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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Modeling of particle transport, neutrals and radiation in magnetically-confined plasmas with Aurora

In this work, we present Aurora, an open-source package for particle transport, neutrals and radiation modeling in magnetic confinement fusion plasmas. Aurora's modern multi-language interface enables simulations of 1.5D impurity transport within high-performance computing frameworks, particularly for the inference of particle transport coefficients. A user-friendly Python library allows simple interaction with atomic rates from the Atomic Data and Atomic Structure database as well as other sources. This enables a range of radiation predictions, both for power balance and spectroscopic analysis. We discuss here the superstaging approximation for complex ions, as a way to group charge states and reduce computational cost, demonstrating its wide applicability within the Aurora forward model and beyond. Aurora also facilitates neutral particle analysis, both from experimental spectroscopic data and other simulation codes. Leveraging Aurora's capabilities to interface SOLPS-ITER results, we demonstrate that charge exchange is unlikely to affect the total radiated power from the ITER core during high performance operation. Finally, we describe the ImpRad module in the one modeling framework for integrated task framework, developed to enable experimental analysis and transport inferences on multiple devices using Aurora.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Parametric raytracing modeling for NSTX-U scenario development with high harmonic fast waves and neutral beam injection

High harmonic fast waves (HHFW) are a versatile heating and current drive tool for scenario development. Extensive modeling scans were performed to find optimal parameters for different uses of HHFW in National Spherical Tokamak Experiment (NSTX-U). Scans of plasma density, temperature, magnetic field, and antenna phasing were performed both with and without neutral beam injection. For speed of calculation, the ray-tracing code GENRAY coupled to the quasilinear Fokker–Planck code CQL3D was used. CQL3D allows for a more accurate description of the fast ion population, as well as for quasilinear effects such as HHFW-induced modifications of the distribution function. Best current drive results are obtained at elevated electron temperatures and with the lowest k φ phasing. Adding neutral beams however typically strongly reduces the HHFW current drive efficiency at the low density cases due to HHFW absorption on beam ions. Results of this parametric study will feed into scenario development and predict-first whole-shot modeling of NSTX-U discharges.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Modelling the Alfvén eigenmode induced fast-ion flow measured by an imaging neutral particle analyzer

An imaging neutral particle analyzer (INPA) provides energy and radially resolved measurements of the confined fast-ion population ranging from the high-field side to the edge on the midplane of the DIII-D tokamak. In recent experiments, it was used to diagnose fast-ion flow in the INPA-interrogated phase-space driven by multiple, marginally unstable Alfvén eigenmodes (AEs). Here, the key features of this measured fast-ion flow are: (I) a fast-ion flow from q min and the injection energy (81 keV) towards lower energies and plasma periphery.(II) A flow from the same location towards higher energies and the plasma core, (III) a phase-space 'hole' at the injected energy and plasma core and (IV) a pile-up at the plasma core at lower energies (~60 keV). Ad hoc energetic particle diffusivity modelling of TRANSP significantly deviates from the observation. Comparably, a reduced modelling, i.e. a combination of NOVA-K and ASCOT5 code with the measured mode structure and amplitude, generally reproduce some key features of the observed phase-space flow, but largely failed to interpret fast ion depletion near the plasma axis. At last, self-consistent, first-principle multi-phase hybrid simulations that include realistic neutral beam injection and collisions are able to reproduce most features of the time-resolved phase-space flow. During consecutive hybrid phases, an RSAE consistent with the experiment grows and saturates, redistributing the injected fast ions. The resulting synthetic INPA images are in good agreement with the measurement near the injection energy. The simulations track the fast-ion redistribution within the INPA range, confirming that the measured fast-ion flow follows streamlines defined by the intersection of phase-space surfaces of constant magnetic moment μ and constant E' = nE + ωP φ , where n and ω are the instability toroidal mode number and frequency, and E and P φ the ion energy and toroidal canonical momentum. Nonperturbative effects are required to reproduce the depletion of fast ions near the magnetic axis at the injection energy.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Inference of main ion particle transport coefficients with experimentally constrained neutral ionization during edge localized mode recovery on DIII-D

