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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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Dissertation Proposal: Innovations in Pulsed Power and Plasma Science Theory Simulation and Experiment

Pulsed power and plasma physics are topics of great study at both Sandia National Laboratories (SNL or Sandia) and the University of New Mexico (UNM). The goal of this research is to further knowledge and understanding of these fields using the resources of both SNL and UNM in three ways. The first way is through the comprehension, application, and testing of theory. Reading and analytically deriving theoretical solutions of problems both real-world and simplified will allow for a fresh perspective and the furthering of the theory. One such theory is Ottinger's generalized theory for voltage measurement in magnetically insulated transmission lines (MITLs). By working through the math, a deeper understanding of the theory is gained from which one may add more physically accurate and/or more detailed physics into the theory. Additionally, understanding the theory lays a good foundation from which one can analyze, test, and compare results to the theory in the following two ways that will advance the fields of pulsed power and plasma physics. The second way is through the modeling and simulation of real-world and simplified problems that utilize and test the afore mentioned theories. Theory can be applied to a simulation domain by using the unstructured time-domain electromagnetic (UTDEM) codes EMPHASIS and EMPIRE as well as the physical modeling software CUBIT, all of which were developed at SNL. Problems such as the modeling and design of the extended MITL on HERMES III, the understanding of space-charge-limited emission from vacuum cathodes, and the interaction between a relativistic electron beam and an ideal gas can all be modeled, simulated, and analyzed with this set of codes. Here the advantage is three-fold. Firstly, theory that describes our understanding of these problems can be put to the test and advanced through iterative simulation and analysis. Secondly, the understanding of these problems will have a positive impact on national security through the advancement of the technological capability of the United States of America. Thirdly, and not unrelated to the prior advantage, is the validation and verification of EMPIRE and EMPHASIS. This segues into the third way, which is through experiment and the comparison of experiment to simulated and theoretical results. Performing experimental comparisons completes the scientific method and grounds all of the work in reality. Being able to physically test theory and simulation is necessary for any real conclusions to be drawn. Another advantage for carrying out experimental work is to advance the physical testing capabilities of SNL. Several systems will be developed and tested through the course of this work that positively impact technological advancement of Sandia National Labs. Lastly, all of the above work will converge to yield a well-rounded perspective that ties the three categories of research together.

42 ENGINEERING↗
NASA NTRS1967

Some studies of whistler mode amplification.

Whistler mode transverse electromagnetic plasma wave interaction with monoenergetic gyrating electron beam, noting instabilities and relevance to whistler amplification

Crawford, F. W.↗
NASA NTRS1981

Implications of photometric and spectroscopic periods of SS433

It is suggested that a comparison of the periodicities inferred from spectroscopic and photometric observations of SS433 may help clarify its structure. The interaction between the orbital and beam motions may produce sideband periods in the photometry. It is found that Lense-Thirring and slaved disk models make differing predictions.

Katz, J. I.↗
NASA NTRS1981

Auroral electron acceleration and atmospheric interactions - /1/ Rocket-borne observations and /2/ scattering calculations

Electron energy and pitch angle spectra are obtained by an instrumented rocket payload launched across a pre-midnight auroral arc. The interaction of the incident electron beam with the atmosphere is described through transport theory including inelastic and multiple-elastic scattering of electrons by neutrals. A two-stream approximation to the electron transport equation is used to compute the hemispherically averaged upcoming electron transport that resulted from the measured downcoming intensity. The model of Evans (1974) is employed to infer a primary electron spectrum within the discrete arc.

Pulliam, D. M.↗
NASA NTRS1981

The case of the noisy derivatives - Evidence for a spacecraft-plasma interaction

Data from the retarding potential analyzers on Atmosphere Explorers C and D indicate the existence of 2-m irregularities in the ion flux to the satellite. These irregularities are seen only occasionally, and usually very near the magnetic dip equator. They occur both in sunlight and eclipse and span at least two decades of ion concentration. They tend to be present when the spacecraft is moving nearly parallel to the magnetic field vector and are not seen at all from the low latitude AE-E orbit. It is believed that the irregularities, whose amplitude is of the order of 1% of the background ion flux, are the result of a spacecraft interaction with the ionospheric plasma. A mechanism for producing this interaction that utilizes a fast beam of ambient ions reflected upstream from the satellite to produce a two-stream instability is examined in some detail.

