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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 OSTI2018

Toroidal merger simulations for the JLEIC bunched beam electron cooler ring

The bunched beam electron cooler ring for the Jefferson Lab Electron-Ion Collider (JLEIC) requires a merger system to transport magnetized electron beams of two different energies to the same energy recovery linac (ERL) beamline. The system is especially challenging compared to existing mergers for ERL or hadron cooling applications (as at COSY) due to the small separation in energy between the two beams; for the JLEIC bunched beam cooler, the two beam energies may only differ by a factor of 4. An additional complication is the use of a magnetized beam. A toroidal merger system is studied using G4Beamline/GEANT4. Preservation of the quality of the low energy beam from the injector is especially vital for efficient cooling performance and compatibility with the ERL. Effects of the toroidal system on transverse and longitudinal emittances of the magnetized beams, as well as space charge effects, are presented and discussed.

Sy, Amy V.↗
DOE OSTI2018

Micro-Bunched Beam Production at FAST for Narrow Band THz Generation Using a Slit-Mask

We discuss simulations and experiments on creating micro-bunch beams for generating narrow band THz radiation at the Fermilab Accelerator Science and Technology (FAST) facility. The low-energy electron beamline at FAST consists of a photoinjector-based RF gun, two Lband superconducting accelerating cavities, a chicane, and a beam dump. The electron bunches are lengthened with cavity phases set off-crest for better longitudinal separation and then micro-bunched with a slit-mask installed in the chicane. We carried out the experiments with 30 MeV electron beams and detected signals of the micro-bunching using a skew quadrupole magnet in the chicane. In this paper, the details of micro-bunch beam production, the detection of micro-bunching and comparison with simulations are described.

Hyun, J.↗
DOE OSTI2026

Neutrino beam bunch structure reconstruction with precision timing in the ICARUS liquid argon time projection chamber

The ICARUS detector has been operating smoothly since 2021 as the far detector in the Short Baseline Neutrino (SBN) program at Fermilab, collecting neutrino interactions from both the Booster Neutrino Beam (BNB) and off-axis from the Neutrinos at the Main Injector (NuMI) beam. Analysis of neutrino interactions in ICARUS requires mitigation of substantial cosmogenic backgrounds. This is achieved by using an external Cosmic Ray Tagger (CRT) and a Photomultiplier Tube (PMT) system embedded in the liquid argon. The intrinsic neutrino beam bunch structure, inherited time structure from the Radio Frequency (RF) system used to accelerate the protons, can be resolved at the ICARUS detector using precise timing information. Located at shallow depth, ICARUS is exposed to a high flux of cosmic rays that can be mistaken for neutrino interactions. To mitigate this background, the CRT and a 3-meter-thick concrete overburden were installed. To better model backgrounds, ICARUS makes use of an overlay technique where simulated neutrino events are superimposed on detector beam-off data. PMTs installed within a Time Projection Chamber detect argon scintillation light emitted by high energy charged particles passing through the chamber and provide the event timing of neutrino interactions. The nanosecond-level beam bunch structure is reconstructed with the PMT system and can be used to further understand backgrounds and enhance neutrino physics capabilities. In this thesis, I will discuss background mitigation techniques using precision timing and present a novel technique to select neutrino events from our unbiased data stream using the beam bunch structure.

Heggestuen, Anna [Colorado State U.] (ORCID:000000↗
DOE OSTI2017

Design and simulation study of ultra-fast beam bunches split for three orthogonal planes high-energy electron dynamic radiography

Here a compact three orthogonal planes high-energy electron radiography system was proposed. One of the critical technologies, the ultra-fast beam bunches split from the bunch train are studied. The separated bunches could be transported to the three orthogonal planes of the target for dynamic radiography diagnostics. The key elements of the ultra-fast bunches split system are transverse deflecting cavity (TDC) and the twin septum magnet (TSM). The principle of TDC and TSM are briefly introduced. An example of the beam bunches split system for test experiment (40 MeV electron beam) with TDC and TSM is designed and studied by particle-tracking simulation and it confirms this method is valid and feasible. Especially with TSM, a compact three orthogonal planes radiography system can be realized. The evolution of the beam parameters along the beam line from simulation are investigated. The detailed design of the beam split system and beam dynamics simulation study are presented in this paper.

