Search NASA⌕ Search

SEARCH · Search NASA

Results for “CRAB”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Advancements in Multiphysics Microdepletion Analysis of an eVinci TM -like Microreactor Leveraging OpenMC-CRAB Workflow

Nuclear microreactors (MRs) are a class of nuclear reactor technology, characterized by reduced dimensions, modular design, and reduced power output in contrast to conventional Light Water Reactors (LWRs). MRs are proposed for supplying electricity and eventual process heat to remote locations, such as military installations and disaster-affected areas. Current research work sponsored by the US Department of Energy Microreactor Program (MRP) is devoted to the development of novel modeling and simulation tools to better support MR vendors and regulatory bodies. Notably, the NRC is projected to utilize the CRAB multiphysics software driver for executing both design and beyond-design-basis accident analyses. Furthermore, the NRC has been utilizing the MELCOR code to calculate mechanistic source terms during accidents. Since MELCOR relies on isotopic inventory and reactor temperature/power profiles under accident conditions, which theoretically can be derived from CRAB, the goal is to establish a comprehensive CRAB-MELCOR computational framework. Past work was focused on testing and demonstrating CRAB's capability to generate results that can be used to inform mechanistic source term calculations in MELCOR. In particular, a computational workflow leveraging OpenMC-generated microscopic cross sections and CRAB was first applied to perform multiphysics microscopic depletion calculation followed by an accident scenario for a stylized microreactor problem. In fiscal year 2024, the research work has been focused on applying the OpenMC-CRAB workflow, which was first tested in fiscal year 2023, to a realistic 3D heat-pipe cooled MR problem representative of the eVinci TM design. The latter computational problem was developed with inputs from WEC to conserve selected neutronic and thermal characteristics of the eVinci TM design without releasing proprietary data. The results of this simulation, encompassing isotopic inventory, power density distribution, and kinetic parameters, will inform both MELCOR and the WEC-developed FATE code for mechanistic source terms calculations. The results from the two codes will then be compared for code verification purposes. This report contains the design characteristics of the realist heat pipe cooled microreactor developed as a use-case for the verification exercise, and the current results for the multiphysics microscopic depletion performed with the OpenMC-CRAB workflow. The results include eigenvalue as a function of time, power distribution at EOL, in addition to nuclides inventory's time evolution and spatial distribution. Finally, we report improvements to the workflow efficiency achieved through a collaboration with the NEAMS programs. Through this collaborative effort, we were able to strongly decrease the computational time for the multiphysics microdepletion calculation (i.e., from 17.4 hours to 5.7 hours on 280 processors) in addition to simplifying the interface to generate isotopics spatial distribution utilizable by FATE and MELCOR. Future work, including the improvement of the current microscopic cross-sections' library and the simulation of an accident scenario at EOL, is also discussed.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2024

Formalism for Local Correction of Vertical Crabbing in Hadron Storage Ring

The Electron-Ion Collider (EIC) incorporates crab cavities in both the Electron Storage Ring (ESR) and the Hadron Storage Ring (HSR) to achieve unprecedented luminosity goals. This technical note presents a formalism for the local correction of vertical crabbing in the HSR, addressing the complexities introduced by the integration of crab cavities and the interplay between betatron coupling and crabbing dispersion. Various strategies, including the use of skew quadrupoles and adjustments of Twiss functions, are explored to compensate vertical crabbing to achieve optimal beam-beam performance. The derived theoretical formulas offer practical guidance for minimizing the required vertical crabbing corrections, and will be implemented in the HSR lattice design.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Impact of beam coupling impedance on crab cavity noise induced emittance growth

Crab cavities will be deployed as a part of the High Luminosity Large Hadron Collider (HL-LHC) upgrade to mitigate the luminosity reduction induced by the crossing angle at the main experiments (ATLAS and CMS). Two prototype crab cavities have been installed in the CERN Super Proton Synchrotron (SPS) in 2018 for studies with proton beams. An issue of concern is the transverse emittance growth induced by noise in the crab cavity radio frequency (rf) system, which is anticipated to limit the performance of the HL-LHC. In measurements conducted in the SPS in 2018, the crab cavity noise-induced emittance growth was measured to be a factor of 4 lower than predicted from the existing analytical models. In this paper, it is shown that the observed discrepancy is explained by damping effects from the beam coupling impedance, which were not included in the models up to now. Using the van Kampen mode approach, a new theory is developed, suggesting that the impedance can separate the coherent tune from the incoherent spectrum leading to an effective reduction of the crab cavity rf noise-induced emittance growth. This mechanism is validated in tracking simulations using the SPS impedance model as well as in dedicated experimental measurements conducted in the SPS in 2022. The implications for the HL-LHC project are discussed. Published by the American Physical Society 2024

