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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 OSTI2019

Use of the ERD for administrative monitoring of Theta

Monitoring the state of an HPC cluster in a timely and accurate fashion is critical to most system administration functions. For many Cray users, the first step in monitoring is ingestion of log files. Unfortunately, log parsing is an inherently inefficient process, requiring multiple software components to read and write from files on disk. Cray's own utilities use a message bus, the Event Router Daemon (ERD), for a wide variety of purposes. At the Argonne Leadership Computing Facility (ALCF), we have begun to use this message bus for monitoring via a client library written in Go, allowing us to read in structured data directly from Cray's services and, in many instances, bypass log files entirely. In this paper, we will examine the implementation and utilization of this approach on our 4392 node XC40, Theta, as well as the overall benefits and drawbacks to using the ERD for real-time monitoring.

Cray↗
DOE OSTI2020

Double Chooz {theta}13 measurement via total neutron capture detection

Neutrinos were assumed to be massless particles until the discovery of the neutrino oscillation process. This phenomenon indicates that the neutrinos have non-zero masses and the mass eigenstates (nu(1), nu(2), nu(3)) are mixtures of their flavour eigenstates (nu(e), nu(mu), nu(tau)). The oscillations between different flavour eigenstates are described by three mixing angles (theta(12), theta(23), theta(13)), two differences of the squared neutrino masses of the nu(2)/nu(1) and nu(3)/nu(1) pairs and a charge conjugation parity symmetry violating phase delta(CP). The Double Chooz experiment, located near the Chooz Electricite de France reactors, measures the oscillation parameter theta(13) using reactor neutrinos. Here, the Double Chooz collaboration reports the measurement of the mixing angle theta(13) with the new total neutron capture detection technique from the full data set, yielding sin(2)(2 theta(13)) = 0.105 +/- 0.014. This measurement exploits the multidetector configuration, the isoflux baseline and data recorded when the reactors were switched off. In addition to the neutrino mixing angle measurement, Double Chooz provides a precise measurement of the reactor neutrino flux, given by the mean cross-section per fission <sigma(f)& rang; = (5.71 +/- 0.06) x 10(-43) cm(2) per fission, and reports an empirical model of the distortion in the reactor neutrino spectrum. The Double Chooz collaboration reports the neutrino oscillation parameter theta(13) from a measurement of the disappearance of reactor anti-electron neutrinos with the total neutron capture technique.

Djurcic, Z.↗
DOE OSTI2024

FEM Analysis of Hybrid LTS/HTS Cos-Theta Dipole Magnet With Heterogeneous Cable Model

The Lawrence Berkeley National Laboratory (LBNL) and the National High Magnetic Field Laboratory (NHMFL) have published results on Bi-2212 superconductive magnets realized and tested in the canted cosine-theta and solenoid designs, respectively. Fermilab is now preparing for the assembly of the first Bi-2212 stress-managed cosine-theta insert magnet. The insert will be part of the first hybrid cosine-theta magnet made of Nb$_3$Sn outer layers within the US-MDP effort to reach a 20 T bore field. This paper presents the analytical analysis of the cosine-theta Nb$_3$Sn/Bi-2212 hybrid magnet. We report the parameters, logic, and implementation method of the 2D electromagnetic and mechanical FEM analysis of the LTS/HTS hybrid magnet. Results from a detailed heterogeneous model are compared to the homogeneous model implemented in the past. A Python code has been developed to simulate the current degradation due to stresses in the detail-modeled conductor areas. The current degradation has been introduced in the simulation dynamics for the HTS conductor as an iteration process, updating the input load of Lorentz forces of the energization at each step. The magnetic and mechanical analysis results of the 2D cosine-theta LTS/HTS dipole magnet have been described and analyzed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Thermal Hydraulic Experimental Test Article - Report of THETA Commissioning for METL Testing

