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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Inertial electrostatic confinement as a power source for electric propulsion

The potential use of an Inertial Electrostatic Confinement (IEC) power source for space propulsion has previously been suggested by the authors and others. In the past, these discussions have generally followed the charged-particle electric-discharge engine (QED) concept proposed by Bussard, in which the IEC is used to generate an electron beam which vaporizes liquid hydrogen for use as a propellant. However, in the present study, we consider an alternate approach, using the IEC to drive a conventional electric thruster unit. This has the advantage of building on the rapidly developing technology for such thrusters, which operate at higher specific impulse. Key issues related to this approach include the continued successful development of the physics and engineering of the IEC unit, as well as the development of efficient step-down dc voltage transformers. The IEC operates by radial injection of energetic ions into a spherical vessel. A very high ion density is created in a small core region at the center of the vessel, resulting in extremely high fusion power density in the core. Present experiments at the U. of Illinois in small IEC devices (less than 60-cm. dia.) have demonstrated much of the basic physics underlying this concept, e.g. producing approximately 10(exp 6) D-D neutrons/sec steady-state with deuterium gas flow injection. The ultimate goal is to increase the power densities by several orders of magnitude and to convert to D-He-3 injection. If successful, such an experiment would represent a milestone proof-of-principle device for eventual space power use. Further discussion of IEC physics and status will be presented with a description of the overall propulsion system and estimated performance.

Miley, George H.↗
NASA NTRS1997

The attenuation of gamma-ray emission in strongly-magnetized pulsars

Gamma rays from pulsars can be efficiently attenuated in their magnetospheres via the mechanism of single photon pair production and the exotic quantum electrodynamics (QED) process of photon splitting. The modeling of strongly magnetized gamma ray pulsars focusing on the escape or attenuation of photons emitted near the pole at the neutron star surface in dipole fields in a Schwarzschild metric is considered. It was found that pair production and splitting totally inhibit emission above a value of between 10 and 30 MeV in PSR 1509-58 whose surface field is inferred as being high. The principle predictions of the attenuation analysis are reviewed and the observational diagnostic capabilities of the model are considered. The diagnostics include the energy of the gamma ray turnover and the spectral polarization, which constrain the estimated polar cap size and field strength and can determine the relative strength of splitting and pair creation.

Baring, Matthew G.↗
NASA NTRS1998

Cooperation Among Theorem Provers

This is a final report, which supports NASA's PECSEE (Persistent Cognizant Software Engineering Environment) effort and complements the Kestrel Institute project "Inference System Integration via Logic Morphism". The ultimate purpose of the project is to develop a superior logical inference mechanism by combining the diverse abilities of multiple cooperating theorem provers. In many years of research, a number of powerful theorem-proving systems have arisen with differing capabilities and strengths. Resolution theorem provers (such as Kestrel's KITP or SRI's, SNARK) deal with first-order logic with equality but not the principle of mathematical induction. The Boyer-Moore theorem prover excels at proof by induction but cannot deal with full first-order logic. Both are highly automated but cannot accept user guidance easily. The PVS system (from SRI) in only automatic within decidable theories, but it has well-designed interactive capabilities: furthermore, it includes higher-order logic, not just first-order logic. The NuPRL system from Cornell University and the STeP system from Stanford University have facilities for constructive logic and temporal logic, respectively - both are interactive. It is often suggested - for example, in the anonymous "QED Manifesto"-that we should pool the resources of all these theorem provers into a single system, so that the strengths of one can compensate for the weaknesses of others, and so that effort will not be duplicated. However, there is no straightforward way of doing this, because each system relies on its own language and logic for its success. Thus. SNARK uses ordinary first-order logic with equality, PVS uses higher-order logic. and NuPRL uses constructive logic. The purpose of this project, and the companion project at Kestrel, has been to use the category-theoretic notion of logic morphism to combine systems with different logics and languages. Kestrel's SPECWARE system has been the vehicle for the implementation.

