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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Experimental Limit on Nonlinear State-Dependent Terms in Quantum Theory

Linear time evolution is one of the fundamental postulates of quantum theory. Past theoretical attempts to introduce nonlinearity into quantum evolution have violated causality. However, a recent theory has introduced nonlinear state-dependent terms in quantum field theory, preserving causality [D. E. Kaplan and S. Rajendran, Phys. Rev. D 105, 055002 (2022)]. We report the results of an experiment that searches for such terms. Our approach, inspired by the Everett many-worlds interpretation of quantum theory, correlates a binary macroscopic classical voltage with the outcome of a projective measurement of a quantum bit, prepared in a coherent superposition state. Measurement results are recorded in a bit string, which is used to control a voltage switch. Presence of a nonzero voltage reading in cases of no applied voltage is the experimental signature of a nonlinear state-dependent shift of the electromagnetic field operator. We implement blinded measurement and data analysis with three control bit strings. Control of systematic effects is realized by producing one of the control bit strings with a classical random-bit generator. The other two bit strings are generated by measurements performed on a superconducting qubit in an IBM Quantum processor and on a N 15 nuclear spin in a nitrogen-vacancy center in diamond. Our measurements find no evidence for electromagnetic quantum state-dependent nonlinearity. We set a bound on the parameter that quantifies this nonlinearity | ε γ | < 4.7 × 10 - 11 , at 90% confidence level.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS2005

Coherent Anti-Stokes Raman Spectroscopy (CARS) Measurements in Supersonic Combustors at NASA Langley Research Center

This paper describes the recent use of coherent anti-Stokes Raman spectroscopy (CARS) to study supersonic combustion at NASA Langley Research Center. CARS is a nonlinear optical measurement technique used to measure temperature and species mole fractions remotely in harsh environments. A CARS system has been applied to two different combustor geometries at NASA Langley. Both experiments used the same vitiated wind-tunnel facility to create an air flow that simulates flight at Mach numbers of 6 and 7 for the combustor inlet and both experiments used hydrogen fuel. In the first experiment, the hydrogen was injected supersonically at a 30-degree angle with respect to the incoming flow. In the second experiment, the hydrogen was injected sonically at normal incidence. While these injection schemes produced significantly different flow features, the CARS method provided mean temperature, N2, O2 and H2 maps at multiple downstream locations for both. The primary aim of these measurements was to provide detailed flowfield information for computational fluid dynamics (CFD) code validation.

Danehy, Paul M.↗
NASA NTRS2014

Preliminary Results of the NASA Beacon Receiver for Alphasat Aldo Paraboni TDP5 Propagation Experiment

NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have initiated a joint propagation campaign within the framework of the Alphasat propagation experiment to characterize rain attenuation, scintillation, and gaseous absorption effects of the atmosphere in the 40 GHz band. NASA GRC has developed and installed a K/Q-band (20/40 GHz) beacon receiver at the POLIMI campus in Milan, Italy, which receives the 20/40 GHz signals broadcast from the Alphasat Aldo Paraboni TDP#5 beacon payload. The primary goal of these measurements is to develop a physical model to improve predictions of communications systems performance within the Q-band. Herein, we describe the design and preliminary performance of the NASA propagation terminal, which has been installed and operating in Milan since May 2014. The receiver is based upon a validated Fast Fourier Transform (FFT) I/Q digital design approach utilized in other operational NASA propagation terminals, but has been modified to employ power measurement via a frequency estimation technique and to coherently track and measure the amplitude of the 20/40 GHz beacon signals. The system consists of a 1.2-m K-band and a 0.6-m Qband Cassegrain reflector employing synchronous open-loop tracking to track the inclined orbit of the Alphasat satellite. An 8 Hz sampling rate is implemented to characterize scintillation effects, with a 1-Hz measurement bandwidth dynamic range of 45 dB. A weather station with an optical disdrometer is also installed to characterize rain drop size distribution for correlation with physical based models.

propagation↗
NASA NTRS2015

Performance of the NASA Beacon Receiver for the Alphasat Aldo Paraboni TDP5 Propagation Experiment

NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have initiated a joint propagation campaign within the framework of the Alphasat propagation experiment to characterize rain attenuation, scintillation, and gaseous absorption effects of the atmosphere in the 40 gigahertz band. NASA GRC has developed and installed a K/Q-band (20/40 gigahertz) beacon receiver at the POLIMI campus in Milan, Italy, which receives the 20/40 gigahertz signals broadcast from the Alphasat Aldo Paraboni Technology Demonstration Payload (TDP) no. 5 beacon payload. The primary goal of these measurements is to develop a physical model to improve predictions of communications systems performance within the Q-band. Herein, we describe the design and preliminary performance of the NASA propagation terminal, which has been installed and operating in Milan since June 2014. The receiver is based upon a validated Fast Fourier Transform (FFT) I/Q digital design approach utilized in other operational NASA propagation terminals, but has been modified to employ power measurement via a frequency estimation technique and to coherently track and measure the amplitude of the 20/40 gigahertz beacon signals. The system consists of a 1.2-meter K-band and a 0.6-meter Q-band Cassegrain reflector employing synchronous open-loop tracking to track the inclined orbit of the Alphasat satellite. An 8 hertz sampling rate is implemented to characterize scintillation effects, with a 1-hertz measurement bandwidth dynamic range of 45 decibels. A weather station with an optical disdrometer is also installed to characterize rain drop size distribution for correlation with physical based models.

propagation↗
NASA NTRS1973

Telecommunication systems engineering

Telecommunication network concepts are discussed together with carrier-tracking loops employing the phase-lock principle, phase and Doppler measurements in two-way phase-coherent tracking systems, range measurements by phase-coherent techniques, and questions of phase-coherent detection with perfect reference signals and with noisy reference signals. The design of one-way and two-way phase-coherent communication systems is considered, giving attention to the optimal design of single-channel systems, the design of two-channel systems, and the design of multichannel systems. Other topics explored include the design and the performance of phase-coherent systems preceded by band-pass limiters, symbol synchronization and its effects on data detection, noncoherent communication over the Gaussian channel, and tracking loops with improved performance.

Lindsey, W. C.↗
DOE OSTI2020

Measurement of neutrino-induced neutral-current coherent $π^0$ production in the NOvA near detector

The cross section of neutrino-induced neutral-current coherent $\pi^0$ production on a carbon-dominated target is measured in the NOvA near detector. This measurement uses a narrow-band neutrino beam with the average neutrino energy of 2.7\,GeV, xwhich is of interest to the ongoing and future long-baseline neutrino oscillation experiments. The measured, flux-averaged cross section is $\sigma = 14.0\pm0.9$\,(stat.)$\pm2.1$\,(syst.)$\times 10^{-40}$ $\text{cm}^2/$nucleus, consistent with model prediction. This result is the most precise measurement of neutral-current coherent $\pi^0$ production in the few-GeV neutrino energy region.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS2009

Wind Profiling from a New Compact, Pulsed, 2-Micron, Coherent-Detection Doppler Lidar Transceiver during Wind Measurement Intercomparison

NASA Langley Research Center has a long history of developing 2-micron laser transmitter for wind sensing. With support from NASA Laser Risk Reduction Program (LRRP) and Instrument Incubator Program (IIP), NASA Langley Research Center has developed a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement. This lidar system was recently deployed at Howard University facility in Beltsville, Maryland, along with other wind lidar systems. Coherent Doppler wind lidar ground-based wind measurements and comparisons with other lidars and other sensors will be presented.

Singh, Upendra N.↗
DOE OSTI2021

New methodology for measuring electron density perturbations caused by plasma coherent modes using profile reflectometry: Magnitudes and radial profiles in DIII-D

New capabilities of fast-sweep frequency-modulated profile reflectometry are explored to measure electron density ne perturbation magnitudes and radial profiles due to plasma coherent modes in DIII-D. The first approach is based on the frequency analysis of phase perturbations associated with high frequency (~MHz) Alfvén eigenmodes (AEs). The measurement of ~5.5 MHz fast-ion-driven global Alfvén eigenmodes (GAEs) is demonstrated in a neutral beam-heated DIII-D plasma. The GAE induced a broad radial distribution of phase perturbations in the profile reflectometer data. Analysis of these data determined the effective cutoff location displacement and the estimated ne fluctuation profile. In the second approach, high resolution ne profiles are used directly to determine the radial structure of ne perturbations due to a neo-classical tearing mode. These new measurements broaden the application of profile reflectometry and advance the development of AE spectroscopy as a tool for non-invasive diagnosis of fast-ion-driven modes in DIII-D and burning plasmas such as ITER.

