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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

Testbed for LISA Photodetectors

The Laser Interferometer Space Antenna (LISA) is a gravitational wave observatory consisting of three spacecraft separated by 5 million km in an equilateral triangle whose center follows the Earth in orbit around the Sun but offset in orbital phase by 20 degrees. LISA is designed to observe sources in the frequency range of 0.1 mHz-100 mHz by measuring fluctuations of the inter-spacecraft separation with laser interferometry. Quadrant photodetectors are used to measure both separation and angular orientation. Noise level, phase and amplitude inhomogeneities of the semiconductor response, and channel cross-talk between quadrant cells need to be assessed in order to ensure the 10 pm/Square root(Hz) sensitivity required for the interferometric length measurement in LISA. To this end, we are currently developing a testbed that allows us to evaluate photodetectors to the sensitivity levels required for LISA. A detailed description of the testbed and preliminary results will be presented.

Guzman, Felipe↗
NASA NTRS2010

Characterization of Photodetectors for LISA

The Laser Interferometer Space Antenna (LISA) is a gravitational wave observatory in the frequency range of 0.1 mHz - 100 mHz consisting of three spacecraft separated by :5 million km in an equilateral triangle whose center follows the Earth in a heliocentric orbit with an orbital phase offset of 20 degrees. Gravitational waves will be measured as distance fluctuations between test masses moving along geodetic trajectories that are located in different spacecraft. Quadrant photo diodes are used as detectors in inter-spacecraft laser interferometers to measure both angular orientation and separation with a sensitivity of better than 10 pm/(square root of (HZ)). A laboratory testbed for the characterization of photodetectors has been set up to measure noise levels, phase and amplitude spatial inhomogeneities and cross-talk level between detector quadrants We will present a detailed description of our test plan and current results of these investigations.

Guzman, Felipe↗
NASA NTRS2010

LISA and LISA Pathfinder: Gravitational Wave Observation in Space

The Laser Interferometer Space Antenna (LISA) is a planned NASA-ESA gravitational wave observatory in the frequency range of 0.1 mHz--100 mHz. This observation band is inaccessible to ground-based detectors due to fluctuations in the Earth gravitational field. Gravitational wave sources for LISA include galactic binaries, mergers of supermassive black-hole binaries, extreme-mass-ratio inspirals, and cosmology backgrounds and bursts. LISA is a constellation of three spacecraft separated by 5 million km in an equilateral triangle, whose center follows the Earth in a heliocentric orbit with an orbital phase offset of 20 degrees. Challenging technology is required to ensure pure geodetic trajectories of the six onboard test masses, whose distance fluctuations will be measured by interspacecraft laser interferometers with picometer accuracy. LISA Pathfinder is an ESA-launched technology demonstration mission of key LISA subsystems such as spacecraft control with micronewton thrusters, test mass drag-free control, and precision laser interferometry between free-flying test masses. Ground testing of hardware of the Gravitational Reference Sensor and Optical Metrology subsystems of LISA Pathfinder is currently ongoing. A detailed description of the two missions and an overview of current investigations conducted by the community will be discussed. The current status in development and implementation of LISA Pathfinder pre-flight systems and latest results of the ongoing ground testing efforts will also be presented.

Guzman, Felipe↗
NASA NTRS2013

Chaos and Beyond in a Water Filled Ultrasonic Resonance System

Finite amplitude ultrasonic wave resonances in a one-dimensional liquid-filled cavity, formed by a narrow band transducer and a plane reflector, are reported. The resonances are observed to include not only the expected harmonic and subharmonic signals (1,2) but chaotic signals as well. The generation mechanism requires attaining a threshold value of the driving amplitude that the liquid-filled cavity system becomes sufficiently nonlinear in response. The nonlinear features of the system were recently investigated via the construction of an ultrasonic interferometer having optical precision. The transducers were compressional, undamped quartz and lithium niobate crystals having the frequency range 1-10 MHz, driven by a high power amplifier. Both an optical diffraction system to characterize the diffraction pattern of laser light normally incident to the cavity and a receiving transducer attached to an aligned reflector with lapped flat and parallel surfaces were used to assess the generated resonance response in the cavity. At least 5 regions of excitation are identified.