Waldinger, Richard J.↗
NASA NTRS2000

Coupling, Q-Factor, and Integration Aspects of Microsphere Applications

With suggested applications varying from microlaser and cavity QED through optical locking of diode lasers to modulators and sensors, high-Q silica microspheres with whispering-gallery (WG) modes so far remain the subject of tabletop feasibility demonstrations. Despite the uniquely high quality-factor and submillimeter dimensions suitable for tight packaging, this novel type of high-finesse cavity still has to be adapted to fiber- and integrated-optic hardware. In the visible and near infrared-band experiments (633-850nm) measuring the ringdown time tau of free oscillations, Q = (0.6 to 0.8 ) x 10(exp 10) has been obtained in silica spheres of diameter -800 microns (corresponding tau = 3 to 4 microseconds). It was proved that under normal laboratory conditions, quality-factor is subject to deterioration within several-minute scale down to (2 ... 3 ) x 10(exp 9). The responsible mechanism was identified as adsorption of a monolayer of atmospheric water, so that preservation of the ultimate Q requires manipulation in dry environment, or fast packaging into sealed devices. Larger Q can be expected closer to minimum of attenuation in fused silica alpha = 0.2 dB/km; Q greater than or equal to 1 x 10(exp 11) at lambda=1.55 microns, with corresponding energy storage time tau approx. 0.1ms. Experiments are currently underway to determine whether this high Q can be realized experimentally. The evident difficulty is that OH-related optical absorption has its peaks located near the reported minimum of attenuation in silica. We can also mention here that some of proposed fiber materials, yet not ready for fiber drawing, have been predicted to have smaller attenuation than fused silica and may be suitable for microsphere fabrication (sodium-magnesium silicate glass, alpha = 0.06dB/km). WG modes possess very small radiative loss (it does not prevent Q-10(exp 20) and more) and therefore are electromagnetically isolated and cannot be excited by free-space beams. If no modification (such as grating) is made on the sphere surface, the coupling has to he provided by an appropriate near-field device. A systematic theoretical approach has been recently developed to quantify the performance of near-field couplers for WG modes. Efficient coupling can be obtained upon fulfillment of two main conditions: (1) mode matching and (2) sufficient coupling strength to provide the buildup of a WG mode with a given intrinsic loss. In other words, the wave in the coupler has to be phase-matched and sufficiently overlapped with the WG mode to provide enough buildup in the cavity. If the coupling efficiency is characterized by the fractional depth K(sup 2) of the resonance dip in intensity transmittance observed upon varying the frequency of the exciting wave in the coupler.

Ilchenko, V. S.↗
NASA NTRS1999

Magnetic Photon Splitting: The S-Matrix Formulation in the Landau Representation

Calculations of reaction rates for the third-order QED process of photon splitting gamma yields gamma.gamma in strong magnetic fields traditionally have employed either the effective Lagrangian method or variants of Schwinger's proper-time technique. Recently, Mentzel, Berg and Wunner [1] presented an alternative derivation via an S-matrix formulation in the Landau representation. Advantages of such a formulation include the ability to compute rates near pair resonances above pair threshold. This paper presents new developments of the Landau representation formalism as applied to photon splitting, providing significant, advances beyond the work of [1] by summing over the spin quantum numbers of the electron propagators, and analytically integrating over the component of momentum of the intermediate states that is parallel to field. The ensuing tractable expressions for the scattering amplitudes are satisfyingly compact, and of an appearance familiar to S-matrix theory applications. Such developments can facilitate numerical computations of splitting considerably both below and above pair threshold. Specializations to two regimes of interest are obtained, namely the limit of highly supercritical fields and the domain where photon energies are far inferior to that for the threshold of single-photon pair creation. In particular, for the first time the low-frequency amplitudes are simply expressed in terms of the Gamma function, its integral and its derivatives. In addition, the equivalence of the asymptotic forms in these two domains to extant results from effective Lagrangian/proper- time formulations is demonstrated.

Baring, Matthew G.↗
NASA NTRS2004

Cryogenic Test Results of Hextek Mirror

A 250 mm diameter lightweight borosilicate mirror has been interferometrically tested from room-temperature down to 30 K at the X-Ray Calibration Facility (XRCF) at Marshall Space Flight Center (MSFC). The minor blank was manufactured by Hextek Corporation using a high-temperature gas fusion process and was then polished at MSFC. It is a sandwich-type mirror consisting of a thin face-sheet (approx.1.5 mm thick), a core structure (20 mm thick, approx.43 mm diameter cells, & 0.5-1.2 mm thick walls), and a thin back-sheet (3 mm thick). The mirror has a 2500 mm spherical radius-of- curvature @/lo). The areal density is 14 kg/sq m. The mirror was tested in the 1 m x 2 m chamber using an Instantaneous Phase Interferometer (PI) from ADE Phase Shift Technologies. The mirror was tested twice. The first test measured the change in surface figure from ambient to 30 K and the repeatability of the change. An attempt was then made by QED Technologies to cryo-figure the mirror using magnetorheological finishing. The second test measured the effectiveness of the cryo- figuring. This paper will describe the test goals, the test instrumentation, and the test results for these cryogenic tests.