47 OTHER INSTRUMENTATION↗
NASA NTRS1991

Infrared lidars for atmospheric remote sensing

Lidars using pulsed TEA-CO2 transmitters and coherent receivers have been developed at JPL and used to measure atmospheric backscatter and extinction at wavelengths in the 9-11 micron region. The global winds measurement application of coherent Doppler lidar requires intensive study of the global climatology of aerosol and cloud backscatter and extinction. An airborne lidar was recently flown on the NASA DC-8 research aircraft for operation during two Pacific circumnavigation missions. The instrument characteristics, as well as representative measurement results, are discussed.

Menzies, Robert T.↗
NASA NTRS1986

Coherent lidar signal fluctuation reduction by means of frequency diversity technique

The atmospheric return measured by a coherent lidar is typically characterized by rapid and deep fluctuations in signal strength. These fluctuations result from the interference of the fields backscattered to the lidar from randomly located aerosol particles which move relative to the lidar pulse. In many applications, it is necessary to determine the average value of the lidar signal intensity at some range. A new method utilizes frequency diversity initially suggested by Goldstein and subsequently studied in the microwave radar domain by others. It is expected that the application of the frequency diversity method in the coherent lidar domain will eventually provide greater efficiency and speed in the return signal averaging needed to obtain accurate intensity estimates. The frequency diversity method recognizes that the transmitted lidar pulse is very long compared to a wavelength and consequently a given phase, theta sub i, is repeated many times within the pulse. In order to test this concept, a fairly simple laboratory experiment was designed which simulates scattering of a lidar pulse from atmospheric aerosol. The testing of the frequency diversity method is discussed.

Schotland, R. M.↗
DOE OSTI2023

Plasma-assisted deflagration to detonation transition in a microchannel with fast-frame imaging and hybrid fs/ps coherent anti-Stokes Raman scattering measurements

Our study examines kinetic enhancement by nanosecond dielectric barrier discharge (ns-DBD) plasma on fuellean dimethyl ether (DME), oxygen (O 2 ), and argon (Ar) premixtures during deflagration to detonation transition (DDT) experiments in a microchannel. Non-equilibrium plasma produces active species and radicals and creates fast and slow heating of a mixture to promote ignition due to electronic and vibrational excitation. Experiments have been conducted to examine the influence of the plasma discharge on the premixture and on the resultant deflagration to detonation transition (DDT) onset time and distance through the use of high speed imaging and one-dimensional, two-beam, femtosecond/picosecond, coherent anti-Stokes Raman scattering (CARS). A highspeed camera is used to trace the time histories of flame front position and velocity and to identify the dynamics and onset of DDT. The results show that plasma discharge can nonlinearly affect the onset time and distance of DDT. It is shown that a small number of plasma discharge pulses prior to ignition result in reduced DDT onset time and distance by 60% and 40%, respectively, when compared to the results without pre-excitation by ns discharges. The results also show that an increase of plasma discharge pulses results in an extended DDT onset time and distance of 224% and 94%, respectively. Time history of the deflagration wave speed of DME and the analysis of ignition timescale under the choking condition of the deflagration front suggest low temperature ignition may play a role for DME near the isobaric choking condition of the burned gas and the DDT. Plasmainduced conversion of the reactive mixture was assessed via the O 2 to CO 2 ratio as measured through fs/ps CARS during the DBD discharges. The present experiments demonstrate the ability of non-equilibrium plasma to alter the chemistry of DME/O 2 /Ar premixtures in order to control DDT for applications in advanced propulsion engines.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1986

Wavelength dependence of coherent and incoherent satellite-based lidar measurements of wind velocity and aerosol backscatter

The results are presented of a capability study of Earth orbiting lidar systems, at various wavelengths from 1.06 to 10.6 microns, for the measurement of wind velocity and aerosol backscatter, and for the detection of clouds. Both coherent and incoherent lidar systems were modeled and compared for the aerosol backscatter and cloud detection applications.

