification of this observable with respect to the traditional Woods-Saxon modeling. Our results suggest a significantly smaller CME signal to background ratio for the experimental charge separation measurement in peripheral collisions with the isobar systems than previously expected.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Nonlinear dynamics of proton beams with hollow electron lens in the CERN high-luminosity LHC

The design stored beam energy in the CERN high-luminosity large hadron collider (HL-LHC) upgrade is about 700 MJ, with about 36 MJ in the beam tails, according to estimates based on scaling considerations from measurements at the LHC. Such a large amount of stored energy in the beam tails poses serious challenges on its control and safe disposal. In particular, orbit jitters can cause significant losses on primary collimators, which can lead to accidental beam dumps, magnet quenches, or even permanent damage to collimators and other accelerator elements. Thus, active control of the diffusion speed of halo particles is necessary and the use of hollow electron lenses (HELs) represents the most promising approach to handle overpopulated tails at the HL-LHC. HEL is a very powerful and advanced tool that can be used for controlled depletion of beam tails, thus enhancing the performance of beam halo collimation. For these reasons, HELs have been recently included in the HL-LHC baseline. In this paper, we present detailed beam dynamics calculations performed with the goal of defining HEL specifications and operational scenarios for HL-LHC. The prospects for effective halo control in HL-LHC are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Improved measurements of nonlinear integrable optics at IOTA

Nonlinear integrable optics (NIO) are a promising novel approach at improving the stability of high intensity beams. Implementations of NIO based on specialized magnetic elements are being tested at the Integrable Optics Test Accelerator (IOTA) at Fermilab. One method of verifying proper implementation of these solutions is by measuring the analytic invariants predicted by theory. The initial measurements of nonlinear invariants were performed during IOTA run in 2019/20, however the covid-19 pandemic prevented the full-scale experimental program from being completed. Several important improvements were implemented in IOTA for the 2022/23 run, including the operation at higher beam energy of 150 MeV, improved optics control, and chromaticity correction. This report presents on the improved calibrations of the NIO for nonlinear invariant measurements.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Fermilab Automation of Coil Winding System

The automated coil winder project creates a repeatable, scalable method for producing superconducting magnet coils with increased accuracy and efficiency. The design uses an ortho cyclic winding method to achieve high fill factors by combining computer numerical control (CNC), microcontroller-based controls, and sophisticated optimization techniques. The method optimizes coil turns, core geometry, and current consumption by utilizing analytical models based on magnetic moment, Ohm’s law, and power constraints. For particle accelerator applications, prototype testing using a 3D-printed coil winder has shown enhanced winding repeatability, thermal management, and manufacturability.

Dzida, Rafal [Northern Illinois U.]↗
DOE OSTI2025

Current Progress on the High-Field Cable Testing Facility at Fermilab

Fermi National Accelerator Laboratory (Fermilab) is constructing a new High Field Vertical Magnet Test Facility (HFVMTF) with capabilities comparable to the European facilities EDIPO and FRESCA2. The facility, located at Fermilab, will feature a background magnetic field of 15 T, generated by a magnet provided by Lawrence Berkeley National Laboratory (LBNL). The HFVMTF will support two U.S. national programs under the DOE Office of Science: the U.S. Fusion Energy Science (FES) program and the Magnet Development Program (MDP). It will enable the testing of HTS samples in high magnetic fields across a wide range of temperatures and facilitate the development of hybrid magnets combining LTS and HTS superconductors. This paper presents an overview of the current progress in constructing the facility, including updates on the test cryostat, power supplies, and systems for quench protection and monitoring.