Abstract The plasma and neutral density dynamics after an edge localized mode are investigated and utilized to infer the plasma transport coefficients for the density pedestal. The Lyman-Alpha Measurement Apparatus (LLAMA) diagnostic provides sub-millisecond profile measurements of the ionization and neutral density and shows significant poloidal asymmetries in both. Exploiting the absolute calibration of the LLAMA diagnostic allows quantitative comparison to the electron and main ion density profiles determined by charge-exchange recombination, Thomson scattering and interferometry. Separation of diffusion and convection contributions to the density pedestal transport are investigated through flux gradient methods and time-dependent forward modeling with Bayesian inference by adaptation of the Aurora transport code and IMPRAD framework to main ion particle transport. Both methods suggest time-dependent transport coefficients and are consistent with an inward particle pinch on the order of 1 m s −1 and diffusion coefficient of 0.05 m 2 s −1 in the steep density gradient region of the pedestal. While it is possible to recreate the experimentally observed phenomena with no pinch in the pedestal, low diffusion in the core and high outward convection in the near scrape-off layer are required without an inward pedestal pinch.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

First fluctuation measurements using an Imaging Neutral Particle Analyzer on DIII-D

A recent upgrade to the Imaging Neutral Particle Analyzer (INPA) on DIII-D has allowed for the first fluctuation measurements using an INPA to be taken during a neoclassical tearing mode (NTM). The INPA signal tracked the mode over 150 ms as the mode frequency dropped to zero, capturing both the NTM with poloidal and toroidal mode numbers $m/n=2/1$ and a $3/2$ mode at double the frequency. Analysis shows that the signals originate from charge exchange events near the edge of the plasma, and relative fluctuation amplitudes are greater than 25% for the duration of the NTM. Filtered signals show frequency beating patterns that are phase-space dependent. Simulated signal is dominated by prompt transport from the neutral beams to the INPA sightline, while the contribution from the slowing down distribution is significantly lower. Simulated measurements in the range of pitches that the diagnostic is sensitive to (0.5≤|v∥/v|≤ 0.75) show the signal is dominated by trapped orbits that pass through magnetic islands near the edge of the plasma. Calculations of expected fluctuation levels show that only direct interaction with the NTM can provide the strong relative fluctuation levels seen experimentally. The prompt nature of the orbits and thin radial layer found to contribute to synthetic signals suggest INPA passive data may be used to measure the perturbations of confined orbits on a single pass through a plasma instability.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

The neutral hydrogen mass in galaxies estimated via optical spectroscopy

ABSTRACT We propose to employ emission line luminosities obtained via optical spectroscopy to estimate the content of neutral hydrogen (H i) in galaxies. We use the optical spectroscopy data from the Mapping of Nearby Galaxies at APO (MaNGA) survey released in the frames of public DR17 of the Sloan Digital Sky Survey (SDSS). We compare the H i mass estimated by us for a large sample of SDSS/MaNGA galaxies with direct H i measurements from the Arecibo Legacy Fast ALFA survey and find a tight correlation between the masses with the correlation coefficient (CC) of 0.91 and the rms scatter of 0.15 dex for the logarithmic mass. The obtained relationship is verified via another sample of MaNGA galaxies with H i masses measured with the Green Bank Telescope. Despite the coarser angular resolution of the radio data, the relation between the estimated and measured directly H i mass is tight as well – in this case CC = 0.74 and the rms is 0.29 dex. The established relations allow us to estimate the total mass of neutral hydrogen as well as the spatial distribution of H i surface density in galaxies from optical spectroscopic observations only in a simple and efficient way.

Bizyaev, Dmitry (ORCID:000000023601133X)↗
DOE OSTI2026

Mode Multiplexing for Scalable Cavity-Enhanced Operations in Neutral-Atom Arrays

Neutral-atom arrays provide a versatile platform for quantum information processing. However, in large-scale arrays, efficient photon collection remains a bottleneck for key tasks such as fast, nondestructive qubit readout and remote entanglement distribution. We propose a cavity-based approach that enables fast, parallel operations over many atoms using multiple modes of a single optical cavity. By selectively shifting the relevant atomic transitions, each atom can be coupled to a distinct cavity mode, allowing independent simultaneous processing. We present practical system designs that support cavity-mode multiplexing with up to 50 modes, enabling rapid mid-circuit syndrome extraction and significantly enhancing entanglement distribution rates between remote atom arrays. This approach offers a scalable solution to core challenges in neutral-atom arrays, advancing the development of practical quantum technologies.

