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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS2001

Electronic Model of a Ferroelectric Field Effect Transistor

A pair of electronic models has been developed of a Ferroelectric Field Effect transistor. These models can be used in standard electrical circuit simulation programs to simulate the main characteristics of the FFET. The models use the Schmitt trigger circuit as a basis for their design. One model uses bipolar junction transistors and one uses MOSFET's. Each model has the main characteristics of the FFET, which are the current hysterisis with different gate voltages and decay of the drain current when the gate voltage is off. The drain current from each model has similar values to an actual FFET that was measured experimentally. T'he input and o Output resistance in the models are also similar to that of the FFET. The models are valid for all frequencies below RF levels. No attempt was made to model the high frequency characteristics of the FFET. Each model can be used to design circuits using FFET's with standard electrical simulation packages. These circuits can be used in designing non-volatile memory circuits and logic circuits and is compatible with all SPICE based circuit analysis programs. The models consist of only standard electrical components, such as BJT's, MOSFET's, diodes, resistors, and capacitors. Each model is compared to the experimental data measured from an actual FFET.

MacLeod, Todd C.↗
DOE OSTI2024

OPTIMIZATION OF COOLING DISTRIBUTION OF THE EIC SHC COOLER ERL

The Electron-Ion Collider (EIC) Hadron Storage Ring (HSR) will use strong hadron cooling to maintain the beam brightness and high luminosity during long collision ex?periments. An Energy Recovery Linac is used to deliver the high-current high-brightness electron beam for cooling. For the best cooling effect, the electron beam requires low emittance, small energy spread, and uniform longitudinal distribution. In this work, we simulate and optimize the longitudinal laser-beam distribution shaping at the photo?cathode, modeling space charge forces accurately. Machine parameters such as RF cavity phases are optimized in con?junction with the beam distribution using a genetic optimizer. We demonstrate improvement of the cooling distribution in key parameters.

Wang, N.↗
DOE OSTI2024

Integration Development and Testing of Rear Transition Monitor for Beam Current Monitoring System

Addressing baseline effects in accelerator environments is crucial for accurate data acquisition and analysis, since baseline effects can obscure signal clarity and impact the reliability of beam current monitoring systems. There are many potential contributors to baseline noise, such as variations in beam dynamics, electromagnetic interference from nearby equipment, or RF interference. Previous applications of noise reduction systems don t sufficiently filter sources of asynchronous noise, so a new algorithm was implemented. A simulation dataset was created to replicate beam conditions and a Red Pitaya FPGA was used to collect data through the streaming application. A Python script was developed to implement noise reduction algorithms and efforts were made to integrate real-time data streaming with the Redis platform and Acnet Front End infrastructure.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1979

Power combining in an array of microwave power rectifiers

This work analyzes the resultant efficiency degradation when identical rectifiers operate at different RF power levels as caused by the power beam taper. Both a closed-form analytical circuit model and a detailed computer-simulation model are used to obtain the output dc load line of the rectifier. The efficiency degradation is nearly identical with series and parallel combining, and the closed-form analytical model provides results which are similar to the detailed computer-simulation model.

Gutmann, R. J.↗
NASA NTRS1998

A Comparison of Space and Ground Based Facility Environmental Effects for FEP Teflon

Fluorinated Ethylene Propylene (FEP) Teflon is widely used as a thermal control material for spacecraft, however, it is susceptible to erosion, cracking, and subsequent mechanical failure in low Earth orbit. One of the difficulties in determining whether FEP Teflon will survive during a mission is the wide disparity of erosion rates observed for this material in space and in ground based facilities. Each environment contains different levels of atomic oxygen, ions, and vacuum ultraviolet (VUV) radiation in addition to parameters such as the energy of the arriving species and temperature. These variations make it difficult to determine what is causing the observed differences in erosion rates. This paper attempts to narrow down which factors affect the erosion rate of FEP Teflon through attempting to change only one environmental constituent at a time. This was attempted through the use of a single simulation facility (plasma asher) environment with a variety of Faraday cages and VUV transparent windows. Isolating one factor inside of a radio frequency (RF) plasma proved to be very difficult. Two observations could be made. First, it appears that the erosion yield of FEP Teflon with respect to that of polyimide Kapton is not greatly affected by the presence or lack of VUV radiation present in the RF plasma and the relative erosion yield for the FEP Teflon may decrease with increasing fluence. Second, shielding from charged particles appears to lower the relative erosion yield of the FEP to approximately that observed in space, however it is difficult to determine for sure whether ions, electrons, or some other components are causing the enhanced erosion.