Hanson, W. B.↗
NASA NTRS1982

Observations of gyrating ions in the foot of the nearly perpendicular bow shock

A beam of secondary ions which gyrate about the magnetic field have been detected by ISEE-1 satellite measurements of ion velocity distributions during a high Mach number bow shock crossing under nearly perpendicular conditions. The ions are encountered as the satellite enters the region ahead of the foot of the shock, and their behavior is that of solar wind ions reflected off the shock and then returned to it under the combined influence of magnetic field deflection and interplanetary electric field acceleration. Beam densities increase from 0.2 to 30% of the total plasma density as the main shock is approached, and the ion beam is not degraded through interaction with the counterstreaming solar wind upstream of the ramp. The gyrating ions provide strong dispersion in velocity space, and therefore constitute the first step in the process by which solar wind streaming energy is converted into the thermal energy of the ions at the bow shock.

Paschmann, G.↗
NASA NTRS1984

Theory of high-harmonic rectangular gyrotron for TE(mn) modes

In this paper, the linearized relativistic Vlasov equation is solved and a dispersion relation is calculated for the interaction between a relativistic electron beam and the electromagnetic fields of a rectangular waveguide supporting TE(mn) modes. The dispersion relation is simplified to the special case of a frame of reference moving with the electrons and the resulting coupling coefficient epsilon(mn)super l is calculated for various TE(mn) modes. The dependence of epsilon(mn)super l on the parity of the harmonic number l and various mn modes of the waveguide are discussed.

Ferendeci, A. M.↗
NASA NTRS1990

Low Mach number parallel and quasi-parallel shocks

The properties of low-Mach-number parallel and quasi-parallel shocks are studied using the results of one-dimensional hybrid simulations. It is shown that both the structure and ion dissipation at the shocks differ considerably. In the parallel limit, the shock remains coupled to the piston and consists of large-amplitude magnetosonic-whistler waves in the upstream, through the shock and into the downstream region, where the waves eventually damp out. These waves are generated by an ion beam instability due to the interaction between the incident and piston-reflected ions. The excited waves decelerate the plasma sufficiently that it becomes stable far into the downstream. The increase in ion temperature along the shock normal in the downstream region is due to superposition of incident and piston-rflected ions. These two populations of ions remain distinct through the downstream region. While they are both gyrophase-bunched, their counterstreaming nature results in a 180-deg phase shift in their perpendicular velocities.

Omidi, N.↗
NASA NTRS1993

Current loop coalescence studied by 3-D electromagnetic particle code

Solar flare plasma data from the Yohkoh satellite is analyzed. The interactions of current loops were observed in the active regions on the Sun. This observation pointed out the importance of the idea that the solar flare is generated by the coalescence of current loops. The three dimensional electromagnetic particle simulations are to help in understanding the global interaction between two current loops including the evolution of the twist of loops due to instabilities. Associated rapid dynamics of current loop coalescence such as reconnection, shock waves and associated kinetic processes such as energy transfer, acceleration of particles, and electromagnetic emissions are to be studied by the code to complement analytical theories and magnetohydrodynamic simulations of the current loop coalescence. The simulation results show the strong interactions between two current loops, beam and whistler instabilities, and associated parallel and perpendicular particle heating.

Nishikawa, Ken-Ichi↗
NASA NTRS2004

Participation of D.O. Muhleman as a Co-Investigator on the Mars Observer Laser Altimeter (MOLA) Team

The Co-I has been a principle member of the MOLA Team since the beginning of the Mars Observer Project and the MOLA Team formation. The basic area of research for the Co-I involved the interactions of the MOLA laser beam with the Mars atmosphere, ice fields and surface in general. The Co-I was assisted by one graduate student, and later a research assistant, Anton Ivanov, throughout the reporting period. Dr. Ivanov received a PhD from Caltech in 2000 from research involving the MOLA project. Dr. Ivanov continued with the MOLA project after receiving his degree as a research assistant to Professor Muhleman. Most of the funding from this grant was used to support Dr. Ivanov during the later years. The primary results of these investigations included the measurement of Mars atmospheric opacity at the 1 micron wavelength of the laser, the effects of dust within the craters and canyons of Mars, and a detailed study of the North Polar Ice Cap in terms of ice sublimation and the current structure of that ice cap. We were able to show that the sublimation of the ice on the polar cap would create the current average shape of the norther cap. Extensive data collection and study were made of the Mars surface 1 micron reflectivity until the laser mechanically failed during the reporting period. Reflectivity maps of Mars were produced although there were serious problems of the laser echo signal strength calibration. After that event the efforts were mainly to complete the older investigations. All of the work supported by this grant was theoretical in nature and did not lead to any patents.

