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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Beam halo formation with different cathode distributions

Beam halo refers to the low-density distribution of particles extending beyond the beam core, and its generation and mitigation are important topics in particle accelerator design. Effective mitigation of beam halo is essential for the cooler design based on Energy Recovery Linac (ERL), which must deliver an electron beam with average beam current of 100 mA and a charge 1 nC per bunch. In the ERL injector and booster linacs, space charge effects are stronger due to relatively low beam energy (6 MeV). Additionally, the longer bunch length of approximately 100 ps in this regime vs the RF period of 5.08 ns makes the formation of beam halos more likely. Therefore, effective collimation of beam halo is critical to maintaining the required beam parameters. To design an effective collimation scheme, several halo distributions were generated at the cathode and used to study halo formation within the injector-merger. This paper presents different halo distributions and halo formation, providing insights on halo collimation strategy.

Accelerator Physics↗
DOE OSTI2026

Current status of the electron transport line from RCS to ESR: RTE line

The electron injection system of the U.S. Electron-Ion Collider (EIC) is located outside of the RHIC tunnel. Electrons beams accelerated by the Rapid Cycling Synchrotron (RCS) must be transported to the Electron Storage Ring (ESR), which resides within the RHIC tunnel. To accomplish this, a dedicated beam transport line, referred to as RTE (RCS-to-ESR) line is being designed. The proposed conceptual design comprises three main sections; RCS extraction, a vertical bend and dispersion suppression region, and ESR injection matching. The extraction section uses pulsed kickers and septum magnets to achieve a total deflection angle of 3 degrees. To align the injection section with ESR, the beamline must provide a vertical elevation of 1.68 m, and an array of FODO cells is used to suppress the vertical dispersion. The total length of the RTE line is approximately 133 m, and this paper presents the current design status and considerations for this transport line.

Accelerator Physics↗
DOE OSTI2026

Design update on the transition beamline for the CEBAF Energy Upgrade

For Jefferson Lab’s 22GeV upgrade, two new permanent-magnet Fixed-Field Alternating Gradient (FFA) arcs will be integrated to serve the accelerator’s six highest-energy recirculation passes. Connecting these FFA arcs to the existing linear accelerator (linac) requires a carefully engineered transition section. The current design has two parts where the first part adiabatically matches the beam dispersion and orbit trajectories, while the second part aligns the Twiss parameters (alpha and beta functions) with those at the linac entrance. Given the tight spatial constraints and multiple matching requirements, a genetic algorithm is being explored to optimize the beam optics matching. This paper presents the current progress in developing and optimizing this transition.

Accelerator Physics↗
DOE OSTI2026

Linac to BAR/RCS transfer line design for EIC electron injection system

A transfer line has been designed for the Electron-Ion Collider (EIC) to transport electron bunches from the linac to the Rapid Cycling Synchrotron (RCS). In its initial operational stage, the line accommodates 1 nC electron bunches directly from the linac. To support a future upgrade involving a Beam Accumulator Ring (BAR), which will stack individual bunches to form high-charge 28 nC bunches, the design incorporates two switching dipoles enabling injection into and extraction from the BAR. Additionally, a beam dump has been included for operational flexibility and safety. The final segment of the line interfaces with the RCS through a modified Penner bend, preserving beam quality while satisfying geometric constraints. This layout ensures compatibility with both current and future operational modes of the EIC injection system.

Accelerator Physics↗
DOE OSTI2026

New measurement techniques for gear-changing research using DESIREE

In this work we cover some of the newer techniques developed to measure the effects of a gear changing system maintained in DESIREE at Stockholm University. Gear-changing is a collider synchronization method where two rings with different harmonic numbers in them maintain collisions through different velocities, pathlengths or a combination of the two. This system has been demonstrated using the low energy ion collider DESIREE at Stockholm university. We have not only continued our previous methods of studying the beam using a repeating pattern technique where one bucket in each ring is intentionally left empty, but we now also use recently installed pickups outside of the merger region to study the beams separately while they collide.

Accelerator Physics↗
DOE OSTI2026

Space charge studies on strong hadron cooler energy recovery linac

An Energy Recovery Linac (ERL) based cooler, using Coherent electron Cooling (CeC) is being designed for cooling hadron beams of the Electron-Ion Collider (EIC). The ERL design utilizes highcurrent, high-brightness electron beams with low emittance and a uniform longitudinal distribution for efficient hadron cooling. This is designed to operate in two modes to accommodate cooling requirements for hadron bunches at 100 GeV and 275 GeV, each with an average current of 100 mA and 1 nC bunch charge. With these parameters, the space charge effects become significant in this ERL design due to the low beam energy and high beam current. In this paper, we discuss strategies for including space charge effects in the optics design and implementation of an interface for space charge dominated and non-dominated regions of this ERL lattice.

