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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Energetic particle recurrence and escape during solar cycle 20

Low-energy solar particle data have been combined from a multi-spacecraft near-earth data set covering most of solar cycle 20 (1966-1976). Particle intensity profiles have been ordered in the natural heliographic coordinate system of the estimated high coronal connection longitude of the foot point of the interplanetary field line. The recurrence trends of approximately 1-MeV solar particles become more apparent in this coordinate system than when plotted versus time, and thereby extend the evidence for regions of continual injection and escape from the corona. Intercomparison of solar particles and solar wind streams in heliographic longitude suggests that the origin of stream-associated spatial particle events seen at 1 AU is solar rather than interplanetary.

Gold, R. E.↗
NASA NTRS1980

Encounters with Jupiter - The Low Energy Charged Particle results of Voyager

Results of the Low Energy Charged Particle (LECP) experiments on board the Voyager spacecraft, designed to measure the fluxes and compositions of ions of energies 28 keV or greater and electrons of energies 15 keV or greater, during Jupiter encounter are presented. Observations of intense particle bursts coming from Jupiter several weeks before Jovian magnetosphere entry, magnetopause crossings, a hot corotating outer magnetospheric plasma, decreases in particle fluxes at the orbits of the Galilean satellites 10-hr particle flux periodicities and a magnetospheric wind are discussed. A new model of the Jovian magnetosphere based on the Voyager results is presented, and areas of continuing LECP Jovian data analysis are indicated.

Carbary, J. F.↗
NASA NTRS1995

Ulysses observations of energetic ions over the south pole of the Sun

The Ulysses spacecraft began its journey out-of-the-ecliptic in February of 1992, when it encountered the planet Jupiter. In April of 1993, the spacecraft had reached 29 deg S, and from then on was completely immersed in the flow from the southern polar coronal hole. Accelerated ions were observed, recurring with a main peak once per solar rotation, with the intensity at the peak slowly decreasing with increasing latitude. This decrease continued to the end of 1993, when the spacecraft was at approximately 50 deg S. During the first three months of 1994 the intensity of the accelerated ions rose again, due either to an increase in magnetic activity on the sun or a reconfiguration of the heliospheric magnetic field. Recurrent accelerated ions were still being seen at the beginning of July 1994, when the spacecraft was at a latitude of 70 deg S, although with reduced intensity. The accelerated ions were no longer seen at latitudes higher than 70 deg S, the ion intensity staying constant at around the cosmic ray background level. This continued on until the highest latitude reached, 80.2 deg S, on 13 September 1994. The spacecraft then began its journey back towards lower latitudes, a small increase in the particle intensity being observed at the end of October whilst at approximately 72 deg S, and thereafter no more increases until the end of 1994, when the spacecraft was at approximately 45 deg S. We present interpretations for this asymmetry in latitude dependence.

Sanderson, T. R.↗
DOE OSTI2025

Rapid SACR Observations of Convection at Bankhead National Forest (RAPID) Field Campaign Report

Improving our representation of convective cell processes requires better quantification of convective clouds throughout their entire life cycle. This includes gaining a clearer understanding of the controls on key convective cloud properties, such as updraft intensity, particle size distributions, rainfall rates, and hydrometeor species. Our inability to improve convective cloud process modeling stems, in part, from a limited understanding of convective cell properties, particularly given how rapidly these storms evolve. This lack of detailed observations in the most intense and organized convective storms is especially significant, as large errors remain in representing these clouds, which are critical for severe weather prediction and Earth system model performance. Cloud and precipitation radars are essential tools for studying cloud microphysics and dynamics, particularly in deeper convective clouds. The recent U.S. Department of Energy Atmospheric Radiation Measurement (ARM) User Facility’s third Mobile Facility (AMF3) Bankhead National Forest (BNF) deployment provides a unique opportunity to investigate important land–atmosphere interactions, as well as the environmental controls on deep convective cloud processes, in a location favorable for frequent convection. We operate the X/Ka-band Scanning ARM Cloud Radar (X/Ka SACR) using a scan strategy optimized to capture these rapidly evolving clouds and their properties, thereby improving studies of deep convective cloud processes. This effort is strengthened by a complementary and coordinated partnership with ongoing university and multi-agency radar activities collocated in north Alabama—a unique opportunity to examine clouds and precipitation from a lifetime-centric perspective.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1980