The Thermal Hydraulic Experimental Test Article (THETA) is a facility that will be used to develop sodium components and instrumentation as well as acquire experimental data for validation of reactor thermal hydraulic and safety analysis codes. The facility will simulate nominal conditions as well as protected/unprotected loss of flow accidents in a sodium-cooled fast reactor (SFR). High fidelity distributed temperature profiles of the developed flow field will be acquired with Rayleigh backscatter based optical fiber temperature sensors. The facility is being designed in partnership with systems code experts to tailor the experiment to ensure the most relevant and highest quality data for code validation. THETA is comprised of a traditional primary and secondary system. The primary system is submerged in the pool of sodium and consists of a pump, electrically heated core, intermediate heat exchanger, and connected piping and thermal barriers (redan). The secondary system, located outside of the sodium pool, consists of a pump, sodium to air heat exchanger, and connected piping and valves. Figure 1 illustrates the main components of the primary system. THETA has been installed in the Mechanisms Engineering Test Loop (METL) with the primary system in the 28 inch Test Vessel #4, Figure 2 and Figure 3. Since the FY20 THETA status report, [1], further water shakedown testing was performed, some final welding modifications were performed, all system components were sanitized, dry assembled, and commissioned before installing into METL test vessel #4. The THETA submersible electromagnetic flowmeter was welded closed to hermetically seal internal components from sodium followed by a helium leak check for the final time

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2024

FEM Analysis of Hybrid LTS/HTS Cos-Theta Dipole Magnet

After the recent results on Bi-2212 superconductive magnets realized and tested in canted cosine-theta and solenoid designs, respectively, at Lawrence Berkeley National Laboratory (LBNL) and NHMFL, the first Bi-2212 stress-managed cosine-theta insert magnet is in the assembly phase at Fermilab. This insert will be part of the first hybrid cosine-theta magnet made of Nb3Sn outer layers within the US-MDP effort to reach 20 T bore field. This paper reports the analytical analysis of the cosine-theta Nb3Sn/Bi-2212 hybrid magnet. As an introduction, it shows the validation of the finalized HTS coils' design optimized using the ROXIE code. Subsequently, it reports the parameters, logic, and implementation method of the 2D electromagnetic and mechanical FEM analysis of the LTS/HTS hybrid magnet. Results from the ANSYS detailed model made with sub-modeling geometry are compared with the homogeneous model implemented in the past. Moreover, a Python code was implemented to simulate the current degradation due to stresses in the detail-modeled conductor areas. The current degradation is introduced in the simulation dynamics for both conductors as an iteration process during the energization load step only after applying pre-stress and thermal loads. The numerical and graphic results of the 2D cosine-theta LTS/HTS magnet cross-section will be described and analyzed.

D'Agliano, A.↗
DOE OSTI2024

Report on Initial Sodium Testing on the Thermal Hydraulic Experimental Test Article (THETA) (Fiscal Year 2024 Final Report)

The Thermal Hydraulic Experimental Test Article (THETA) is a facility that is used to develop sodium components and instrumentation as well as to acquire experimental data for validation of reactor thermal hydraulic and safety analysis codes. The facility simulates nominal thermal hydraulic conditions as well as protected/unprotected loss of flow accidents in a sodium-cooled fast reactor (SFR). High fidelity distributed temperature profiles of the developed flow field may be acquired with Rayleigh backscatter based optical fiber temperature sensors. The facility was designed in partnership with systems code experts to tailor the experiment to ensure the most relevant and highest quality data for code validation. THETA is comprised of a traditional primary coolant and secondary coolant system. The primary system is submerged in the pool of sodium and consists of a pump, electrically heated core, intermediate heat exchanger, and connected piping and thermal barriers (redan). The secondary system, located outside of the sodium pool, consists of a pump, sodium to air heat exchanger, and connected piping and valves. In fiscal year 2023, thermal stratification tests were completed with the primary system online, while the secondary system was being constructed [1]. These tests had shown that the core barrel and intermediate heat exchanger (IHX) outlet required increased thermal insulation. The THETA primary system was removed from METL, cleaned, thermal insulators installed, and then inserted into METL Test Vessel 4. At the time of this writing the THETA primary and secondary system are operational. During this fiscal year 100+ hours of testing was completed to characterize thermal hydraulic phenomena associated with steady state and transient conditions in a pool type liquid metal cooled reactor. A majority of the testing campaign was completed to satisfy the experimental data acquisition requirements for the GAIN Voucher with Oklo, CRADA 2021-21121. THETA is still operational at the time of this publication and future testing is planned for fiscal year 2025. Work is underway to publish existing and future data to an online database to facilitate collaboration with SFR engineers looking to validate their systems code or computational fluid dynamics models.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2013

