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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

BEAM ACCELERATION WITH A Nb3Sn CRYOMODULE AT JLAB

We report on the electron beam acceleration experiment with a Nb3Sn cryomodule at Thomas Jefferson National Laboratory (JLAB). Two CEBAF-style 5-cell 1.5 GHz Nb3Sn cavities operated at 4 K, accelerating a 100 nA continuous-wave (CW) electron beam from 200 keV to 4 MeV at JLAB’s Upgraded Injector Test Facility (UITF). The acceleration gradients in each cavity reached 11 MV/m and 7 MV/m, respectively. No field emission was observed. The unloaded quality factors reached 2¿109 at low fields at 4 K.

Geng, R. [Thomas Jefferson National Accelerator Fa↗
DOE OSTI2025

Cooling plate assembly for plasma windows positioned in a beam accelerator system

A beam accelerator system operable to produce a medical isotope, including an ion accelerator that generates an ion beam; a low-pressure chamber; an anode adjacent and fluidly connected to the low-pressure chamber; a plasma window adjacent and fluidly connected to the anode; and a cathode housing adjacent and fluidly connected to the plasma window. The plasma window has a plurality of plates, each plate having an aperture that is aligned with an aperture in one or more adjacent plates to form a plasma channel. One or more plates in the plurality of plates includes a unitary plate having an aperture therein, and one or more cooling channels entering the unitary plate at a first side of the unitary plate and exiting the unitary plate at a second side of the unitary plate. The one or more cooling channels run through a thickness of the unitary plate.

Gribb, Tye↗
NASA NTRS1981

Ion beam accelerator system

A system is described that combines geometrical and electrostatic focusing to provide high ion extraction efficiency and good focusing of an accelerated ion beam. The apparatus includes a pair of curved extraction grids with multiple pairs of aligned holes positioned to direct a group of beamlets along converging paths. The extraction grids are closely spaced and maintained at a moderate potential to efficiently extract beamlets of ions and allow them to combine into a single beam. An accelerator electrode device downstream from the extraction grids is at a much lower potential than the grids to accelerate the combined beam. The application of the system to ion implantation is mentioned.

Aston, G.↗
NASA NTRS1984

Ion beam accelerator system

A system is described that combines geometrical and electrostatic focusing to provide high ion extraction efficiency and good focusing of an accelerated ion beam. The apparatus includes a pair of curved extraction grids (16, 18) with multiple pairs of aligned holes positioned to direct a group of beamlets (20) along converging paths. The extraction grids are closely spaced and maintained at a moderate potential to efficiently extract beamlets of ions and allow them to combine into a single beam (14). An accelerator electrode device (22) downstream from the extraction grids, is at a much lower potential than the grids to accelerate the combined beam.

Aston, Graeme↗
DOE OSTI2026

Characterization of High-Entropy Alloys for Accelerator Beam Window Applications

Particle production targets and accelerator beam windows receive millions of high-energy/intensity beam pulses throughout their service lifetime. For next-generation multi-MW accelerators, it is necessary for beam windows to be able to withstand higher levels of thermal shock and radiation damage, while also having good high-temperature mechanical properties. Novel High-Entropy Alloys (HEAs) that form a single-phase microstructure, have nanoscale precipitates, and are made from low-Z elements are good candidates for beam window materials. This is due to their high-temperature strength and high resistance to radiation-induced swelling and hardening, as well as their beam transparency, allowing for maximized particle production and a longer service lifetime.

Kidwell, Tristan [U. Chicago (main)] (ORCID:000900↗
DOE OSTI2024

The Continuous Electron Beam Accelerator Facility at 12 GeV

This review paper describes the energy-upgraded Continuous Electron Beam Accelerator Facility (CEBAF) accelerator. This superconducting linac has achieved 12 GeV beam energy by adding 11 new high-performance cryomodules containing 88 superconducting cavities that have operated cw at an average accelerating gradient of 20 MV / m . After reviewing the attributes and performance of the previous 6 GeV CEBAF accelerator, we discuss the upgraded CEBAF accelerator system in detail with particular attention paid to the new beam acceleration systems. In addition to doubling the acceleration in each linac, the upgrade included improving the beam recirculation magnets, adding more helium cooling capacity to allow the newly installed modules to run cold, adding a new experimental hall, and improving numerous other accelerator components. We review several of the techniques deployed to operate and analyze the accelerator performance and document system operating experience and performance. In the final portion of the document, we present much of the current planning regarding projects to improve accelerator performance and enhance operating margins, and our plans for ensuring CEBAF operates reliably into the future. For the benefit of potential users of CEBAF, the performance and quality measures for the beam delivered to each of the experimental halls are summarized in the Appendix. Published by the American Physical Society 2024