The energetic charged particle absorption signature of Mimas

In the present paper, the average long-term effect of Saturn's satellite Mimas on the distribution of trapped radiation (macrosignature) is examined, along with a microsignature of satellite absorption, specifically, a brief dip in charged particle intensities observed on the inbound pass of Pioneer 11 as it passed through the orbital range of Mimas. It is hypothesized that it is indeed the shadow of Mimas, in the sense that the observations reveal the effect of this satellite on a distribution of particles which interacted with it in the recent past and then drifted in longitude to the observational location. The hypothesis led to a characterization of the electron energy spectrum in Saturn's inner magnetosphere and to an estimate of the radial diffusion coefficient for such electrons.

Van Allen, J. A.↗
NASA NTRS1992

Focused transport of energetic particles along magnetic field lines draped around a coronal mass ejection

Evidence is presented for focused transport of energetic particles along magnetic field lines draped around a coronal mass ejection. This evidence was obtained with the University of Maryland/Max-Planck-Institute experiment on the ISEE-3 spacecraft during the decay phase of the June 6, 1979, solar particle event. During the early portion of the decay phase of this event, interplanetary magnetic field lines were apparently draped around a coronal mass ejection, leading to a small focusing length on the western flank where ISEE 3 was located. A period of very slow decrease of particle intensity was observed, along with large sunward anisotropy in the solar wind frame, which is inconsistent with predictions of the standard Fokker-Planck equation models for diffusive transport. It was found possible to fit the observations, assuming that focused transport dominates and that the particle pitch angle scattering is isotropic.

Tan, L. C.↗
NASA NTRS2017

SAMPEX Observations of the South Atlantic Anomaly Secular Drift During Solar Cycles 22-24

It is observed that charged particle intensities are very high near the South Atlantic anomaly (SAA) and are a potential hazard to spacecraft passing through the region. In this study, we examine the secular drift of the SAA location at approximately 400-600 kilometers altitude over nearly two solar cycles, using particle count rates to trace the geomagnetic field lines in the region near the SAA. We use data from the Low-Energy Ion Composition Analyzer sensor on board the SAMPEX (Solar, Anomalous, and Magnetospheric Particle Explorer) spacecraft to measure both the longitudinal and latitudinal drifts of the SAA. We find that the longitudinal drift rate is 0.20 plus or minus 0.04 degrees west per year and that the latitudinal drift rate is 0.11 plus or minus 0.01 degrees south per year. These measurements are compared with the IGRF12 (International Geomagnetic Reference Field) model calculations based on an analysis of magnetic field minima in the region of the SAA. Our results, which are in good agreement with model results and prior measurements when declining spacecraft altitude is taken into account, have important space weather implications.

Jones, A. D.↗
DOE OSTI2025

Convergence study of wakefield simulations with GdfidL and ECHO3D

The interaction of charged particle beams with vacuum chamber components gives rise to electromagnetic wakefields, whose frequency-domain representation is known as beam coupling impedance. Geometric impedance arising from discontinuities and transitions in the vacuum chamber is the focus of this study. Minimizing this impedance is essential to mitigate adverse collective effects in modern storage rings operating with high-intensity particle beams. Accurate and reliable impedance simulations is a key factor of the vacuum chamber design. This paper presents the results of a convergence study of two widely used electromagnetic solvers, GdfidL and ECHO3D, applied to key vacuum-chamber components of the National Synchrotron Light Source II (NSLS-II) storage ring. Detailed comparisons are performed for several geometries, including flange absorbers, RF bellows, button-type beam position monitors, and an in-vacuum undulator (IVU). The results show notable differences in convergence and computational efficiency between the two codes. While GdfidL provides highly resolved results and serves as a common benchmark tool, ECHO3D yields consistent results with coarser meshes, significantly reducing simulation time and memory demands. Simulations with a full-geometry IVU model demonstrate that simplified taper-transition models can miss important impedance contributions. In conclusion, these findings provide practical guidelines for efficient and accurate impedance modeling to optimize design of vacuum chamber components for accelerators.

