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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Interaction of an ultrarelativistic electron bunch train with a W-band accelerating structure: High power and high gradient

Electron beam interaction with high frequency structures (beyond microwave regime) has a great impact on future high energy frontier machines. We report on the generation of multimegawatt pulsed rf power at 91 GHz in a planar metallic accelerating structure driven by an ultrarelativistic electron bunch train. This slow-wave wakefield device can also be used for high gradient acceleration of electrons with a stable rf phase and amplitude which are controlled by manipulation of the bunch train. To achieve precise control of the rf pulse properties, a two-beam wakefield interferometry method was developed in which the rf pulse, due to the interference of the wakefields from the two bunches, was measured as a function of bunch separation. As a result, measurements of the energy change of a trailing electron bunch as a function of the bunch separation confirmed the interferometry method.

Wang, D.↗
DOE OSTI2019

Determination of Energy and Fluences of Protons Collectively Accelerated in a Luce Diode Accelerator

Plates of boron carbide B{sub 4}C were used as refractory targets for determination of energy and fluences of protons collectively accelerated in a Luce diode accelerator by control of {sup 7}Be and {sup 13}N gamma radioactivity induced by nuclear reactions {sup 10}B(p, α){sup 7}Be and {sup 12}C(p, γ){sup 13}N, respectively. The Luce diode exploited a cylindrical tungsten rod as a cathode and a polyethylene washer as an anode, producing pulsed electron beams with durations and currents of up to 100 ns and 30 kA at voltages of 250 kV. The technique allows controlling proton energies within the range of 500–1500 keV and fluences of up to 5 × 10{sup 13} protons per cm{sup 2} per pulse.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Exascale Programming Approaches for Accelerated Climate Modeling for Energy

The Accelerated Climate Modeling for Energy (ACME) program is a leading-edge climate and Earth system model designed to address the U.S. Department of Energy (DOE) mission needs. The ACME project involves collaboration between seven National Laboratories, the National Center for Atmospheric Research, four academic institutions, and one private-sector company. The ACME project funds ongoing efforts to ensure the model continues to make efficient use of DOE Leadership Computing Facilities (LCFs) in order to best address the three driving grand challenge science questions:Water cycle: How will more realistic portrayals of features important to the water cycle (resolution, clouds, aerosols, snowpack, river routing, land use) affect river flow and associated freshwater supplies at the watershed scale?Cryosphere systems: Could a dynamical instability in the Antarctic ice sheet be triggered within the next 40 years?Biogeochemistry: What are the contributions and feedbacks from natural and managed systems to current greenhouse gas fluxes, and how will those factors and associated fluxes evolve in the future?

Norman, Matthew↗
DOE OSTI2024

Considerations for Export Control of Accelerators and Accelerator Components

Although nuclear reactors have been the sole source for producing plutonium in all nuclear weapons states, accelerator-driven subcritical reactors are a tantalizing alternative. This report provides a review of accelerator driven technologies and components with a focus on export control.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2013

GPU-accelerated Software Library for Unsteady Flamelet Modeling of Turbulent Combustion with Complex Chemical Kinetics

Modeling and simulation of turbulent combustion are computationally demanding and challenging problems due to the complexity of turbulent flows and the complex chemical reaction kinetics. Recent advances in high performance computing (HPC) has allowed simulations to utilize increasing computer power to obtain newer insights that were not feasible before. The arrival of GPUs and many-core processors is set to revolutionize the HPC landscape. This paper presents an unsteady flamelet software library developed for utilizing GPUs as an onboard accelerator while the flow solver continues to run on conventional host processors using legacy software. The software was architected to expose multiple levels of parallelism and concurrency available in the unsteady flamelet model which is also necessary to realize the full potential of these accelerators. While the model and its coupling with the flow solver have been known for some time, the potential to target these models and libraries for newer HPC architectures provides a greater incentive for pursuing combustion model development.