Lazlo, Adler↗
NASA NTRS2013

Height of Shock Formation in the Solar Corona Inferred from Observations of Type II Radio Bursts and Coronal Mass Ejections

Employing coronagraphic and EUV observations close to the solar surface made by the Solar Terrestrial Relations Observatory (STEREO) mission, we determined the heliocentric distance of coronal mass ejections (CMEs) at the starting time of associated metric type II bursts. We used the wave diameter and leading edge methods and measured the CME heights for a set of 32 metric type II bursts from solar cycle 24. We minimized the projection effects by making the measurements from a view that is roughly orthogonal to the direction of the ejection. We also chose image frames close to the onset times of the type II bursts, so no extrapolation was necessary. We found that the CMEs were located in the heliocentric distance range from 1.20 to 1.93 solar radii (Rs), with mean and median values of 1.43 and 1.38 Rs, respectively. We conclusively find that the shock formation can occur at heights substantially below 1.5 Rs. In a few cases, the CME height at type II onset was close to 2 Rs. In these cases, the starting frequency of the type II bursts was very low, in the range 25-40 MHz, which confirms that the shock can also form at larger heights. The starting frequencies of metric type II bursts have a weak correlation with the measured CME/shock heights and are consistent with the rapid decline of density with height in the inner corona.

EUV↗
NASA NTRS2018

The NANOGrav 11-year Data Set: High-Precision Timing of 45 Millisecond Pulsars

We present high-precision timing data over time spans of up to 11 years for 45 millisecond pulsars observed as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project, aimed at detecting and characterizing low-frequency gravitational waves. The pulsars were observed with the Arecibo Observatory and/or the Green Bank Telescope at frequencies ranging from 327 MHz to 2.3 GHz. Most pulsars were observed with approximately monthly cadence, and six high-timing-precision pulsars were observed weekly. All were observed at widely separated frequencies at each observing epoch in order to fit for time-variable dispersion delays. We describe our methods for data processing, time-of-arrival (TOA) calculation, and the implementation of a new, automated method for removing outlier TOAs. We fit a timing model for each pulsar that includes spin, astrometric, and (for binary pulsars) orbital parameters; time-variable dispersion delays; and parameters that quantify pulse-profile evolution with frequency. The timing solutions provide three new parallax measurements, two new Shapiro delay measurements, and two new measurements of significant orbital-period variations. We fit models that characterize sources of noise for each pulsar. We find that 11 pulsars show significant red noise, with generally smaller spectral indices than typically measured for non-recycled pulsars, possibly suggesting a different origin. A companion paper uses these data to constrain the strength of the gravitational-wave background

Arzoumanian, Zaven↗
NASA NTRS2020

Automated Noise Calibration System (VT-1000)

This paper details an automated Noise Source calibration system in development at Jet Propulsion Laboratory, California Institute of Technology (JPL). The paper begins with a discussion on Noise Figure and Excess Noise Ratio (ENR) theory, fundamentals and governing equations. As part of the fundamentals is a discussion of the system’s use of the Y-factor method to obtain accurate measurements of the Unit Under Test (UUT), and how these measurements are compared against a known ENR standard to obtain the UUT’s ENR values. There is also an in-depth discussion on uncertainty quantification for Noise Source system calibrations. The architecture of the automated calibration system is provided, which includes both the system’s hardware and software configuration. The software is written in Python 3, and provides the user detailed instruction on how to proceed, including step-by-step connection requirements. This system automates much of the measurement process, including real-time uncertainty quantification and report generation, as well as real-time feedback to the user to allow intervention if necessary. The system takes advantage of a database of results from previous measurements to compare calibration history of the ENR measurements. The automated system presented here operates over a frequency range from 10 MHz to 50 GHz, and has shown substantial time savings over traditional manual methods of performing this calibration.

Timpe, Scott↗
NASA NTRS2022

Measurement of SST and SSS Using Frequencies in the Range 0.3–2.0 GHz

Wide bandwidth radiometer systems that make measurements at multiple frequencies in the range from 300 MHz to 2 GHz have been proposed to address parameters important for understanding issues in the cryosphere associated with climate change such as ice sheet thickness and temperature. It is also possible with such a system to retrieve sea surface salinity (SSS), which is important for understanding the impact of climate change on ocean circulation at high latitude. In contemporary sensors for retrieving SSS, such as on Soil Moisture and Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP), sea surface temperature (SST), another parameter important for understanding ocean circulation and necessary in the retrieval of salinity, is treated as an ancillary parameter obtained from an independent source. However, both SSS and SST have peaks in sensitivity below 1 GHz; and it has been shown that measurements at multiple frequencies in this portion of the spectrum can take advantage of this peak in sensitivity to improve the accuracy of the retrieval of SSS. In this manuscript, it will be shown that there is also the potential to retrieve SST and, in cold water, the possibility for improved accuracy over existing retrievals.

