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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Coherent Gate Operations in Hybrid Magnonics

Electromagnonics-the hybridization of spin excitations and electromagnetic waves-has been recognized as a promising candidate for coherent information processing in recent years. Among its various implementations, the lack of available approaches for real-time manipulation on the system dynamics has become a common and urgent limitation. In this work, by introducing a fast and uniform modulation technique, we successfully demonstrate a series of benchmark coherent gate operations in hybrid magnonics, including semiclassical analogies of Landau-Zener transitions, Rabi oscillations, Ramsey interference, and controlled mode swap operations. Finally, our approach lays the groundwork for dynamical manipulation of coherent signals in hybrid magnonics and can be generalized to a broad range of applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Wind Turbine Lightning Mitigation System Radar Cross Section Reduction

Modern wind turbines employ Lightning Mitigation Systems (LMSs) in order to reduce costly damages caused by lightning strikes. Lightning strikes on wind turbines occur frequently making LMS configurations a necessity. An LMS for a single turbine includes, among other equipment, cables running inside each blade, along the entire blade length. These cables are connected to various metallic receptors on the outside surface of the blades. The LMS cables can act as significant electromagnetic scatterers which may cause interference to radar systems. This interference may be mitigated by reducing the Radar Cross-Section (RCS) of the wind turbine's LMS. This report investigates proposed modifications to LMS cables in order to reduce the RCS when illuminated by Re locatable Over the Horizon Radar (ROTHR) systems which operate in the HF band (3 - 30 MHz). The proposed modifications include breaking up the LMS cables using spark gap connections, and changing the orientation of the LMS cable within the turbine blade. Both simulated analyses of such RCS mitigation techniques is provided as well as recommendations on further research.

17 WIND ENERGY↗
NASA NTRS2009

The 50 Constellation Priority Sites

The Constellation program (CxP) has developed a list of 50 sites of interest on the Moon which will be targeted by the LRO narrow angle camera. The list has also been provided to the M~ team to supplement their targeting list. This list does not represent a "site selection" process; rather the goal was to find "representative" sites and terrains to understand the range of possible surface conditions for human lunar exploration to aid engineering design and operational planning. The list compilers leveraged heavily on past site selection work (e.g. Geoscience and a Lunar Base Workshop - 1988, Site Selection Strategy for a Lunar Outpost - 1990, Exploration Systems Architecture Study (ESAS) - 2005). Considerations included scientific, resource utilization, and operational merits, and a desire to span lunar terrain types. The targets have been organized into two "tiers" of 25 sites each to provide a relative priority ranking in the event of mutual interference. A LEAG SAT (special action team) was established to validate and recommend modifications to the list. This SAT was chaired by Dr. Paul Lucey. They provided their final results to CxP in May. Dr. Wendell Mendell will organize an on-going analysis of the data as they come down to ensure data quality and determine if and when a site has sufficient data to be retired from the list. The list was compiled using the best available data, however, it is understood that with the flood of new lunar data, minor modifications or adjustments may be required.

Noble, S.↗
NASA NTRSDate not supplied

HIRF Avoidance Approach for Advanced Air Mobility Vehicles

Advanced Air Mobility (AAM), including Urban Air Mobility (UAM), vehicles may be required to meet stringent High-Intensity Radiated Fields (HIRF) certification requirements. HIRF can cause interference and even damage to vehicle systems. A recently proposed map-based HIRF avoidance approach can help reduce HIRF protection costs compared to the standard approach. However, it necessitates knowing the locations, frequencies, and transmit powers of high-power antennas within the operating area. This study aims to provide the necessary transmitter data by utilizing regulatory license databases. Using New York City as a representative urban area, fixed transmitter data are presented for AM, FM, TV, satellite uplink, land-mobile radio, microwave link, weather radars, and others. The maximum antenna effective isotropic radiated powers are reported. The associated electric field envelopes at 100 feet (30.48 m) distance are compared against the current rotorcraft HIRF standard. The results show the current standards are far adequate in protecting the vehicles. Maps of regions with high HIRF are illustrated. Data for several other cities are also being considered.