36 MATERIALS SCIENCE↗
NASA NTRS2023

A Data-driven, Physics-based Transport Model of Solar Energetic Particles Accelerated by Coronal Mass Ejection Shocks Propagating through the Solar Coronal and Heliospheric Magnetic Fields

In an effort to develop computational tools for predicting radiation hazards from solar energetic particles (SEPs), we have created a data-driven physics-based particle transport model to calculate the injection, acceleration, and propagation of SEPs from coronal mass ejection (CME) shocks traversing through the solar corona and interplanetary magnetic fields. The model runs on an input of corona and heliospheric plasma and magnetic field configuration from a magnetohydrodynamic model driven by solar photospheric magnetic field measurements superposed with observed CME shocks determined from coronagraph images. SEP source particles are injected at the shock using the result of diffusive shock acceleration formulation from a characteristic obliquity-dependent injection from a heated solar wind thermal tail population. With several advanced computation techniques involving stochastic simulation and integration, the model obtains the particle intensity at any location in interplanetary space through the rigorous solution to the time-dependent 5D focus transport equation in the phase space that includes perpendicular diffusion. We apply the model to the 2011 November 3 CME event. The calculation results reproduce multispacecraft SEP observations at Earth and STEREO-B reasonably well without normalization of particle flux. The observations at STEREO-A can be reproduced by rescaling particle energy or modified energy dependence of particle diffusion coefficients. This circumsolar SEP event seen by spacecraft at Earth, STEREO-A, and STEREO-B at widely separated longitudes can be explained by diffusive shock acceleration by a single CME shock with a moderate speed.

Solar energetic particles↗
DOE OSTI2025

An explicit, energy-conserving particle-in-cell scheme

We present an explicit temporal discretization of particle-in-cell schemes for the non-relativistic Vlasov equation that results in exact energy conservation when combined with an appropriate spatial discretization. The scheme is inspired by a simple, second-order explicit scheme that conserves energy exactly in the Eulerian context. We show that direct translation to particle-in-cell does not result in strict conservation, but derive a simple correction based on an analytically solvable optimization problem that recovers conservation. While this optimization problem is not guaranteed to have a real solution for every particle, we provide a correction that makes imaginary values extremely rare and still admits $\mathcal{O}$(10 –12 ) fractional errors in energy for practical simulation parameters. We present the scheme in both electrostatic – where we use the Ampère formulation – and electromagnetic contexts. With an electromagnetic field solve, the field update is most naturally linearly implicit, but the more computationally intensive particle update remains fully explicit. Here, we also show how the scheme can be extended to use the fully explicit leapfrog and pseudospectral analytic time-domain (PSATD) field solvers. The scheme is tested on standard kinetic plasma problems, confirming its conservation properties.

Energy conservation↗
NASA NTRS1973

IMP-6 observations of the energy spectra of cosmic gamma-ray bursts

The occurrence of intense, short bursts of 0.1 to 1.2 MeV cosmic gamma rays, recently found using multiple Vela satellites was confirmed with measurements from the IMP-6 satellite. Observations regarding times of occurrence, photon flux, and temporal and spectral characteristics of the bursts are outlined. In particular, since the IMP-6 instrument incorporates a hard X-ray detector with active particle rejection and full-time omnidirectional particle intensity monitoring, the results fully confirm and establish the hard X-ray or gamma-ray nature of the incident flux. Detailed differential energy spectra were obtained with the IMP-6 for six of the eight known events occurring during the March 1971 to September 1972 lifetime of the instrument. All of these are multiple-pulse events, with several seconds separation between distinct pulses of one or two seconds duration. The pulse spectra do not obey single-index power laws in energy, but can be represented by exponentials in photon flux throughout the 100 to 1200 KeV region.