Sankaran, Ramanan↗
DOE OSTI2023

Accelerated Aging of PV Cables - The Development of Methods Towards Combined-Accelerated Stress Testing

PV cables allow the collection and distribution of electricity from modules to the energy grid. Durable cabling allows continuous operation of PV installations. Cables with a life less than that of the modules must be replaced - reducing electricity generation and adding to the system operating expense. We have examined the durability of a variety of representative cable samples using artificial UV weathering (IEC TS 62788-7-2) and combined accelerated stress testing (C-AST). Jackets in this study include PV-rated (polyolefin), building wire (PVC/PA), and multi-conductor (rubber, as in PV trackers), with some examples of black and red cables. Characterizations at read points include appearance (camera and optical microscope), surface roughness (linear profilometry), instrumented indentation, surface morphology (SEM), chemical composition (EDS), thermal decomposition (TGA), phase transition (DSC), crystalline structure (WAXS), and polymer chemical structure (FTIR). Complimentary examinations confirm damage to the external and interior layer(s) of less durable samples, including changes in morphology (e.g., cracking), chemistry (e.g., oxidation), structure, and mechanical performance (e.g., through-thickness modulus and hardness). The results may be generally compared to other examples from the field (PV installations) or after accelerated testing (IEC 61215). The methods in this study are presently being applied in a follow-on C-AST study, incorporating both dynamic and kinematic fixtures.

balance of systems↗
DOE OSTI2026

Modular Accelerator Robotics Framework Implementation For Accelerator Inspection

Accelerator tunnels, such as the ones at Fermilab, remain highly radioactive after beam shutoff due to induced radiation from the beam. This residual radiation creates a hazardous environment for manual inspection and repair of beamline components. To minimize worker radiation dose and reduce beam downtime, the AD Robotics Initiative previously built a fleet of low-cost custom mobile robots. However, the custom Python sockets server-client architecture lacked standardization, causing development delays and complicating the integration of new sensors and actuators. Here, we developed a modular system using ROS2 and Docker to standardize the teleoperation and control interfaces. This system was validated by implementing a teleoperation controller with real-time, low-latency, and high-definition video feedback. The aim of this framework is for a new feature or even a robot to be integrated into the system simply by documenting the hardware configuration. Current integration of LiDAR, Odometry, and Depth Cameras provides the foundation for Simultaneous Localization and Mapping (SLAM) tasks. Finally, future work involves integration into the accelerator control system and the attachment of a 6 degree-of-freedom robotic arm for telemanipulation.

Rayyan Khana, M. [Unlisted, US, IL] (ORCID:0009000↗
DOE OSTI2014

Development of the C{sup 6+} laser ablation ion source for the KEK digital accelerator

A laser ion source that provides a fully ionized carbon ion beam is under joint development at the High Energy Accelerator Research Organization and Brookhaven National Laboratory. Long-pulse (6 ns) and short-pulse (500 ps) laser systems were tested by using them to irradiate a graphite target. Notable differences between the systems were observed in these experiments. Preliminary experimental results, such as the charge-state spectrum, beam intensity, and stability, are discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Calculation of spin resonance harmonics in an accelerator with Snakes

In this work, the ASPIRRIN code has been extended to provide the calculation of resonance harmonics for the case of machine with Siberian Snakes and spin rotators. Examples are shown for RHIC accelerator, including the case of the configuration with six Snakes per RHIC ring.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Accelerated increase in the Arctic tropospheric warming events surpassing stratospheric warming events during winter: Accelerated Increase in Arctic Warming

In January 2016, a robust reversal of the Arctic Oscillation (AO) took place associated with a rapid tropospheric warming in the Arctic region; this was followed by the occurrence of a classic sudden stratospheric warming in March-April. The succession of these two distinct Arctic warming events provides a stimulating opportunity to examine their characteristics in terms of similarities and differences. Historical cases of these two types of Arctic warming were identified and validated based upon tropical linkages with the Madden-Julian Oscillation and El Niño as well as those documented in previous studies. Our results indicate a recent and accelerated increase in the tropospheric warming type versus a flat trend in stratospheric warming type. Given that tropospheric warming events occur twice as fast than the stratospheric warming type, the noted increase in the former implies further intensification in midlatitude winter weather extremes similar to those experienced in early 2016. Forced simulations with an atmospheric general circulation model suggest that the reduced Arctic sea ice contributes to the observed increase in the tropospheric warming events and associated impact on the anomalously cold Siberia.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Charge-and-energy conserving moment-based accelerator for a multi-species Vlasov–Fokker–Planck–Ampère system, part II: Collisional aspects