Hadaway, James↗
NASA NTRS2004

Improved Edge Performance in MRF

The fabrication of large segmented optics requires a polishing process that can correct the figure of a surface to within a short distance from its edges-typically, a few millimeters. The work here is to develop QED's Magnetorheological Finishing (MRF) precision polishing process to minimize residual edge effects.

Shorey, Aric↗
NASA NTRS2004

Study of Vacuum Energy Physics for Breakthrough Propulsion

This report summarizes the accomplishments during a three year research project to investigate the use of surfaces, particularly in microelectromechanical systems (MEMS), to exploit quantum vacuum forces. During this project, we developed AFM instrumentation to repeatably measure Casimir forces in the nanoNewton range at 10 6 torr, designed an experiment to measure attractive and repulsive quantum vacuum forces, developed a QED based theory of Casimir forces that includes non-ideal material properties for rectangular cavities and for multilayer slabs, developed theoretical models for a variety of microdevices utilizing vacuum forces, applied vacuum physics to a gedanken spacecraft, and investigated a new material with a negative index of refraction.

Millis, Marc G.↗
NASA NTRS1995

Mirror Birefringence in a Fabry-Perot Cavity and the Detection of Vacuum Birefringence in a Magnetic Field

We discuss the effect of mirror birefringence in two optical schemes designed to detect the quantum-electrodynamics (QED) predictions of vacuum birefringence under the influence of a strong magnetic field, B. Both schemes make use of a high finesse Fabry-Perot cavity (F-P) to increase the average path length of the light in the magnetic field. The first scheme, which we called the frequency scheme, is based on measurement of the beat frequency of two orthogonal polarized laser beams in the cavity. We show that mirror birefringence contributes to the detection uncertainties in first order, resulting in a high susceptibility to small thermal disturbances. We estimate that an unreasonably high thermal stability of ~10-9 K is required to resolve the effect to 0.1%. In the second scheme, which we called the polarization rotation scheme, laser polarized at 45 relative to the B field is injected into the cavity.

Vacuum Birefringence↗
NASA NTRS2011

A New Limit on Planck Scale Lorentz Violation from Gamma-ray Burst Polarization

Constraints on possible Lorentz invariance violation (UV) to first order in E/M(sub Plank) for photons in the framework of effective field theory (EFT) are discussed, taking cosmological factors into account. Then. using the reported detection of polarized soft gamma-ray emission from the gamma-ray burst GRB041219a that is indicative' of an absence of vacuum birefringence, together with a very recent improved method for estimating the redshift of the burst, we derive constraints on the dimension 5 Lorentz violating modification to the Lagrangian of an effective local QFT for QED. Our new constraints are more than five orders of magnitude better than recent constraints from observations of the Crab Nebula.. We obtain the upper limit on the Lorentz violating dimension 5 EFT parameter absolute value of zeta of 2.4 x 10(exp -15), corresponding to a constraint on the dimension 5 standard model extension parameter. Kappa (sup 5) (sub (v)oo) much less than 4.2 X 10(exp -3)4 / GeV.

Stecker, Floyd W.↗
NASA NTRS2016

eXTP: Enhanced X-Ray Timing and Polarimetry Mission

eXTP is a science mission designed to study the state of matter under extreme conditions of density, gravity and magnetism. Primary goals are the determination of the equation of state of matter at supra-nuclear density, the measurement of QED effects in highly magnetized star, and the study of accretion in the strong-field regime of gravity. Primary targets include isolated and binary neutron stars, strong magnetic field systems like magnetars, and stellar-mass and supermassive black holes. The mission carries a unique and unprecedented suite of state-of-the-art scientific instruments enabling for the first time ever the simultaneous spectral-timing-polarimetry studies of cosmic sources in the energy range from 0.5-30 keV (and beyond). Key elements of the payload are: the Spectroscopic Focusing Array (SFA) - a set of 11 X-ray optics for a total effective area of approx. 0.9 m(exp. 2) and 0.6 m(exp. 2) at 2 keV and 6 keV respectively, equipped with Silicon Drift Detectors offering less than 180 eV spectral resolution; the Large Area Detector (LAD) - a deployable set of 640 Silicon Drift Detectors, for a total effective area of approx. 3.4 m(exp. 2), between 6 and 10 keV, and spectral resolution better than 250 eV; the Polarimetry Focusing Array (PFA) - a set of 2 X-ray telescope, for a total effective area of 250 cm(exp. 2) at 2 keV, equipped with imaging gas pixel photoelectric polarimeters; the Wide Field Monitor (WFM) - a set of 3 coded mask wide field units, equipped with position-sensitive Silicon Drift Detectors, each covering a 90 degrees x 90 degrees field of view. The eXTP international consortium includes major institutions of the Chinese Academy of Sciences and Universities in China, as well as major institutions in several European countries and the United States. The predecessor of eXTP, the XTP mission concept, has been selected and funded as one of the so-called background missions in the Strategic Priority Space Science Program of the Chinese Academy of Sciences since 2011. The strong European participation has significantly enhanced the scientific capabilities of eXTP. The planned launch date of the mission is earlier than 2025.

