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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Heavy ion linear accelerator for radiation damage studies of materials

A new eXtreme MATerial (XMAT) research facility is being proposed at Argonne National Laboratory to enable rapid in situ mesoscale bulk analysis of ion radiation damage in advanced materials and nuclear fuels. This facility combines a new heavy-ion accelerator with the existing high-energy X-ray analysis capability of the Argonne Advanced Photon Source. The heavy-ion accelerator and target complex will enable experimenters to emulate the environment of a nuclear reactor making possible the study of fission fragment damage in materials. Material scientists will be able to use the measured material parameters to validate computer simulation codes and extrapolate the response of the material in a nuclear reactor environment. Utilizing a new heavy-ion accelerator will provide the appropriate energies and intensities to study these effects with beam intensities which allow experiments to run over hours or days instead of years. The XMAT facility will use a CW heavy-ion accelerator capable of providing beams of any stable isotope with adjustable energy up to 1.2 MeV/u for 238 U 50+ and 1.7 MeV for protons. This energy is crucial to the design since it well mimics fission fragments that provide the major portion of the damage in nuclear fuels. The energy also allows damage to be created far from the surface of the material allowing bulk radiation damage effects to be investigated. Furthermore, the XMAT ion linac includes an electron cyclotron resonance ion source, a normal-conducting radio-frequency quadrupole and four normal-conducting multi-gap quarter-wave resonators operating at 60.625 MHz. This paper presents the 3D multi-physics design and analysis of the accelerating structures and beam dynamics studies of the linac.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Development of the Marble experimental platform at the National Ignition Facility

The Marble experimental platform at the National Ignition Facility (NIF) was developed to quantify the influence of heterogeneous mix on fusion burn. The platform utilizes a plastic capsule filled with a deuterated plastic foam of controlled coarseness, with tritium gas filling the voids in the foam. The capsule implosion is driven with x rays generated in an NIF Hohlraum in which the time-dependent symmetry of the implosion can be controlled via dynamic beam phasing. Importantly, the Hohlraum drive conditions can be understood via integrated 2D radiation-hydrodynamic simulations, and capsule implosions can be reliably calculated. After several years of development and experimentation, the NIF Marble platform has become successful and has produced important experimental results. Here, the experimental results, which will be presented in a future publication by the LANL Marble team, provide the first definitive examination of the influence of heterogeneous mix on thermonuclear burn.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Design of the Multi-Ion Injector Linac for the JLAB EIC (JLEIC)

An Electron Ion Collider (EIC) is the highest priority for future U.S. accelerator-based nuclear physics facility following the completion of the Facility for Rare Isotope Beams (FRIB). Two laboratories are competing to host the future EIC: Brookhaven National Lab. (BNL) and Jefferson Lab. (JLab). The baseline design of JLab's Electron Ion Collider (JLEIC) ion complex comprises a pulsed superconducting (SC) linac injector capable of accelerating all ions from protons to lead, where proton and light ion beams can be polarized. After reviewing the design requirements for the injector linac, important design choices such as the room-temperature (RT) section design, the transition energy between the RT and SC sections and the stripping energy for heavy ions will be discussed. The design of the different linac sections will be presented as well as the results of end-to-end beam dynamics simulations for polarized deuterons and unpolarized lead ions.

Mustapha, B.↗
DOE OSTI2018

Racetrack FFAG muon decay ring for nuSTORM with triplet focusing

The neutrino beam produced from muons decaying in a storage ring would be an ideal tool for precise neutrino cross section measurements and the search for sterile neutrinos due to its precisely known flavour content and spectrum. In the proposed nuSTORM facility, pions would be directly injected into a racetrack storage ring, where the circulating muon beam would be captured. In this paper we show that a muon decay ring based on a racetrack scaling FFAG (Fixed Field Alternating Gradient) with triplet focusing structures is a very promising option with potential advantages over the FODO based solution. Finally, we discuss the ring concept, machine parameters, linear optics design, beam dynamics and the injection system.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

An adaptive masking method for beam halo measurement by a digital micro mirror device

We report that in high intensity particle beams, irregularities in cathode emission, scattering effects, dark current and space charge forces can lead to a common phenomenon termed beam halo with associated emittance growth, beam loss and overall beam quality degradation. It is of fundamental interest and practical importance to precisely monitor such beam halo, which could offer valuable insights into the experimental strategy for the suppression of this undesired feature. A Digital Micro mirror Device (DMD) is a computer-controlled micro-electrical-mechanical system that contains a compact array of physically independent reflective mirrors. Using a standard DMD, we come up with an adaptive masking method for halo measurement, which demonstrates superior robustness and efficiency comparing to the conventional approaches as confirmed by simulation and experimental results. Our development includes an integrated package of hardware, software and a graphic user interface (GUI) that is robust and portable and can be applied as a beam halo diagnostic for electron guns or radiating charged particle beams in general.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