Muhleman, Duane O.↗
DOE OSTI2021

Experiment Simulation Configurations Approximating DUNE TDR

The Deep Underground Neutrino Experiment (DUNE) is a next-generation long-baseline neutrino oscillation experiment consisting of a high-power, broadband neutrino beam, a highly capable near detector located on site at Fermilab, in Batavia, Illinois, and a massive liquid argon time projection chamber (LArTPC) far detector located at the 4850L of Sanford Underground Research Facility in Lead, South Dakota. The long-baseline physics sensitivity calculations presented in the DUNE Physics TDR, and in a related physics paper, rely upon simulation of the neutrino beam line, simulation of neutrino interactions in the near and far detectors, fully automated event reconstruction and neutrino classification, and detailed implementation of systematic uncertainties. The purpose of this posting is to provide a simplified summary of the simulations that went into this analysis to the community, in order to facilitate phenomenological studies of long-baseline oscillation at DUNE. Simulated neutrino flux files and a GLoBES configuration describing the far detector reconstruction and selection performance are included as ancillary files to this posting. A simple analysis using these configurations in GLoBES produces sensitivity that is similar, but not identical, to the official DUNE sensitivity. DUNE welcomes those interested in performing phenomenological work as members of the collaboration, but also recognizes the benefit of making these configurations readily available to the wider community.

Abi, B↗
DOE OSTI2025

A search for Heavy Neutral Leptons with masses up to 150 MeV and studies on scintillation light detection in SBND

Introduction Neutrino physics is one of today’s most promising fields in particle physics. The discovery of neutrino oscillations is an evidence of their mass not being null. However, the Standard Model of elementary particles (SM) does not contain a mechanism that generates them, so we have to search beyond the SM to find answers. Other unknowns remain open, such as the amount of CP symmetry violated in the lepton sector that could help explain the differences between matter and antimatter that formed the present universe. Nor is it understood why these particles are so light, more than six orders of magnitude below the next fermion, the electron. A possible explanation is the existence of heavier neutrino mass states usually referred as heavy neutral leptons (HNLs). One of the most advanced technologies for detecting neutrino interactions is the liquid argon time projection chamber (LArTPC). LArTPC detectors form a 3D image of the ionized electrons in the interaction, producing a detailed description of each neutrino event. Argon is also a prolific scintillator (40k photons/MeV) with light signals indicating the interaction time. The Short-Baseline Near Detector (SBND), a 112-active mass LArTPC at Fermilab, will measure millions of neutrino interactions from the Booster Neutrino Beam (BNB). As the near (L=110 m) detector of the Short-Baseline neutrino program, SBND will search for a fourth light neutrino (∼ eV) in the coming years. This hypothesis could explain the anomalous data observed in the LSND and MiniBooNE experiments.

Álvarez Garrote, Rodrigo [Madrid U.] (ORCID:000000↗
DOE OSTI2020

Understanding Critical Systematics on Neutrino Oscillation Experiments from Neutrino-Nucleus Interactions. Final report

This is a final report on the DOE grant DE-SC0017946: Understanding Critical Systematics on Neutrino Oscillation Experiments from Neutrino-Nucleus Interactions. The goal of this proposal was to better understand the complex many-body dynamics of neutrino-nucleus interactions in order to control the systematic uncertainties that will dominate current and future long-baseline neutrino experiments. This work was focused on a new and experimentally challenging aspect of the problem: measuring the abundance and kinematics of final state nucleons. The research leveraged two different detectors and beam energies: the Near Detector (ND) of the NOvA Experiment, off-axis on the NuMI beam- line, and the Accelerator Neutrino Neutron Interaction Experiment (ANNIE), on the Booster Neutrino Beam (BNB). The techniques developed will also help reject the dominant neutrino-induced backgrounds limiting future proton decay searches.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

First Differential Measurement of the Single 𝜋 + Production Cross Section in Neutrino Neutral-Current Scattering