Accelerator Physics↗
DOE OSTI2025

SRF cavity instability detection with machine learning at CEBAF

During the operation of the Continuous Electron Beam Accelerator Facility (CEBAF), one or more unstable superconducting radio-frequency (SRF) cavities often cause beam loss trips while the unstable cavities themselves do not necessarily trip off. The present RF controls for the legacy cavities report at only 1 Hz, which is too slow to detectfast transient instabilities during these trip events. These challenges make the identification of an unstable cavity out of the hundreds installed at CEBAF a difficult and time-consuming task. To tackle these issues, a fast data acquisition system (DAQ) for the legacy SRF cavities has been developed, which records the sample at 5 kHz. An unsupervised learning framework has been developed to identify anomalous SRF cavity behavior. We will discuss the present status of the DAQ system and our framework, along with recent successes in detecting anomalous cavity behavior. Overall, our method offers a practical solution for identifying unstable SRF cavities, contributing to increased beam availability and machine reliability.

Accelerator Physics↗
DOE OSTI2025

A reactive ferroelectric tuner for microphonics compensation

Jefferson Lab (JLab) is actively pursuing an extensive research program focused on developing advanced Nb₃Sn superconducting technology for particle accel-eration. Due to the brittle nature of Nb₃Sn coatings, a Ferroelectric Tuner (FRT) currently represents the most viable approach for microphonics compensation in these next-generation cavities. We suggest a novel, fast-responding FRT integrated directly into the main coupler, eliminating the need for an additional RF port. Leveraging a unique RF design based on a magic-T configuration, this advanced FRT will enable micro-phonics compensation in the ±30 Hz range without undesirable changes to the external quality factor.

Accelerator Physics↗
DOE OSTI2025

Analytical Approximations for Beamstrahlung at Very High Energy Electron-Positron Colliders

Among the many effects that occur in beam-beam electron-positron collisions at TeV energies, emission of hard synchrotron radiation, or beamstrahlung, has special importance. Beamstrahlung determines the energy spectrum of the most energetic electrons, positrons, and photons and supplies the initial condition for the calculation of all other QED processes. In this paper, we show that the description of beamstrahlung simplifies in the limit of large quantum parameter $Υ$, which is realized in 10 TeV collider designs. The beamstrahlung spectra for electrons and photons are given in terms of universal functions. We supply approximations to these functions that will be useful for more general studies of the beam-beam interaction at very high energies.

Accelerator Physics (physics.acc-ph)↗
DOE OSTI2026

Laboratory Tests of Laser Control of Electron Beams for Future Colliders

Laser-driven Compton backscattering (CBS) has been proposed as method for controlling the intensity of colliding bunches in the FCC-ee so as to avoid the flip-flop instability caused by intensity asymmetry in colliding bunches. Laser-based collimation has also been proposed as an indestructible collimator for high-intensity electron beams. We have initiated a laboratory-based test program of these concepts with the E344 experiment at FACET-II. In this paper, we describe simulations of laser-beam interactions at FACET-II and the relevant scaling for FCC-ee. We also describe the experimental setup and diagnostics that will be used to make the measurements at FACET-II.

Accelerator Physics (physics.acc-ph)↗
DOE OSTI2026

Monochromation of pulsed electron beams with terahertz radiation at a planar mirror

Exquisite control of electron beam energy is required for many electron spectroscopy and imaging applications. For both continuous and pulsed beams, the beam energy spread is fundamentally limited by the electron source, and is typically a sizable fraction of an electron-volt. In this paper, we present a means to reduce electron beam energy spread after emission to the level of a few 10s of meV rms using femtosecond photoemission and an interaction with laser-derived single- to few-cycle terahertz (THz) radiation. We show analytically and in particle tracking simulations that this interaction can remove energy spread stored in both the transverse and longitudinal degrees of freedom. We analytically formulate the limit of energy spread that this technique can achieve, and map the non-ideal affects arising at high frequencies. The interaction is mediated by the beam's passage through a mirror which is reflective to terahertz radiation but allows transmission of the majority of the electron beam (e.g. a wire mesh). This method then only requires beam current losses of a few tens of percent, far smaller than what is achieved in prism and slit-based electron monochromators.

