Results for “reference array design” — Page 5

NASA NTRS2007

On the Mutual Coupling between Circular Resonant Slots

For near- and far-field microwave imaging purposes, array of circular resonant slots can be utilized to sample the electric field at a given reference plane. In general, the sensitivity of such an array is impaired by the existing mutual coupling between the radiating elements or in this case circular slots. The mutual coupling problem imposes a design tradeoff between the resolution of the array and the overall system sensitivity and dynamic range. In this paper, the mutual coupling between circular resonant slots in conducting ground plane is investigated both numerically and experimentally. In particular, the mutual coupling in the E- and H-plane configurations of two identical slots is studied.

Abou-Khousa, M. A.↗

NASA NTRS2005

Preliminary Report on Mission Design and Operations for Critical Events

Mission-critical events are defined in the Jet Propulsion Laboratory s Flight Project Practices as those sequences of events which must succeed in order to attain mission goals. These are dependent on the particular operational concept and design reference mission, and are especially important when committing to irreversible events. Critical events include main engine cutoff (MECO) after launch; engine cutoff or parachute deployment on entry, descent, and landing (EDL); orbital insertion; separation of payload from vehicle or separation of booster segments; maintenance of pointing accuracy for power and communication; and deployment of solar arrays and communication antennas. The purpose of this paper is to report on the current practices in handling mission-critical events in design and operations at major NASA spaceflight centers. The scope of this report includes NASA Johnson Space Center (JSC), NASA Goddard Space Flight Center (GSFC), and NASA Jet Propulsion Laboratory (JPL), with staff at each center consulted on their current practices, processes, and procedures.

Hayden, Sandra C.↗

NASA NTRS1980

Modified reference SPS with solid state transmitting antenna

The motivations for considering solid state microwave power amplifiers for the solar power satellite transmitting antenna are the possibilities of greatly increased system reliability due to elimination of electron tube cathodes, a lower mass per unit power and transmitting array area due to the high power densities obtainable in semiconductors, and, probably, cost savings due to development of small hardware items that can be handled by individuals instead of organizations. In order to provide a fair assessment where we stand today with regard to solid state SPS technology, the design described here is close to that of the NASA/DOE reference and is implemented using today's solid state technology with only a small "push". The small push is raising the efficiency of DC-RF conversion from the .68 obtained by RCA in 1975 to somewhat over .8 of the solid state SPS. This is generally considered feasible by semiconductor industry representatives. Other solid state SPS configurations can yield somewhat better performance. However, these generally do not provide as fair a vehicle for comparison with the reference and usually also incorporate somewhat more advanced technologies.

Woodcock, G. R.↗

NASA NTRS1996

Contamination control engineering design guidelines for the aerospace community

Thermal control surfaces, solar arrays, and optical devices may be adversely affected by a small quantity of molecular and/or particulate contamination. What is rarely discussed is how one: (1) quantifies the level of contamination that must be maintained in order for the system to function properly, and (2) enforces contamination control to ensure compliance with requirements. This document is designed to address these specific issues and is intended to serve as a handbook on contamination control for the reader, illustrating process and methodology while providing direction to more detailed references when needed. The effects of molecular contamination on reflecting and transmitting surfaces are examined and quantified in accordance with MIL STD 1246C. The generation, transportation, and deposition of molecular contamination is reviewed and specific examples are worked to illustrate the process a design engineer can use to estimate end of life cleanliness levels required by solar arrays, thermal control surfaces, and optical surfaces. A similar process is used to describe the effect of particulate contamination as related to percent area coverage (PAC) and bi-directional reflectance distribution function (BRDF). Relationships between PAC and surface cleanliness, which include the effects of submicron sized particles, are developed and BRDF is related to specific sensor design parameters such as Point Source Transmittance (PST). The pros and cons of various methods of preventing, monitoring, and cleaning surfaces are examined and discussed.