HIRF↗
DOE OSTI2026

DOE CESER 6 GHz Interference Study

DOE CESER has sponsored Idaho National Laboratory (INL) to conduct an objective and independent study of potential 6 GHz interference from outdoor operation of unlicensed devices in the 6 GHz band on fixed service (FS) microwave communication links operated by electrical sector incumbents in that band. INL is collaborating with University of Notre Dame (UND), Electric Power Research Institute (EPRI), Lockard & White, Southern Company, and AT&T, to gather data with real-world 6 GHz interference experiments and identify (1) the potential for interference from unlicensed devices and (2) the interference necessary to cause harm to the incumbents. In addition to the functional assessment, a security assessment of the FCC mandated Automatic Frequency Coordination (AFC) System to regulate use of unlicensed 6 GHz standard power devices is also being conducted. A major objective is to create a science-based and defensible methodology used to produce the necessary data and to derive objective conclusions. This proven methodology can then be used to produce objective data and conclusions for other spectrum bands with similar incumbent uses including 4.4 – 4.9 GHz and 7.125 – 7.4 GHz, identified in the reconciliation bill that was adopted on July 4, 2025, as well as the National Spectrum Strategy discussions that are ongoing. This report contains 6 GHz field experiments and findings in the following real-world scenarios with commercial unlicensed standard power (SP) 6 GHz devices regulated by Automated Frequency Coordination (AFC): • University of Notre Dame (UND) Stadium with a capacity of 80,000 spectators, where Wi-Fi operating in 6 GHz has been deployed recently • Southern Company 6 GHz FS microwave link between Columbus and Fortson, Georgia Following are the following key findings from this study. 1. The AFC is under-protective of FS when line-of-sight exists along the path centerline. Data collected at Southern’s 6 GHz fixed link site shows significant erosion of as much as 21.4-24.4 dB of under-protection that can lead to potential service degradation under typical operating conditions. This first key finding is most likely the result of erroneous use of the RF propagation model. INL will collaborate with EPRI and the AFC Functional Requirements Working Group to submit a change request to the WinnForum TS-1014 standard towards correct use of the propagation model by the AFC. 2. There is additive interference effect of about 3 dB from nearly equal power interferers measured from simultaneous operation of two SP AP's operating co-channel with the FS receive from different locations along the path. This second key finding should be used to add the impact of additive interference of operation of multiple APs in the same geographical area, to the next generation of AFCs. INL will collaborate with FCC on the need for the AFC to consider additive interference. We also recommend that additional experiments are conducted on 6 GHz spectrum interference to further improve the AFC operation as the number of outdoor Wi-Fi devices continues to increase. These proposed steps and recommendations will make the co-existence of the incumbents and the 6 GHz outdoor Wi-Fi providers possible without any impact on the incumbents with a win-win outcome for all.

6 GHz↗
NASA NTRS2001

Intersymbol Interference Investigations Using a 3D Time-Dependent Traveling Wave Tube Model

For the first time, a physics based computational model has been used to provide a direct description of the effects of the TWT (Traveling Wave Tube) on modulated digital signals. The TWT model comprehensively takes into account the effects of frequency dependent AM/AM and AM/PM conversion; gain and phase ripple; drive-induced oscillations; harmonic generation; intermodulation products; and backward waves. Thus, signal integrity can be investigated in the presence of these sources of potential distortion as a function of the physical geometry of the high power amplifier and the operational digital signal. This method promises superior predictive fidelity compared to methods using TWT models based on swept amplitude and/or swept frequency data. The fully three-dimensional (3D), time-dependent, TWT interaction model using the electromagnetic code MAFIA is presented. This model is used to investigate assumptions made in TWT black box models used in communication system level simulations. In addition, digital signal performance, including intersymbol interference (ISI), is compared using direct data input into the MAFIA model and using the system level analysis tool, SPW (Signal Processing Worksystem).