Rutledge, Sharon K.↗
NASA NTRSDate not supplied

Development and Ground Demonstration of a Satellite Communication Terminal for Future Space Missions

As commercial companies continue to develop communication services and infrastructure in near-Earth orbit, NASA is actively pursuing commercially-led satellite communications for future missions. Many of these commercial services are offered in the K/Ka-band, ranging from 17 to 31 GHz, covering spectrum allocated to commercial networks, military, and civilian government space operations, and can be tailored to support orbiting spacecraft. A key enabling technology needed for this vision is a multi-frequency (wideband), multi-waveform user terminal which can operate over multiple services. This presentation discusses the work undertaken at NASA’s Glenn Research Center to develop a RF user spacecraft terminal. Specifications and design considerations that support interoperability will be discussed as well as off the shelf technology gaps. Furthermore, simulation and benchtop testing results will be discussed as well as details of the initial successful over-the-air demonstrations using NASA, Inmarsat, and SES services.

Radio↗
NASA NTRS2023

Ames Contrail Simulation Model: Modeling Aviation Induced Contrails and the Computation of Contrail Radiative Forcing Using Air Traffic Data

NASA is developing traffic flow management strategies to reduce the impact of aviation on climate and improve efficiency of aircraft routes in the presence of limited airport and airspace capacity constraints, which are partly due to convective weather and natural calamities. Development of Strategic Traffic Flow Management (STFM) requires models of aircraft emissions and contrails, and models of their effect on climate. There is extensive literature on the modeling of contrails and the Radiative Forcing (RF) associated with contrails. This report captures the latest NASA developments in this research area and describes the integrated modeling, analysis, and software development to support STFM. Aircraft contrails are long, thin and often linear clouds triggered by aircraft engine exhausts in the high-altitude ice-saturated atmosphere. Contrails, similar to that of natural cirrus clouds, can impact global climate by reflecting shortwave radiation and trapping longwave radiation. Recent studies from the Intergovernmental Panel on Climate Change (IPCC) have shown that aircraft contrails are estimated to have greater impact on global warming than aircraft CO 2 emissions. The Ames Contrail Simulation Model (ACSM) presented in this report simulates the full life cycle of aircraft contrails, including their formation, dynamic evolution, and dissipation, and calculates the associated RF with actual meteorological and air traffic data. ACSM combines models from previous studies that focus on contrail formation and persistence based on the Schmidt-Appleman theoretical criteria, and it incorporates elements of cloud dynamics, microphysics, and climate modeling found in other surveyed contrail models, while also making adjustment for improved computational efficiency. In addition, ACSM is integrated with NASA's state-of-the-art flight simulation software for rapid assessment of aircraft contrail impacts. Applications include assessments of long-term global climate impact resulting from aviation-induced contrails and the design of optimal contrail-mitigation aircraft operation strategies.

aviation contrails↗
DOE OSTI2026

Technical Report for Bayesian Optimization and Reinforcement Learning for Beam Polarization Increase in the BNL Hadron Injectors

This project developed and evaluated physics-informed Bayesian learning and machine learning (ML)-based optimization methods for improving beam polarization preservation in the BNL hadron injector chain. The work focused on uncertainty-aware digital twin modeling, Bayesian calibration of accelerator simulations using beam measurements, and data-efficient optimization strategies including Bayesian optimization and reinforcement learning. These methods were applied to injector tuning and RF control problems in realistic accelerator settings to support improved operational robustness and readiness for RHIC operations and future Electron–Ion Collider facilities. No subject inventions were disclosed under this award.