Tribble, A. C.↗

NASA NTRS2007

Broadband Achromatic Telecentric Lens

A new type of lens design features broadband achromatic performance as well as telecentricity, using a minimum number of spherical elements. With appropriate modifications, the lens design form can be tailored to cover the range of response of the focal-plane array, from Si (400-1,000 nm) to InGaAs (400-1,700 or 2,100 nm) or InSb/HgCdTe reaching to 2,500 nm. For reference, lenses typically are achromatized over the visible wavelength range of 480-650 nm. In remote sensing applications, there is a need for broadband achromatic telescopes, normally satisfied with mirror-based systems. However, mirror systems are not always feasible due to size or geometry restrictions. They also require expensive aspheric surfaces. Non-obscured mirror systems can be difficult to align and have a limited (essentially one-dimensional) field of view. Centrally obscured types have a two-dimensional but very limited field in addition to the obscuration. Telecentricity is a highly desirable property for matching typical spectrometer types, as well as for reducing the variation of the angle of incidence and cross-talk on the detector for simple camera types. This rotationally symmetric telescope with no obscuration and using spherical surfaces and selected glass types fills a need in the range of short focal lengths. It can be used as a compact front unit for a matched spectrometer, as an ultra-broadband camera objective lens, or as the optics of an integrated camera/spectrometer in which the wavelength information is obtained by the use of strip or linear variable filters on the focal plane array. This kind of camera and spectrometer system can find applications in remote sensing, as well as in-situ applications for geological mapping and characterization of minerals, ecological studies, and target detection and identification through spectral signatures. Commercially, the lens can be used in quality-control applications via spectral analysis. The lens design is based on the rear landscape lens with the aperture stop in front of all elements. This allows sufficient room for telecentricity in addition to making the stop easily accessible. The crucial design features are the use of a doublet with an ultra-low dispersion glass (fluorite or S-FPL53), and the use of a strong negative element, which enables flat field and telecentricity in conjunction with the last (field lens) element. The field lens also can be designed to be in contact with the array, a feature that is desirable in some applications. The lens has a 20deg field of view, for a 50-mm focal length, and is corrected over the range of wavelengths of 450-2,300 nm. Transverse color, which is the most pernicious aberration for spectroscopic work, is controlled at the level of 1 m or below at 0.7 m field and 5 m at full field. The maximum chief ray angle is less than 1.7 , providing good telecentricity. An additional feature of this lens is that it is made exclusively with glasses that provide good transmission up to 2,300 nm and even some transmission to 2,500 nm; thus, the lens can be used in applications that cover the entire solar-reflected spectrum. Alternative realizations are possible that provide enhanced resolution and even less transverse color over a narrower wavelength range.

Mouroulis, Pantazis↗

NASA NTRS1981

Design study for Thermal Infrared Multispectral Scanner (TIMS)

The feasibility of dividing the 8-12 micrometer thermal infrared wavelength region into six spectral bands by an airborne line scanner system was investigated. By combining an existing scanner design with a 6 band spectrometer, a system for the remote sensing of Earth resources was developed. The elements in the spectrometer include an off axis reflective collimator, a reflective diffraction grating, a triplet germanium imaging lens, a photoconductive mercury cadmium telluride sensor array, and the mechanical assembly to hold these parts and maintain their optical alignment across a broad temperature range. The existing scanner design was modified to accept the new spectrometer and two field filling thermal reference sources.

Stanich, C. G.↗

DOE OSTI2024

Accelerating data acquisition with FPGA-based edge machine learning: a case study with LCLS-II

New scientific experiments and instruments generate vast amounts of data that need to be transferred for storage or further processing, often overwhelming traditional systems. Edge machine learning (EdgeML) addresses this challenge by integrating machine learning (ML) algorithms with edge computing, enabling real-time data processing directly at the point of data generation. EdgeML is particularly beneficial for environments where immediate decisions are required, or where bandwidth and storage are limited. In this paper, we demonstrate a high-speed configurable ML model in a fully customizable EdgeML system using a field programmable gate array (FPGA). Our demonstration focuses on an angular array of electron spectrometers, referred to as the ‘CookieBox,’ developed for the Linac Coherent Light Source II project. The EdgeML system captures 51.2 Gbps from a 6.4 GS s −1 analog to digital converter and is designed to integrate data pre-processing and ML inside an FPGA. Our implementation achieves an inference latency of 0.2 µs for the ML model, and a total latency of 0.4 µs for the complete EdgeML system, which includes pre-processing, data transmission, digitization, and ML inference. The modular design of the system allows it to be adapted for other instrumentation applications requiring low-latency data processing.