Zhao, Q. T.↗
DOE OSTI2018

Development of a bunched beam electron cooler for the Jefferson Lab electron-ion collider

Jefferson Lab is in the process of designing an electron-ion collider with unprecedented luminosity at a 65 GeV center-of-mass energy. This luminosity relies on ion cooling in both the booster and the storage ring of the accelerator complex. The cooling in the booster will use a conventional DC cooler similar to the one at COSY. The high-energy storage ring, operating at a momentum of up to 100 GeV/nucleon, requires novel use of bunched-beam cooling. We will present a new design for a Circulator Cooler Ring for bunched-beam electron cooling. This requires the generation and transport of very high-charge magnetized bunches, acceleration of the bunches in an energy recovery linac, and transfer of these bunches to a circulating ring that passes the bunches 11 times through the proton or ion beam inside cooling solenoids. This design requires the suppression of the effects of space charge and coherent synchrotron radiation using shielding and RF compensation.

Benson, Stephen V.↗
DOE OSTI2026

Thermal and electromechanical response of ultra-thin carbon-strip polarimeter targets in relativistic bunched beams

Thin carbon-strip targets provide fast relative hadron beam polarimetry, but their response in intense relativistic bunched beams is not governed by local stopping-power heating alone. We develop a coupled response model that combines beam-target overlap, secondary-electron escape, retained heat, target motion, transient heat transport, RF-induced strip-end heating, beam-induced forces, resistance changes, and slack-strip deformation. RHIC target observations constrain the relevant motion, force, and nonlocal-heating scales and show that target survival depends on both beam-center heating and electromagnetic boundary conditions near the strip ends. Applying the model to Booster, AGS, RHIC, and EIC proton and 3 He cases shows that the RHIC proton lifetime scale is reproduced at the order-of-magnitude level, while the RHIC target-holder fin results require the additional RF/end-heating mechanism. For EIC proton flattop operation, carbon-strip polarimetry may remain viable only with reduced dwell time, sufficient detector acceptance, and suppression of RF-induced end heating. For cooled-emittance 3 He, the calculated sublimation-loss scale is far beyond a straightforward RHIC-like carbon-strip extrapolation. Conventional carbon strips are therefore unlikely to remain viable for the most demanding EIC light-ion cases without major changes in target motion, target technology, or diagnostic concept.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Emittance growth generated by bunched beam electron cooling

The low energy RHIC electron cooling (LEReC) project at Brookhaven employs a linac to supply electrons with kinetic energies from 1.6 to 2.6 MeV. Along with cooling the stored ion beam the electron bunches create a coherent space charge field which can cause emittance growth. This process is investigated both analytically and through simulation.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Generation of ultrahigh-brightness pre-bunched beams from a plasma cathode for X-ray free-electron lasers

The longitudinal coherence of X-ray free-electron lasers (XFELs) in the self-amplified spontaneous emission regime could be substantially improved if the high brightness electron beam could be pre-bunched on the radiated wavelength-scale. Here, we show that it is indeed possible to realize such current modulated electron beam at angstrom scale by exciting a nonlinear wake across a periodically modulated plasma-density downramp/plasma cathode. The density modulation turns on and off the injection of electrons in the wake while downramp provides a unique longitudinal mapping between the electrons’ initial injection positions and their final trapped positions inside the wake. The combined use of a downramp and periodic modulation of micrometers is shown to be able to produces a train of high peak current (17 kA) electron bunches with a modulation wavelength of 10’s of angstroms - orders of magnitude shorter than the plasma density modulation. The peak brightness of the nano-bunched beam can be $\textit{O}$(10 21 A/m 2 /rad 2 ) orders of magnitude higher than current XFEL beams. Such prebunched, high brightness electron beams hold the promise for compact and lower cost XEFLs that can produce nanometer radiation with hundreds of GW power in a 10s of centimeter long undulator.

47 OTHER INSTRUMENTATION↗
DOE OSTI2018

Development of a Bunched Beam Electron Cooler based on ERL and Circulator Ring Technology for the Jefferson Lab Electron-Ion Collider

Jefferson Lab is in the process of designing an electron ion collider with unprecedented luminosity at a 45 GeV center-of-mass energy. This luminosity relies on ion cooling in both the booster and the storage ring of the accelerator complex. The cooling in the booster will use a conventional DC cooler similar to the one at COSY. The high-energy storage ring, operating at a momentum of up to 100 GeV/nucleon, requires novel use of bunched-beam cooling. There are two designs for such a cooler. The first uses a conventional Energy Recovery Linac (ERL) with a magnetized beam while the second uses a circulating ring to enhance both peak and average currents experienced by the ion beam. This presentation will describe the design of both the Circulator Cooling Ring (CCR) design and that of the backup option using the stand-alone ERL operated at lower charge but higher repetition rate than the ERL injector required by the CCR-based design.

