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At least 1,675 records · Page 93
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

2D Simulations of Diamagnetic Loop Calibrations

Diamagnetic loops can be used as a non-invasive method for measurements of beam size in electron beam accelerators that use solenoidal magnetic transport. A comprehensive theory for interpreting data from a diamagnetic loop relates the rms beam radius to the excluded flux measured by the loop and the beam current. Thus, primary calibration of the loop must relate the loop signal directly to the exclude d flux. We have simulated these calibrations with a 2D field solver in order to identify possible sources of uncertainty in our calibration technique.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Full Cycle Simulations of The Fermilab Booster

The Proton Improvement Plan phase II (PIP-II) project currently under construction at FNAL will replace the existing 400 MeV normal conducting linac with a new 800 MeV superconducting linac. The beam power in the downstream rapid-cycling Booster synchrotron will be doubled by raising the machine cycle frequency from 15 to 20 Hz and by increasing the injected beam intensity by a factor 1.5. This has to be accomplished without raising uncontrolled losses beyond the administrative limit of 500 W. In addition, slip-stacking efficiency in the Recycler, the next machine in the accelerator chain, sets an upper limit on the longitudinal emittance of the beam delivered by the Booster. As part of an effort to better understand potential losses and emittance blow-up in the Booster, we have been conducting full cycle 6D simulations using the code PyORBIT. The simulations include space charge, wall impedance effects and transition crossing. In this paper, we discuss our experience with the code and present representative results for possible operational scenarios.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Novel Concepts for High Gradient Acceleration (Final Technical Report)

We have conducted an intensive, pioneering program to demonstrate novel concepts for achieving high gradient acceleration at frequencies from the conventional microwave bands up to the millimeter wave /THz bands. High gradient accelerators hold the promise of smaller and less costly accelerators for applications ranging from the largest scale accelerators used for discovery science down to the smallest accelerators used for industrial, homeland security and medical applications. The research consisted of two major research thrusts: 1.) Structure-based wakefield accelerator (SWFA) research in collaboration with the Argonne Wakefield Accelerator research group and 2.) Millimeter Wave / THz high gradient acceleration in collaboration with SLAC. The specific goals of the research program were: Design novel metallic metamaterial structures that increase the beam-wave coupling for the accelerator mode and reduce the effect of high order modes; test novel metamaterial structures to achieve higher output power, > 1 GW at X-Band (11.7 GHz), in test at the Argonne Wakefield Accelerator (AWA); determine the experimental breakdown threshold for nanosecond-scale pulses at X-Band in testing at the AWA; test a 110 GHz accelerator structure with a field emission electron gun, built at SLAC, using pulses from a 1 MW, 110 GHz gyrotron; design, build and test a 110 GHz quasi-optical, resonant-ring pulse compressor to compress microsecond pulses from the 1 MW gyrotron into > 20 MW, 5 ns output pulses for accelerator structure testing. The proposed research program built on our successes in our research program including: Generation of 510 MW, 2.1 ns (FWHM) pulses at 11.7 GHz from a metallic metamaterial structure in test at the Argonne Wakefield Accelerator using a train of eight 65 MeV electron bunches spaced at 1.3 GHz with a total charge of 280 nC. The metamaterial structure consisted of 100 copper unit cells each consisting of a “wagon-wheel” plate and a spacer plate with a total structure length of 0.2 m. The 510 MW pulse generated an on-axis wakefield of 130 MV/m that could be used to accelerate a trailing witness bunch. Demonstration of coupling of an unprecedented rf power level of 575kW into a 110 GHz accelerator structure using a quasi-optical setup. The standing structure consisted of a central copper cavity located between two matching cavities fed by a TM01 mode. The 6 ns input pulses were sliced from 3 microsecond pulses from the gyrotron using a laser-driven silicon switch. We obtained an unprecedented high gradient up to 230MV/m corresponding to a peak surface electric field of more than 520 MV/m.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Plasma window performance and scaling for an accelerator-based neutron source

A “plasma window” was developed for use with a SHINE accelerator-based neutron source. In this work, the design of the plasma window is presented along with results demonstrating successful operation in deuterium over a range of aperture diameters (5–12 mm), gas flow rates (3.5 to 12.5 slm), and input powers (10–55 kW). Here, an empirically determined relationship between the aperture diameter, deuterium gas flow rate, input power, and plasma window pressure differential is also presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Proposal for a proton-bunch compression experiment at IOTA in the strong space-charge regime