An 8 GeV linac as the Booster replacement in the Fermilab Power Upgrade

Increasing the Main Injector beam power above ~ 1.2 MW requires replacement of the 8 GeV Booster by a higher intensity alternative. In this paper, we consider an 8 GeV linac Booster replacement that produces 8 GeV H$^{-}$ beam for injection into the Recycler Ring or Main Injector. This upgrade will maximize the beam available for neutrino production for the long baseline DUNE experiment to greater than 2.5 MW and enable a next generation frontier experiments. The 8 GeV linac takes ~ 1 GeV beam from the PIP-II Linac and accelerates it to ~ 2 GeV in a650 MHz superconducting RF linac, followed by a ~ 2 to 8 GeV pulsed linac using 1300 MHz cryomodules. The linac components incorporate recent improvements in superconducting RF technology. The linac configuration and beam dynamics requirements are presented. Injection options are discussed, including use of an8 GeV Accumulator Ring. Foil-based injection is the present standard but R&D toward implementing laser-assisted injection could enable a significant improvement. Research needed to implement the Booster replacement is described.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Approximating accelerator impedances with resonator networks

It is common in the accelerator community to use the impedance of accelerator components to describe wake interactions in the frequency domain. However, it is often desirable to understand such wake interactions in the time domain in a general manner for excitations that are not necessarily Gaussian in nature. Here, the conventional method for doing this involves taking the inverse Fourier Transform of the component impedance, obtaining the Green's Function, and then convolving it with the desired excitation distribution. This method can prove numerically cumbersome, for a convolution integral must be evaluated for each individual point in time when the wake function is desired. An alternative to this method would be to compute the wake function analytically, which would sidestep the need for repetitive integration. Only a handful of cases, however, are simple enough for this method to be tenable. One of these cases is the case where the component in question is an RLC resonator, which has a closed-form analytical wake function solution. This means that a component which can be represented in terms of resonators can leverage this solution. As it happens, common network synthesis techniques may be used to map arbitrary impedance profiles to RLC resonator networks in a manner the accelerator community has yet to take advantage of. In this work, we will use Foster Canonical Resonator Networks and partial derivative descent optimization to develop a technique for synthesizing resonator networks that well approximate the impedances of real-world accelerator components. We will link this synthesis to the closed-form resonator wake function solution, giving rise to a powerful workflow that may be used to streamline beam dynamics simulations.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Preliminary results of the 2023 International Fermilab Booster Studies

Here, an overview is given of the methods and preliminary results from dedicated beam studies on three topics conducted over five days in July 2023. In the first study, the Fermilab Booster magnets were held constant at magnetic fields corresponding to the injection energy. The beam loss and emittance growth were observed under varying intensity, tunes, and sextupole resonances. The corresponding beam conditions were also simulated with the MADX-SC code [1]. In the second study, measurements of the vertical half-integer resonance and correction methods are conducted for high-intensity beams ramping in the Booster. Finally, syncho-betatron instabilities are observed during transition-crossing in the Booster under strong space-charge conditions.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Rapid thermal emittance and quantum efficiency mapping of a cesium telluride cathode in an rf photoinjector using multiple laser beamlets

Thermal emittance and quantum efficiency (QE) are key figures of merit of photocathodes, and their uniformity is critical to high-performance photoinjectors. Several QE mapping technologies have been successfully developed; however, there is still a dearth of information on thermal emittance maps. This is because of the extremely time-consuming procedure to gather measurements by scanning a small beam across the cathode with fine steps. To simplify the mapping procedure and to reduce the time required to take measurements, we propose a new method that requires only a single scan of the solenoid current to simultaneously obtain thermal emittance and QE distribution by using a pattern beam with multiple beamlets. In this paper, its feasibility has been confirmed by both beam dynamics simulation and theoretical analysis. The method has been successfully demonstrated in a proof-of-principle experiment using an L-band radio-frequency photoinjector with a cesium telluride cathode. In the experiment, seven beamlets were generated from a microlens array system and their corresponding thermal emittance and QE varied from 0.93 to 1.14 mu m/nun and from 4.6% to 8.7%, respectively. We also discuss the limitations and future improvements of the method in this paper.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Uncertainty quantification for deep learning in particle accelerator applications

With the advent of increased computational resources and improved algorithms, machine learning-based models are being increasingly applied to complex problems in particle accelerators. However, such data-driven models may provide overly confident predictions with unknown errors and uncertainties. For reliable deployment of machine learning models in high-regret and safety-critical systems such as particle accelerators, estimates of prediction uncertainty are needed along with accurate point predictions. In this investigation, we evaluate Bayesian neural networks (BNN) as an approach that can provide accurate predictions along with reliably quantified uncertainties for particle accelerator problems, and compare their performance with bootstrapped ensembles of neural networks. We select three accelerator setups for this evaluation: a storage ring, a photoinjector, and a linac. The problems span different data volumes and dimensionalities (e.g., scalar predictions as well as image outputs). It is found that BNN provide accurate predictions of the mean along with reliable estimates of predictive uncertainty across the test cases. In this vein, BNN may offer an attractive alternative to deterministic deep learning tools to generate accurate predictions with quantified uncertainties in particle accelerator applications.

43 PARTICLE ACCELERATORS↗