New simple A{sub 4} neutrino model for nonzero {theta}{sub 13} and large {delta}{sub CP}

In a new simple application of the non-Abelian discrete symmetry A{sub 4} to charged-lepton and neutrino mass matrices, we show that for the current experimental central value of sin{sup 2} 2{theta}{sub 13} Asymptotically-Equal-To 0.1, leptonic CP violation is necessarily large, i.e. Double-Vertical-Line tan{delta}{sub CP} Double-Vertical-Line > 1.3. We also consider T{sub 7} model with one parameter to be complex, thus allowing for one Dirac CP phase {delta}{sub CP} and two Majorana CP phases {alpha}{sub 1,2}. We find a slight modification to this correlation as a function of {delta}{sub CP}. For a given set of input values of {Delta}m{sup 2}{sub 21}, {Delta}m{sup 2}{sub 32}, {theta}{sub 12}, and {theta}{sub 13}, we obtain sin{sup 2} 2{theta}{sub 23} and m{sub ee} (the effective Majorana neutrino mass in neutrinoless double beta decay) as functions of tan {delta}{sub CP}. We find that the structure of this model always yields small Double-Vertical-Line tan {delta}{sub CP} Double-Vertical-Line .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Discrete theta angles, symmetries and anomalies

Gauge theories in various dimensions often admit discrete theta angles, that arise from gauging a global symmetry with an additional symmetry protected topological (SPT) phase. We discuss how the global symmetry and ’t Hooft anomaly depends on the discrete theta angles by coupling the gauge theory to a topological quantum field theory (TQFT). We observe that gauging an Abelian subgroup symmetry, that participates in symmetry extension, with an additional SPT phase leads to a new theory with an emergent Abelian symmetry that also participates in a symmetry extension. The symmetry extension of the gauge theory is controlled by the discrete theta angle which comes from the SPT phase. We find that discrete theta angles can lead to two-group symmetry in 4d 4 d QCD with SU(N),SU(N)/\mathbb{Z}_k S U ( N ) , S U ( N ) / ℤ k or SO(N) S O ( N ) gauge groups as well as various 3d 3 d and 2d 2 d gauge theories.

Hsin, Po-Shen↗
DOE OSTI2017

Introducing Argonne’s Theta Supercomputer

Theta, the Argonne Leadership Computing Facility’s (ALCF) new Intel-Cray supercomputer, is officially open to the research community. Theta’s massively parallel, many-core architecture puts the ALCF on the path to Aurora, the facility’s future Intel-Cray system. Capable of nearly 10 quadrillion calculations per second, Theta enables researchers to break new ground in scientific investigations that range from modeling the inner workings of the brain to developing new materials for renewable energy applications.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2025

Analytical expression of a finite, long, conical canted-cosine-theta coil for particle collider interaction regions

Magnets in the accelerator interaction region (IR) present significant challenges because of high field requirements and limited available space. Conical-shaped magnets offer advantages in these environments by allowing closer placement to the interaction point while maintaining clearance from synchrotron radiation. Interestingly, numerical studies have shown that conical canted-cosine-theta (CCT) designs produce a constant field distribution along the axial direction in the IR quadrupoles for the Electron-Ion Collider (EIC) at Brookhaven National Laboratory. However, the field harmonics generated by conical CCT windings are not yet fully understood. This paper presents an analytical approach to describe the magnetic field produced by a conical surface current and proposes a method for designing conical CCT magnets for accelerator applications. First, we begin with a surface current sheet having a general cosine-theta distribution in spherical coordinates and solve the vector potential using the Green’s function. The magnetic fields generated by the conical current sheet are expressed using associated Legendre polynomials. These results are then related to circular field harmonics and integral field harmonics for designing a coil that produces a pure multipole field. Next, a single layer of the conical CCT winding path is produced based on the cosine-theta current distribution. Finally, the magnetic field quality of dipole and quadrupole conical CCT coils with multiple layers is verified using the Biot-Savart law.