97 MATHEMATICS AND COMPUTING↗

NASA NTRS1980

Satellite power systems (SPS) concept definition study. Volume 2, part 1: System engineering

Top level trade studies are presented, including comparison of solid state and klystron concepts, higher concentration on the solar cells, composite and aluminum structure, and several variations to the reference concept. Detailed trade studies are presented in each of the subsystem areas (solar array, power distribution, structures, thermal control, attitude control and stationkeeping, microwave transmission, and ground receiving station). A description of the selected point design is also presented.

Hanley, G. M.↗

NASA NTRS1990

Design considerations for Mars photovoltaic power systems

Considerations for operation of a photovoltaic power system on Mars are discussed with reference to Viking Lander data. The average solar insolation at Mars is 590 W/sq m, which is reduced yet further by atmospheric dust. Of major concern are dust storms, which have been observed to occur on local as well as on global scales, and their effect on solar array output. While atmospheric opacity may rise to values ranging from 3 to 9, depending on storm severity, there is still an appreciable large diffuse illumination, even at high opacities, so that photovoltaic operation is still possible. If the power system is to continue to generate power even on high-optical-opacity (i.e., dusty atmosphere) days, it is important that the photovoltaic system be designed to collect diffuse irradiance as well as direct. Energy storage will be required for operation during the night. Temperature and wind provide additional considerations for array design.

Landis, Geoffrey A.↗

NASA NTRS2009

Solid State Light Evaluation in the U.S. Lab Mockup

This document constitutes the publication of work performed by the Space Human Factors Laboratory (mail code SF5 at the time) at the Johnson Space Center (JSC) in the months of June and July of 2000. At that time, the Space Human Factors Laboratory was part of the Space Human Factors Branch in the Flight Projects Division of the Space and Life Directorate. This report was originally to be a document for internal consumption only at JSC as it was seen to be only preliminary work for the further development of solid state illumination for general lighting on future space vehicles and the International Space Station (ISS). Due to funding constraints, immediate follow-on efforts were delayed and the need for publication of this document was overcome by other events. However, in recent years and with the development and deployment of a solid state light luminaire prototype on ISS, the time was overdue for publishing this information for general distribution and reference. Solid state lights (SSLs) are being developed to potentially replace the general luminaire assemblies (GLAs) currently in service in the International Space Station (ISS) and included in designs of modules for the ISS. The SSLs consist of arrays of light emitting diodes (LEDs), small solid state electronic devices that produce visible light in proportion to the electrical current flowing through them. Recent progressive advances in electrical power-to-light conversion efficiency in LED technology have allowed the consideration of LEDs as replacements for incandescent and fluorescent light sources in many circumstances, and their inherent advantages in ruggedness, reliability, and life expectancy make them attractive for applications in spacecraft. One potential area of application for the SSLs in the U.S. Laboratory Module of the ISS. This study addresses the suitability of the SSLs as replacements for the GLAs in this application.

Maida, James c.↗

NASA NTRS2011

The Primordial Inflation Explorer (PIXIE) Mission

The Primordial Inflation Explorer (PIXIE) is an Explorer-class mission to map the absolute intensity and linear polarization of the cosmic microwave background and diffuse astrophysical foregrounds over the full sky from frequencies 30 GHz to 6 THz (I cm to 50 I-tm wavelength). PIXIE uses a polarizing Michelson interferometer with 2.7 K optics to measure the difference spectrum between two orthogonal linear polarizations from two co-aligned beams. Either input can view either the sky or a temperature-controlled absolute reference blackbody calibrator. The multimoded optics and high etendu provide sensitivity comparable to kilo-pixel focal plane arrays, but with greatly expanded frequency coverage while using only 4 detectors total. PIXIE builds on the highly successful COBEIFIRAS design by adding large-area polarization-sensitive detectors whose fully symmetric optics are maintained in thermal equilibrium with the CMB. The highly symmetric nulled design provides redundant rejection of major sources of systematic uncertainty. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r much less than 10(exp -3). PIXIE will also return a rich data set constraining physical processes ranging from Big Bang cosmology, reionization, and large-scale structure to the local interstellar medium. Keywords: cosmic microwave background, polarization, FTS, bolometer

Kogut, Alan J.↗

NASA NTRS2023

Overview of the NASA Spacecraft Trade Modeling System (NSTRDMS), A Rapid Mission Analysis Tool

