Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “particle beams”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Latent diffusion can map beam loss to two-dimensional phase-space projections

Beam loss monitors (BLMs) and beam current monitors (BCMs) are ubiquitous at particle accelerators around the world. These simple devices provide noninvasive high-level beam measurements but give no insight into the detailed 6D (𝑥,𝑦,𝑧,𝑝 𝑥 ,𝑝 𝑦 ,𝑝 𝑧 ) beam phase-space distributions or dynamics. We show that generative conditional latent diffusion models can learn intricate patterns to solve the extreme inverse problem of mapping waveforms of tens of BLMs or BCMs along an accelerator to detailed 2D projections of a charged particle beam’s 6D phase-space density. This transformational method can be used at any particle accelerator to transform simple noninvasive devices into detailed beam phase-space diagnostics. We demonstrate this concept via multiparticle simulations of the high-intensity beam in the kilometer-long Los Alamos Neutron Science Center linear proton accelerator.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Online multi-objective particle accelerator optimization of the AWAKE electron beam line for simultaneous emittance and orbit control

Multi-objective optimization is important for particle accelerators where various competing objectives must be satisfied routinely such as, for example, transverse emittance vs bunch length. We develop and demonstrate an online multi-time scale multi-objective optimization algorithm that performs real time feedback on particle accelerators. We demonstrate the ability to simultaneously minimize the emittance and maintain a reference trajectory of a beam in the electron beamline in CERN’s Advanced Proton Driven Plasma Wakefield Acceleration Experiment.

43 PARTICLE ACCELERATORS↗
NASA NTRS1987

Stellar occultation probes of the Uranian rings at 0.1 and 2.2 microns - A comparison of Voyager UVS and earth-based results

A comparison between Voyager 2 UV spectrometer data for stellar occultations of the Uranian ring system obtained at 0.11 microns and 2.2-micron earth-based occultation data reveals the anticipated factor-of-two reduction in observed optical depths relative to those observed from earth. This is due to Voyager's proximity to the rings, which allows light diffracted out of the direct beam by ring particles to be replaced by light diffracted into the direct beam light from other particles, and further permits the placing of firm lower limits on typical particle sizes of 0.3 and 1 cm for the epsilon and delta rings, respectively. As a function of true anomaly, the epsilon ring profile is noted to remain very similar in shape and essentially constant in equivalent depth, even very near periapse.

Holberg, J. B.↗
DOE OSTI2024

Studying fast-ion populations using oscillations in solid-state neutral-particle analyzer signal and neutral-beam injection power

A method for determining the fast-ion population density in magnetically confined plasmas as a function of pitch-radius, (λ, R), using a solid-state neutral-particle analyzer (ssNPA) signal and neutral-beam injection (NBI) power-output data has been developed. Oscillations in the NBI power output are replicated only in the active part of the ssNPA signal, allowing this to be separated from the passive and background signals, which usually complicate data from this diagnostic. Results obtained using this method are compared with those from standard techniques using data from the Mega-Amp Spherical Tokamak Upgrade spherical tokamak.

Instruments & Instrumentation↗
DOE OSTI2026

Optics and Systems Design of the Ring-to-Second Target Transport Beam-Line for the SNS Second Target Station

The Second Target Station (STS) project at the Spallation Neutron Source (SNS) is being developed to provide world-leading cold neutron brightness for next-generation neutron scattering experiments. The STS Accelerator Systems (AS) scope includes the design and implementation of the Ring-to-Second Target (RTST) proton beam transport line, which extracts 1.3 GeV proton beam pulses from the existing Ring-to-Beam Transport (RTBT) system and delivers them to the STS target. The RTST design emphasizes operational reliability [high reliability], low activation [minimum activation of components and the tunnel], maintainability, and compatibility with existing SNS infrastructure through extensive reuse of proven RTBT systems and components. The beamline includes a new extraction region, a transport lattice consisting of dipole, quadrupole, and corrector magnets, beam instrumentation systems, vacuum systems, personnel protection systems, and radiation shielding systems. Beam optics and particle tracking studies were performed using PyORBIT to validate extraction trajectories, beam transport, and target beam spot requirements [60–90 cm² beam spot area]. This paper presents the optics design philosophy, extraction system architecture, transport lattice design, instrumentation strategy, vacuum system approach, and radiation protection integration for the RTST beamline. Particle tracking simulations indicate successful beam transport without beam loss under nominal operating conditions. The RTST is designed to transport 1.3 GeV proton beam pulses at repetition rates up to 15 Hz, delivering nominal beam power of 700 kW to the Second Target Station.