Velev, G. [Fermilab]↗
DOE OSTI2023

Improved Measurements of Nonlinear Integrable Optics Invariants at IOTA

Nonlinear integrable optics (NIO) are a promising novel approach at improving the stability of high intensity beams. Implementations of NIO based on specialized magnetic elements are being tested at the Integrable Optics Test Accelerator (IOTA) at Fermilab. One method of verifying proper implementation of these solutions is by measuring the analytic invariants predicted by theory. The initial measurements of nonlinear invariants were performed during IOTA run in 2019/20, however the covid-19 pandemic prevented the full-scale experimental program from being completed. Several important improvements were implemented in IOTA for the 2022/23 run, including the operation at higher beam energy of 150 MeV, improved optics control, and chromaticity correction. This report presents the results of improved measurements of nonlinear invariants.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

AUP first Pre-series Cold Mass Installation into the Cryostat

For the Hi-Lumi LHC Upgrade (HL-LHC) new high field and large-aperture quadrupole magnets for the low-beta inner triplets (Q1, Q2, Q3) are being built. These new quadrupole magnets are based on Nb3Sn superconducting technology. As part of the US-HiLumi Accelerator Upgrade Project (AUP) ten Cryostat Assemblies (LQXFA) for Q1 and Q3 replacement will be built, tested and delivered to CERN. The first of the LQXFA was assembled and tested at Fermi National Accelerator Laboratory (FNAL) during the fall of 2022 and spring 2023. We will present the integration work of the Cold Mass assembly into the Cryostat Kit provided by CERN. Each Cold Mass contains two trained MQXFA magnets of ~ 5 m length installed in a stainless-steel helium pressure vessel. The Cold Mass will be surrounded by cryostat shields, piping, and vacuum vessel. We will discuss the metrology survey results and present the LQXFA measurements prior testing at the Fermilab Magnet Test facility and lessons learned.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Understanding sextupole

In this study, we reassess the dynamics within a simple accelerator lattice featuring a single degree of freedom and incorporating a sextupole magnet. In the initial segment, we revisit the H\'enon quadratic map, a representation of a general transformation with quadratic nonlinearity. In the subsequent section, we unveil that a conventional sextupole is essentially a composite structure, comprising an integrable McMillan sextupole and octupole, along with non-integrable corrections of higher orders. This fresh perspective sheds light on the fundamental nature of the sextupole magnet, providing a more nuanced understanding of its far-from-trivial chaotic dynamics. Importantly, it enables the description of driving terms of the second and third orders and introduces associated nonlinear Courant-Snyder invariant.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Impact of solenoid induced residual magnetic fields on the prototype SSR1 CM performance

A prototype cryomodule containing eight Single Spoke Resonators type-1 (SSR1) operating at 325 MHz and four superconducting focusing lenses was successfully assembled, cold tested, and accelerated beam in the framework of the PIP-II project at Fermilab. The impact of induced residual magnetic fields from the solenoids on performance of cavities is presented in this contribution. In addition, design optimizations for the production cryomodules as a result of this impact are highlighted.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Role of Electron Correlation beyond the Active Space in Achieving Quantitative Predictions of Spin-Phonon Relaxation

Single-molecule magnets (SMMs) are promising candidates for molecular-scale data storage and processing due to their strong magnetic anisotropy and long spin relaxation times. However, as temperature rises, interactions between electronic states and lattice vibrations accelerate spin relaxation, significantly limiting their practical applications. Recently, ab initio simulations have made it possible to advance our understanding of phonon-induced magnetic relaxation, but significant deviations from experiments have often been observed. The description of molecules’ electronic structure has been mostly based on complete active space self-consistent field (CASSCF) calculations, and the impact of electron correlation beyond the active space remains largely unexplored. In this study, we provide the first systematic investigation of spin-phonon relaxation in SMMs with post-CASSCF multiconfigurational methods, specifically CAS followed by second-order perturbation theory and multiconfiguration pair-density functional theory. Taking Co(II)- and Dy(III)-based SMMs as case studies, we analyze how electron correlation influences spin-phonon relaxation rates across a range of temperatures, comparing theoretical predictions with experimental observations. Our findings demonstrate that post-CASSCF treatments make it possible to achieve quantitative predictions for Co(II)-based SMMs. For Dy(III)-based systems, however, accurate predictions require consideration of additional effects, underscoring the urgent necessity of further advancing the study of the effects of electronic correlation in these complex systems.