Kory, Carol L.↗
DOE OSTI2020

High frequency lithium niobate film-thickness-mode optomechanical resonator

High-frequency optomechanical resonators are in demand as transduction devices to bridge microwave and optical fields. Thin-film lithium niobate is a promising platform for implementing high-frequency optomechanics for its low optical loss and strong piezoelectric coefficients. However, its strong piezoelectricity is also known to introduce excess phonon loss. Here, we present lithium niobate optomechanical resonators with film-thickness-mode mechanical resonances up to 5.2 GHz, reaching the operating frequency regime of superconducting qubits. By engineering the mechanical anchor to minimize the phonon loss, we achieve a high quality factor up to 12 500 at cryogenic temperatures and, hence, a frequency-quality factor product of 6.6 × 10 13 . Our system also features interference between piezo-optomechanical and electro-optic modulation. A theoretical model is derived to analyze these two effects and their interference.

42 ENGINEERING↗
NASA NTRS2002

Ultrawideband Electromagnetic Interference to Aircraft Radios: Results of Limited Functional Testing With United Airlines and Eagles Wings Incorporated, in Victorville, California

On February 14, 2002, the FCC adopted a FIRST REPORT AND ORDER, released it on April 22, 2002, and on May 16, 2002 published in the Federal Register a Final Rule, permitting marketing and operation of new products incorporating UWB technology. Wireless product developers are working to rapidly bring this versatile, powerful and expectedly inexpensive technology into numerous consumer wireless devices. Past studies addressing the potential for passenger-carried portable electronic devices (PEDs) to interfere with aircraft electronic systems suggest that UWB transmitters may pose a significant threat to aircraft communication and navigation radio receivers. NASA, United Airlines and Eagles Wings Incorporated have performed preliminary testing that clearly shows the potential for handheld UWB transmitters to cause cockpit failure indications for the air traffic control radio beacon system (ATCRBS), blanking of aircraft on the traffic alert and collision avoidance system (TCAS) displays, and cause erratic motion and failure of instrument landing system (ILS) localizer and glideslope pointers on the pilot horizontal situation and attitude director displays. This report provides details of the preliminary testing and recommends further assessment of aircraft systems for susceptibility to UWB electromagnetic interference.

Ely, Jay J.↗
NASA NTRS2001

Time-Dependent Traveling Wave Tube Model for Intersymbol Interference Investigations

For the first time, a computational model has been used to provide a direct description of the effects of the traveling wave tube (TWT) on modulated digital signals. The TWT model comprehensively takes into account the effects of frequency dependent AM/AM and AM/PM conversion, gain and phase ripple; drive-induced oscillations; harmonic generation; intermodulation products; and backward waves. Thus, signal integrity can be investigated in the presence of these sources of potential distortion as a function of the physical geometry of the high power amplifier and the operational digital signal. This method promises superior predictive fidelity compared to methods using TWT models based on swept-amplitude and/or swept-frequency data. The fully three-dimensional (3D), time-dependent, TWT interaction model using the electromagnetic code MAFIA is presented. This model is used to investigate assumptions made in TWT black-box models used in communication system level simulations. In addition, digital signal performance, including intersymbol interference (ISI), is compared using direct data input into the MAFIA model and using the system level analysis tool, SPW.

Kory, Carol L.↗
DOE OSTI2012

Development of a mirror-based endoscope for divertor spectroscopy on JET with the new ITER-like wall (invited)

A new endoscope with optimised divertor view has been developed in order to survey and monitor the emission of specific impurities such as tungsten and the remaining carbon as well as beryllium in the tungsten divertor of JET after the implementation of the ITER-like wall in 2011. The endoscope is a prototype for testing an ITER relevant design concept based on reflective optics only. It may be subject to high neutron fluxes as expected in ITER. The operating wavelength range, from 390 nm to 2500 nm, allows the measurements of the emission of all expected impurities (W I, Be II, C I, C II, C III) with high optical transmittance ({>=}30% in the designed wavelength range) as well as high spatial resolution that is {<=}2 mm at the object plane and {<=}3 mm for the full depth of field ({+-}0.7 m). The new optical design includes options for in situ calibration of the endoscope transmittance during the experimental campaign, which allows the continuous tracing of possible transmittance degradation with time due to impurity deposition and erosion by fast neutral particles. In parallel to the new optical design, a new type of possibly ITER relevant shutter system based on pneumatic techniques has been developed and integrated into the endoscope head. The endoscope is equipped with four digital CCD cameras, each combined with two filter wheels for narrow band interference and neutral density filters. Additionally, two protection cameras in the {lambda} > 0.95 {mu}m range have been integrated in the optical design for the real time wall protection during the plasma operation of JET.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS2004