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

Graphite for Accelerator Beam Intercepting Devices

Nuclear grade fine-grain graphite has played a central role in particle accelerator Beam Intercepting Devices, BID (e.g. targets or beam dumps) for decades, especially for high beam power facilities, such as at Fermilab, CERN, PSI and JPARC. Operations of these facilities have demonstrated graphite’s reliable performance at beam powers up to about 1 MW and enduring over 10 million thermal shock cycles of over 3x10 7 K/s. Planned future accelerator facilities will push BID beam power capability into the multi-MW regime. The material challenges of such MW-class accelerator facilities, how graphite may meet those challenges, as well as an overview of recent and current research on graphite for high power accelerator BID will be presented.

Burleigh, Abe [Fermilab]↗
DOE OSTI2024

Conditional guided generative diffusion for particle accelerator beam diagnostics

Abstract Advanced accelerator-based light sources such as free electron lasers (FEL) accelerate highly relativistic electron beams to generate incredibly short (10s of femtoseconds) coherent flashes of light for dynamic imaging, whose brightness exceeds that of traditional synchrotron-based light sources by orders of magnitude. FEL operation requires precise control of the shape and energy of the extremely short electron bunches whose characteristics directly translate into the properties of the produced light. Control of short intense beams is difficult due to beam characteristics drifting with time and complex collective effects such as space charge and coherent synchrotron radiation. Detailed diagnostics of beam properties are therefore essential for precise beam control. Such measurements typically rely on a destructive approach based on a combination of a transverse deflecting resonant cavity followed by a dipole magnet in order to measure a beam’s 2D time vs energy longitudinal phase-space distribution. In this paper, we develop a non-invasive virtual diagnostic of an electron beam’s longitudinal phase space at megapixel resolution (1024 × 1024) based on a generative conditional diffusion model. We demonstrate the model’s generative ability on experimental data from the European X-ray FEL.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Charge lifetime improvement of the Continuous Electron Beam Accelerator Facility photogun with a biased anode

GaAs photocathodes in dc high-voltage photoguns are highly susceptible to ion back-bombardment, which reduces the photocathode quantum efficiency and limits the useful operating lifetime for producing polarized electron beams. This paper demonstrates that applying a small positive bias to the photogun anode can significantly suppress ion back-bombardment and increase charge lifetime. This technique was studied extensively using the Continuous Electron Beam Accelerator Facility photogun, where highly polarized electron beams created using a strained-superlattice GaAs / GaAsP photocathode were used and charge lifetimes improved by almost a factor of 2. A new simulation code was developed to model ion production and tracking in order to better understand and explain the factors that led to the performance improvement. Results of the experiments and simulations are discussed in detail. Published by the American Physical Society 2024

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

High-Entropy Alloy R&D for Accelerator Beam Window Applications

High-Entropy Alloys are a class of novel material that can offer improved resistance to beam-induced radiation damage and thermal shock. Development of these new alloys to serve as beam windows in multi-megawatt accelerator target applications is ongoing at Fermilab. Currently we are investigating AlCoCrMnTiV alloy systems of 4-6 components for service as beam windows; these compositions are predicted by CALPHAD simulation to have a low density and single-phase BCC crystal structure. The microstructures of these systems are being studied by electron microscopy techniques such as energy dispersive X-ray spectroscopy (EDS) to determine elemental homogeneity and composition, electron backscatter diffraction (EBSD) to quantify grain structure and orientation, and transmission electron microscopy (TEM) to observe defect structures and precipitate formation; nanoindentation is used to probe microstructural mechanical properties. Initial bulk property characterization utilizes differential scanning calorimetry to quantify specific heat capacity (cp), dilatometry to determine the coefficient of thermal expansion (CTE), and time-domain thermoreflectance (TDTR) to measure thermal conductivity (K). A miniature tensile testing apparatus is also being developed to test tensile properties. Post-irradiation examination is currently ongoing for several of these compositions that have been irradiated by low-energy ions to damage levels and at a temperature relevant to beam window applications at future next-generation accelerator facilities. This talk will briefly describe the alloy design and synthesis before going into more depth covering microstructural pre-characterization, and post-irradiation examination results from low-energy ion irradiated specimens. This will be followed by the plans for alloy down selection and future prototypic proton irradiations.