Physics↗
DOE OSTI2025

Electron-ion collider transverse instabilities due to the crab cavity fundamental impedance

The electron-ion collider crab Cavities will present a significant transverse impedance to the beam. The low-level radio frequency system will have to reduce the crab cavity impedance to prevent transverse instabilities, while regulating the crabbing voltage and minimizing the radio frequency noise levels injected into the beam. This work presents an estimate of the crab cavity impedance in the presence of feedback and the resulting stability margins using simplified stability criteria. Generalized stability criteria are also presented in this work and are used to more accurately estimate stability margins.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Experience from the US contribution to HL-LHC: Nb3Sn focusing quadrupoles and SRF crab cavities

The Interaction Regions (IR) of many colliders benefit from the application of leading-edge technologies to ensure the highest possible luminosity delivered to the experiments. Leading-edge low-beta focusing magnets and crab cavities to handle individual bunches are critically important to increase the instantaneous and integrated luminosity in future Colliders.The High-Luminosity LHC Upgrade, HL-LHC, with Nb3Sn Magnets (called MQXF) and Superconducting Radio Frequency (SRF) crab cavities (of two types, called DQW and RFD) is a world-wide collaborative project under construction in this decade to utilize the solutions mentioned above as key ingredients to increase tenfold the integrated luminosity delivered to the CMS and ATLAS experiments in the next decade. The HL-LHC AUP is the US effort to contribute approximately 50% of the low-beta focusing magnets and crab cavities for the HL-LHC.In this contribution we present the valuable lessons learned by the US efforts in the procurement, construction, and testing phases of the Nb3Sn focusing magnets and SRF crab cavities. We will report on the experience gathered by HL-LHC AUP in the production of the first half of deliverables (magnets MQXFA03 to MQXFA13). We will also report on the test of the first cryoassemblies and the status of the cavities’ development, production and testing.Both the technical and project management lessons-learned will inform applications of these technologies to future colliders and projects.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Crab Cavities for ILC

For the 14 mrad crossing angle proposed, crab cavity systems are fundamentally anticipated for the viable operation of the International Linear Collider (ILC), in order to maximise its luminosity performance. Since 2021, a specialist development team have been defining optimum crab cavity technologies which can fulfil the operational requirements for ILC, both for its baseline centre-of-mass energy of 250 GeV, but also extending those requirements out to higher beam collision intensities. Five design teams have established crab cavity technology solutions, which have the capability to also operate up to 1 TeV centre-of-mass. This presentation showcases the key performance capabilities of these designs and their associated benefits for both manufacture and integration into the ILC Interaction Region. The recommended outcome of the recently conducted crab cavity technology down-selection, will also be highlighted.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Higher Order Multipole Analysis of Beam Crabbing Mode at 197 MHz for Electron-Ion Collider

In the local crabbing scheme for Electron Ion Collider interaction region, beam rotation is initiated by one set of crab cavities at a high beta region with near 90 deg phase advance to the interaction point (IP), and ceased by an identical set of cavities on the symmetrically opposite side. The fundamental mode of all crab cavities is designed to apply a momentum kick to the particle bunches to complete this half cycle of rotation in the horizontal plane, meanwhile the electromagnetic (EM) field can be expanded into a series of harmonics. Despite the lowest dipole mode, higher harmonics cause instabilities during beam operation and loss of particles. We used SimTrack, which is the 6-d symplectic element-by-element tracking code developed at Brookhaven National Laboratory in 2015, to study the threshold of each higher-order harmonic multipolar mode with the criteria of maintaining a dynamic aperture of 6 σ or greater for the Hadron Storage Ring (HSR). In this paper, we showed the threshold for each higher harmonic multipole and their comparison with the multipole strength for the current crab cavity design.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Pickup Specifications for Crab Cavity Noise Feedback Pickup

The Electron-Ion Collider will employ crab cavities to compensate for the significant 25 mrad crossing angle, leading to an order of magnitude increase in luminosity. The crab cavity Radio Frequency system will inject low levels of noise to the crabbing field, generating transverse emittance growth and potentially limiting luminosity lifetime. A novel dedicated feedback system acting through the crab cavities has been proposed to mitigate emittance growth. The perfor mance of the noise feedback will largely depend on its pickup precision. In this note we present pickup specifications to achieve the required performance.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Spectrum and extension of the inverse-Compton emission of the Crab Nebula from a combined Fermi -LAT and H.E.S.S. analysis