Aqua, Ziv [Massachusetts Institute of Technology (↗
DOE OSTI2025

Measurement of magnetic dipole strength in 40 Ar between 9.3 and 10.3 MeV excitation energy and impact on neutral current neutrino interaction

The magnetic dipole strength 𝐵⁡(𝑀⁢1 ↑) of 40 Ar was measured in the excitation energy range between 9.3 and 10.3 MeV. The nuclear resonance fluorescence technique was used with monoenergetic, linearly polarized incident photon beams. The new data increase the known 𝐵⁡(𝑀⁢1 ↑) strength in this important excitation energy range by a factor of 2, resulting in an equivalent increase of the calculated neutral current neutrino cross section of 40 Ar . This observation is of special interest for liquid-argon (LAr)-based neutrino detectors. 𝐵⁡(𝑀⁢1 ↑) strength has not been found between 10.3 and 11.7 MeV excitation energy. In conclusion, with the new data, a more reliable detection capability of the large Deep Underground Neutrino Experiment LAr detectors can be derived for potential core-collapse supernova neutrinos via the neutral current interaction.

Energy levels↗
DOE OSTI2025

Suppression of neutral-pion production in deep-inelastic scattering off nuclei with the CLAS detector

We present the first threefold differential measurement for neutral-pion multiplicity ratios produced in semi-inclusive deep-inelastic electron scattering on carbon, iron, and lead nuclei normalized to deuterium from CLAS at Jefferson Lab. We found that the neutral-pion multiplicity ratio is maximally suppressed for the leading hadrons (energy fraction 𝑧 → 1), suppression varying from 25% in carbon up to 75% in lead. An enhancement of the multiplicity ratio at low 𝑧 and high 𝑝$^2_𝑇$ is observed, suggesting an interconnection between these two variables. This behavior is qualitatively similar to the previous twofold differential measurement of charged pions by the HERMES Collaboration and, recently, by CLAS Collaboration. The largest enhancement was observed at high 𝑝$^2_𝑇$ for heavier nuclei, namely, iron and lead, while the smallest enhancement was observed for the lightest nucleus, carbon. This behavior suggests a competition between partonic multiple scattering, which causes enhancement, and hadronic inelastic scattering, which causes suppression.

color confinement↗
DOE OSTI2022

Laser-induced-fluorescence imaging of a spin-polarized ultracold neutral plasma in a magnetic field

In this work, we report Doppler-sensitive laser-induced-fluorescence (LIF) imaging of an ultracold neutral plasma in a magnetic field. Local values of ion density, hydrodynamic fluid velocity, temperature, and spin polarization are obtained using a fluorescence model based on velocity-resolved rate equations (REs) including the transfer of ions between states due to laser coupling and spontaneous emission. The RE approach captures optical pumping of ions into states that are not driven by the LIF excitation laser, and this is validated with experimental data. Combined molecular-dynamics and quantum-trajectories simulations verify that velocity-changing collisions have a negligible impact on the state population evolution for typical experimental conditions. Relative intensities of Zeeman components of the LIF spectra provide clear evidence that the ions are electron-spin-polarized when created by photoionization of magnetically trapped 88 Sr atoms. This probe opens many possibilities for studying thermal transport and the equilibration of neutral plasmas in overlapping regimes of strong coupling and magnetization.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Na 22 activation level measurements of fused silica rods in the LHC target absorber for neutrals compared to simulations