43 PARTICLE ACCELERATORS↗
NASA NTRS2010

Fully Printed High-Frequency Phased-Array Antenna on Flexible Substrate

To address the issues of flexible electronics needed for surface-to-surface, surface-to-orbit, and back-to-Earth communications necessary for manned exploration of the Moon, Mars, and beyond, a room-temperature printing process has been developed to create active, phased-array antennas (PAAs) on a flexible Kapton substrate. Field effect transistors (FETs) based on carbon nanotubes (CNTs), with many unique physical properties, were successfully proven feasible for phased-array antenna systems. The carrier mobility of an individual CNT is estimated to be at least 100,000 sq cm/V(dot)s. The CNT network in solution has carrier mobility as high as 46,770 sq cm/V(dot)s, and has a large current-density carrying capacity of approx. 1,000 mA/sq cm , which corresponds to a high carrying power of over 2,000 mW/ sq cm. Such high carrier mobility, and large current carrying capacity, allows the achievement of high-speed (>100 GHz), high-power, flexible electronic circuits that can be monolithically integrated on NASA s active phasedarray antennas for various applications, such as pressurized rovers, pressurized habitats, and spacesuits, as well as for locating beacon towers for lunar surface navigation, which will likely be performed at S-band and attached to a mobile astronaut. A fully printed 2-bit 2-element phasedarray antenna (PAA) working at 5.6 GHz, incorporating the CNT FETs as phase shifters, is demonstrated. The PAA is printed out at room temperature on 100-mm thick Kapton substrate. Four CNT FETs are printed together with microstrip time delay lines to function as a 2-bit phase shifter. The FET switch exhibits a switching speed of 0.2 ns, and works well for a 5.6-GHz RF signal. The operating frequency is measured to be 5.6 GHz, versus the state-of-the-art flexible FET operating frequency of 52 MHz. The source-drain current density is measured to be over 1,000 mA/sq cm, while the conventional organic FETs, and single carbon nanotube-based FETs, are typically in the mA to mA/sq cm range. The switching voltage used is 1.8 V, while the state-of-the-art flexible FET has a gate voltage around 50 V. The gate voltage can effectively control the source-drain current with an ON-OFF ratio of over 1,000 obtained at a low Vds bias of 1.8 V. The azimuth steering angles of PAA are measured at 0deg, -14.5deg, -30deg, and 48.6deg. The measured far-field patterns agree well with simulation results. The efficiency of the 2-bit 2-element PAA is measured to be 39 percent, including the loss of transmission line, FET switch, and coupling loss of RF probes. With further optimization, the efficiency is expected to be around 50-60 percent.

Chen, Yihong↗
NASA NTRS2025

Code Migration and Optimization for Calculating Atmospheric Attenuation in RF Link Budgets Within Glenn Research Center Communication Analysis Suite

This technical report encompasses development completed on the Glenn Research Center Communication Analysis Suite (GCAS) as it relates to converting code from the original MATLAB® (The MathWorks, Inc.) GCAS code base to C++. It focuses on a majority of the functions, structures, and intermediate code developed for radiofrequency (RF) links calculations. The report serves as a comprehensive record of the current progress and outlines the technical challenges overcome during this research. Throughout this project, numerous functions and structures were migrated end to end, with validation test cases conducted in accordance with NASA’s verification and validation efforts for standard models and simulations. This report also provides high-level documentation of the completed work; detailed low-level documentation has been compiled to provide a line-by-line explanation in alignment with NASA’s goals. This development has largely been focused on atmospheric effects on calculating RF link budgets for both terrestrial and space links. Some developments outside of atmospheric functions are also covered throughout this report; these are largely related to mathematical operations and MATLAB® structure conversions.