X-ray astronomy↗
NASA NTRS2019

Magnetars as Astrophysical Laboratories of Extreme Quantum Electrodynamics: The Case for a Compton Telescope

A next generation of Compton and pair telescopes that improve MeV-band detection sensitivity by more than a decade beyond current instrumental capabilities will open up new insights into a variety of astrophysical source classes. Among these are magnetars, the most highly magnetic of the neutron star zoo, which will serve as a prime science target for a new mission surveying the MeV window. This paper outlines the core questions pertaining to magnetars that can be addressed by such a technology. These range from global magnetar geometry and population trends, to incisive probes of hard X-ray emission locales, to providing cosmic laboratories for spectral and polarimetric testing of exotic predictions of QED, principally the prediction of the splitting of photons and magnetic pair creation. Such fundamental physics cannot yet be discerned in terrestrial experiments. State of the art modeling of the persistent hard X-ray tail emission in magnetars is presented to outline the case for powerful diagnostics using Compton polarimeters. The case highlights an inter-disciplinary opportunity to seed discovery at the interface between astronomy and physics.

Wadiasingh, Zorawar↗
NASA NTRS2022

High-energy Photon Opacity in the Twisted Magnetospheres of Magnetars

Magnetars are neutron stars characterized by strong surface magnetic fields generally exceeding the quantum critical value of 44.1 TG. High-energy photons propagating in their magnetospheres can be attenuated by QED processes like photon splitting and magnetic pair creation. In this paper, we compute the opacities due to photon splitting and pair creation by photons emitted anywhere in the magnetosphere of a magnetar. Axisymmetric, twisted dipole field configurations embedded in the Schwarzschild metric are treated. The paper computes the maximum energies for photon transparency that permit propagation to infinity in curved spacetime. Special emphasis is given to cases where photons are generated along magnetic field loops and/or in polar regions; these cases directly relate to resonant inverse Compton scattering models for the hard X-ray emission from magnetars and Comptonized soft gamma-ray emission from giant flares. We find that increases in magnetospheric twists raise or lower photon opacities, depending on both the emission locale and the competition between field-line straightening and field strength enhancement. Consequently, given the implicit spectral transparency of hard X-ray bursts and persistent "tail" emission of magnetars, photon splitting considerations constrain their emission region locales and the twist angle of the magnetosphere; these constraints can be probed by future soft gamma-ray telescopes such as COSI and AMEGO. The inclusion of twists generally increases the opaque volume of pair creation by photons above its threshold, except when photons are emitted in polar regions and approximately parallel to the field.

radiation mechanisms: non-thermal↗
NASA NTRSDate not supplied

Optimization Algorithms as Quantum Performance Benchmarks

Combinatorial optimization is anticipated to be one of the primary use cases for quantum computation in the coming years. The Quantum Approximate Optimization Algorithm (QAOA) and Quantum Annealing (QA) have the potential to demonstrate significant run-time performance benefits over current state-of-the-art solutions. Using existing methods for characterizing classical optimization algorithms, we analyze solution quality obtained by solving Max-Cut problems using a quantum annealing device and gate-model quantum simulators and devices. This is used to guide the development of an advanced benchmarking framework for quantum computers designed to evaluate the trade-off between run-time execution performance and the solution quality for iterative hybrid quantum-classical applications. The framework generates performance profiles through effective visualizations that show performance progression as a function of time for various problem sizes and illustrates algorithm limitations uncovered by the benchmarking approach. The framework is an enhancement to the existing open-source QED-C Application-Oriented Benchmark suite and can connect to the open-source analysis libraries. The suite can be executed on various quantum simulators and quantum hardware systems.