The longitudinal compression of intense proton bunches with strong space-charge force is an essential component of a proton-based muon source for a muon collider. This paper discusses a proton-bunch compression experiment at the Integrable Optics Test Accelerator (IOTA) storage ring at Fermilab to explore optimal radio frequency (RF) cavity and lattice configurations. IOTA is a compact fixed-energy storage ring that can circulate a 2.5-MeV proton beam with varying beam parameters and lattice configurations. The study will aim to demonstrate a bunch-compression factor of at least 2 in the IOTA ring while examining the impact of intense space-charge effects on the compression process.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Preliminary Design of a LAMP DTL (Update)

Present report is a continuation of the previously published report LA-UR-23-26600 from 19-Jun-2023 and incorporates the mentioned report as its part. All the additional information is contained in the part III of this report, the DTL Transverse Focusing Scheme. A preliminary Drift Tube Linac (DTL) layout was designed to create an algorithm for developing the conceptual design of the proposed LANSCE Accelerator Modernization Project (LAMP) final section: the proton linear accelerator from 3 MeV to 100 MeV. Preceding reports describe the proposed layouts of the LEBT, the RFQ, and the MEBT subsections of the linac. Initial estimates of the needed RF power for the DTL are also presented in the report. Present report describes the initial layout of the DTL and the first longitudinal beam dynamics (BD) results of the simulations in simplified models. The part III of this report includes the transverse focusing scheme and transverse BD in details.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Initial Conditioning of the Rod-style RFQ

The RFQ test stand will allow new sources to be tested and will provide information on the performance of our RFQ designs. The RFQ must sustain the high peak power that will be necessary for bunching and accelerating beam, and that peak power must be sustained at a duty factor that is higher than other facilities that use similar rod-style RFQs. The conditioning of the RFQ allows both requirements to be tested, and in addition the intricacies of its operation are discovered and can be corrected for future work. In addition, the conditioning procedure was able to be done concurrently with the source development.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Commissioning of the Low Energy Electron Gun Test Stand at the University of Chicago

We built a test stand for evaluating the performance of the thermionic electron sources for the electron lens project at the Integrable Optics Test Accelerator (IOTA) in Fermilab. The lens will be used to study nonlinear dynamics and electron cooling of 2.5 MeV protons with strong space charge. The test stand will validate the characteristics of the thermionic sources and the main parameters of the generated beams. In this paper we present the results of the commissioning of the UChicago test stand and validation of the hollow beam source.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Fabrication of superconducting Nb 3 Sn film by Co-sputtering

High-efficiency SRF cavities are the key technology to construct cost-effective CW SRF accelerators. Improvements in the efficiency of SRF cavities are realized by using novel materials, such as niobium-tin. Advances in niobium-tin coatings on the inner surface of SRF cavities showed the potential for this material to increase the operating temperature of the SRF cavity to above 4 K, leading to significant reduction of the capital and operating cost of SRF accelerators. Among the techniques used to apply the niobium-tin coating to the surface of the SRF cavity is sputtering. Old Dominion University, Jefferson Lab, and Fermilab are collaborating on developing an optimized niobium-tin coating of the inside surface of niobium SRF cavities using a recently-developed cylindrical sputtering system. This research will result in optimized sputtering coating techniques leading to high efficiency SRF structures.

42 ENGINEERING↗
DOE OSTI2022

FAST-GREENS: A High Efficiency Free Electron Laser Driven by Superconducting RF Accelerator

In this paper we’ll describe the FAST-GREENS experimental program where a 4 m-long strongly tapered helical undulator with a seeded prebuncher is used in the high gain TESSA regime to convert a significant fraction (up to 10 %) of energy from the 240 MeV electron beam from the FAST linac to coherent 515 nm radiation. We’ll also discuss the longer term plans for the setup where by embedding the undulator in an optical cavity matched with the high repetition rate from the superconducting accelerator (3,9 MHz), a very high average power laser source can be obtained. Eventually, the laser pulses can be redirected onto the relativistic electrons to generate by inverse compton scattering a very high flux of circularly polarized gamma rays for polarized positron production.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Pulse Length Monitor for Breakdown Diagnostics in THz and Mm-Wave Accelerators

