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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

The track-length extension fitting algorithm for energy measurement of interacting particles in liquid argon TPCs and its performance with ProtoDUNE-SP data

This paper introduces a novel track-length extension fitting algorithm for measuring the kinetic energies of inelastically interacting particles in liquid argon time projection chambers (LArTPCs). The algorithm finds the most probable offset in track length for a track-like object by comparing the measured ionization density as a function of position with a theoretical prediction of the energy loss as a function of the energy, including models of electron recombination and detector response. The algorithm can be used to measure the energies of particles that interact before they stop, such as charged pions that are absorbed by argon nuclei. The algorithm's energy measurement resolutions and fractional biases are presented as functions of particle kinetic energy and number of track hits using samples of stopping secondary charged pions in data collected by the ProtoDUNE-SP detector, and also in a detailed simulation. Additional studies describe the impact of the dE/dx model on energy measurement performance. The method described in this paper to characterize the energy measurement performance can be repeated in any LArTPC experiment using stopping secondary charged pions.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Mixing model with multi-particle interactions for Lagrangian simulations of turbulent mixing

We report on the numerical study of the mixing volume model (MVM) for molecular diffusion in Lagrangian simulations of turbulent mixing problems. The MVM is based on the multi-particle interaction in a finite volume (mixing volume). A priori test of the MVM, based on the direct numerical simulations of planar jets, is conducted in the turbulent region and the interfacial layer between the turbulent and non-turbulent fluids. The results show that the MVM predicts well the mean effects of the molecular diffusion under various numerical and flow parameters. The number of the mixing particles should be large for predicting a value of the molecular diffusion term positively correlated to the exact value. The size of the mixing volume relative to the Kolmogorov scale η is important in the performance of the MVM. The scalar transfer across the turbulent/non-turbulent interface is well captured by the MVM especially with the small mixing volume. Furthermore, the MVM with multiple mixing particles is tested in the hybrid implicit large-eddy-simulation/Lagrangian-particle-simulation (LES–LPS) of the planar jet with the characteristic length of the mixing volume of O(100η). Despite the large mixing volume, the MVM works well and decays the scalar variance in a rate close to the reference LES. The statistics in the LPS are very robust to the number of the particles used in the simulations and the computational grid size of the LES. Both in the turbulent core region and the intermittent region, the LPS predicts a scalar field well correlated to the LES.

42 ENGINEERING↗
NASA NTRSDate not supplied

Gas-Particle Interaction Model Development in Plume Surface Interaction Erosion and Cratering

As part of the Game Changing Development (GCD) Program, funded by NASA’s Space Technology Mission Directorate (STMD), the development of simulation capability for the prediction of extra-terrestrial Plume Surface Interaction (PSI) environments has been undertaken by the Fluid Dynamics Branch at NASA/MSFC. The GCD PSI Project, planned to be completed over a four year period, contains a Predictive Simulation Capability (PSC) Element focused on creating simulation capability for the reliable and accurate prediction of PSI in Martian (~650 Pa) and Lunar (vacuum) ambient environments. In addition to the PSC Element, the GCD Program also contains a companion Ground Testing Element for development of focused datasets for validation of predictive capability as well as a Flight-focused Instrumentation Element. This paper describes the activities and accomplishments of the past year in the gas-particle interaction modeling portion of the GCD PSI project. The objectives of this task are to investigate and construct models of particle drag and gas-particle cloud interactions leading to what is known as particle turbulent kinetic energy (PTKE). While drag on a lone particle suspended in a flow gas of gas is well-known, the drag and drag-induced dynamics of a cloud of particles in a gas flow are not. The PSC element of the PSI project requires models of gas-particle cloud interactions to implement in the Gas Granular Flow Solver (GGFS) in order to arrive at a predictive simulation capability for PSI-induced soil erosion, cratering and ejecta transport. Experiments of dilute mixtures of soil particles in supersonic gas flow are being conducted at Johns Hopkins University in order to provide a dataset describing gas-particle cloud interactions. Augmented by a separate funding source are efforts to perform small-scale particle-resolved direct numerical simulations (PR-DNS) and larger scale Eulerian-Lagrangian simulations. Together, these experiments and simulations are being used to devise models of particle cloud drag and particle cloud drag-induced dynamics. The final product of these efforts will be particle drag models suitable for implementation into the GGFS application and a PTKE model suitable for the same purpose.

Jeff West↗
NASA NTRS2016

Accurately Characterizing the Importance of Wave-Particle Interactions in Radiation Belt Dynamics: The Pitfalls of Statistical Wave Representations

Wave-particle interactions play a crucial role in energetic particle dynamics in the Earths radiation belts. However, the relative importance of different wave modes in these dynamics is poorly understood. Typically, this is assessed during geomagnetic storms using statistically averaged empirical wave models as a function of geomagnetic activity in advanced radiation belt simulations. However, statistical averages poorly characterize extreme events such as geomagnetic storms in that storm-time ultralow frequency wave power is typically larger than that derived over a solar cycle and Kp is a poor proxy for storm-time wave power.

