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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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Dynamic Focusing to Suppress Emittance Transfer in Crab-Crossing Flat Beam Collisions

Flat hadron beam collisions, though expected to enhance peak luminosity by about an order of magnitude, have not yet been demonstrated. We identify a new mechanism in which the hourglass-induced synchrobetatron resonance, when coupled to unavoidable machine fluctuations, drives emittance transfer and degrades the flat-beam condition. This effect becomes a critical limitation for maintaining flat hadron beams on operational timescales. Using Electron-Ion Collider (EIC) parameters, we show that it imposes stringent tolerances on machine noise. We further demonstrate that a dynamic focusing scheme, implemented by combining sextupoles with crab cavities, suppresses the resonance and relaxes these constraints, providing a practical path toward robust flat-beam collisions in future lepton-hadron colliders.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Model-Based Reconstruction for Multi-Frequency Collimated Beam Ultrasound Systems

Collimated beam ultrasound systems are a technology for imaging inside multi-layered structures such as geothermal wells. These systems work by using a collimated narrow-band ultrasound transmitter that can penetrate through multiple layers of heterogeneous material. A series of measurements can then be made at multiple transmit frequencies. However, commonly used reconstruction algorithms such as Synthetic Aperture Focusing Technique (SAFT) tend to produce poor quality reconstructions for these systems both because they do not model collimated beam systems and they do not jointly reconstruct the multiple frequencies. Here, in this article, we propose a multi-frequency ultrasound model-based iterative reconstruction (UMBIR) algorithm designed for multi-frequency collimated beam ultrasound systems. The combined system targets reflective imaging of heterogeneous, multi-layered structures. For each transmitted frequency band, we introduce a physics-based forward model to accurately account for the propagation of the collimated narrow-band ultrasonic beam through the multi-layered media. We then show how the joint multi-frequency UMBIR reconstruction can be computed by modeling the direct arrival signals, detector noise, and incorporating a spatially varying image prior. Results using both simulated and experimental data indicate that multi-frequency UMBIR reconstruction yields much higher reconstruction quality than either single frequency UMBIR or SAFT.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Information encoding in the spatial correlations of entangled twin beams

The ability to use the temporal and spatial degrees of freedom of quantum states of light to encode and transmit information is crucial for a robust and efficient quantum network. In particular, the potential offered by the large dimensionality of the spatial degree of freedom remains unfulfilled, as the necessary level of control required to encode information remains elusive. We encode information in the distribution of the spatial correlations of entangled twin beams by taking advantage of their dependence on the angular spectrum of the pump needed for four-wave mixing. We show that the encoded information can only be extracted through joint spatial measurements of the twin beams and not through individual beam measurements and that the temporal quantum correlations are not modified. The ability to engineer the spatial properties of twin beams will enable high-capacity quantum networks and quantum-enhanced spatially resolved sensing and imaging.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Probing charged lepton flavor violation with a positron beam at CEBAF (JLAB)

The addition of a high intensity 11 GeV polarized positron beam at the Continuous Electron Beam Accelerator Facility (CEBAF) at JLAB would allow for a search of Charged Lepton Flavor Violation (CLFV) via the process $e^+N \rightarrow \mu^+ X$. The proposed Solenoidal Large Intensity Detector (SoLID) spectrometer, in the configuration with muon chambers, would be ideal for such CLFV searches. Various new physics scenarios, including the phenomenologically convenient Leptoquark (LQ) framework, predict CLFV rates that are within reach of current or planned experiments. A positron beam with instantaneous luminosity, ${\cal L}\sim 10^{38}$ cm$^{-2}$s$^{-1}$, could improve on existing HERA limits by two or three orders of magnitude. The availability of positron beam polarization would also allow for distentangling CLFV effects mediated by left-handed vs. right-handed LQs.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Scalable FBP decomposition for cone-beam CT reconstruction