Energy↗
DOE OSTI2020

Compact, Achromatic Non-scaling FFAG Accelerator for HEP, Commercial and Medical Applications (CRADA FRA-2008-0005 Final Report)

Proton and light-ion accelerators have many research and medical applications, but the current state of technology in accelerators severely limits their widespread use: (1) synchrotrons have an intrinsic low duty cycle and become quite large for light ions; and (2) cyclotrons do not have energy variability and require complex superconducting magnets for high energy. A new concept in non-scaling Fixed-Field Alternating-Gradient (FFAGs) has been invented that incorporates both the energy variability of the synchrotron and the high duty cycle of the cyclotron. The concept uses normal-conducting, combined-function magnets that apply only constant (dipole) and linear-gradient (quadrupole) fields to stabilize the accelerator. This project will develop an optimized design for a new non-scaling and cost-effective innovation in FFAG accelerators. The accelerator design will have optics that can stably accelerate protons to 250 MeV (or higher) and carbon ions to =200 MeV, an energy considered ideal for radiation therapy. Phase I will optimize, fully simulate, and demonstrate the feasibility of this accelerator. Commercial Applications and other Benefits as described by the awardee: The fixed-field acceleration concept should eliminate some of the most pronounced technical difficulties, expense, maintenance, and required expertise faced in conventional proton and light-ion accelerators. In addition to the application for high energy physics, these accelerators should have application in cancer treatment, radiopharmaceuticals, and medical isotope production, and materials science.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Electron pulse train accelerated by a linearly polarized Laguerre–Gaussian laser beam

A linearly polarized Laguerre–Gaussian (LP-LG) laser beam with a twist index $l$ = –1 has field structure that fundamentally differs from the field structure of a conventional linearly polarized Gaussian beam. Close to the axis of the LP-LG beam, the longitudinal electric and magnetic fields dominate over the transverse components. This structure offers an attractive opportunity to accelerate electrons in vacuum. It is shown, using three-dimensional particle-in-cell simulations, that this scenario can be realized by reflecting an LP-LG laser off a plasma with a sharp density gradient. The simulations indicate that a 600 TW LP-LG laser beam effectively injects electrons into the beam during the reflection. The electrons that are injected close to the laser axis experience a prolonged longitudinal acceleration by the longitudinal laser electric field. The electrons form distinct monoenergetic bunches with a small divergence angle. The energy in the most energetic bunch is 0.29 GeV. The bunch charge is 6 pC and its duration is approximately 270 as. The divergence angle is just 0.57° (10 mrad). By using a linearly polarized rather than a circularly polarized Laguerre–Gaussian beam, our scheme makes it easier to demonstrate the electron acceleration experimentally at a high-power laser facility.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Preface for frontiers of magnetic reconnection research in heliophysical, astrophysical, and laboratory plasmas

Magnetic reconnection—the topological rearrangement of magnetic field—underlies many explosive phenomena across a wide range of natural and laboratory plasmas.3 It plays a pivotal role in electron and ion heating, particle acceleration to high energies, energy transport, and self-organization. Reconnection can have a complex relationship with turbulence at both large and small scales, leading to various effects that are only beginning to be understood. In heliophysics, magnetic reconnection plays a key role in solar flares, coronal mass ejections, coronal heating, solar wind dissipation, the interaction of interplanetary plasma with magnetospheres, dynamics of planetary magnetospheres such as magnetic substorms, and the heliospheric boundary with the interstellar medium. Here, the magnetic reconnection is integral to the solar and planetary dynamo processes.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Hints of primordial magnetic fields at recombination and implications for the Hubble tension