Baron, Alex [ORNL]↗
NASA NTRS1989

Numerical investigation of a plasma beam entering transverse magnetic fields

Two-dimensional electrostatic and electromagnetic particle-in-cell codes are used to investigate plasma beam propagation across transverse magnetic fields. Both large- and small-ion-gyroradius beams are studied in the case of small beam momentum or energy (low drift kinetic beta). Large-ion-gyroradius beams with a large dielectric constant epsilon much greater than (M/m) to the 1/2 (where M/m is the ion-to-electron mass ratio) are found to propagate across the magnetic field via E x B drifts at nearly the initial injection velocity. Beam degradation and undulations are observed, in agreement with previous experimental and analytical results. When epsilon is of order (M/m) to the 1/2 the plasma beam propagates across field lines at only half its initial velocity and loses its coherent structure. When epsilon is much less than (M/m) to the 1/2 the beam particles decouple at the magnetic field boundary, scattering the electrons and deflecting the ions slightly.

Koga, J.↗
DOE OSTI2025

First observation of antiproton annihilation at rest on argon in the LArIAT experiment

We report the first observation and measurement of antiproton annihilation at rest on argon track and shower multiplicities and particle identification conducted with the LArIAT experiment. Stopping antiprotons from the Fermilab Test Beam Facility’s charged particle test beam are identified using beamline instrumentation and LArIAT’s liquid argon time projection chamber (LArTPC). The charged particle multiplicity from the annihilation vertex is manually evaluated via hand scanning, yielding a mean of 3.2 ± 0.4 tracks and a standard deviation of 1.3 tracks, consistent with a semiautomated reconstruction resulting in 2.8 ± 0.4 tracks and a standard deviation of 1.2 tracks. Both methods are consistent with Monte Carlo simulations within statistical uncertainty. The shower multiplicities and particle identification for outgoing tracks are also consistent with eant4 model predictions. These results, obtained from a low-statistics sample, provide a foundation for higher-statistics studies in larger LArTPCs, which could refine modeling of intranuclear annihilation on argon and inform scenarios such as neutron-antineutron oscillations. Published by the American Physical Society 2025

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Four-dimensional phase-space reconstruction of flat and magnetized beams using neural networks and differentiable simulations

Beams with cross-plane coupling or extreme asymmetries between the two transverse phase spaces are often encountered in particle accelerators. Flat beams with large transverse-emittance ratios are critical for future linear colliders. Similarly, magnetized beams with significant cross-plane coupling are expected to enhance the performance of electron cooling in hadron beams. Preparing these beams requires precise control and characterization of the four-dimensional transverse phase space. In this study, we employ generative phase-space reconstruction techniques to rapidly characterize magnetized and flat-beam phase-space distributions using a conventional quadrupole-scan method. The reconstruction technique is experimentally demonstrated on an electron beam produced at the Argonne Wakefield Accelerator and successfully benchmarked against conventional diagnostics techniques. Specifically, we show that predicted beam parameters from the reconstructed phase-space distributions (e.g., as magnetization and flat-beam emittances) are in excellent agreement with those measured from the conventional diagnostic methods. Published by the American Physical Society 2024