Filtered Back-Projection (FBP) is a fundamental compute intense algorithm used in tomographic image reconstruction. Cone-Beam Computed Tomography (CBCT) devices use a cone-shaped X-ray beam, in comparison to the parallel beam used in older CT generations. Distributed image reconstruction of cone-beam datasets typically relies on dividing batches of images into different nodes. This simple input decomposition, however, introduces limits on input/output sizes and scalability.We propose a novel decomposition scheme and reconstruction algorithm for distributed FPB. This scheme enables arbitrarily large input/output sizes, eliminates the redundancy arising in the end-to-end pipeline and improves the scalability by replacing two communication collectives with only one segmented reduction. Finally, we implement the proposed decomposition scheme in a framework that is useful for all current-generation CT devices (7th gen). In our experiments using up to 1024 GPUs, our framework can construct 40963 volumes, for real-world datasets, in under 16 seconds (including I/O).

Chen, Peng↗
DOE OSTI2020

Optical characterization of the on-target OMEGA focal spot at high energy using the full-beam in-tank diagnostic

The full-beam in-tank (FBIT) diagnostic has been deployed to directly measure the target-plane beam fluence profile, when operated at high energy, of the OMEGA Laser System at the University of Rochester’s Laboratory for Laser Energetics. This article presents the results of early measurements taken with this diagnostic and discusses an improvement that has overcome performance limitations discovered during the initial testing. The diagnostic gives new insight into the ability of the OMEGA Laser System to provide uniform fluence profiles that are consistent across all 60 beams in the laser. Overall, the ultimate goal of the FBIT diagnostic is to allow accurate assessment of the fluence uniformity on a spherical target in 60-beam implosion experiments

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Generation and control of phase-locked Bessel beams with a persistent noninterfering region

We present, to the best of our knowledge, a novel method for the generation of multiple Bessel-like (Bessel–Gauss) beams with tilted wavefronts whose optical phases can be controlled independently. In the far field multiple field-free regions develop that are persistent to interference effects and the optical phase. The extent of these field-free regions can be controlled through the tilt angle of the wavefront with a theoretical maximum resolution of 0.1 mrad. Experimentally we employ a spatial light modulator, a lens, and an axicon, each suitable for narrow-band (continuous-wave) and broadband operation. Because of the simplicity in the optical elements, the number of noninterfering Bessel-like beams can be scaled on demand for applications that require multiple sources for coherent imaging or multiple intense beams over a controllable region with the added benefit of a field-free region for detection. Here, for reasons of clarity, we characterized two beams.

Rodnova, Zhanna↗
DOE OSTI2022

Iterative wavefront optimization of ultrafast laser beams carrying orbital angular momentum

Structured intense laser beams offer degrees of freedom that are highly attractive for high-field science applications. However, the performance of high-power laser beams in these applications is often hindered by deviations from the desired spatiotemporal profile. This study reports the wavefront optimization of ultrafast Laguerre-Gaussian beams through the synergy of adaptive optics and genetic algorithm-guided feedback. The results indicate that the intensity fluctuations along the perimeter of the target ring-shaped profile can be reduced up to ~15%. Furthermore, the radius of the ring beam profile can be tailored to a certain extent by establishing threshold fitting criteria. The versatility of this approach is experimentally demonstrated in conjunction with different focusing geometries.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Nanometer flat blazed x-ray gratings using ion beam figure correction

With the development of nanometer accuracy stitching interferometry, ion beam figuring (IBF) of x-ray mirrors can now be achieved with unprecedented performance. However, the process of producing x-ray diffraction gratings on these surfaces may degrade the figure quality due to process errors introduced during the ruling of the grating grooves. To address this challenge, we have investigated the post-production correction of gratings using IBF, where stitching interferometry is used to provide in-process feedback. A concern with ion beam correction in this case is that ions will induce enough surface mobility of atoms to cause smoothing of the grating structure and degradation of diffraction efficiency. In this study we found however that it is possible to achieve a nanometer-level planarity of the global grating surface with IBF, while preserving the grating structure. The preservation was so good, that we could not detect a change in the diffraction efficiency after ion beam correction. This is of major importance in achieving ultra-high spectral resolution, and the preservation of brightness for coherent x-ray beams.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Demonstration of controlled spatial incoherence for beam smoothing