Yang, Ye↗
DOE OSTI2019

Measurement of $\Delta m^2_{32}$ and $\sin^2\!\theta_{23}$ using Muon Neutrino and Antineutrino Beams in the NOvA Experiment

NOvA is a long-baseline neutrino oscillation experiment located in the mid-west United States. It consists of two functionally identical tracking calorimeters, known as the near and far detector, that measure neutrino interactions induced by the NuMI beam at baselines of 1~km and 810~km. NuMI can be configured to provide a muon neutrino or antineutrino beam. Analysis of \numu~+~\numubar disappearance allows constraint of the $|\Delta m^2_{32}|$ and \sint oscillation parameters. This thesis presents the first NOvA disappearance results using both neutrino and antineutrino data - previous NOvA analyses have only used neutrino beam data. Two analysis improvements are delineated in dedicated chapters - the design of selection criteria to identify events that are fully contained in the far detector and the optimization of particle identification selection criteria in a multi-dimensional parameter space. The full-detector equivalent beam exposures used for this thesis are $8.85\ti mes 10^{20}$ and $6.91\times 10^{20}$~protons~on~target for neutrino and antineutrino data respectively. Under the assumption of a normal (inverted) neutrino mass hierarchy, analysis of the data gives $\Delta m^2_{32}=+2.49^{+0.09}_{-0.07}\times10^{-3}~\text{eV}^2$ ($\Delta m^2_{32}=-2.54\pm0.08\times10^{-3}~\text{eV}^2$) and $\sin^2\theta_{23} = 0.59\pm0.03$ ($\sin^2\theta_{23} = 0.44\pm0.03$). Maximal mixing ($\sin^2\theta_{23} = 0.5$) is disfavoured at the 1.7~\sig level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Extraction of $\sin^2\theta^{\rm lept}_{\rm eff}$ and indirect measurement of $m_w$ from the 9 fb$^{-1}$ full run ii sample of $\mu^+\mu^-$ events at cdf

We report on the extraction of $\sin^2\theta^{\rm lept}_{\rm eff}$ and indirect measurement of the mass of the W boson from the forward-backward asymmetry of $\mu^+\mu^-$ events in the $Z$ boson mass region. The data sample collected by the CDF detector corresponds to the full 9 fb$^{-1}$ run II sample. We measure $\sin^2 \theta^{\rm lept}_{\rm eff} = 0.2315 \pm 0.0010$,$ \sin^2 \theta_W = 0.2233 \pm 0.0009$ and $M_W ({\rm indirect}) = 80.365 \pm 0.047 \;{\rm GeV}/c^2$, where each uncertainty includes both statistical and systematic contributions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

A model code for the radiative theta pinch

A model for the theta pinch is presented with three modelled phases of radial inward shock phase, reflected shock phase, and a final pinch phase. The governing equations for the phases are derived incorporating thermodynamics and radiation and radiation-coupled dynamics in the pinch phase. A code is written incorporating correction for the effects of transit delay of small disturbing speeds and the effects of plasma self-absorption on the radiation. Two model parameters are incorporated into the model, the coupling coefficient f between the primary loop current and the induced plasma current and the mass swept up factor f{sub m}. These values are taken from experiments carried out in the Chulalongkorn theta pinch.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Hydrogen plasma dynamics in the spherical theta pinch plasma target for heavy ion stripping