The Crab Nebula is a unique laboratory for studying the acceleration of electrons and positrons through their non-thermal radiation. Observations of very-high-energy γ rays from the Crab Nebula have provided important constraints for modelling its broadband emission. We present the first fully self-consistent analysis of the Crab Nebula’s γ-ray emission between 1 GeV and ∼100 TeV, that is, over five orders of magnitude in energy. Using the open-source software package GAMMAPY, we combined 11.4 yr of data from the Fermi Large Area Telescope and 80 h of High Energy Stereoscopic System (H.E.S.S.) data at the event level and provide a measurement of the spatial extension of the nebula and its energy spectrum. We find evidence for a shrinking of the nebula with increasing γ-ray energy. Furthermore, we fitted several phenomenological models to the measured data, finding that none of them can fully describe the spatial extension and the spectral energy distribution at the same time. Especially the extension measured at TeV energies appears too large when compared to the X-ray emission. Our measurements probe the structure of the magnetic field between the pulsar wind termination shock and the dust torus, and we conclude that the magnetic field strength decreases with increasing distance from the pulsar. We complement our study with a careful assessment of systematic uncertainties.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Transverse emittance growth due to rf noise in crab cavities: Theory, measurements, cure, and high luminosity LHC estimates

The High-Luminosity LHC (HL-LHC) upgrade with planned operation from 2029 onward has a goal of achieving a tenfold increase in the integrated number of recorded collisions thanks to a doubling of the intensity per bunch ( 2.2 × 10 11 protons) and a reduction of β * (the β value in the two high luminosity detectors, namely ATLAS and CMS) to 15 cm. Such an increase in recorded collisions would significantly expedite new discoveries and exploration. Crab cavities are an important component of the HL-LHC upgrade and will contribute strongly to achieving an increase in the number of recorded collisions. However, noise injected through the crab cavity radio frequency (rf) system could cause significant transverse emittance growth and limit luminosity lifetime. We presented a theoretical formalism relating transverse emittance growth to rf noise in an earlier work. In this follow-up paper, we summarize measurements in the super-proton synchrotron (SPS) at CERN that validate the theory, we present estimates of the emittance growth rates using state-of-the-art rf and low-level rf (LLRF) technologies, and we set the rf noise specifications to achieve acceptable performance. A novel dedicated feedback system acting through the crab cavities to mitigate emittance growth will be required. In this work, we develop a theoretical formalism to evaluate the performance of such a feedback system in any collider, identify limiting components, present simulation results to validate these studies, and derive key design parameters for an HL-LHC implementation of such a feedback system. Published by the American Physical Society 2024

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Crabbing Angle Measurement

Electron-ion collider will employ transverse deflecting (crabbing) cavities to increase luminosity. There will be multiple cavities which will create localized crab bump in the interaction region. For proper compensation of the crossing angle each crab cavity should individually calibrated and phased.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

EIC Crab Cavity LLRF Studies

The Electron-Ion Collider Crab Cavity Low-Level Radio Frequency system will have to reduce the Crab Cavity impedance to prevent transverse instabilities, while regulating the crabbing voltage and minimizing the Radio Frequency noise levels injected to the beam. These are challenging and partly conflicting requirements. This works summarizes the specifications to achieve these requirements and investigates the possible trade-offs in the architecture.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Exploration of the polarization angle variability of the Crab Nebula with POLARBEAR and its application to the search for axionlike particles

The Crab Nebula, also known as Tau A, is a polarized astronomical source at millimeter wavelengths. It has been used as a stable light source for polarization angle calibration in millimeter-wave astronomy. However, it is known that its intensity and polarization vary as a function of time at a variety of wavelengths. Thus, it is of interest to verify the stability of the millimeter-wave polarization. If detected, polarization variability may be used to better understand the dynamics of Tau A, and for understanding the validity of Tau A as a calibrator. One intriguing application of such observation is to use it for the search of axionlike particles (ALPs). Ultralight ALPs couple to photons through a Chern-Simons term, and induce a temporal oscillation in the polarization angle of linearly polarized sources. After assessing a number of systematic errors and testing for internal consistency, we evaluate the variability of the polarization angle of the Crab Nebula using 2015 and 2016 observations with the 150 GHz P instrument. We place a median 95% upper bound of polarization oscillation amplitude A < 0.06 5 ° over the oscillation frequencies from 0.75 year − 1 to 0.66 hour − 1 . Assuming that no sources other than ALP are causing Tau A’s polarization angle variation, that the ALP constitutes all the dark matter, and that the ALP field is a stochastic Gaussian field, this bound translates into a median 95% upper bound of ALP-photon coupling g a γ γ < 2.16 × 10 − 12 GeV − 1 × ( m a / 10 − 21 eV ) in the mass range from 9.9 × 10 − 23 eV to 7.7 × 10 − 19 eV . This demonstrates that this type of analysis using bright polarized sources is as competitive as those using the polarization of cosmic microwave background in constraining ALPs. Published by the American Physical Society 2024