Kavaya, M. J.↗
DOE OSTI2021

On turbulence models and lidar measurements for wind turbine control

Abstract. To provide comprehensive information that will assist in making decisions regarding the adoption of lidar-assisted control (LAC) in wind turbine design, this paper investigates the impact of different turbulence models on the coherence between the rotor-effective wind speed and lidar measurement. First, the differences between the Kaimal and Mann models are discussed, including the power spectrum and spatial coherence. Next, two types of lidar systems are examined to analyze the lidar measurement coherence based on commercially available lidar scan patterns. Finally, numerical simulations have been performed to compare the lidar measurement coherence for different rotor sizes. This work confirms the association between the measurement coherence and the turbulence model. The results indicate that the lidar measurement coherence with the Mann turbulence model is lower than that with the Kaimal turbulence model. In other words, the potential value creation of LAC based on simulations during the wind turbine design phase, evaluated using the Kaimal turbulence model, will be diminished if the Mann turbulence model is used instead. In particular, the difference in coherence is more significant for larger rotors. As a result, this paper suggests that the impacts of different turbulence models should be considered uncertainties while evaluating the benefits of LAC.

17 WIND ENERGY↗
NASA NTRS1979

Coherent anti-Stokes Raman spectroscopy - Spectra of water vapor in flames

The results of experimental measurements of the coherent anti-Stokes Raman spectra of water vapor in flames are reported. A pulsed, frequency-doubled neodymium laser was used to supply the pump beam and to pump a dye laser to provide a broadband Stokes beam at 6600 A. Spectra were obtained in the postflame region of a premixed methane-air flame in the Raman frequency shift region of the symmetric stretch mode (3651.7 kaysers) at an approximate temperature of 1675 K. A theoretical calculation of the coherent anti-Stokes Raman spectrum of water vapor at this temperature was made, taking into account only isotropic Q-branch transitions, and using the energy level data of Floud et al. (1976). The theoretical prediction is shown essentially to reproduce all qualitative features of the experimental spectrum, and to exhibit a strong temperature dependence.

Hall, R. J.↗
NASA NTRS1999

High-Efficiency Autonomous Coherent Lidar

A useful measure of sensor performance is the transceiver system efficiency n (sub sys). Which consists of the antenna efficiency n (sub a) and optical and electronic losses. Typically, the lidar equation and the antenna efficiency are defined in terms of the telescope aperture area. However, during the assembly of a coherent transceiver, it is important to measure the system efficiency before the installation of the beamexpanding telescope (i.e., the untruncated-beam system efficiency). Therefore, to accommodate both truncated and untruncated beam efficiency measurements, we define the lidar equation and the antenna efficiency in terms of the beam area rather than the commonly used aperture area referenced definition. With a well-designed Gaussian-beam lidar, aperture area referenced system efficiencies of 15 to 20 % (23-31% relative to the beam area) are readily achievable. In this paper we compare the differences between these efficiency definitions. We then describe techniques by which high efficiency can be achieved, followed by a discussion several novel auto alignment techniques developed to maintain high efficiency.

Philip Gatt↗
DOE OSTI2026

Coherence-mediated quantum thermometry in a hybrid circuit quantum electrodynamics architecture

Quantum thermometry plays a critical role in the development of low-temperature sensors and quantum information platforms. Here, in this work, we propose and analyze a hybrid circuit quantum electrodynamics architecture in which a superconducting qubit is dispersively coupled to two distinct bosonic modes: one initialized in a weak coherent state as a phase reference and information buffer and the other coupled to a thermal environment. We show that the qubit serves as a sensitive readout of the probe mode, mapping the interplay between thermal and coherent photon-number fluctuations onto measurable dephasing. This coherence-mediated mechanism enables improved sensitivity to thermal energy fluctuations in the sub-millikelvin regime through Ramsey interferometry. We derive analytic expressions for the probe coherence envelope, compute the quantum Fisher information for temperature estimation, and demonstrate numerically that the presence of a coherent reference enhances the qubit's sensitivity to small changes in thermal photon occupancy. Our results establish a coherence-enabled approach to thermometry and provide a scalable platform for future calorimetric sensing in high-energy physics and quantum metrology.

Zhu, Shaojiang [Fermi National Accelerator Laborat↗