Accelerator Physics (physics.acc-ph)↗
DOE OSTI2026

Broadband hard X-ray attosecond pulses from extremely chirped electron beams

Attosecond pulses from free-electron lasers have opened the doors to atomic site-specific studies of bound electronic dynamics on their natural, sub-femtosecond timescales. Key to their success has been electron beam shaping techniques enabling the generation of sub-femtosecond current spikes with peak currents on the order of 10 kA. We demonstrate in an RF linac the generation of current spikes with extreme chirps on the order of 350 MeV/micron, directly competitive with the chirps expected from beam-driven plasma wakefield accelerators. Leveraging chirp-taper compensation, we use these highly chirped beams to generate hard X-ray attosecond pulses with bandwidths exceeding 30 eV, a factor of two beyond previous demonstrations. We simultaneously present the first explicit experimental evidence of chirp-taper compensation in an attosecond XFEL, finding that optimal tapering improves the bandwidth and pulse energy by factors of two and five, respectively, for our conditions. In addition to the immediate utility of such broadband hard X-ray pulses, electron beams with such extreme chirps can be utilized for unique new experimental modalities by performing further compression after the undulators. Such post-lasing compression can enable subsequent superradiant light emission at longer wavelengths, or direct excitation of quantum systems with the beam's intense space-charge field for unique attosecond pump-probe possibilities.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

Transversely pumped laser driven particle accelerator

We present a novel acceleration scheme capable of accelerating electrons and ions in an underdense plasma. Transversely Pumped Acceleration (TPA) uses multiple arrays of counter-propagating laser beamlets that focus onto a central acceleration axis. Tuning the injection timing and the spacing between the adjacent beamlets allows for precise control over the position and velocity of the intersection point of the counter-propagating beam arrays. This results in an accelerating structure that propagates orthogonal to the direction of laser propagation. We present the theory that sets the injection timing of the incoming pulses to accelerate electrons and ions with a tunable phase velocity plasma wave. Simulation results are also presented which demonstrate 1.12 GeV proton beams accelerated in 3.6 mm of plasma and electron acceleration gradients on the order of 1 TeV/m in a scheme that circumvents dephasing. This work has potential applications as a compact accelerator for medical physics and high energy physics colliders.

Laser-produced plasmas↗
DOE OSTI2025

Accelerators for the Future: R&D at the Fermilab FAST Facility

High energy physics in the U.S. has ambitious plans requiring new and improved accelerator technologies, including an upgraded complex at Fermilab for DUNE, next-generation light sources, and the potential of a future collider to be built on U.S. soil. To address these requirements, Fermilab operates the Fermilab Accelerator Science and Technology (FAST) facility, dedicated to accelerator R&D. FAST includes an electron gun and superconducting RF linac (up to 300 MeV), a storage ring, and an upcoming proton source and injector line (up to 2.5 MeV). In addition to the future of Fermilab accelerators, the broad physics program includes general R&D with potential impact across the DOE science program. This colloquium will provide a basic introduction to accelerator technologies and describe the principles of proton and electron accelerators, including the challenges associated with next-generation operations. We will discuss the exciting R&D ongoing at FAST to address the required technological advancements, focusing on Non-Linear Integrable Optics (NIO) for improved beam intensity and Optical Stochastic Cooling (OSC) for improved beam quality, and touching on a wide range of additional ongoing research. I intend to make the content interesting and accessible to those who have never taken any formal courses in accelerator physics.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

High Energy Neutrino Physics

Of the twelve subatomic particles that are the building blocks of all the known matter in the universe, three are neutrinos, small neutral particles that interact through the weak interaction with other particles in the Universe. These three neutrinos, paired with the three charged leptons, the familiar electron, the heavier muon, and the still heavier tau, are some of the least well understood particles of these building blocks. Experiments using accelerator beams, like those that are the subject of this grant, can address some of the key questions scientists are posing with respect to the neutrino. Specifically, are there differences between neutrinos and their anti-particles, anti-neutrinos, that could give us some clue to the matter dominated universe, do we understand the spectrum of masses of the three neutrinos, and are there other kinds of neutirnos than the three neutrinos? Coupled with advances in precision neutrino detection, the US is addressing these questions from small scale experiments to the massive DUNE experiment. PI Fleming and her team play critical roles in accelerator based neutrino physics at short and long baseline with participation on MicroBooNE, SBND, and with the group's participation in DUNE. These experiments are at the heart of the US-based high energy physics program.

43 PARTICLE ACCELERATORS↗