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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 91 records · Page 5

Design and Preliminary Experimental Results on a Uniform-Field Test Fixture for Power Flow Experiments

Electrodes that produce a uniform electric field across their surfaces are desired for a variety of high-voltage systems including spark-gap switches and transversely excited atmospheric lasers. Here, the implementation of uniform-field electrodes to a parallel-plate load is described for the study of vacuum power flow under pulsed-power applications. We begin with an overview of general uniform-field geometries, and provide an open-source program that generates these geometries as described by Ernst. Following that, a modification to an existing power-flow experimental platform, that adopts a uniform-field geometry, is introduced and its utility is described. Lastly, preliminary experimental results are presented and future steps are outlined.

Capacitors↗

Multi-KW dc distribution system technology research study

The Multi-KW DC Distribution System Technology Research Study is the third phase of the NASA/MSFC study program. The purpose of this contract was to complete the design of the integrated technology test facility, provide test planning, support test operations and evaluate test results. The subjet of this study is a continuation of this contract. The purpose of this continuation is to study and analyze high voltage system safety, to determine optimum voltage levels versus power, to identify power distribution system components which require development for higher voltage systems and finally to determine what modifications must be made to the Power Distribution System Simulator (PDSS) to demonstrate 300 Vdc distribution capability.

Dawson, S. G.↗

Selected OAST/OSSA space experiment activities in support of Space Station Freedom

The Space Experiments Division at NASA Lewis Research Center is developing technology and science space experiments for the Office of Aeronautics and Space Technology (OAST) and the Office of Space Sciences and Applications (OSSA). Selected precursor experiments and technology development activities supporting the Space Station Freedom (SSF) are presented. The Tank Pressure Control Experiment (TPCE) is an OAST-funded cryogenic fluid dynamics experiment, the objective of which is to determine the effectiveness of jet mixing as a means of equilibrating fluid temperatures and controlling tank pressures, thereby permitting the design of lighter cryogenic tanks. The information from experiments such as this will be utilized in the design and operation of on board cryogenic storage for programs such as SSF. The Thermal Energy Storage Flight Project (TES) is an OAST-funded thermal management experiment involving phase change materials for thermal energy storage. The objective of this project is to develop and fly in-space experiments to characterize void shape and location in phase change materials used in a thermal energy storage configuration representative of an advanced solar dynamic system design. The information from experiments such as this will be utilized in the design of future solar dynamic power systems. The Solar Array Module Plasma Interaction Experiment (SAMPIE) is an OAST-funded experiment to determine the environmental effects of the low earth orbit (LEO) space plasma environment on state-of-the-art solar cell modules biased to high potentials relative to the plasma. Future spacecraft designs and structures will push the operating limits of solar cell arrays and other high voltage systems. SAMPIE will provide key information necessary for optimum module design and construction. The Vibration Isolation Technology (VIT) Advanced Technology Development effort is funded by OSSA to provide technology necessary to maintain a stable microgravity environment for sensitive payloads on board spacecraft. The proof of concept will be demonstrated by laboratory tests and in low-gravity aircraft flights. VIT is expected to be utilized by many SSF microgravity science payloads. The Space Acceleration Measurement System (SAMS) is an OSSA-funded instrument to measure the microgravity acceleration environment for OSSA payloads on the shuttle and SSF.

Delombard, Richard↗

High-voltage and electrode system for a cryogenic experiment to search for the neutron electric dipole moment

The cryogenic approach to the search for the neutron electric dipole moment—performing the experiment in superfluid liquid helium—holds promise for a substantial increase in sensitivity, potentially enabling a sensitivity level of 10 −28 𝑒cm. A crucial component in realizing such an experiment is the high-voltage and electrode system capable of providing an electric field of 75 kV/cm. This, in turn, requires an electric potential of 635 kV to be applied to the high-voltage electrode, while simultaneously satisfying other experimental constraints, such as those on heat load and magnetic noise requirements. In this work, we describe the outcome of a comprehensive development program addressing these challenges. It outlines the system requirements, discusses new insights into relevant physical phenomena, and details selected technical solutions with their corresponding experimental demonstrations and expected performance. The results collectively demonstrate the successful development of the necessary technology for the high-voltage and electrode system for this approach.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Flight Readiness of Mochii S: Portable Spectroscopic Scanning Electron Microscope Facility on the International Space Station (ISS)