Microwave remote sensing↗
NASA NTRS2022

Low Frequency ULF Waves in the Earth’s Inner Magnetosphere: Power Spectra During High Speed Streams and Quiet Solar Wind and Seeding of EMIC Waves

Here we extend the scope of the Gamayunov and Engebretson (2021, hereinafter Paper 1) work by analyzing the low frequency ultra-low-frequency (ULF) wave power spectra in the Earth’s inner magnetosphere during high speed stream (HSS) and quiet solar wind (QSW) driving conditions in the upstream solar wind (SW) and comparing our results to the results of Paper 1, where the statistics of ULF wave power spectra during coronal mass ejections (CMEs) are presented. The most important results of our statistical and comparative analyses are as follows. (a) During CMEs, HSSs, and QSW, the magnetic field power spectra of the transverse and compressional fluctuations are well approximated by power-laws in the ∼ mHz - Hz frequency range, where on average the parameters of power-law fits during CMEs and HSSs are close, and those during QSW differ considerably from the respective parameters during CMEs and HSSs. (b) The dominance of the average compressional power over the average transverse power for the low frequency ULF waves during the 0 < SYM/H . 25 nT geomagnetic conditions may serve as a proxy of HSSs in the upstream SW, whereas the opposite relation between the average powers is an indication of CMEs. (c) Independently of the SW driving conditions, a turbulent energy cascade from low frequencies in the ULF wave frequency range into the higher frequency range exists in the Earth’s inner magnetosphere, supplying the nonthermal electromagnetic seed fluctuations needed for the growth of electromagnetic ion cyclotron (EMIC) waves (∼ Hz) due to relaxation of unstable distributions of energetic magnetospheric ions.

Konstantin V. Gamayunov↗
NASA NTRS2015

Compatibility of the Radio Frequency Mass Gauge with Graphite-Epoxy Composite Tanks

The radio frequency mass gauge (RFMG) is a low-gravity propellant quantity gauge being developed at NASA for possible use in long-duration space missions utilizing cryogenic propellants. As part of the RFMG technology development process, we evaluated the compatibility of the RFMG with a graphite-epoxy composite material used to construct propellant tanks. The key material property that can affect compatibility with the RFMG is the electrical conductivity. Using samples of 8552/IM7 graphite-epoxy composite, we characterized the resistivity and reflectivity over a range of frequencies. An RF impedance analyzer was used to characterize the out-of-plane electrical properties (along the sample thickness) in the frequency range 10 to 1800 MHZ. The resistivity value at 500 MHz was 4.8 ohm-cm. Microwave waveguide measurements of samples in the range 1.7 - 2.6 GHz, performed by inserting the samples into a WR-430 waveguide, showed reflectivity values above 98%. Together, these results suggested that a tank constructed from graphite/epoxy composite would produce good quality electromagnetic tank modes, which is needed for the RFMG. This was verified by room-temperature measurements of the electromagnetic modes of a 2.4 m diameter tank constructed by Boeing from similar graphite-epoxy composite material. The quality factor Q of the tank electromagnetic modes, measured via RF reflection measurements from an antenna mounted in the tank, was typically in the range 400 less than Q less than 3000. The good quality modes observed in the tank indicate that the RFMG is compatible with graphite-epoxy tanks, and thus the RFMG could be used as a low-gravity propellant quantity gauge in such tanks filled with cryogenic propellants.

Propellant tanks↗
NASA NTRS2015

Compatibility of the Radio Frequency Mass Gauge with Composite Tanks

The radio frequency mass gauge (RFMG) is a low-gravity propellant quantity gauge being developed at NASA for possible use in long-duration space missions utilizing cryogenic propellants. As part of the RFMG technology development process, we evaluated the compatibility of the RFMG with a graphite-epoxy composite material used to construct propellant tanks. The key material property that can affect compatibility with the RFMG is the electrical conductivity. Using samples of 8552IM7 graphite-epoxy composite, we characterized the resistivity and reflectivity over a range of frequencies. An RF impedance analyzer was used to characterize the out-of-plane electrical properties (along the sample thickness) in the frequency range 10 to 1800 MHZ. The resistivity value at 500 MHz was 4.8 ohm-cm. Microwave waveguide measurements of samples in the range 1.7 2.6 GHz, performed by inserting the samples into a WR-430 waveguide, showed reflectivity values above 98. Together, these results suggested that a tank constructed from graphite-epoxy composite would produce good quality electromagnetic tank modes, which is needed for the RFMG. This was verified by room-temperature measurements of the electromagnetic modes of a 2.4 m diameter tank constructed by Boeing from similar graphite-epoxy composite material. The quality factor Q of the tank electromagnetic modes, measured via RF reflection measurements from an antenna mounted in the tank, was typically in the range 400 Q 3000. The good quality modes observed in the tank indicate that the RFMG is compatible with graphite-epoxy tanks, and thus the RFMG could be used as a low-gravity propellant quantity gauge in such tanks filled with cryogenic propellants.