Due to the superior ability of dense and highly ionised plasmas to ionise penetrating heavy ion beams to degrees beyond those reachable by common gas strippers, many experiments have been performed to find suitable plasma generators for this application. In the field of gas discharges, mainly z-pinch devices have been investigated so far, which are known to be limited by the nonlinear focusing effects of the plasma columns sustaining current and by electrode erosion. The spherical theta pinch has therefore been proposed as a substitution for the z-pinch, promising progress by inductive rather than capacitive coupling and displacement of the outer magnetic field by the dense, diamagnetic discharge plasma. As yet mainly experiments with argon/hydrogen mixture gas have been performed, which is not suitable for the application as a plasma stripper, this paper describes the first detailed analysis of the plasma parameters and dynamics of a hydrogen plasma created by the spherical theta pinch. These include the time integrated and time resolved electron density, the dynamics of the plasma in the discharge vessel, the comparison with the argon dominated plasma, and an outlook to reachable characteristics with similar devices.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

New model of calculating the energy transfer efficiency for the spherical theta-pinch device

Ion-beam-plasma-interaction plays an important role in the field of warm dense matter and inertial confinement fusion. A spherical theta pinch is proposed to act as a plasma target in various applications including a plasma stripper cell. One key parameter for such applications is the free electron density. A linear dependency of this density to the amount of energy transferred into the plasma from an energy storage was found by Teske. Since the amount of stored energy is known, the energy transfer efficiency is a reliable parameter for the design of a spherical theta pinch device. As the main assumption of a constant reflected plasma resistance is contradictory by the measured data, the traditional two models of energy transfer efficiency will lead to wrong results. From measurements, the parasitic resistance is derived as constant. Based on this key parameter, a new model is proposed. Due to no assumption, the new model is considered as exact. Further, a comparison of these three different models is given at a fixed operation voltage for the full range of working gas pressures. Due to the inappropriate assumptions included in the traditional models, one owns a tendency to overestimate the energy transfer efficiency whereas the other leads to an underestimation. Applying our new model to a wide spread set of operation voltages and gas pressures, an overall picture of the energy transfer efficiency results.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

Fabrication of Bi-2212 Canted-Cosine-Theta Dipole Prototypes

The U.S. Magnet Development Program (MDP) is exploring the possibility of combining low-and higherature superconductor technologies, using cosine-theta and canted-cosine-theta (CCT) Nb3Sn dipole magnets together with Bi-2212 CCT inserts, with the ultimate goal of constructing a 20-T dipole. The MDP short-term goal is a Bi-2212 CCT insert capable of reaching 5 T in the bore when operating as a stand-alone and 3 T when operating under a background field of 15 T. This paper reports on the fabrication of our BIN4 dipole magnet and our BIN5a and BIN5b coils, designed and built at the Lawrence Berkeley National Laboratory to address potential fabrication issues of Bi-2212 coils and verify the design of our 18-20-T dipole magnet. BIN4 is a two-layer 50-cm-long CCT magnet that uses a nine-strand Rutherford cable made with 0.8-mm-diameter Bi-2212 strands. Its goal is to investigate critical current, insulation integrity, manufacturing challenges, and quench protection issues after heat treating both layers together under oxygen at standard atmosphere (1 bar). BIN5a and BIN5b are two identical coils, similar to the outer layer of BIN4, with the difference that the length is 39 cm, and they will undergo 50-bar overpressure processing heat treatment. Finally, BIN5 coils are made from the state-of-the-art strand with an engineering critical current density of 1150 A/mm 2 at 4.2 K and 5 T.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Conceptual Design of A 20 T Dipole Based on Hybrid REBCO/Nb 3 Sn Cos-theta Coil

This paper presents a design concept of an HTS/LTS hybrid dipole with 50 mm aperture and 20 T nominal field based on a cos-theta coil and a cold iron yoke. The HTS part of magnet coil uses REBCO Twisted Stacked Tape cable. The LTS part is graded and made of two Nb3Sn Rutherford cables. Due to high sensitivity of HTS/LTS coils to large stresses and strains at high fields, a Stress Management (SM) concept combined with the cos-theta coil geometry is used. The results of magnet magnetic analysis are presented and discussed.

43 PARTICLE ACCELERATORS↗