The Target Absorbers for Neutrals (TANs) are located in a high intensity radiation environment inside the tunnel of the Large Hadron Collider (LHC). TANs are positioned about 140 m downstream from the beam interaction points. Seven 40-cm long fused silica rods with different dopant specifications were irradiated in the TAN by the Beam RAte of Neutrals (BRAN) detector group during p + p data taking from 2016 to 2018 at the LHC. The peak dose delivered to the fused silica rods was 18 MGy. We report measurements of the 22 Na activation of the fused silica rods carried out at the University of Illinois at Urbana-Champaign and Argonne National Laboratory. At the end of the irradiation campaign, the maximum 22 Na activity observed was A = 21 kBq/cm 3 corresponding to a density, ρ = 2.5 x 10 12 /cm 3 , of 22 Na nuclei. FLUKA Monte Carlo simulations have been performed by the CERN FLUKA team to estimate 22 Na activities for the irradiated BRAN rod samples. The simulations reproduce the 22 Na activity profile measured along the rods, with a 35% underestimation of the experimental measurement results.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

False vacuum decay and nucleation dynamics in neutral atom systems

Metastable states of quantum many-body systems with confinement offer a means to simulate false vacuum phenomenology, including nonequilibrium dynamical processes like decay by nucleation, in truncated limits. Recent work has examined the decay process in one-dimensional (1D) ferromagnetic Ising spins and superfluids. Here, in this paper, we study nucleation dynamics in 1D antiferromagnetic neutral atom chains with Rydberg interactions, using both numerical simulations and analytic modeling. We apply a staggered local detuning field to generate the metastable and ground states. Our efforts focus on two dynamical regimes: decay and annealing. In the first, we corroborate the phenomenological decay rate scaling and determine the associated parameter range for the decay process; in the second, we uncover and elucidate a procedure to anneal the metastable state from the initial to the final system, with intermediate nucleation events. We further propose experimental protocols to prepare the required states and perform quenches on near-term neutral atom quantum simulators, examining the experimental feasibility of our proposed setup and parameter regime.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

Measurement of neutrino-induced neutral-current coherent $π^0$ production in the NOvA near detector

The cross section of neutrino-induced neutral-current coherent $\pi^0$ production on a carbon-dominated target is measured in the NOvA near detector. This measurement uses a narrow-band neutrino beam with the average neutrino energy of 2.7\,GeV, xwhich is of interest to the ongoing and future long-baseline neutrino oscillation experiments. The measured, flux-averaged cross section is $\sigma = 14.0\pm0.9$\,(stat.)$\pm2.1$\,(syst.)$\times 10^{-40}$ $\text{cm}^2/$nucleus, consistent with model prediction. This result is the most precise measurement of neutral-current coherent $\pi^0$ production in the few-GeV neutrino energy region.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Magnetized neutral 2SC color superconductivity and possible origin of the inner magnetic field of magnetars

In this paper, the neutral 2SC phase of color superconductivity is investigated in the presence of a magnetic field and for diquark coupling constants and baryonic densities that are expected to characterize neutron stars. Specifically, the behavior of the charged gluons Meissner masses is investigated in the parameter region of interest, taking into account, in addition, the contribution of a rotated magnetic field. It is found that up to moderately high diquark coupling constants the mentioned Meissner masses become tachyonic independently of the applied magnetic-field amplitude, hence signalizing the chromomagnetic instability of this phase. To remove the instability, the restructuring of the system ground state is proposed, which now will be formed by vortices of the rotated charged gluons. These vortices boost the applied magnetic field, having the most significant increase for relatively low applied magnetic fields. Finally, considering that with the stellar rotational frequency observed for magnetars a field of the order of 10 8 G can be generated by dynamo effect, we show that by the boosting effect just described the field can be amplified to 10 17 G that is in the range of inner core fields expected for magnetars. Thus, we conclude that the described mechanism could be the one responsible for the large fields characterizing magnetars if the cores of these compact objects are formed by neutral 2SC matter. Published by the American Physical Society 2024