Space Technology 5: Pathfinder for Future Micro-Sat Constellations

The Space Technology 5 (ST-5) Project, currently in the implementation phase, is part of the National Aeronautics and Space Administration (NASA) s New Millennium Program (NMP). ST-5 will consist of a constellation of three miniature satellites, each with mass less than 25 kg and size approximately 60 cm by 30 cm. ST-5 addresses technology challenges, as well as fabrication, assembly, test and operations strategies for future micro-satellite missions. ST-5 will be deployed into a highly eccentric, geo-transfer orbit (GTO). This will expose the spacecraft to a high radiation environment as well as provide a low level magnetic background. A three-month flight demonstration phase is planned to validate the technologies and demonstrate concepts for future missions. Each ST-5 spacecraft incorporates NMP competitively-selected breakthrough technologies. These include Cold Gas Micro-Thrusters for propulsion and attitude control, miniature X-band transponder for space-ground communications, Variable Emittance Coatings for dynamic thermal control, and CULPRiT ultra low power logic chip used for Reed-Solomon encoding. The ST-5 spacecraft itself is a technology that can be infused into future missions. It is a fully functional micro-spacecraft built within tight volume and mass constraints. It is built to withstand a high radiation environment, large thermal variations, and high launch loads. The spacecraft power system is low-power and low-voltage, and is designed to turn on after separation &om the launch vehicle. Some of the innovations that are included in the ST-5 design are a custom spacecraft deployment structure, magnetometer deployment boom, nutation damper, X-band antenna, miniature spinning sun sensor, solar array with triple junction solar cells, integral card cage assembly containing single card Command and Data Handling and Power System Electronics, miniature magnetometer, and lithium ion battery. ST-5 will demonstrate the ability of a micro satellite to perform research-quality science. Each ST-5 spacecraft will deploy a precision magnetometer to be used both for attitude determination and as a representative science instrument. The spacecraft has been developed with a low magnetic signature to avoid interference with the magnetometer. The spacecraft will be able to detect and respond autonomously to science events, i.e. significant changes in the magnetic field measurements. The three spacecraft will be a pathfinder for future constellation missions. They will be deployed to demonstrate an appropriate geometry for scientific measurements as a constellation. They will be operationally managed as a constellation, demonstrating automation and communication strategies that will be useful for future missions. The technologies and future mission concepts will be validated both on the ground and in space. Technologies will be validated on the ground by a combination of component level and system level testing of the flight hardware in a thermal vacuum environment. In flight, specific validation runs are planned for each of the technologies. Each validation run consists of one or more orbits with a specific validation objective. This paper will describe the ST-5 mission, and the applicability of the NMP technologies, spacecraft, and mission concepts to future missions. It will also discuss the validation approach for the ST-5 technologies and mission concepts.