Benson, Stephen V.↗
DOE OSTI2016

Harmonic stripline kicker for MEIC bunched beam cooler

In the current MEIC design, the ion collider ring needs to be cooled by a bunched electron beam of up to 200 mA 55 MeV, with the possibility to upgrade to 1.5 A. Although it?s not impossible to design and build an ERL to provide such a beam, the technical risk and cost associated with such an ERL will be very high. An alternative is to recirculate the electron bunches in a ring for several turns until the bunch?s quality is degraded, reducing the beam current in the ERL by a factor of up to 25. This scheme requires a pair of fast kickers that kick one in every 10 or 25 bunches. In this paper, we will analyze the dynamics of a harmonic stripline kicker for this application, and compare to the harmonic resonator kicker.

Guo, J.↗
DOE OSTI2015

Compensating tune spread induced by space charge in bunched beams

The effects of space charge play a significant role in modern-day accelerators, frequently constraining the beam parameters attainable in an accelerator or in an accelerator chain. They also can limit the luminosity of hadron colliders operating either at low energies or with sub-TeV high-brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. Using an appropriate electron beam would compensate both the tune shift and the tune spread in the hadron beam in a coasting beam. But these methods cannot compensate space charge tune spread in a bunched hadron beam. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with mismatched longitudinal velocity to compensate the space charge induced tune-shift and tune spread.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Coherent transverse instability of bunched beams in circular accelerators

Coherent transverse oscillations of a bunch in a ring accelerator are considered. Three different models of the bunch are used: a hollow bunch in a square potential well, a square bunch in a parabolic potential well, and a parabolic bunch in a parabolic well. The bunch space-charge field, wakefield, and chromaticity are taken into account in all the cases. The bunch eigenmodes and various instabilities are studied. The results are compared and analyzed to establish the range of applicability of the models. Role of the Landau damping due to dependence of the SC field on the longitudinal coordinate is discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Micro-aligned 1 Tesla Solenoid for High-energy Bunched-beam Electron Cooling

Electron cooling of ion beams requires precise alignment of the electron beam with the equilibrium trajectory of the ion bunch. In magnetized cooling the cooling rate is enhanced by transverse confinement of each electron on a magnetic line of force. The magnetic lines of force must therefore be aligned with the ion bunch trajectory everywhere along the extent of the solenoid. For the parameters required for JLEIC, a solenoid with bore field ~1 T, length ~30 m, and rms alignment of ~micro-radian is required. Such alignment has never been accomplished. The design of a micro-aligned solenoid is presented. A gap-separated stack of thin steel washers is located along the bore of the solenoid. The flux plate stack shields transverse magnetic fields from the interior, so that axial alignment is enhanced by a factor of ~10.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Stopped, Bunched Beams for the TwinSol Facility

Tests of the unitarity of the Cabbibo-Kobayashi-Masakawa (CKM) matrix offer an important avenue for constraining the Standard Model of the electroweak interaction. Several methods are currently used to determine V-ud, the largest element in the top-row normalization test. One such method is through the study of superallowed T =1/2 mixed mirror transitions, which offers a complementary method to the current most-precise value that is determined from superallowed pure Fermi 0(+) 0(+) transitions. The precision currently achievable by this method is currently limited by the very low number of transitions for which the Fermi-to-Gamow-Teller mixing ratio has been measured. St. Benedict, the Superallowed Transition Beta-Neutrino Decay-Ion-Coincidence Trap, is currently under development at the University of Notre Dame's Nuclear Science Laboratory, and intends to determine for a range of new isotopes through measurements of the -neutrino asymmetry parameter a using a linear Paul trap. In order to trap these ions, the fast, continuous secondary beam separated by the TwinSol twin solenoid separator must be thermalized and bunched. The system through which this will be done will feature a large-volume gas cell in which the ions will be thermalized, a double-RF-funnel-based ion guide system for the extraction of the ions, and a radiofrequency quadrupole (RFQ) to provide cooled ion bunches for capture in the Paul trap.

beam cooling↗