A rapid mission analysis tool is developed to support the ongoing design of the Lunar Transit trajectory of the Power and Propulsion Element (PPE). A 50-kW class electric propulsion system is envisioned to transit a massive vehicle be-tween a Medium Earth Orbit (MEO) parking orbit and a lunar L2 southern Near Rectilinear Halo Orbit (NRHO). A parameterization is developed by which the Lunar Transit can be analyzed in the context of varying vehicle mass, solar elec-tric propulsion (SEP) configurations, and solar array power output. A rapid and novel mission analysis tool enables a wide array of these trade analyses to be completed without the need for extensive computing resources or time. This tool is shown to be useful in the analysis of a reference trajectory, where changes to the baseline vehicle architecture or off-nominal operational scenarios (such as electric thruster failures) can be rapidly assessed by the mission designer.

Low thrust↗

NASA NTRSDate not supplied

NASA Spacecraft Trade Modeling System (NSTRDMS)

A rapid mission analysis tool is developed to support the ongoing design of the Lunar Transit trajectory of the Power and Propulsion Element (PPE). A 50-kW class electric propulsion system is envisioned to transit a massive vehicle be-tween a Medium Earth Orbit (MEO) parking orbit and a lunar L2 southern Near Rectilinear Halo Orbit (NRHO). A parameterization is developed by which the Lunar Transit can be analyzed in the context of varying vehicle mass, solar elec-tric propulsion (SEP) configurations, and solar array power output. A rapid and novel mission analysis tool enables a wide array of these trade analyses to be completed without the need for extensive computing resources or time. This tool is shown to be useful in the analysis of a reference trajectory, where changes to the baseline vehicle architecture or off-nominal operational scenarios (such as electric thruster failures) can be rapidly assessed by the mission designer.

Low thrust↗

NASA NTRS2018

Diagnostic for Verifying the Thrust Vector Requirement of the AEPS Hall-Effect Thruster and Comparison to the NEXT-C Thrust Vector Diagnostic

A diagnostic has been designed and fabricated to verify the thrust vector requirement for the Advanced Electric Propulsion System (AEPS) Hall Effect Rocket with Magnetic Shielding (HERMeS) thruster. This diagnostic will be used to verify that the propulsion system thrust vector offset from the mounting surface normal vector does not exceed 1.5 degrees over the entire throttling range and over the course of 23,000 hours of thruster testing. The diagnostic will also not violate the thruster's required voltage standoff capability in the presence of carbon backsputter by being minimally intrusive and not significantly adding to the facility backsputtered rate. Based on these requirements, an appropriate diagnostic design was determined to comprise of an array of 23 Faraday probes swept through the plume in an arc 1m from the thruster to map the beam current density. The beam current density centroid of the plume is assumed to track the thrust vector within an acceptable level of uncertainty. Additionally, a reference system, including optical alignment to the mounting surface normal vector and tilt sensors, was devised to periodically calibrate the probe position and motion throughout the long duration wear test campaign. Initial measurements of the thruster plume have been acquired to demonstrate the diagnostics functionality, verify procedures, and assess any necessary improvements prior to implementation of the diagnostic during the AEPS Engineering Development Unit (EDU) long duration wear test. To illustrate the merits of differing approaches to thrust vector determination for different classes of electric propulsion thrusters, NASA's Evolutionary Xenon Thruster-Commercial (NEXT-C) thrust vector diagnostic design details and recent data are also discussed (Appendix A).

Benavides, Gabriel F.↗

NASA NTRS2018

Diagnostic for Verifying the Thrust Vector Requirement of the AEPS Hall-Effect Thruster and Comparison to the NEXT-C Thrust Vector Diagnostic

A diagnostic has been designed and fabricated to verify the thrust vector requirement for the Advanced Electric Propulsion System (AEPS) Hall Effect Rocket with Magnetic Shielding (HERMeS) thruster. This diagnostic will be used to verify that the propulsion system thrust vector offset from the mounting surface normal vector does not exceed 1.5 degrees over the entire throttling range and over the course of 23,000 hours of thruster testing. The diagnostic will also not violate the thruster's required voltage standoff capability in the presence of carbon backsputter by being minimally intrusive and not significantly adding to the facility backsputtered rate. Based on these requirements, an appropriate diagnostic design was determined to comprise of an array of 23 Faraday probes swept through the plume in an arc 1m from the thruster to map the beam current density. The beam current density centroid of the plume is assumed to track the thrust vector within an acceptable level of uncertainty. Additionally, a reference system, including optical alignment to the mounting surface normal vector and tilt sensors, was devised to periodically calibrate the probe position and motion throughout the long duration wear test campaign. Initial measurements of the thruster plume have been acquired to demonstrate the diagnostics functionality, verify procedures, and assess any necessary improvements prior to implementation of the diagnostic during the AEPS Engineering Development Unit (EDU) long duration wear test. To illustrate the merits of differing approaches to thrust vector determination for different classes of electric propulsion thrusters, NASA's Evolutionary Xenon Thruster-Commercial (NEXT-C) thrust vector diagnostic design details and recent data are also discussed (Appendix A).