Carlisle, Candace↗
NASA NTRS2023

Basic Theory and Operating Principles of Optical Frequency Domain Reflectometry Measurement Systems as Applied to Fiber Bragg Grating Sensors

Optical frequency domain reflectometer (OFDR) systems provide for the interrogation of hundreds of fiber Bragg gratings (FBGs) within a single optical fiber. The coupling of FBG sensors to an OFDR interrogator results in a highly distributed measurement system utilizing sensors that are lightweight, immune to electromagnetic interference, and low-profile. This paper presents and explores a basic derivation of OFDR-FBG signals, the processing of those signals, the assembly of a basic OFDR system, an example measurement scenario, and the effects of specific component and configuration changes on interrogator speed, resolution, and accuracy.

optical frequency domain reflectometry↗
DOE OSTI2022

Development of a Radiation-Tolerant Front End Digitizer

High-radiation and high-temperature environments represent notoriously detrimental conditions for electronics. Yet sensors and instrumentation are critically important for the safe operation of nuclear reactors and for the validity of the scientific experiments conducted within them. Traditionally, sensors in such extreme environments operate with few active components, resulting in small signals (mV–V, nA–µA range) that must be transmitted through long cable runs before digitization by sensitive data acquisition systems located in clean, less-harsh environments. Long cables are prone to picking up noise through electromagnetic interference and distortion caused by their parasitic impedances, resulting in signal degradation. The Front End Digitizer (FREND) system described and demonstrated herein seeks to address these issues by enabling the placement of a radiation-resistant analog front end within reactor containment, or other high-radiation environments. FREND will enable early signal pre-amplification, digitization, and optical encoding within the high-radiation field to transmit sensor signals over an optical fiber to the non-nuclear environment of an instrument room. Early signal pre-amplification and digitization maintain signal integrity, whereas optical transmission renders the system blind to induced electromagnetic noise over the long cable runs. This report describes the FREND initial prototype, which can multiplex and optically encode data from up to four sensor inputs, though, in principle, this can be extended to any number of sensor inputs. The end result is an extremely flexible, high-fidelity system.

42 ENGINEERING↗
NASA NTRS1975

Vector thrust induced lift effects for several ejector exhaust locations on a V/STOL wind tunnel model at forward speed

The results and analysis of aerodynamic force data obtained from a small scale model of a V/STOL research vehicle in a low speed wind tunnel are presented. The analysis of the data includes the evaluation of aerodynamic-propulsive lift performance when operating twin ejector nozzles with thrust deflected. Three different types of thrust deflector systems were examined: 90 deg downward deflected nozzle, 90 deg slotted nozzle with boundary layer control, and an externally blown flap configuration. Several nozzle locations were tested, including over and underwing positions. The interference lift of the nacelle and model due to jet exhaust thrust is compared and results show that 90 deg turned nozzles located over the wing (near the trailing edge) produce the largest interference lift increment for an untrimmed aircraft, and that the slotted nozzle located under the wing near the trailing edge (in conjunction with a BLC flap) gives a comparable interference lift in the trimmed condition. The externally blown flap nozzle produced the least interference lift and significantly less total lift due to jet thrust effects.

Sharon, A. D.↗
NASA NTRS1980

Adaptive rain fade compensation

A large available margin must be provided for satellite communications systems operating near 20 GHz, which occasionally experience fades due to rain attenuation. It is proposed that this margin may be achieved in high-capacity FDMA satellites by dynamically providing a large margin to those links which are experiencing deep fades, while maintaining a small fade margin on all others. Single-beam SCPC operation and multiple-beam, satellite-switched FDMA systems are described, and the optimization of the dynamic FDMA links in a severely fading environment is investigated. A solution is derived which takes into account: (1) transponder intermodulation distortion, (2) cochannel and cross-polarization antenna interference, and (3) rain fade characteristics. The sample system configuration presented shows that such systems reach availability levels approaching 0.9999 at Ka-Band.

Rautio, J. C.↗
NASA NTRS1985

Second-generation mobile satellite system. A conceptual design and trade-off study

In recent years, interest has grown in the mobile satellite (MSAT) system, a satellite-based communications system capable of providing integrated voice and data services to a large number of users. To explore the potential of a commercial mobile satellite system (MSS) beyond the horizon of the first generation, using technologies of the 1990's and to assist MSAT-X in directing its efforts, a conceptual design has been performed for a second-generation system to be launched around the mid-1990's. The design goal is to maximize the number of satellite channels and/or minimize the overall life-cycle cost, subject to the constraint of utilizing a commercial satellite bus with minimum modifications. To provide an optimal design, a series of trade-offs are performed, including antenna sizing, feed configurations, and interference analysis. Interference is a serious problem for MSAT and often an overlapping feed design is required to reduce interbeam interference. The trade-off studies will show that a simple non-overlapping feed is sufficient for the second-generation system, thus avoiding the need for the complicated beam-forming network that is associated with the overlapping feed designs. In addition, a system that operates at L-band, an alternative frequency band that is being considered by some for possible MSAT applications, is also presented.