A concept for beam smoothing of high-energy laser systems is demonstrated. Multiple coherent beams are multiplexed so that their incoherent mix decreases the far-field nonuniformity after random spatial phase modulation introduced by a phase plate. Modeling shows that the incoherent mix effectively leads to the expected scaling in terms of the number of uncorrelated beams, and that spatial multiplexing can be combined with smoothing by spectral dispersion. The results of an experimental demonstration of this concept with up to six beams, leading to more than 40 modes with polarization multiplexing and angular dispersion, are consistent with expectations. The potential practical advantages of this smoothing scheme and future developments are discussed.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

ELECTRON COOLING USING A PULSED AND DITHERING BEAM FROM AN ELECTROSTATIC ELECTRON COOLER

Electron cooling continues to be an invaluable technique to reduce and maintain the emittance in hadron storage rings such as the EIC and EICC where stochastic cooling is inefficient and radiative cooling is negligible. Extending the energy range of electron coolers beyond what is feasible with the conventional, electrostatic approach necessitates the use of RF fields for acceleration and, thus, a bunched electron beam. To experimentally investigate how the relative time structure of the two beams affects the cooling properties, we have set up a pulsed-beam cooling device by adding a synchronized pulsing circuit to the conventional electron source of the CSRm cooler at Institute of Modern Physics. Using both constant and modulated synchronization between electron pulses and ion bunches, we have measured the effects of the electron bunch length and longitudinal ion focusing strength on the temporal evolution of the longitudinal and transverse ion beam profile and demonstrated the detrimental effect of timing jitter as predicted by space-charge theory and simulations. Our experiment suggests a need for further investigations of specific aspects of bunched cooling such as synchro-betatron coupling and phase dithering effects when using short electron bunches to cool longer ion bunches. However, given the comparatively long IBS lifetime of higher-energy proton storage rings like the EIC, slow dithering could potentially provide an option to save cost on the electron cooler linac.

Wang, Haipeng↗
DOE OSTI2020

Advanced Laser-driven Plasma Accelerator Electron-beam Diagnostics with COTR Techniques

A significant advance in laser-driven plasma accelerator (LPA) electron-beam diagnostics has recently been demonstrated based on coherent optical transition radiation (COTR) imaging. We find COTR signal strengths from a microbunched subset of beam exiting the LPA to be several orders of magnitude higher than that of incoherent optical transition radiation (OTR). The transverse sizes are only a few microns as deduced from the point-spread-function-related lobe structure. In addition, the far-field COTR interferometric images obtained on the same shot provide beam-size limits plus divergence and pointing information at the sub-mrad level when compared to a modified analytical model. The integrated image intensities can be used to estimate the microbunching fraction and relatable to the LPA process. Initial results in a collaborative LPA experiment will be reported for electron beam energies of about 215 MeV. A revised configuration is proposed to record energy and ene rgy spread via COTR on the same shot with the interferometer.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Direct Observations of Sub-micropulse Electron-beam Effects from Short-range Wakefields in TESLA-type Superconducting RF Cavities

The preservation of the low emittance of electron beams during transport in the accelerating structures of large facilities is an ongoing challenge. In the cases of the TESLA-type superconducting rf cavities currently used in the European X-ray Free-electron Laser (FEL) and the under construction Linac Coherent Light Source upgrade (LCLS-II), off-axis beam transport may result in emittance dilution due to transverse long-range and short-range wakefields (SRW)*. To investigate such effects, experiments were performed at the Fermilab Accelerator Science and Technology (FAST) facility with its unique two-cavity configuration after the photocathode rf gun. We used optical transition radiation (OTR) imaging with a UV-visible synchroscan streak camera to display sub-micropulse y-t effects in the 41-MeV beam. The head-tail transverse kicks within the 11-ps-long micropulses were observed at the 100-micron level for steering off-axis in one cavity and several 100 microns for two cavities. Since the SRW kick angles go inversely with energy, these results may inform the commissioning plans of the LCLS-II injector where beam will be injected at ~1 MeV into a cryomodule.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Real-Time Longitudinal Profile Measurement of Operational H⁻ Beam at the SNS Linac Using a Laser Comb