Yuan, Shuai↗
DOE OSTI2024

Heavy Neutral Leptons via Axionlike Particles at Neutrino Facilities

Heavy neutral leptons (HNLs) are often among the hypothetical ingredients behind nonzero neutrino masses. If sufficiently light, they can be produced and detected in fixed-target-like experiments. We show that if the HNLs belong to a richer—but rather generic—dark sector, their production mechanism can deviate dramatically from expectations associated with the standard-model weak interactions. In more detail, we postulate that the dark sector contains an axionlike particle (ALP) that naturally decays into HNLs. Since ALPs mix with the pseudoscalar hadrons, the HNL flux might be predominantly associated with the production of neutral mesons (e.g., π 0 , η ) as opposed to charge hadrons (e.g., π ± , K ± ). In this case, the physics responsible for HNL production and decay are not directly related and experiments like DUNE might be sensitive to HNLs that are too weakly coupled to the standard model to be produced via weak interactions, as is generically the case of HNLs that play a direct role in the type-I seesaw mechanism. Published by the American Physical Society 2024

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

First Double-Differential Cross Section Measurement of Neutral-Current 𝜋 0 Production in Neutrino-Argon Scattering in the MicroBooNE Detector

We report the first double-differential cross section measurement of neutral-current neutral pion (NC⁢𝜋 0 ) production in neutrino-argon scattering, as well as single-differential measurements of the same channel in terms of final states with and without protons. The kinematic variables of interest for these measurements are the 𝜋 0 momentum and the 𝜋 0 scattering angle with respect to the neutrino beam. A total of 4971 candidate NC⁢𝜋 0 events fully contained within the MicroBooNE detector are selected using data collected at a mean neutrino energy of ∼0.8 GeV from 6.4 ×10 20 protons on target from the Booster Neutrino Beam at the Fermi National Accelerator Laboratory. After extensive data-driven model validation to ensure unbiased unfolding, the Wiener-singular-value-decomposition method is used to extract nominal flux-averaged cross sections. The results are compared to predictions from commonly used neutrino event generators, which tend to overpredict the measured NC⁢𝜋 0 cross section, especially in the 0.2–0.5 GeV/c 𝜋 0 momentum range and at forward scattering angles. Events with at least one proton present in the final state are also underestimated. This data will help improve the modeling of NC⁢𝜋 0 production, which represents a major background in measurements of charge-parity violation in the neutrino sector and in searches for new physics beyond the standard model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Circuit-Based Leakage-to-Erasure Conversion in a Neutral-Atom Quantum Processor

Atom-loss errors are a major limitation of current state-of-the-art neutral-atom quantum computers and pose a significant challenge for scalable systems. In a quantum processor with cesium atoms, we demonstrate proof-of-principle circuit-based conversion of this form of leakage error to erasure errors via leakage-detection units (LDUs), which nondestructively map information about the presence or absence of the qubit onto the state of an ancilla. We benchmark the performance of the LDU using a three-outcome low-loss state-detection method and find that the LDU detects atom-loss errors with approximately 93.4% accuracy, limited by technical imperfections of our apparatus. We further compile and execute a SWAP LDU, wherein the roles of the original data atom and ancilla atom are exchanged under the action of the LDU, providing “free refilling” of atoms in the case of atom loss. This circuit-based leakage-to-erasure error conversion is a critical component of a neutral-atom quantum processor where the quantum information may significantly outlive the lifetime of any individual atom in the quantum register. Finally, we demonstrate that LDUs may also be used to handle other forms of leakage errors where population moves to states outside of the computational subspace.

Chow, Matthew N. H. [Sandia National Laboratories ↗
DOE OSTI2026

Microwave Imaging of Edge Conductivity in Graphene at Charge Neutrality and Quantum Hall States

Here, we report local conductivity imaging of edge states in monolayer graphene by millikelvin microwave impedance microscopy. At the charge-neutrality point, as the magnetic field increases, the local conductivity at the edge drops to zero more slowly than in the bulk. This behavior is consistent with the calculated spatial profile of the charge gap in the canted antiferromagnetic phase. For comparison, we also perform microwave imaging of integer quantum Hall states away from neutrality, which host dissipationless chiral edge channels. The evolution of the edge signal as a function of the bulk gap is fundamentally different between the Landau level filling factor 𝜈 = 0 and |𝜈| ≥ 1 integer quantum Hall states, which can be qualitatively explained by numerical simulations and theoretical analysis. Our results provide a comprehensive microscopic picture of the edge and bulk states as the Fermi level moves across the unique Landau-level spectrum of graphene.

Hall effect↗