Primordial Magnetic Fields (PMFs), long studied as relics of the early Universe, accelerate recombination and have been proposed as a way to relieve the Hubble tension. However, previous studies relied on simplified toy models. Here, in this study, we use recent evaluations of recombination with PMFs, incorporating full magnetohydrodynamic (MHD) simulations and detailed Lyman-alpha radiative transfer, to test PMF-enhanced recombination (bΛCDM) against observational data from the cosmic microwave background (CMB), baryon acoustic oscillations (BAO), and Type Ia supernovae (SN). Focusing on non-helical PMFs with a Batchelor spectrum, we find a preference for presentday total field strengths of approximately 5-10 pico-Gauss. Depending on the dataset combination, this preference ranges from mild (∼ 1.8σ with Planck + DESI) to moderate (∼ 3σ with Planck + DESI + SH0ES-calibrated SN) significance. The bΛCDM has Planck + DESI χ 2 values equal to or better than ΛCDM while predicting a higher Hubble constant. Future high-resolution CMB temperature and polarization measurements will be crucial for confirming or further constraining PMFs at recombination. Field strengths of 5-10 pico-Gauss align closely with those required for cluster magnetic fields to originate entirely from primordial sources, without the need for additional dynamo amplification.

Jedamzik, Karsten [Centre National de la Recherche↗
DOE OSTI2022

Preliminary Results from Magnetic Field Scanning System for a Single-Cell Niobium Cavity

One of the building blocks of modern particle accelerators is superconducting radiofrequency (SRF) cavities. Niobium is the material of choice to build such cavities, which operate at liquid helium temperature (2 - 4 K) and have some of the highest quality factors found in Nature. There are several sources of residual losses, one of them is trapped magnetic flux, which limits the quality factor in SRF cavities. The flux trapping mechanism depends on different niobium surface preparations and cool-down conditions. Suitable diagnostic tools are not yet available to study the effects of such conditions on magnetic flux trapping. A magnetic field scanning system (MFSS) for SRF cavities using Hall probes and Fluxgate magnetometer has been designed, built, and is commissioned to measure the local magnetic field trapped in 1.3 GHz single-cell SRF cavities at 4 K. In this contribution, we will present the preliminary results from MFSS for a single cell niobium cavity.

Ciovati, G.↗
DOE OSTI2021

Design and Construction of a High Field Cable Test Facility at Fermilab

Fermi National Accelerator Laboratory, together with Lawrence Berkeley National Laboratory, is building a new High Field Vertical Magnet Test Facility (HFVMTF) to be situated in the Magnet Test Facility at Fermilab. The HFVMTF is jointly funded by the US DOE Offices of Science, High Energy Physics, and Fusion Energy Sciences, and will serve as a superconducting cable test facility for both communities. The background magnetic field for test samples is 15 T and will be produced by a magnet provided by LBNL operating at 1.9 K in superfluid helium. The samples will be placed in the background magnetic field, cooled to between 4.5 K and a user-specified upper limit, and will be powered with a super-conducting transformer at up to 100 kA. Additionally, this facility will be used to test high-field superconducting magnet models and demonstrators, including hybrid magnets, produced by the US Magnet Development Program. Presently, the various tasks of the project are at different stages of execution, from conceptual to ready-for-construction designs. Here, this paper describes the parameters and design status of the pit construction, cryostat, heat exchanger, lambda plate, power system, and quench protection and monitoring systems of the facility.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Relativistic Magnetic Reconnection in Astrophysical Plasmas: A Powerful Mechanism of Nonthermal Emission

Magnetic reconnection—a fundamental plasma physics process, where magnetic field lines of opposite polarity annihilate—is invoked in astrophysical plasmas as a powerful mechanism of nonthermal particle acceleration, able to explain fast-evolving, bright high-energy flares. Near black holes and neutron stars, reconnection occurs in the relativistic regime, in which the mean magnetic energy per particle exceeds the rest mass energy. This review reports recent advances in our understanding of the kinetic physics of relativistic reconnection (RR): ▪ Kinetic simulations have elucidated the physics of plasma heating and nonthermal particle acceleration in RR. ▪ The physics of radiative RR, with its self-consistent interplay between photons and reconnection-accelerated particles—a peculiarity of luminous, high-energy astrophysical sources—is the new frontier of research. ▪ RR plays a key role in global models of high-energy sources, in terms of both global-scale layers and reconnection sites generated as a by-product of local magnetohydrodynamic instabilities. We summarize themes of active investigation and future directions, emphasizing the role of upcoming observational capabilities, laboratory experiments, and new computational tools.

acceleration of particles↗