Cline, T. L.↗
NASA NTRS1984

Characteristics of suprathermal H(+) and He(++) in plasmoids in the distant magnetotail

Rest frame distribution functions were obtained for suprathermal H(+) and He(2+) ions during 20 particle intensity increases that were observed in the distant magnetotail by ISEE-3. All of these increases were characterized by isotropic, approximately 100-keV electrons, preceded by beaming electrons and velocity-dispersed protons distributions whose signatures are typically associated with plasmoids. In each of the plasmoids, both H(+) and He(2+) are found to be convected tailward, with speeds that range from 200 to 1000 km/sec. The acceleration mechanism is found to depend on particle velocity, and it is established that the solar wind is a dominant plasma source. The plasmoids appear to be expanding at about 100 km/sec during their tailward propagation.

Gloeckler, G.↗
NASA NTRS2006

Europa Surface Radiation Environment for Lander Assessment

The Jovian magnetospheric particle environment at Europa's surface is critical to assessment of landed astrobiological experiments in three respects: (1) the landing site must be chosen for the best prospects for detectable organic or inorganic signs of Life, e.g. regions of freshly emergent flows from the subsurface; (2) lander systems must reach the surface through the Jovian magnetospheric environment and operate long enough on the surface to return useful data; (3) lander instrumentation must be capable of detecting signs of life in the context of the local environmental radiation and associated chemistry. The Galileo, Voyager, and Pioneer missions have provided a wealth of data on energetic particle intensities throughout the Jovian magnetosphere including from many flybys of Europa. cumulative radiation dosages for spacecraft enroute to Europa can be well characterized, but knowledge of the surface radiation environment is very limited. Energetic electrons should primarily impact the trailing hemisphere with decreasing intensity towards the center of the leading hemisphere and are the most significant radiation component down to meter depths in the surface regolith due to secondary interactions. Observed surface distribution for sulfates is suggestive of electron irradiation but may have alternative interpretations. Having much-larger magnetic gyroradii than electrons, energetic protons and heavier ions irradiate more of the global surface. The particular orientations of electron, proton, and ion gyromotion would project into corresponding directional (e.g., east-west) anisotropies of particle flu into the surface. Particular topographic features at the landing site may therefore offer shielding from part of the incident radiation.

Cooper, John F.↗
DOE OSTI2025

Performance assessment after long-term irradiation of ATLAS Micromegas detectors using 120 GeV muons at the Gamma Irradiation Facility at CERN

The ATLAS muon spectrometer will face an increased particle rate as a result of the increased instantaneous luminosity expected during the High-Luminosity LHC (HL-LHC) upgrade. The HL-LHC will provide a luminosity of $\mathscr{L}$ = 7.5 × 10 34 cm −2 s −1 and 3000 fb −1 of integrated luminosity in 10 years, about 9 times more data of the ones so far collected by the ATLAS experiment. Micromegas chambers are used in the New Small Wheel(s), the first forward muon spectrometer station, to provide tracking and triggering at the intense particle rates expected. The detectors are operated with a ternary gas mixture composed of Ar + 5%CO 2 + 2%iC 4 H 10 , providing good high voltage stability and a large pulse height, important for inclined track reconstruction of particles crossing the detector. To ensure the long-term stable operation of the detector during the whole HL-LHC period, and due to the hydrocarbon content in the mixture, an extensive aging campaign has been ongoing since 2021 at the CERN Gamma Irradiation Facility, where spare production chambers are long-term exposed to a 14 TBq 137 Cs 𝛾-source, accumulating so far, a charge equivalent to five years of HL-LHC operations under the highest expected background rate. This paper describes the results of the Micromegas chamber performance studies after two years of gamma irradiation and using the SPS/H4 120 GeV muon beams at CERN.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1984

Ozone Measurements in the Mesosphere During a Solar Proton Event

Charged particle precipitation in the Earth's atmosphere produces odd nitrogen and odd hydrogen. These species take part in catalytic reactions which destroy atmospheric ozone in the stratosphere and mesosphere. Modeling efforts regarding the impact of these ionization events on the neutral atmosphere describe ozone depletions in good agreement with observations in the stratosphere and mesosphere. The photochemical effects of the solar proton event (SPE) of August 1972 are discussed, and calculations for higher altitudes (70 to 90 km) are presented that indicate after a brief reduction during and immediately following intense particle precipitation, ozone will later reach higher concentrations than those present before the event.