Brady M. Phelps↗
NASA NTRS1992

Simulation of the synergistic low Earth orbit effects of vacuum thermal cycling, vacuum UV radiation, and atomic oxygen

In order to assess the low Earth orbit (LEO) durability of candidate space materials, it is necessary to use ground laboratory facilities which provide LEO environmental effects. A facility combining vacuum thermal cycling and vacuum ultraviolet (VUV) radiation has been designed and constructed at NASA Lewis Research Center for this purpose. This facility can also be operated without the VUV lamps. An additional facility can be used to provide VUV exposure only. By utilizing these facilities, followed by atomic oxygen exposure in an RF plasma asher, the effects of the individual vacuum thermal cycling and VUV environments can be compared to the effect of the combined vacuum thermal cycling/VUV environment on the atomic oxygen durability of materials. The synergistic effects of simulated LEO environmental conditions on materials were evaluated by first exposing materials to vacuum thermal cycling, VUV, and vacuum thermal cycling/VUV environments followed by exposure to atomic oxygen in an RP plasma asher. Candidate space power materials such as atomic oxygen protected polyimides and solar concentrator mirrors were evaluated using these facilities. Characteristics of the Vacuum Thermal Cycling/VUV Exposure Facility which simulates the temperature sequences and solar ultraviolet radiation exposure that would be experienced by a spacecraft surface in LEO are discussed. Results of durability evaluations of some candidate space power materials to the simulated LEO environmental conditions will also be discussed. Such results have indicated that for some materials, atomic oxygen durability is affected by previous exposure to thermal cycling and/or VUV exposure.

Dever, Joyce A.↗
NASA NTRS1978

Space plasma laboratory - Experiment in simulated ionospheric plasma

Several experiments with simulated ionospheric plasma were performed in the Johnson Space Center's large (17 m diameter x 27 m height) vacuum chamber. Two of these, the RF discharge and the electron-beam plasma discharge, are described here. The RF experiment involved measurement of the loading on a 5 m dipole and a 5 m loop antenna caused by the presence of a plasma. The results indicate that when the RF frequency is near the electron gyro frequency a self-sustained plasma discharge is set up and the real part of the complex antenna impedance increases. The beam-plasma experiment was carried out to study a discharge produced by an electron beam with an energy of about 1 keV when the electron beam was injected parallel to the ambient magnetic field. As the beam current was raised to a critical level, a spontaneous transition occurred whereby a luminous halo was formed around the electron beam indicating a sustained discharge.

Konradi, A.↗
NASA NTRS2005

Space Shuttle Underside Astronaut Communications Performance Evaluation

The Space Shuttle Ultra High Frequency (UHF) communications system is planned to provide Radio Frequency (RF) coverage for astronauts working underside of the Space Shuttle Orbiter (SSO) for thermal tile inspection and repairing. This study is to assess the Space Shuttle UHF communication performance for astronauts in the shadow region without line-of-sight (LOS) to the Space Shuttle and Space Station UHF antennas. To insure the RF coverage performance at anticipated astronaut worksites, the link margin between the UHF antennas and Extravehicular Activity (EVA) Astronauts with significant vehicle structure blockage was analyzed. A series of near-field measurements were performed using the NASA/JSC Anechoic Chamber Antenna test facilities. Computational investigations were also performed using the electromagnetic modeling techniques. The computer simulation tool based on the Geometrical Theory of Diffraction (GTD) was used to compute the signal strengths. The signal strength was obtained by computing the reflected and diffracted fields along the propagation paths between the transmitting and receiving antennas. Based on the results obtained in this study, RF coverage for UHF communication links was determined for the anticipated astronaut worksite in the shadow region underneath the Space Shuttle.

