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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Calibration of the analog beam-signal hardware for the credited engineered beam power limit system at the Proton Power Upgrade Project at the Spallation Neutron Source

A programmable signal processor-based credited safety control that calculates pulsed beam power based on beam kinetic energy and charge was designed as part of the Proton Power Upgrade (PPU) project at the Spallation Neutron Source (SNS). The system must reliably shut off the beam if the average power exceeds 2.145 MW averaging over 60 seconds. System calibration requires pedigree in measurements, calibration setup, and calculations. This paper discusses the calibration of the analog beam signal components up to and including the Analog Digital Convertors (ADCs) for implementation into the Safety Programmable Logic Controllers (PLCs) and Field Programmable Gate Arrays (FPGAs).

Bobrek, Miljko↗
DOE OSTI2025

Image mapping for multiple charge state beams using a beam induced fluorescence profile monitors

Work continues on a minimally invasive, nitrogen fluorescence gas sheet at the Facility for Rare Isotope Beams (FRIB). A low density gas sheet may be used to observe the 2D transverse beam profile of high intensity, multiple charge state beams with minimal interference. Spatially and temporally correlated profiles are of particular interest in locations where there is significant charge state spread, such as the FRIB linac folding segments. A low-density gas sheet measurement system offers advantages for gas handling in nitrogen sensitive areas, however signal intensity is significantly lower than techniques using higher density gas sheets and jets. This work discusses measurement considerations for photon distributions generated by several spatially separated interaction points and design considerations for a high-sensitivity optics system for handling the expected low signal intensity.

Accelerator Physics↗
DOE OSTI2021

Beam power scale-up in micro-electromechanical systems based multi-beam ion accelerators

We report on the development of multi-beam RF linear ion accelerators that are formed from stacks of low cost wafers and describe the status of beam power scale-up using an array of 120 beams. The total argon ion current extracted from the 120-beamlet extraction column was 0.5 mA. The measured energy gain in each RF gap reached as high as 7.25 keV. We present a path of using this technology to achieve ion currents >1 mA and ion energies >100 keV for applications in materials processing.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

Beam particle identification and tagging of incompletely stripped heavy beams with HEIST

A challenge preventing successful inverse kinematics measurements with heavy nuclei that are not fully stripped is identifying and tagging the beam particles. For this purpose, the HEavy ISotope Tagger (HEIST) has been developed. HEIST utilizes two micro-channel plate timing detectors to measure the time-of-flight, a multi-sampling ion chamber to measure energy loss, and a high-purity germanium detector to identify isomer decays and calibrate the isotope identification system. HEIST has successfully identified 198 Pb and other nearby nuclei at energies of about 75 MeV/A. In the experiment discussed, a typical cut containing 89% of all 198 Pb 80+ in the beam had a purity of 86%. We examine the issues of charge state contamination. Here, the observed charge state populations of these ions are presented and, using an adjusted beam energy, are well described by the charge state model GLOBAL.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

Beam-pointing verification using x-ray pinhole cameras on the 60-beam OMEGA laser

On the OMEGA laser system, the beam-pointing accuracy is verified by irradiating a 4 mm diameter Au-coated spherical target with ~23 kJ of laser energy. Up to ten x-ray pinhole cameras record the x-ray emission from all 60-beam spots. A new set of algorithms has been developed to improve the accuracy of the pointing evaluation. An updated edge-finding procedure allows one to infer the center of the sphere with subpixel accuracy. A new approach was introduced to back-propagate the pixel locations on the 2D image to the 3D surface of the sphere. Furthermore, a fast Fourier transform-based de-noising method significantly improves the signal-to-noise of the data. Based on the beam-pointing analysis, hard-sphere calculations of the laser-drive illumination uniformity on the target surface and the decomposition of the illumination distribution into lower order modes (1–10) are evaluated.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

Experimental investigation of beam-ion losses induced by magnetic perturbations using the light ion beam probe technique in the ASDEX Upgrade tokamak

The impact of externally applied magnetic perturbations (MPs) on fast-ion losses has been investigated by means of the light ion beam probe (LIBP) technique in the ASDEX Upgrade tokamak. The LIBP technique allows to experimentally infer the fast-ion orbit displacement induced by MPs via first-orbit losses using scintillator based fast-ion loss detector (FILD) measurements. The fast-ion orbit displacement against different applied MP spectra has been studied. These shots were conducted in ELM mitigated H-mode plasmas. A rigid rotation of the MP coils was applied with a frequency of 1 Hz, with an n = 2 configuration and changing the differential phase between the upper and lower set of coils (ΔΦ ul ) on a shot-to-shot basis. Beam sources Q7 (tangential) and Q8 (radial) were used to probe different fast-ion orbits with FILD1. The measured fast-ion orbit displacement ranges from 3 to 20 mm approximately, and no qualitative difference is observed between ions from beam sources Q7 and Q8. The minimum is found for a ΔΦ ul ~ 50°, which is shifted with respect to the minimum of the plasma boundary displacement, found at ΔΦ ul ~ 0°. A first attempt to validate the orbit following code ASCOT—including the plasma response calculated with the MARS-F code—against these experimental measurements is performed. Finally, while the dependence of the first-orbit fast-ion displacement with ΔΦ ul does not match the experimental measurements, these simulations do capture other features such as the order of magnitude of the orbit displacement and the importance of the toroidal spectrum of the applied perturbation.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Measurement and modeling of beam transport in the FODO line of the Spallation Neutron Source Beam Test Facility