The development of novel high-gradient accelerating structures operating at THz frequencies is critical for future free-electron lasers and TeV scale linear colliders. To reach high energies with reasonable length requires high accelerating gradients of ~100 MV/m. The main limitation to reaching these high-energy gradients is the vacuum RF breakdown phenomenon, which disrupts normal accelerator operations. For stable operations and to understand the breakdown microscopic dynamics, a new device capable of detecting the breakdown occurrences is required. In this paper, we provide the design of a pulse length monitor based on an analog to digital converter for fast signal digitization without the need to use high-speed digitizers to be used in a commercial mm-wave heterodyne spectrometer.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Visual, Optical and Replica Inspections: Surface Preparation of 650 MHz NB Cavity for PIP-II Linac

Surface preparation of niobium superconducting RF cavities is a critical step for achieving good RF performance under the superconducting state. Surface defect, roughness, and contamination affect the accelerating gradient and quality factor of the cavities. We report surface inspection methods used to control the surface processing of 650 MHz cavities designated for the pre-production and prototype cryomodules for PIP-II linac. The cavity surface was routinely inspected visually, with an optical camera, and by microscopic scanning of surface replicas. This article covers details on the surface inspection methods and surface polishing process used to repair the surface.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Exploring New Resin Systems for Nb3Sn Accelerator Magnets

Epoxy resins have long been a focus of magnet design. They provide strength and stability to the superconductor, to allow coil fabrication and consistent magnet performance. They are often cited as a main contributor to magnet performance, often as a limiting factor, from epoxy cracking and energy release. New resin systems are being designed to improve magnet quench and training performance through several means. Baseline candidate resin systems are evaluated for neat resin mechanical properties as well as behavior in Nb 3 Sn subscale composites. Furthermore, this data feeds additional resin system tuning to meet the goals stated above.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Longitudinal space charge kick in Coherent Electron Cooling

In recent EIC Coherent electron Cooling (CeC) design, we adopted 591 MHz SRF LINAC to accelerate electron beam to certain energy(150 MeV, 54.1 MeV and 22.3 MeV). To reduce the energy spread caused by the RF curvature, a short bunch is preferred and results in high peak current. The longitudinal space charge kick will cause the energy spread increasing and lengthen the bunch length when through the R56 elements. This slippage of modulated microbunches may misalign with hadrons providing imprinting at kicker section. In this note, we will estimate this effect and discuss possible solution.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

QXFA 167 Coil Fabrication Report

QXFA is a cosine theta coil used in the MQXFA, a Nb3Sn superconducting accelerator quadrupole magnet to be installed in the High-Luminosity LHC Interaction Regions. A series of MQXFA magnets is fabricated and tested by the US High-Luminosity LHC Accelerator Upgrade Project (AUP). This report details the fabrication process of the QXFA coil (QXFA 167) using Wind-and-React method, conducted from February 6 to March 20, 2025. The content covers coil winding, curing, and reaction, based on the travelers of FNAL as well as the observations and records by the author. The coil fabrication processes following heat reaction, including the impregnation process, are not covered in this report, as they were carried out after March 20.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

(NOICE) Neural Optical Image Categorizer for the E-log

The Fermilab Accelerator Division Electronic logbook (E-log) is a record of all the activities and events in the Division for the past 10 years and more. The E-log search function is a valuable resource and the institutional memory of the accelerator complex. About 300,000 files are stored in the E-log, of which the vast majority are images attached to entries and comments. The visual information contained in the images is not presently searchable. The goal of team NOICE (Neural Optical Image Categorizer for the E-log) was to design a neural network able to produce label categories for these images for use by searches. The group developed a dataset and trained a convolutional neural network (CNN) with optimized hyperparameter

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Finding Beam Loss Locations at PIP2IT Accelerator With Oscillating Dipole Correctors

The PIP2IT accelerator was assembled in multiple stages in 2014 - 2021 to test concepts and components of the future PIP-II linac that is being constructed at Fermilab. In its final configuration, PIP2IT accelerated a 0.55 ms x 20 Hz x 2 mA H- beam to 16 MeV. To determine location of the beam loss in the accelerators low-energy part, where radiation monitors are ineffective, a method using oscillating trajectories was implemented. If the beam is scraped at an aperture limitation, moving its centroid with two dipole correctors located upstream and oscillating in sync, produces a line at the corresponding frequency in spectra of BPM sum signals downstream of the loss point. Comparison of these responses along the beam line allows to find the loss location. The paper describes the method and results of its implementation at PIP2IT.

43 PARTICLE ACCELERATORS↗