Hwu, Shian U.↗
NASA NTRS1999

The Biolink Implantable Telemetry System

Most biotelemetry applications deal with the moderated data rates of biological signals. Few people have studied the problem of transcutaneous data transmission at the rates required by NASA's Life Sciences-Advanced BioTelemetry System (LS-ABTS). Implanted telemetry eliminate the problems associated with wire breaking the skin, and permits experiments with awake and unrestrained subjects. Our goal is to build a low-power 174-216MHz Radio Frequency (RF) transmitter suitable for short range biosensor and implantable use. The BioLink Implantable Telemetry System (BITS) is composed of three major units: an Analog Data Module (ADM), a Telemetry Transmitter Module (TTM), and a Command Receiver Module (CRM). BioLink incorporates novel low-power techniques to implement a monolithic digital RF transmitter operating at 100kbps, using quadrature phase shift keying (QPSK) modulation in the 174-216MHz ISM band. As the ADM will be specific for each application, we focused on solving the problems associated with a monolithic implementation of the TTM and CRM, and this is the emphasis of this report. A system architecture based on a Frequency-Locked Loop (FLL) Frequency Synthesizer is presented, and a novel differential frequency that eliminates the need for a frequency divider is also shown. A self sizing phase modulation scheme suitable for low power implementation was also developed. A full system-level simulation of the FLL was performed and loop filter parameters were determined. The implantable antenna has been designed, simulated and constructed. An implant package compatible with the ABTS requirements is also being proposed. Extensive work performed at 200MHz in 0.5um complementary metal oxide semiconductors (CMOS) showed the feasibility of integrating the RF transmitter circuits in a single chip. The Hajimiri phase noise model was used to optimize the Voltage Controlled Oscillator (VCO) for minimum power consumption. Two test chips were fabricated in a 0.5pm, 3V CMOS process. Measured phase noise for a 1.5mW, 200MHz ring oscillator VCO is -80dBc/Hz at 100KHZ offset, showing good agreement with the theory. We also propose a novel superregenerative receiver architecture for implementing the command receiver. The superregenerative receiver's simplicity, low cost, and low power consumption has made it the receiver of choice for short-distance data communications, remote control and home automation. We present the design of a superregenerative AM receiver implemented in a 0.5um CMOS technology that operates at 433.92MHz and dissipates only 300uW. Further work entails detailed transistor-level design of the FLL and superregenerative receiver and a monolithic implementation of an implantable transceiver in 0.5um CMOS technology.

Betancourt-Zamora, Rafael J.↗
NASA NTRS1980

Analysis of airborne RF measurements from U.S.A. urban areas

The paper presents in-situ, airborne survey radio-frequency measurements, which were made over the 400-1000 MHz range in May 1977 during the ASSESS-II Space Shuttle/Spacelab simulation aircraft flights. Measurements were made from altitudes of 10,000 to 33,000 feet with a downward-directed 70 deg wide, half-power beamwidth receiving antenna pattern. Channel occupancy percentages are given within a 50 MHz spectrum width, and continuous spectrum-scan measurements are presented for selected locations on the USA West Coast, showing the channel occupancy environment within the 806-890 MHz mobile-service band.

Taylor, R. E.↗
NASA NTRS2018

Simulation and Analysis of Opportunistic MSPA for Multiple Cubesat Deployments

We describe a software approach for simultaneous demodulation and decoding of multiple frequency- multiplexed spacecraft across multiple ground stations. The approach involves the use of a single ground antenna with wide enough aperture to receive multiple angularly adjacent spacecraft simultaneously. This technique uses a wide-band RF signal digitizer coupled with easily and cheaply duplicated software-receiver modules to independently process the frequency-channelized downlink signals from the spacecraft. This approach relaxes the need for realizable modems at each antenna, for example in the Deep-SpaceNetwork (DSN), and can also function as a delayed data retrieval method for cubesat missions with routine science data return. Thus, we hope that this solution can enable more efficient utilization of DSN assets. We concentrate on a simulation similar to the proposed Exploration Mission 1 (EM-1) mission from a geometric perspective. To that end, the simulated scenario involves ten secondary cubesats deployed and tracked for a span of four days (the modeled motion over the first four days of the mission does not include any Trajectory Correction Maneuvers (TCMs) that may be necessary as the cubesats approach the moon). Transmissions from the cubesats may be received through a combination of DSN ground sites based on visibility. The cubesats are assumed to utilize typical cubesat transmit powers and a waveform similar to that of the Iris radio. One cubesat is chosen as the “target” and is considered tracked by all ground-stations throughout the simulation (i.e., it is consistently at the center of the main lobe of each ground station antenna when the ground station is in view of the cubesat in terms of elevation angle). The simulation effort involves synthesizing a wideband signal that includes the ten cubesats across a large bandwidth due to each cubesat having its own center-frequency in X-band, near 8.4 GHz. Each signal is characterized by its own Doppler-frequency shift and free-space path-loss computed through the underlying geometry of the simulation as well as the cubesat transmit power. Finally, each cubesat signal experiences a unique antenna gain at each ground station due to the underlying antenna pattern and spacecraft-ground station geometry. We establish two interesting findings: First, the link-budget for the EM-1-like scenario is almost completely limited by the angle between the center of the antenna main beam and the cubesat, which means that the signal-to-noise ratio is wholly adequate for demodulation and decoding at the simulated bitrates unless the cubesat exits the main beam. Secondly, and fortunately due to the use of a software radio architecture, we show that it is possible to successfully receive signals from most cubesats for the entire 4-day simulation. Due to the signal-to-noise ratio being sufficient for demodulation even after the side-lobe’s 17dB reduction in SNR, the software radio can still demodulate such cubesats as long as the radio is capable of re-establishing carrier lock as the cubesats leave the main beam and enter the side-lobe. Considering that the target application utilizes offline processing, a loss of lock can be detected and lock can be re-established by iterating over the data. Extensive simulations demonstrate these results.