benchmarking↗
DOE OSTI2021

Excitation dynamics in inductively coupled fluxonium circuits

We propose a near-term quantum simulator based on the fluxonium qubits inductively coupled to form a chain. This system provides long coherence time, large anharmonicity, and strong coupling, making it suitable to study Ising spin models. At the half-flux quantum sweet spot, the system is described by the transverse field Ising model (TFIM). We evaluate the propagation of qubit excitations through the system. As disorder increases, the excitations become localized. A single qubit measurement using the circuit QED methods is sufficient to identify localization transition without introducing tunable couplers. We argue that inductively coupled fluxoniums provide opportunities to study localization and many-body effects in highly coherent quantum systems.

Barış Özgüler, A.↗
DOE OSTI2021

Measurements of the Beam Normal Asymmetry using Polarized Elastic Electron Scattering off Various Spin-0 Nuclei at 1 GeV

In this first part of this thesis, I report on the 1 GeV beam normal asymmetry measurements (AT) on various spin-0 nuclei during PREX-II. In a QED framework, this P-even, T-odd observable is a direct probe of the imaginary part of the two-photon exchange amplitude, since time reversal symmetry dictates AT must vanish in the one-photon approximation. At ultrarelativistic energies, the beam normal asymmetry is sensitive to the hadronic structure of the target nucleus. Calculations of the two-photon exchange amplitude are challenging since one has to consider all intermediate hadronic states in the calculation. The treatment of the states are both model and kinematics dependent. Therefore direct measurements of the beam normal asymmetry can test theory models. For experiments which measure the parity-violating asymmetry APV,the beam normal asymmetry can enter as a false asymmetry for APV when the beam is not 100% longitudinally polarized.

Richards, Ryan↗
DOE OSTI2022

Muon Campus at Fermilab

The Muon Campus at Fermilab provides world class accelerator infrastructure supporting the next generation intensity frontier experiments. The anti-proton source from the Tevatron era was converted to the present day Muon Campus at the end of the collider program in 2011. Currently, the Muon Campus delivers highly polarized muon beams to the Muon g-2 experiment and in a few years, it will provide muon beams to the Mu2e experiment. The Muon g-2 experiment is a high precision test of the standard model; it is precise enough to measure QED, Weak, and QCD Standard Model contributions.The Muon g-2 experiment looks for a significant deviation from the Standard Model whereas the Mu2e experiment looks for rare processes using high intensity muon beams. The Muon g-2 experiment has measured the anomalous magnetic moment of muons to an unprecedented 460 ppb precision with Run 1 data. The experiment has completed 5 runs, accumulating 19$\times$ Brookhaven E821 data set. The Mu2e experiment has completed the construction phase and first beam to the Diagnostic Absorber was run on April 14, 2022. Installation and commissioning of the Mu2e experiment will begin in 2023 and beam commissioning and physics run is currently planned for 2026.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Preparation for a Measurement of Charge Asymmetry in the Bethe-Heitler Process

We have prepared a measurement of the energy asymmetry in wide- and medium-angle electron/positron pair production off protons and heavy targets. This asymmetry is caused by the interference between the first- and second-order Born diagrams and the Compton scattering diagram. It directly probes aspects of QED, as well as providing a direct measurement of the real part of the Compton amplitude. It will be conducted at the HI??S facility at Duke University, using a 60 MeV photon beam. This dissertation serves as documentation of the preparation stage of the Bethe-Heitler experiment. The major was the recommissioning of the vertical drift chambers previously used in the Q-weak experiment at the Jefferson Lab. Cosmic test runs were conducted, drift time data were collected and efficiency plateaus were measured. We made modifications to the JLAB Hall A analyzer to suit the geometry and drift characteristics of these wire chambers. The analyzer was used for the reconstruction of the trajectories of cosmic ray test runs with the results confirmed by direct measurement of trigger geometry. Spatial and angular resolution is estimated to ~300?? and 0.17° respectively. Geant 4 simulations with generated Bethe-Heitler pairs satisfying theoretical differential cross sections. It was used to check detector acceptance, optimize apparatus layout, and estimate measurable energy asymmetry. The measurable asymmetries from electron/positron pairs with polar angles around between approximately 5° and 8°, azimuthal angles differing by 180°, and energy differing by approximately 9 MeV to 15 MeV are predicted to be above 10%. The kinematics of primary vertices are reconstructed using the data from wire chambers in the simulation. The energy resolution is determined to be better than 1MeV.

Chen, Haoyu↗