We demonstrate a novel technique to measure the longitudinal profile of an operational hydrogen ion (H⁻) beam in a non intrusive, real-time fashion. The measurement is conducted based on the photo-ionization of the ion beam with a phase modulated laser comb pico-second laser pulses with controllable temporal structure. The measurement technique has been applied to a 1-GeV, 1.4-MW H⁻ beam at the Spallation Neutron Source (SNS) high energy beam transport (HEBT). A stroboscopic photo-graph of H⁻ beamμbunch can be obtained by using a phase modulated laser comb. The entire measurement takes only 700 us.

Liu, Yun↗
DOE OSTI2023

Progress on an Electron Beam Profile Monitor at the Fermilab Main Injector

The current program at Fermilab involves the construction of a new superconducting linear accelerator (LINAC) to replace the existing warm version. The new LINAC, together with other planned improvements, is in support of proton beam intensities in the Main Injector (MI) that will exceed 2 MW. Measuring the transverse profiles of these high intensity beams in a ring requires non-invasive techniques. The MI uses ionization profile monitors as its only profile system. An alternative technique involves measuring the deflection of a probe beam of electrons with a trajectory perpendicular to the proton beam. This type of device was installed in MI and initial studies of it have been previously presented. This paper will present the status and recent studies of the device utilizing different techniques.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Demonstration of Electron Cooling using a Pulsed Beam from an Electrostatic Electron Cooler

Electron cooling continues to be an invaluable technique to reduce and maintain the emittance in hadron storage rings in cases where stochastic cooling is inefficient and radiative cooling is negligible. Extending the energy range of electron coolers beyond what is feasible with the conventional, electrostatic approach necessitates the use of RF fields for acceleration and, thus, a bunched electron beam. To experimentally investigate how the relative time structure of the two beams affects the cooling properties, we have set up a pulsed-beam cooling device by adding a synchronized pulsing circuit to the conventional electron source of the CSRm cooler at Institute of Modern Physics *. We show the effect of the electron bunch length and longitudinal ion focusing strength on the temporal evolution of the longitudinal and transverse ion beam profile and demonstrate the detrimental effect of timing jitter as predicted by theory and simulations. Compared to actual RF-based coolers, the simplicity and flexibility of our setup will facilitate further investigations of specific aspects of bunched cooling such as synchro-betatron coupling and phase dithering.

Bruker, M. W.↗
DOE OSTI2021

Space-Charge Effects in Ionization Beam Profile Monitors

Ionization profile monitors (IPMs) are widely used in accelerators for non-destructive and fast diagnostics of high energy particle beams. At high beam intensities, the space-charge forces make the measured IPM profiles significantly different from those of the beams. We analyze dynamics of the secondaries in IPMs and develop an effective algorithm to reconstruct the beam sizes from the measured IPM profiles. Efficiency of the developed theory is illustrated in application to the Fermilab 8 GeV proton Booster IPMs.

Shiltsev, Vladimir D.↗
DOE OSTI2022

Beam-Based Diagnostics of Electric Guide Fields and Lattice Parameters for Run-1 of the Muon g-2 Storage Ring at Fermilab

A portion of the Muon g-2 Storage Ring electric system, which provides vertical beam focusing, exhibited an unexpected time dependence that produced a characteristic evolution of the stored beam during Run-1 of the Muon g-2 Experiment at Fermilab (E989). A method to reconstruct the Run-1 electric guide fields has been developed, which is based on a numerical model of the muon storage ring and optimization algorithms supported by COSY INFINITY. This method takes beam profile measurements from the Muon g-2 straw tracking detectors as input, and it produces a full reconstruction of the time-dependent fields. The fields can then be used for the reproduction of detailed beam tracking simulations and the calculation of ring lattice parameters for acceptance studies and systematic error evaluations.

43 PARTICLE ACCELERATORS↗