Abraham, Douglas S.↗
DOE OSTI2025

Convergence study of wakefield simulations with GdfidL and ECHO3D

The interaction of charged particle beams with vacuum chamber components gives rise to electromagnetic wakefields, whose frequency-domain representation is known as beam coupling impedance. Geometric impedance arising from discontinuities and transitions in the vacuum chamber is the focus of this study. Minimizing this impedance is essential to mitigate adverse collective effects in modern storage rings operating with high-intensity particle beams. Accurate and reliable impedance simulations is a key factor of the vacuum chamber design. This paper presents the results of a convergence study of two widely used electromagnetic solvers, GdfidL and ECHO3D, applied to key vacuum-chamber components of the National Synchrotron Light Source II (NSLS-II) storage ring. Detailed comparisons are performed for several geometries, including flange absorbers, RF bellows, button-type beam position monitors, and an in-vacuum undulator (IVU). The results show notable differences in convergence and computational efficiency between the two codes. While GdfidL provides highly resolved results and serves as a common benchmark tool, ECHO3D yields consistent results with coarser meshes, significantly reducing simulation time and memory demands. Simulations with a full-geometry IVU model demonstrate that simplified taper-transition models can miss important impedance contributions. In conclusion, these findings provide practical guidelines for efficient and accurate impedance modeling to optimize design of vacuum chamber components for accelerators.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Broadband cross polarization for ultra-wideline magic-angle spinning NMR

Over the past decade, there has been a sustained interest in using frequency-swept (FS) pulses for the efficient acquisition of wideline and ultra-wideline (UW) NMR powder patterns. Such experiments are typically conducted under static conditions, employing both direct- and indirect-excitation methods (i.e., WCPMG and BRAIN-CP/WCPMG, respectively). Recently, Koppe et al. demonstrated that the WCPMG pulse sequence can be used to efficiently acquire wideline and UW NMR spectra with spinning sideband (SSB) manifolds under magic-angle spinning (MAS) conditions, capitalizing on the increased signal-to-noise ratios (SNR) afforded by MAS. To date, there have been only a few instances of broadband cross-polarization (CP) experiments using FS pulses under MAS conditions and no applications to systems exhibiting wideline and/or ultra-wideline powder patterns, despite the clear advantages these experiments could offer. Herein, we demonstrate that FS pulses selectively applied to a single sideband of the S spin can be used for efficient 1 H-S polarization transfer to S = 1/2 nuclides with large anisotropic chemical shift interactions at slow to moderate MAS rates. The Hartmann–Hahn matching conditions in BRAIN-CP/WCPMG-MAS experiments bear similarity to those of standard CP sequences, yet operate over UW frequency ranges and only require low-amplitude RF pulses on the S channel. Crucial to the success of the BRAIN-CP/WCPMG-MAS experiment is careful calibration of the RF amplitude, transmitter offset, and effective frequency sweep of the FS pulse applied to the S spins at a given MAS rate. Thus, by means of numerical simulations and experimental testing, we provide recommendations for the parameterization and setup of BRAIN-CP/WCPMG-MAS experiments for their most efficient use. Results showcasing the capability of the BRAIN-CP/WCPMG-MAS pulse sequence are presented, including applications to 119 Sn, 195 Pt, and 103 Rh NMR.

Kimball, James J. [Florida State University, Talla↗