Adachi, Shunsuke (ORCID:0000000204007555)↗
DOE OSTI2023

Fabrication and Testing of a Prototype RF-Dipole Crabbing Cavity

Crabbing cavities are essential in particle colliders to compensate the luminosity degradation due to beam collision at a crossing angle. The 952.6 MHz 2-cell rf-dipole crabbing cavity system was proposed for the Jef-ferson Lab Electron-Ion Collider to restore the head-on collisions of electron and proton bunches at the interac-tion point. A prototype cavity was designed and devel-oped to demonstrate the performance of multi-cell rf-dipole structures. This paper presents the fabrication pro-cess and cold test results of the first 2-cell rf-dipole proto-type cavity.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Larval connectivity for European green crab management in the Salish Sea and surrounding waters

The presence of invasive species is a growing concern in coastal marine ecosystems because of their adverse effects on biodiversity. The European green crab Carcinus maenas (EGC) is a small crab inhabiting inshore areas. Although it is native to the Northeast Atlantic Ocean and Baltic Sea, its distribution has expanded to North America, where it is an invasive species. Its main food sources are small invertebrate species that support valuable fisheries in the USA. The first presence of EGC in northern Washington was observed around 20 yr ago, along the Pacific Coast of the USA. Recently, EGC has been detected throughout the Salish Sea (Washington, USA, and British Columbia, Canada) wherein spread dynamics are unknown. The overall distribution of EGC is mainly driven by larval dispersal and, in the Salish Sea and surrounding waters, the assessment of EGC population dynamics is essential to understand its migration patterns and prevent its future expansion. To investigate the dispersal patterns of EGC larvae, a larval dispersal model was developed which couples a regional model of hydrodynamic circulation with an individual-based model of ichthyoplankton dynamics. Simulations were performed over 9 yr (2013-2022) to analyze average larval transport trends in the Salish Sea and surrounding waters, interannual variability of EGC larval connectivity, and the influence of larval behavior on connectivity patterns. Lastly, areas were identified to inform invasive species management moving forward. The prediction of likely sources and settlement locations of EGC larvae from the model will help improve the management of the population in the Salish Sea and surrounding waters.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Quality Assurance Project Plan for the Salish Sea Model – Continuing Development of New Capabilities and Applications: European Green Crab (EGC) Larval Transport, Coupling to VELMA and Atlantis, Performance Improvements and Diagnostic Applications

This quality assurance project plan (QAPP) is for proposed FY24-FY27 efforts to (a) develop/expand a predictive European Green Crab (EGC) larval dispersal model for the Salish Sea, (b) add linkage between VELMA (Visualizing Ecosystem Land Management Assessments) watershed model and Atlantis model (ecosystem dynamics and food web) through SSM, and (c) continue SSM capability development through the addition of metals, harmful algal blooms (HABs), and FVCOM-LTRANS (Lagrangian Larval Transport) modules.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Finite element modeling of electropolishing of radio frequency dipole Nb crab cavity in hydrofluoric-sulfuric acid electrolyte

The superior performance of niobium superconducting radio frequency (SRF) cavities is achieved through meticulous surface treatment, notably via chemical electropolishing, ensuring exceptionally smooth surfaces. While this technique has been extensively employed for cylindrically symmetric structures, addressing more intricate geometries poses significant challenges in achieving uniform polishing and controlled material removal, especially when moving away from retractable cathodes. This presents a multifaceted electrochemical, thermal, and fluid dynamics conundrum. A prime example is the 197 MHz radio frequency dipole (RFD) crabbing cavity proposed for the Electron Ion Collider (EIC) project, exemplifying such complex structures. Our groundbreaking work integrates the localized oxide thickness variation, considering its impact on current distribution and Joule heating, within the framework of multi-physics modeling using the COMSOL® simulation suite. This approach was applied to a comprehensive model of the RFD cavity, allowing us to investigate optimal external cooling water flow conditions necessary for achieving desirable outcomes. In conclusion, this illustrates the increasing utility of such multi-physics codes to greatly aid in designing solutions to challenging processing requirements for increasingly complex accelerator cavities.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