Ongoing studies at the Spallation Neutron Source (SNS) Beam Test Facility (BTF) seek to understand and model bunch dynamics in a high-power LINAC front-end. The BTF has recently been upgraded with a reconfiguration from a U-shaped line to a Straight line. We report the current state of model benchmarking, with a focus on RMS beam sizes within the FODO line. The beam measurement is obtained via three camera/screen pairs in the FODO line. This presentation discusses the methodology and results of this measurement.

Thompson, Trent↗
DOE OSTI2021

An examination of different representations of the electrostatic field and potential of an intense relativistic electron beam in a cylindrical conductor and their implications on foil focusing of an elliptical beam

Knowledge of the electrostatic field and potential of an intense relativistic electron beam (IREB) in a cylindrical conductor is essential for understanding the transport of IREBs including the interaction of a grounded conducting foil with the beam. Different representations of the electrostatic field or potential exist in the literature. The different representations are compared and an extension to foil focusing of elliptical beams is discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Beam Dynamics Simulations of Transient Beam Loading Effects in the 10GeV EIC Electron Storage Ring

We report on beam dynamics studies of transient beam loading effects in the 10 GeV EIC electron storage ring [1]. The studies are carried out with time-dependent Vlasov-Fokker-Planck simulations performed with the parallel, particle tracking code SPACE [2], which allows to follow self-consistently the dynamics of h bunches, where h in the number of RF buckets, in arbitrary multi-bunch configurations. The specific goal of the numerical simulations is to determine stable RF cavity settings under heavy beam loading. We also study the option to operate with a passive, third-harmonic cavity (3HC) system for bunch lengthening, addressing both stability and the performance limitation due to a gap in the uniform filling pattern for ion clearing.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

Comments on the paper “Eliminating beam-induced depolarizing effects in the hydrogen jet target for high-precision proton beam polarimetry at the Electron-Ion Collider” (Part I)

A critical review of the methodology used in F. Rathmann et al., Phys. Rev. Accel. Beams 29, 021001 (2026), to evaluate beam-induced depolarization of the Atomic Polarized Hydrogen Gas Jet (HJET) target at the Electron–Ion Collider (EIC) is presented. It is shown that several key assumptions underlying that analysis—including the introduction of a photon emission threshold, the application of Fermi’s Golden Rule to coherent hyperfine transitions, the interpretation of power broadening as a physical linewidth increase, and the treatment of spatial magnetic fields—are either incorrect or internally inconsistent. As a consequence, the predicted large depolarization effects are demonstrated to be artifacts of the adopted methodology rather than genuine physical phenomena. A consistent quantum-mechanical treatment based on the time-dependent Schrödinger equation shows that beam-induced depolarization probabilities at the EIC are negligibly small.

43 PARTICLE ACCELERATORS↗
NASA NTRS1972

Smoke Plume Analysis Using Fan-beam and Single-beam Radiometers

Smoke plume data were taken using the stacks of the Mills Road Steam Plant on Redstone Arsenal, Huntsville, Alabama. The fan-beam unit was placed approximately 235 meters east of the Mills Road Steam Plant, and the single-beam unit was placed approximately 80 meters north of the fan-beam unit. Results of the smoke plume measurements indicate that the smoke plume is a periodic process near the mouth of the smokestack. The usefulness of the system is limited because of inaccurate and cumbersome positioning methods and base line constraints due to cable length. It is recommended that the radiometers be mounted on pedestals which have both azimuth and elevation positions determined by digitally controlled stepper drive motors. It is also recommended that a time multiplex system be used to transmit data from the radiometers to the electronics van.

Dodd, J. L.↗
NASA NTRS1981

Effective path length corrections in beam-beam scattering experiments

The effect of the change of scattering geometry with scattering angle in beam-beam experiments is investigated. Atomic (molecular) target distributions associated with static gas, orifice, tube, capillary array (with and without further collimation), and jet sources have been considered in model calculations for a number of commonly used electron scattering geometries. The relationship between scattering intensity, cross section, and the geometrical integral called 'effective path length' is derived. Volume correction factors (the reciprocal of effective path length) have been calculated for sample cases to illustrate the effect of various beam and scattering geometry characteristics. The validity of the model calculation has been experimentally verified. Most of the commonly used scattering geometries require significant correction of the scattering intensity distributions, but with proper planning scattering geometries can be designed such that the intensity and the cross section angular distribution are identical within 1%.