Murphy, Kyle R.↗
NASA NTRS1990

Wave-particle interactions for relativistic electrons in a recirculation acceleration model

Evidence is presented for the presence of a multistep process, leading to relativistic electron populations, in the magnetospheres of earth and Jupiter. After an initial injection of a spectrally soft electron component in the outer magnetosphere, inward radial diffusion acts to accelerate the electrons perpendicular to the local magnetic field; strong wave-particle interactions deep in the magnetosphere is of primary significance in the pitch-angle scattering of electrons, thereby lowering their mirror points. An additional model element of critical significance, again involving wave-particle interactions, is energy-preserving outward transport near the mirror points where the field strength is large and trans-L distances are small.

Baker, D. N.↗
NASA NTRS1979

Nuclear gamma-rays from energetic particle interactions

Gamma-ray line emission due to nuclear deexcitation following energetic particle interactions with abundant constituents of cosmic matter is studied. Reactions induced by energetic protons and alpha particles in ambient nuclei (He, C, N, O, Ne, Mg, Al, Si, S, Ca, and Fe) are considered, along with inverse reactions in which energetic nuclei interact with ambient H and He. Line-production cross sections are evaluated by analyzing a large body of laboratory nuclear data. Both prompt gamma rays, produced by direct excitation of nuclear levels and by spallation reactions that leave the secondary nucleus in an excited state, and delayed emission from long-lived radioactive nuclei also produced in the energetic particle reactions are investigated. A line list is provided, and the shapes of the gamma-ray lines are determined. Gamma-ray line production in the interstellar medium is evaluated in detail.

Ramaty, R.↗
DOE OSTI2022

Slope parameter of the symmetry energy and the structure of three-particle interactions in nuclear matter

In the first part of this paper, we present a study of the symmetry energy (a s ) and its slope parameter (L) for nuclear matter in the framework of the Fermi liquid theory of Landau and Migdal. We derive an exact relation between a s and L, which involves the nucleon effective masses and three-particle Landau-Migdal parameters. We present simple estimates which suggest that there are two main mechanisms to explain the empirical values of L: The proton-neutron effective mass difference in isospin asymmetric matter and the ℓ = 0 moment of the isovector in-medium three-particle scattering amplitude. In the second part of this paper, we discuss the general structure of three-particle interactions in nuclear matter in the framework of the Fermi liquid theory. The connections to the Bethe-Brueckner-Goldstone theory and other approaches are also discussed. Finally, we show explicitly how the first few terms in the Faddeev series, together with medium induced three-particle interactions, emerge naturally in the Fermi liquid theory.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Advanced Physics Models for Particle-Particle Interactions (UCD final report)

The LDRD "Advanced Physics Models for Particle-Particle Interactions” collaborative research with Professor Jennifer Sinclair Curtis and PhD student Chanh Nguyen at the University of California, Davis involved meso-scale, discrete element method (DEM) modeling of micron-sized particles impacting a substrate. Using DEM, physical insight into the details of particle response upon impact can be obtained. Such details provide the type of information necessary to enhance existing continuum or macro-scale simulation tools so that modeling for material strength and particle breakage models is based on particle physics versus empirical relationships. While molecular dynamics simulations of atoms can also provide physical insight into the particle response to impact, the scale of particles that are treated is on the order of angstroms, not microns. This study gives evidence to the ability of the DEM simulation technique to provide such fundamental, detailed insight for micron-sized particles as a function of particle properties and impact velocity.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1999

Gas-Particle Interactions in a Microgravity Flow Cell

We are developing a microgravity flow cell in which to study the interaction of a flowing gas with relatively massive particles that collide with each other and with the moving boundaries of the cell. The absence of gravity makes possible the independent control of the relative motion of the boundaries and the flow of the gas. The cell will permit gas-particle interactions to be studied over the entire range of flow conditions over which the mixture is not turbulent. Within this range, we shall characterize the viscous dissipation of the energy of the particle fluctuations, measure the influence of particle-phase viscosity on the pressure drop along the cell, and observe the development of localized inhomogeneities that are likely to be associated with the onset of clusters. These measurements and observations should contribute to an understanding of the essential physics of pneumatic transport.

Louge, Michel↗
NASA NTRS1976

Magnetospheric dynamics and wave-particle interactions

It has been demonstrated that two general classes of wave-particle interactions are of great importance for magnetospheric dynamics. Electromagnetic and electrostatic plasma instabilities give rise to relatively narrow-banded spontaneous emissions (e.g., ELF hiss, chorus, three-halves noise, ion cyclotron and ion-plasma-frequency turbulence) that can scatter trapped particles into the loss cone, leading to modified pitch-angle distributions, stable trapping limits, diffuse aurora, proton precipitation events, etc. The current-driven plasma instabilities give rise to impulsive ion acoustic or Buneman mode turbulence that provides very effective energy transfer (via the anomalous conductivity mechanism) at the bow shock and in regions where strong field-aligned currents are observed. We review these interactions and identify significant open questions that must be investigated during the IMS.