In this study, we extend the moment-based acceleration algorithm for the charge, momentum, and energy conserving Vlasov–Ampère discretization developed in Ref. [1] by including a reduced Fokker–Planck operator. We propose an energy conserving discretization for the Fokker–Planck collision operator. We show by numerical experiment that the new algorithm 1) efficiently converges the nonlinearly coupled Vlasov–Fokker–Planck–Ampère system, and 2) accurately steps over stiff time-scales such as the inverse electron plasma frequency, and the electron–electron collision time-scale. We demonstrate that discrete energy conservation is critical to eliminate numerical heating issues when strong density gradients exist.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Charge-and-energy conserving moment-based accelerator for a multi-species Vlasov–Fokker–Planck–Ampère system, part I: Collisionless aspects

In this study, we propose a charge, momentum, and energy conserving discretization for the 1D–1V Vlasov–Ampère system of equations on an Eulerian grid. The new conservative discretization is nonlinear in nature, but can be efficiently converged with a moment-based nonlinear accelerator algorithm. We demonstrate the conservation and convergence properties of the scheme with various numerical examples, including a multi-scale ion–acoustic shockwave problem.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

Ion acceleration from laser-driven electrostatic shocks

Multi-dimensional particle-in-cell simulations are used to study the generation of electrostatic shocks in plasma and the reflection of background ions to produce high-quality and high-energy ion beams. Electrostatic shocks are driven by the interaction of two plasmas with different density and/or relative drift velocity. The energy and number of ions reflected by the shock increase with increasing density ratio and relative drift velocity between the two interacting plasmas. It is shown that the interaction of intense lasers with tailored near-critical density plasmas allows for the efficient heating of the plasma electrons and steepening of the plasma profile at the critical density interface, leading to the generation of high-velocity shock structures and high-energy ion beams. Our results indicate that high-quality 200 MeV shock-accelerated ion beams required for medical applications may be obtained with current laser systems.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2014

Note: Numerical simulation and experimental validation of accelerating voltage formation for a pulsed electron accelerator

This paper describes the development of a computation model of a pulsed voltage generator for a repetitive electron accelerator. The model is based on a principle circuit of the generator, supplemented with the parasitics elements of the construction. Verification of the principle model was achieved by comparison of simulation with experimental results, where reasonable agreement was demonstrated for a wide range of generator load resistance.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Vertical Magnetic Measurements of the First Full-Length Prototype MQXFAP2 Quadrupole for the LHC Hi-Lumi Accelerator Upgrade Project

This paper reports the commissioning of the vertical magnetic measurement system and the room temperature (warm) and cryogenic (cold) magnetic field measurements of the first full-length (4.2 m) quadrupole built by the U.S. Accelerator Upgrade Project (AUP) (formerly the LARP collaboration) for the high luminosity upgrade of the Large Hadron Collider at CERN. The magnet, designated MQXFAP2, is a prototype preceding production for the AUP which will provide ten sets of 8.4-m superconducting insertion region quadrupoles for the Hi-Lumi Upgrade. The quadrupoles will be built by assembling two 4.2-m magnets in a single cryostat. Agreement between Brookhaven National Laboratory's (BNL's) and Lawrence Berkeley National Laboratory's (LBNL's) warm measurement data has indicated that the upgraded vertical magnetic measurement system at Brookhaven National Laboratory is ready for MQXFA magnet production testing. Lastly, the cold magnetic measurement has been performed and preliminary data analysis has been conducted.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