Radio frequencies↗
NASA NTRS1989

Small Mercury Relativity Orbiter

The accuracy of solar system tests of gravitational theory could be very much improved by range and Doppler measurements to a Small Mercury Relativity Orbiter. A nearly circular orbit at roughly 2400 km altitude is assumed in order to minimize problems with orbit determination and thermal radiation from the surface. The spacecraft is spin-stabilized and has a 30 cm diameter de-spun antenna. With K-band and X-band ranging systems using a 50 MHz offset sidetone at K-band, a range accuracy of 3 cm appears to be realistically achievable. The estimated spacecraft mass is 50 kg. A consider-covariance analysis was performed to determine how well the Earth-Mercury distance as a function of time could be determined with such a Relativity Orbiter. The minimum data set is assumed to be 40 independent 8-hour arcs of tracking data at selected times during a two year period. The gravity field of Mercury up through degree and order 10 is solved for, along with the initial conditions for each arc and the Earth-Mercury distance at the center of each arc. The considered parameters include the gravity field parameters of degree 11 and 12 plus the tracking station coordinates, the tropospheric delay, and two parameters in a crude radiation pressure model. The conclusion is that the Earth-Mercury distance can be determined to 6 cm accuracy or better. From a modified worst-case analysis, this would lead to roughly 2 orders of magnitude improvement in the knowledge of the precession of perihelion, the relativistic time delay, and the possible change in the gravitational constant with time.

Bender, Peter L.↗
DOE OSTI2023

Dark matter axion search using a Josephson Traveling wave parametric amplifier

Here, we describe the first implementation of a Josephson Traveling Wave Parametric Amplifier (JTWPA) in an axion dark matter search. The operation of the JTWPA for a period of about two weeks achieved sensitivity to axion-like particle dark matter with axion–photon couplings above 10 -13 Ge V -1 over a narrow range of axion masses centered around 19.84 µeV by tuning the resonant frequency of the cavity over the frequency range of 4796.7–4799.5 MHz. The JTWPA was operated in the insert of the axion dark matter experiment as part of an independent receiver chain that was attached to a 0.56-l cavity. The ability of the JTWPA to deliver high gain over a wide (3 GHz) bandwidth has engendered interest from those aiming to perform broadband axion searches, a longstanding goal in this field.

47 OTHER INSTRUMENTATION↗
NASA NTRS1988

An electronically tuned, stable 8415-MHz dielectric resonator FET oscillator for space applications

A voltage-controlled 8415 MHz FET oscillator stabilized by a dielectric resonator is described. The oscillator provides a linear electronic tuning range of over 3.2 MHz with a flat power output equal to +1.8 dBm (27 C nominal), a single-sideband noise to carrier ratio of -68 dBc/Hz at 1 kHz off carrier, and a frequency temperature coefficient of 0.54 part per million/C over a -24 to 75 C range. The oscillator withstood 150 krads(Si) of gamma radiation with no significant performance degradation. The overall performance of the oscillator is in many ways far superior to that of an equivalent bipolar oscillator for space applications.

Lakshminarayana, M.↗
NASA NTRS2003

Electronic Power System Application of Diamond-Like Carbon Films

A prototype manufacturing technology for producing high volume efficiency and high energy density diamond-like carbon (DLC) capacitors has been developed. Unique dual ion-beam deposition and web-handling systems have been designed and constructed to deposit high quality DLC films simultaneously on both sides of capacitor grade aluminum foil and aluminum-coated polymer films. An optimized process, using inductively coupled RF ion sources, has been used to synthesize electrically robust DLC films. DLC films are amorphous and highly flexible, making them suitable for the production of wound capacitors. DLC capacitors are reliable and stable over a wide range of AC frequencies from 20 Hz to 1 MHz, and over a temperature range from .500 C to 3000 C. The compact DLC capacitors offer at least a 50% decrease in weight and volume and a greater than 50% increase in temperature handling capability over equal value capacitors built with existing technologies. The DLC capacitors will be suitable for high temperature, high voltage, pulsed power and filter applications.

Wu, Richard L. C.↗