Scarf, F. L.↗
NASA NTRS1977

Wave-particle interaction phenomena associated with shocks in the solar wind

Microscopic wave-particle interaction phenomena must generally affect the evolution of a traveling interplanetary discontinuity such as a collisionless shock, and solar wind plasma instabilities should also be associated with interplanetary acceleration, diffusion, and dissipation. Recent local measurements from diagnostics on widely separated spacecraft illustrate some examples of these interaction phenomena, and two bounding cases are considered in detail here. It is shown that the interplanetary shock of September 14, 1974 (detected on IMP-7, 8, Hawkeye-1, and Pioneer 11) was associated with intense local electrostatic noise and ion acceleration, while the shock of January 6, 1975 (detected on IMP-7 and Helios-1) had no detectable electrostatic turbulence.

Scarf, F. L.↗
NASA NTRS1971

Magnetospheric plasma - Sources, wave-particle interactions and acceleration mechanisms.

Some of the basic problems associated with magnetospheric physics are reviewed. The sources of magnetospheric plasma, with auroral particles included as a subset, are discussed. The possible ways in which the solar wind plasma can gain access to the magnetosphere are outlined. Some important consequences of wave-particle interactions are examined. Finally, the basic mechanisms which energize or accelerate particles by reconnection and convection are explained.

Speiser, T. W.↗
DOE OSTI2018

A novel algorithm of immersed moving boundary scheme for fluid-particle interactions in DEMLBM

This paper presents an efficient and accurate Immersed Moving Boundary (IMB) algorithm for solving fluid-particle interactions in the framework of the Lattice Boltzmann Method (LBM). Although the IMB scheme has been widely employed in many fluid-particle coupling problems in a wide range of applications, the algorithm of its implementation, especially in identifying both fluid and solid boundary nodes for particles, is seldom reported. Besides, the computational cost of handling fluid-particle coupling is very expensive. To provide a bridge between theory and application and improve the computing efficiency of IMB, a novel boundary tracing procedure and an efficient method for computing the solid nodal ratio using Gaussian quadrature are proposed in this paper. Both accuracy and efficiency of the proposed algorithm are examined by two benchmark tests. It is also found that the IMB scheme are more efficient and stable compared to another widely used the Immersed Boundary Method (IBM) in LBM.

42 ENGINEERING↗
DOE OSTI2021

The Search for Feebly Interacting Particles

At the dawn of a new decade, particle physics faces the challenge of explaining the mystery of dark matter, the origin of matter over antimatter in the Universe, the apparent fine-tuning of the electroweak scale, and many other aspects of fundamental physics. Perhaps the most striking frontier to emerge in the search for answers involves New Physics at mass scales comparable to that of familiar matter—below the GeV scale but with very feeble interaction strength. New theoretical ideas to address dark matter and other fundamental questions predict such feebly interacting particles (FIPs) at these scales, and existing data may even provide hints of this possibility. Emboldened by the lessons of the LHC, a vibrant experimental program to discover such physics is underway, guided by a systematic theoretical approach that is firmly grounded in the underlying principles of the Standard Model. We give an overview of these efforts, their motivations, and the decadal goals that animate the community involved in the search for FIPs, and we focus in particular on accelerator-based experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1995

Particle interactions with obliquely propagating magnetosonic waves

Four cases of nonlinear obliquely propagating magnetosonic (MS) waves are considered using a test particle approach for particles interaction with (1) monochromatic waves propagating both sunward and antisunward, (2) monochromatic waves propagating unidirectionally toward the Sun, (3) a broad band spectrum, propagating both sunward and antisunward, and (4) a broadband spectrum, propagating sunward only. As the solar wind decelerates rapidly inside the bow shock, the interplanetary magnetic field (IMF) increases. Calculations have been performed taking into account such a spatially dependent IMF (based on observations). We find that significant particle acceleration is achieved for both the monochromatic wave and the 'turbulent' MS waves, for oblique propagation (angles between the interplanetary magnetic field and the propagation vector larger than 30 deg). This is due to the fact that at oblique angles resonance width increases. We have compared the relative acceleration of particles for the four cases. Pitch angle scattering and acceleration of particles are found to be much larger in the case of sunward and antisunward propagating waves than those for the sunward waves only. This is due to larger relative phase velocities in the two cases. Also, acceleration of particles is less in the case of a uniform magnetic field than that in the case of spatially increasing magnetic field. The particles get more pitch angle scattered and accelerated in the latter case.

Srivastava, Krishna M.↗