Brinkmann, R. T.↗
NASA NTRS1989

Far field beam pattern of one MW combined beam of laser diode array amplifiers for space power transmission

The far-field beam pattern and the power-collection efficiency are calculated for a multistage laser-diode-array amplifier consisting of about 200,000 5-W laser diode arrays with random distributions of phase and orientation errors and random diode failures. From the numerical calculation it is found that the far-field beam pattern is little affected by random failures of up to 20 percent of the laser diodes with reference of 80 percent receiving efficiency in the center spot. The random differences in phases among laser diodes due to probable manufacturing errors is allowed to about 0.2 times the wavelength. The maximum allowable orientation error is about 20 percent of the diffraction angle of a single laser diode aperture (about 1 cm). The preliminary results indicate that the amplifier could be used for space beam-power transmission with an efficiency of about 80 percent for a moderate-size (3-m-diameter) receiver placed at a distance of less than 50,000 km.

Kwon, Jin H.↗
NASA NTRS1993

Gaussian-Beam/Physical-Optics Design Of Beam Waveguide

In iterative method of designing wideband beam-waveguide feed for paraboloidal-reflector antenna, Gaussian-beam approximation alternated with more nearly exact physical-optics analysis of diffraction. Includes curved and straight reflectors guiding radiation from feed horn to subreflector. For iterative design calculations, curved mirrors mathematically modeled as thin lenses. Each distance Li is combined length of two straight-line segments intersecting at one of flat mirrors. Method useful for designing beam-waveguide reflectors or mirrors required to have diameters approximately less than 30 wavelengths at one or more intended operating frequencies.

Veruttipong, Watt↗
NASA NTRS1995

A Coupled Layerwise Analysis of the Thermopiezoelectric Response of Smart Composite Beams Beams

Thermal effects are incorporated into previously developed discrete layer mechanics for piezoelectric composite beam structures. The updated mechanics explicitly account for the complete coupled thermoelectromechanical response of smart composite beams. This unified representation leads to an inherent capability to model both the sensory and actuator responses of piezoelectric composite beams in a thermal environment. Finite element equations are developed and numerical results are presented to demonstrate the capability of the current formulation to represent the behavior of both sensory and active smart structures under thermal loadings.

Lee, H.-J.↗
DOE OSTI2021

A BEAM SCREEN TO PREPARE THE RHIC VACUUM CHAMBER FOR EIC HADRON BEAMS: CONCEPTUAL DESIGN AND REQUIREMENTS

The Electron Ion Collider (EIC) Hadron Storage Ring (HSR) will use the existing Relativistic Heavy Ion Collider storage rings, including the superconducting magnet arcs [1]. The vacuum chambers in the superconducting magnets and the cold mass interconnects were not designed for EIC beams and so must be updated to reduce resistive-wall heating and to suppress e-clouds. To do so without compromising the EIC luminosity goal, a stainless steel beam screen with colaminated copper and a thin layer of amorphous carbon will be installed. This paper describes the main requirements that our solution for the hadron ring vacuum chamber needs to satisfy, including impedance, aperture limitations, vacuum, thermal and structural stability, mechanical design, installation and operation. The conceptual design of the beam screen currently under development is introduced.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

A rotor-based multileaf collimator for beam shaping

We introduce a new style of multileaf collimator which employs rotors with angularly dependent radius to control the masking aperture: a rotor-based multileaf collimator (RMLC). Using a padlock-inspired mechanism, a single motor can set dozens of rotors, i.e. leaves, independently. This is especially important for an ultra-high vacuum (UHV) compatible MLC, since this reduces the number of actuators and vacuum feedthroughs required by more than an order of magnitude. This new RMLC will complement previous work employing a UHV compatible MLC with an emittance exchange beamline to create arbitrarily shaped beams on demand. A feed-forward control system which abstracts away the complexity of the RMLC operation, and is adaptable to real beamline conditions, is discussed and demonstrated in simulation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Interferometric bunch length measurements of 3 MeV picocoulomb electron beams

We report picosecond bunch length measurements using an interferometric method for a 3 MeV electron beam having bunch charge ranging from 1 to 14 pC. The method senses the single-cycle sub-terahertz (THz) pulse emitted by each electron bunch as coherent transition radiation which, in turn, is analyzed using a Michelson-type interferometer, forming an interferogram that is then processed to yield the nominal electron bunch length. This sub-THz coherent radiation intensity was measured using a quasi-optical detector (QOD) operated at room temperature. This experiment was quite challenging since the divergence angle of the sub-THz pulse emitted by the low-energy electron bunch exceeds ±10°, and its pulse energy at the entrance to the detector was as low as 100 pJ. When compared to a conventional helium-cooled silicon composite bolometer designed for frequencies above 0.5 THz, the QOD provided much better signal-to-noise ratio in the ~80 GHz frequency range, which was critical for the successful measurement of the bunch length.

36 MATERIALS SCIENCE↗