Since its first observation in the 1970s, neutrino-induced neutral-current single positive pion production (NC⁢1⁢𝜋 + ) has remained an elusive and poorly understood interaction channel. This process is a significant background in neutrino oscillation experiments and studying it further is critical for the physics program of next-generation accelerator-based neutrino oscillation experiments. In this Letter, we present the first double-differential cross-section measurement of NC⁢1⁢𝜋 + interactions using data from the ND280 detector of the T2K experiment collected in 𝜈-beam mode. The measured flux-averaged integrated cross section is 𝜎 = (6.07 ± 1.22) × 10 −41 cm 2 /nucleon. We compare the results on a hydrocarbon target to the predictions of several neutrino interaction generators and final-state-interaction models. While model predictions agree with the differential results, the data show a weak preference for a cross-section normalization approximately 30% higher than predicted by most models studied in this Letter.

Neutrino detection↗
DOE OSTI2020

New Septum Dump Quadrupole Magnet Design

The purpose of the septum dump quadrupole (SDQ) magnet is to expand the beam size on the septum dump of the DARHT Axis 2 downstream transport in the same manner as the S2 magnet expands the beam on the beam stop for mode 1 operations of DARHT Axis 2. This is necessary in order to minimize the heating of the carbon beam dump and suppress desorption of ions. Initially, ions are generated through stimulated desorption and ionization of the monolayers of water vapor stuck to the beam dump surface. These ions propagate upstream at high speeds and act as an electrostatic focusing lens by reducing the beam space charge. As the beam size on the dump decreases, the dump is sufficiently heated so that a surface plasma is formed and much greater quantities of ions are generated through space charge limited emission. The interaction of these ions with the beam causes significant disruption of the beam.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

Searching for the Most Harmful Field Errors in the HSR IR Superconducting Magnets

In this project, we improve beam stability for the Electron-Ion Collider. Magnetic field errors can reduce beam stability, making it essential to identify the field errors that have the greatest impact on accelerator performance. However, this is particularly challenging because beam stability depends on the complex interactions of many magnetic field errors, resulting in a high-dimensional and nonlinear optimization problem. We determine which field errors are the most influential for the large physical aperture superconducting magnet B2PF, a critical magnet in the Interaction Region (IR) in the Hadron Storage Ring (HSR). We complete and analyze nearly 30,000 simulations on the Brookhaven National Laboratory Linux Cluster by varying 18 nonlinear magnetic field errors. We evaluate beam stability using the dynamic aperture and the tune diffusion. We identify the field errors that most strongly influence beam stability and establish quantitative field error tolerances that improve accelerator performance.

43 PARTICLE ACCELERATORS↗
NASA NTRS1983

Electron-photon coincidence technique for the absolute calibration of VUV detectors

A method is described whereby VUV photon detectors can be accurately calibrated. This method is illustrated by taking the 58.4-nm transition of He as an example. The technique consists of crossing a monoenergetic electron beam with a beam of He atoms. When inelastically scattered electrons which have excited the 2 1P state are detected in coincidence with the 58.4-nm photons emitted in the decay of the excited state, the interaction volume formed by the crossed beams constitutes a standard source of photons. By comparing the number of detected coincidences with the predicted number the calibration can be made. A total detector efficiency of 0.024 + or - 0.003 is obtained for a Galileo 4830 channeltron.

Mcadams, R.↗
DOE OSTI2020

Detector Performances Studies at Muon Collider

The Muon Collider is a possible option for the next generation of high energy collider machines. It would permit to achieve the energy frontier in lepton collisions, without occurring in significant synchrotron radiation losses as in electrons rings.Among the technological challenges in the realization of such a machine, the treatment of the beam-induced background is one of the most critical issues for the detectors.Beams with intensity of the order of $10^{12}$ muons per bunch are necessary to obtain the desired luminosity, therefore the muons decay rate is very high. Beam decay products and subsequent particles from secondary interactions with the machine elements can reach the interaction point, limiting the physical performance of the detector. A study of the beam-induced background is presented together with possible strategies for its reduction. Preliminary results on the reconstruction of a benchmark process, $\mu^+\mu^-\to H\nu\bar{\nu}\to b \bar{b}\nu\bar{\nu}$, including the beam-induced background are illustrated as demonstration of physics measurements feasibility in this harsh environment.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