43 PARTICLE ACCELERATORS↗
NASA NTRS1981

High efficiency ion beam accelerator system

An ion accelerator system that successfully combines geometrical and electrostatic focusing principles is presented. This accelerator system uses thin, concave, multiple-hole, closely spaced graphite screen and focusing grids which are coupled to single slot accelerator and decelerator grids to provide high ion extraction efficiency and good focusing. Tests with the system showed a substantial improvement in ion beam current density and collimation as compared with a Pierce electrode configuration. Durability of the thin graphite screen and focusing grids has been proven, and tests are being performed to determine the minimum screen and focusing grid spacing and thickness required to extract the maximum reliable beam current density. Compared with present neutral beam injector accelerator systems, this one has more efficient ion extraction, easier grid alignment, easier fabrication, a less cumbersome design, and the capacity to be constructed in a modular fashion. Conceptual neutral beam injector designs using this modular approach have electrostatic beam deflection plates downstream of each module.

Aston, G.↗
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↗
NASA NTRS2023

Relativistic Electron Beams Accelerated By an Interplanetary Shock

Context: Collisionless shock waves have long been considered to be among the most prolific particle accelerators in the universe. Shocks alter the plasma they propagate through, and often exhibit complex evolution across multiple scales. Interplanetary (IP) traveling shocks have been recorded in situ for over half a century and act as a natural laboratory for experimentally verifying various aspects of large-scale collisionless shocks. A fundamentally interesting problem in both heliophysics and astrophysics is the acceleration of electrons to relativistic energies (> 300 keV) by traveling shocks. Aims: The reason for an incomplete understanding of electron acceleration at IP shocks is due to scale-related challenges and a lack of instrumental capabilities. This Letter presents the first observations of field-aligned beams of relativistic electrons upstream of an IP shock, observed thanks to the instrumental capabilities of Solar Orbiter. This study presents the characteristics of the electron beams close to the source and contributes to the understanding of their acceleration mechanism. Methods: On 25 July 2022, Solar Orbiter encountered an IP shock at 0.98 AU. The shock was associated with an energetic storm particle event, which also featured upstream field-aligned relativistic electron beams observed 14 min prior to the actual shock crossing. The distance of the beam’s origin was investigated using a velocity dispersion analysis (VDA). Peak-intensity energy spectra were analyzed and compared with those obtained from a semi-analytical fast-Fermi acceleration model. Results: By leveraging Solar Orbiter’s high temporal resolution Energetic Particle Detector (EPD), we successfully showcase an IP shock’s ability to accelerate relativistic electron beams. Our proposed acceleration mechanism offers an explanation for the observed electron beam and its characteristics, while we also explore the potential contributions of more complex mechanisms.

acceleration of particles↗
DOE OSTI2025

Investigation of CrMnV and CrMnTiV multi principal element alloys thin films for use as exit windows of electron beam accelerators

Here, this study explores CrMnV and CrMnTiV multi principal element alloy (MPEA) films as candidates for electron beam exit windows in industrial, high-power accelerators. Films were deposited via magnetron sputtering on various substrates and exposed to 66 kGy of 10 MeV e-beam irradiation. Structural and mechanical properties were analyzed using FESEM, XRD, and nanoindentation. CrMnTiV films exhibited superior grain uniformity and hardness, regardless of the substrate type. Compared to bulk materials, both MPEA films demonstrated higher hardness and excellent radiation resistance. These results highlight the potential of MPEA films as durable, radiation-tolerant materials for high-performance accelerator exit window applications.

Electron Beam Irradiation↗