Lippert, W.↗
NASA NTRS1981

Relativistic cosmic rays and corotating interaction regions

The relationships between relativistic galactic cosmic ray intensity variations and corotating interaction regions (CIRs) are examined. Times of CIRs overtaking the earth as indicated by Pioneer 10 and 11 plasma and field observations are compared with nucleonic intensities recorded at the Thule and McMurdo polar stations in a superposed epoch analysis, with the centers of the CIR as zero days. Results indicate a decrease in intensity around the zero days, as well as a maximum around the ninth day and a general upward trend from days -13 to 13. Further examination reveals the observed features to be present only for those CIR- associated streams in which a neutral sheet is embedded. In contrast, superposed epoch analysis of the geomagnetic Ap index with respect to CIR epochs reveals CIRs both with and without neutral sheets to produce geomagnetic storms, although the peak increase in Ap index is greater for neutral-sheet-associated CIRs. Results suggest that the CIRs modulate high-energy particle intensities by means of drifts related to neutral sheets, although diffusion effects cannot yet be ruled out.

Duggal, S. P.↗
DOE OSTI2025

Recrystallization, cracking, and erosion of dispersoid-strengthened tungsten materials during exposure to divertor plasmas

In this study, we investigated the effects of combined intense particle and heat flux exposure on advanced tungsten plasma-facing materials within the DIII-D fusion facility. Our test matrix included two types of dispersoid-strengthened tungsten (containing either 100 nm diameter TiO 2 or Ni particles), along with high-purity polycrystalline tungsten as a reference. This experiment relied on a sample geometry angled at 15° relative to the divertor surface, thereby allowing the surfaces to intercept steady-state perpendicular heat fluxes (q ⟂ ) ranging from 10.1 to 19.6 MW/m 2 . During each shot, the samples were exposed to 42 Hz edge-localized modes (ELMs), allowing us to test the material response to transient heating. We correlated the exposure conditions with extensive post-test surface composition analysis and microscopy to determine how the plasma modified each surface. The angled specimens closest to the strike point received the highest combined heat and particle flux and melted midway through the experiment. EBSD analysis revealed they were completely recrystallized throughout, with an average grain size >100 µm. On the other hand, the specimens that received a lower steady state heat flux survived with more superficial surface damage. Whereas the high-purity polycrystalline tungsten exhibited a higher surface roughness, the dispersoid-strengthened material exhibited more extensive shallow inter-granular cracking. In addition, the surface was depleted of dispersoids following plasma exposure, possibly because of evaporation and/or sputtering. The results described here provide insights into the performance of these materials in a fusion environment which can guide further optimization for use in long-pulse devices.

Kolasinski, Robert D. [Sandia National Laboratorie↗
DOE OSTI2026

Nozzle geometry optimization for high-current aluminum ion beam acceleration via direct plasma injection scheme

We report the generation of a record aluminum ion beam current exceeding 58 mA at the Al 11+ charge state, accelerated to an energy of 5.5 MeV using the direct plasma injection scheme, which integrates a laser ion source (LIS) with a radio frequency quadrupole (RFQ) accelerator. The effect of nozzle geometry on beam extraction was systematically investigated using 8 and 12 mm tapered designs and an 18 mm cylindrical configuration. The 18 mm nozzle achieved the highest Al 11+ beam current, while the 12 mm aperture provided a favorable balance between beam intensity and current density. Beam extraction simulations confirmed effective RFQ matching across multiple charge states, and solenoidal field tuning further enhanced plasma collimation. This work not only establishes a new benchmark for high-current ion beam generation but also provides a fundamental understanding of plasma–beam interface dynamics crucial for the next generation of high-intensity particle accelerators, particularly those employing LIS-RFQ systems.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