Sue, M. K.↗
NASA NTRS2019

Design Considerations and Development Status for Atmospheric Powered Descent of High-Mass Payloads at Mars

Retropropulsion, initiated at supersonic conditions, is the only presently viable approach to the descent and landing of human-scale payloads on Mars, providing both deceleration and control authority for precision landing. Atmospheric powered descent challenges traditional processes and dependencies in system design. Changes to a design by one discipline have a greater potential to affect overall vehicle performance than in the case of powered descent with no atmosphere. The interdependence is due to the sensitivity of propulsive-aerodynamic interference effects to small changes in configuration or operational environment. The fidelity of Mars exploration architectures has increased in recent years, and the conditions and designs with the lowest aerosciences uncertainties are no longer as flight-relevant. At this time, there is no human-rated vehicle relying on retropropulsion for descent and landing in an atmospheric environment. Continued development of powered descent for atmospheric environments is enabled by progressive balanced investments in ground testing, predictive computational capabilities, and flight testing and demonstration.

EDL↗
NASA NTRSDate not supplied

Molten Salt Lattice Confinement Fusion (LCF) Fast Fission Reactor for Lunar and Planetary Surface Power

Molten salt fission reactors (MSR) have been suggested for lunar and planetary surface power systems. They have the advantage of operating at high temperature, for efficient thermal-electrical conversion, low pressure, long-lived with high nuclear fuel burnup. MSR are often designed to breed fissile 233U from natural 232Th by neutron capture and  decay via: 232Th(n,)233Th(,)233Pa(,)233U Unfortunately, this process requires 233Pa isotope separation and segregation to decay to 233U. This requirement prevents additional neutron capture that interferes with 233U breeding. Instead, Wooley’s sub-critical, fast fission, molten salt reactor would use externally generated tokamak fusion neutrons1,2 to fission all actinides.We propose a simpler fusion-fast-fission sub-critical reactor that generates fast neutrons in situ from lattice confinement fusion (LCF) to fission fertile and fissile actinides. This hybrid reactor doesn't require enriched 235U fissile pins to initiate fis-sion reactions, nor 233Pa separation and segregation during operation. Like Wooley’s, this hybrid reactor “burns” natural uranium (238U) or thorium (232Th) which avoids uranium enrichment and additional fissile material launch safety and security costs. The LCF neutron source is initiated by bremsstrahlung photoneutrons (Fig. 1)3 or isotopic neutron sources in electron-screened lattices (Fig. 2)4,5. Alternatively, the electrolytic Pd-deuterium co-deposition6protocol fast fissions7 both 232Th and 238U. However, an aqueous electrolyte-based system, without pressurization similar to conventional pressurized water fission reactors, is incapable of high temperatures due to the boiling point of the electrolyte slightly over 100 C. Molten salts can be used instead as was demonstrated at the University of Hawaii8 using a variety of Ni and Pd cathodes in lithiated, hydrided and deuterated salts. These salts have melting points often exceeding 500C making them suitable to efficiently produce electrical power9 through either Advanced Stirling Genera-tors (< 100 kWe) or closed-Brayton Cycle (> 100 kWe). This hybrid reactor could power a wide range of lunar or Martian applications from unmanned in-struments, to charging vehicles and entire facilities such as human habitats or in situ resource utilization. The power conversion cycles are Carnot Cycle limited, but generally 30% efficient at best. However, waste heat on the moon or Mars is important to surviving either two-week lunar nights or Martian nights as well as providing process heat for mineral extraction and “living off the land”

Lawrence Forsley↗