Benavides, Gabriel F.↗

NASA NTRS2018

Diagnostic for Verifying the Thrust Vector Requirement of the AEPS Hall-Effect Thruster and Comparison to the NEXT-C Thrust Vector Diagnostic

A diagnostic has been designed and fabricated to verify the thrust vector requirement for the Advanced Electric Propulsion System (AEPS) Hall Effect Rocket with Magnetic Shielding (HERMeS) thruster. This diagnostic will be used to verify that the propulsion system thrust vector offset from the mounting surface normal vector does not exceed 1.5 degrees over the entire throttling range and over the course of 23,000 hours of thruster testing. The diagnostic will also not violate the thruster's required voltage standoff capability in the presence of carbon backsputter by being minimally intrusive and not significantly adding to the facility backsputtered rate. Based on these requirements, an appropriate diagnostic design was determined to comprise of an array of 23 Faraday probes swept through the plume in an arc 1m from the thruster to map the beam current density. The beam current density centroid of the plume is assumed to track the thrust vector within an acceptable level of uncertainty. Additionally, a reference system, including optical alignment to the mounting surface normal vector and tilt sensors, was devised to periodically calibrate the probe position and motion throughout the long duration wear test campaign. Initial measurements of the thruster plume have been acquired to demonstrate the diagnostics functionality, verify procedures, and assess any necessary improvements prior to implementation of the diagnostic during the AEPS Engineering Development Unit (EDU) long duration wear test. To illustrate the merits of differing approaches to thrust vector determination for different classes of electric propulsion thrusters, NASA's Evolutionary Xenon Thruster-Commercial (NEXT-C) thrust vector diagnostic design details and recent data are also discussed (Appendix A).

Advanced Electric Propulsion System (AEPS)↗

DOE OSTI2025

Antenna arrays for neutrino mass measurements with cyclotron radiation emission spectroscopy

Cyclotron Radiation Emission Spectroscopy (CRES) is a technique for precision measurements of kinetic energies of charged particles, pioneered by the Project 8 experiment to measure the neutrino mass using the tritium end-point method. It was recently employed for the first time to measure the molecular tritium spectrum and place a limit on the neutrino mass using a cubic-centimeter-scale detector. Future direct neutrino mass experiments are developing the technique to overcome the systematic and statistical limitations of current detectors. Here, this paper describes one such approach, namely the use of antenna arrays for CRES in free space. Phenomenology, detector design, simulation, and performance estimates are discussed, culminating with an example design with a projected sensitivity of 𝑚 𝛽 < ⁢0.04 eV/𝑐 2 . Prototype antenna array measurements are also shown for a demonstrator-scale setup as a benchmark for the simulation. By consolidating these results, this paper serves as a comprehensive reference for the development and performance of antenna arrays for CRES.

Physics - Nuclear physics and radiation physics↗

NASA NTRS2004

Fabrication and Testing of Binary-Phase Fourier Gratings for Nonuniform Array Generation

This effort describes the fabrication and testing of binary-phase Fourier gratings designed to generate an incoherent array of output source points with nonuniform user-defined intensities, symmetric about the zeroth order. Like Dammann fanout gratings, these binary-phase Fourier gratings employ only two phase levels to generate a defined output array. Unlike Dammann fanout gratings, these gratings generate an array of nonuniform, user-defined intensities when projected into the far-field regime. The paper describes the process of design, fabrication, and testing for two different version of the binary-phase grating; one designed for a 12 micron wavelength, referred to as the Long-Wavelength Infrared (LWIR) grating, and one designed for a 5 micron wavelength, referred to as the Mid-Wavelength Infrared Grating (MWIR).

Keys, Andrew S.↗