43 PARTICLE ACCELERATORS↗
NASA NTRS1985

The dispersive evolution of charged-particle bunches in random magnetic fields

Shortly after a strongly anisotropic beam of charged particles is injected along a guiding magnetic field on which is superimposed a small random conponent, the particle density can be represented by a Gaussian profile whose center moves with the coherent velocity and whose width increases with time at a rate controlled by the coefficient of dispersion. Both parameters depend upon the mean free path, which characterizes scattering by the random fields, and the focusing length, which characterizes spatial variations of the guiding field. These dependencies are known explicitly for the coherent velocity. Formulae for coefficient of dispersion are available only in the limits of very weak and very strong focusing. A new expression for coefficient of dispersion, which spans this gap, is presented.

Earl, J. A.↗
NASA NTRS2017

Ion Velocity Distributions in Dipolarization Events: Beams in the Vicinity of the Plasma Sheet Boundary

Using combined MHD/test particle simulations, we further explore characteristic ion velocity distributions in relation to magnetotail reconnection and dipolarization events, focusing on distributions at and near the plasma sheet boundary layer (PSBL). Simulated distributions right at the boundary are characterized by a single earthward beam, as discussed earlier. However, farther inside, the distributions consist of multiple beams parallel and antiparallel to the magnetic field, remarkably similar to recent Magnetospheric Multiscale observations. The simulations provide insight into the mechanisms: the lowest earthward beam results from direct acceleration at an earthward propagating dipolarization front (DF), with a return beam at somewhat higher energy. A higher-energy earthward beam results from dual acceleration, first near the reconnection site and then at the DF, again with a corresponding return beam resulting from mirroring closer to Earth. Multiple acceleration at the X line or the propagating DF with intermediate bounces may produce even higher-energy beams. Particles contributing to the lower energy beams are found to originate from the PSBL with thermal source energies, increasing with increasing beam energy. In contrast, the highest-energy beams consist mostly of particles that have entered the acceleration region via cross-tail drift with source energies in the suprathermal range.

Birn, J.↗
DOE OSTI2025

Post-DTL Beam Delivery

Ensuring that the beam delivered from the upgraded Front-End (FE) meets the Key Performance Parameters (KPPs) at each user facility is critical to the success of the LANSCE Accelerator Modernization Project (LAMP). For a high-intensity, multi-user facility like LANSCE, compliance with beam loss and radiation thresholds is as important as the charge delivered to each target. While early LAMPF/LANSCE operations relied on iterative tuning to minimize losses from beam halo and tail particles, the new FE may introduce different beam distributions and loss modes—making predictive modeling essential. To manage this, the F2E (Front-End to End) effort is developing detailed particle-tracking models that reflect realistic beamline conditions, including halo formation and expected diagnostic readings. These "snapshot" simulations aim to benchmark live machine performance at a given moment. This will help quantify how beam quality from the new FE will propagate downstream through the facility. Only by validating these models can we confidently assess and mitigate the potential impacts of the LAMP FE on beam delivery. Post-DTL, the beam splits to serve five major user facilities. Historically, low-energy beam transport has been modeled using TRACE, and higher-energy sections with TRANSPORT. These have now been unified into MAD-X format and validated with codes such as Elegant, pyOrbit, XSuite, Impact-Z, and HPSim. The primary focus now is on accurate modeling of full particle distributions (including beam halo) as they traverse the accelerator and beamlines to each experimental station. All models are at various stages of validation with empirical data.

43 PARTICLE ACCELERATORS↗
NASA NTRS1974

A lidar system for remote probing of the lower atmosphere

The development and characteristics of a lidar system for atmospheric measurements are discussed. The lidar system employs a Q-switched ruby laser that radiates an intense pulse of light into the atmosphere to illuminate aerosol particles in the laser beam. Light backscattered from the particles is received by a Cassegrain telescope equipped with a sensitive photomultiplier tube. The output signal of the photomultiplier tube is displayed on an oscilloscope and recorded on polaroid film.

Craig, C. D.↗