The ISS (International Space Station) currently lacks the capability to image and chemically analyze nano-to-micron scale particles from numerous engineering systems. To identify these particles, we must wait for a re-entry vehicle to return them from low earth orbit for ground-based SEM (Scanning Electron Microscope) / EDS (Energy Dispersive X-Ray Spectroscopy) analysis. This may take months, potentially delaying the affected system. Having an EDS-equipped SEM (Mochii S) aboard the ISS will accelerate response time thereby enhancing crew and vehicle safety by rapid and accurate identification of microscopic threats, especially in time-critical situations.The Mochii S payload will be stationed in the Japanese Experiment Module (JEM) powered by 120 VAC (Volts Alternating Current) inverter and connected to station Ethernet and WiFi (Fig. 1). To date the Mochii S payload has undergone testing for command and data handling, power quality, flight vibration, and radiation testing at Johnson Space Center (JSC). Mochii's high-RPM (Revolutions Per Minute) rotating vacuum pumps and high voltage systems have been reviewed to meet safety standards by JSC (Johnson Space Center) Engineering. Topology of the system in the JEM module has been baselined by ISS Safety and JAXA (Japan Space Exploration Agency). Digital controls to and from ISS over Joint Station LAN (Local Area Network) uplink have been simulated and the latencies and data rates have been found to be sufficient for successful operation of the payload from ground.Transporting sensitive electron optical instruments aboard a rocket that sustains 7G acceleration for 8 minutes and then operating it the unique microgravity (micro-g) environment is no trivial matter. To meet strict safety requirements and increase robustness for mission success, over 500 unique verifications must be completed before the payload is certified for spaceflight. Two of which will be discussed in detail are: vibroacoustic testing and magnetic susceptibility shielding and validation.

Mochii↗

Electrochemical Degradation Modes in Bifacial Silicon Photovoltaic Modules

Motivated by the rapidly rising deployment of bifacial monocrystalline-silicon photovoltaics (PV), we investigate the durability of various PV module packaging configurations with transparent coverings on both the front and rear sides of the module. We use a series of bifacial passivated emitter and rear cell (p-PERC) mini-modules with systematically varying outer cover materials (glass/glass, G/G, or glass/transparent backsheet, G/TB) and encapsulant chemistries (poly [ethylene-co-vinyl acetate], EVA; or polyolefin, POE). We study degradation modes over 1,000 hours of combined damp heat (DH) exposure and high system voltages that can cause potential-induced degradation (PID) under positive, zero, or negative 1,000 V cell-to-frame bias. We analyze the degradation modes using a combination of current-voltage measurements, impedance spectroscopy, external quantum efficiency, and spatially resolved luminescence and thermal imaging. Our results highlight various types of degradation including shunting, enhanced recombination, and series resistance increases, and we use spatially resolved characterization to separately identify the localized effects. We show that multiple PID and moisture-ingress degradation modes severely affect EVA-containing modules, with previously reported PID processes under negative-bias DH and a unique observation of rear-side surface recombination in G/EVA/G modules under positive-bias DH. We observe significantly less degradation in POE-containing modules, where the G/POE/G configuration exhibits minimal degradation under all stress conditions that we employ.

14 SOLAR ENERGY↗

HIGH VOLTAGE DESIGN AND EVALUATION OF WIEN FILTERS FOR THE CEBAF 200 keV INJECTOR UPGRADE

High-energy nuclear physics experiments at the Jefferson Lab Continuous Electron Beam Accelerator Facility (CEBAF) require highly spin-polarization electron beams, produced from strained super-lattice GaAs photocathodes, activated to negative electron affinity in a photogun operating at 130 kV dc. A pair of Wien filter spin rotators in the injector defines the orientation of the electron beam polarization at the end station target. An upgrade of the CEBAF injector to better support the upcoming MOLLER experiment requires increasing the electron beam energy to 200 keV, to reduce unwanted helicity correlated intensity and position systematics and provide precise control of the polarization orientation. Our contribution describes design, fabrication and testing of the high voltage system to upgrade the Wien spin rotator to be compatible with the 200 keV beam. This required Solidworks modeling, CST and Opera electro- and magnetostatic simulations, upgrading HV vacuum feedthroughs, and assembly techniques for improving electrode alignment. The electric and magnetic fields required by the Wien condition and the successful HV characterization under vacuum conditions are also presented.

Palacios-Serrano, G.↗

Vacuum Insulator Flashover Physics LDRD Report

Large, pulsed power and high voltage systems often employ a stack of insulators to separate a vacuum section away from water or oil sections. The size of this insulator stack often drives overall costs and feasibility of these systems. An electric breakdown along the insulator surface is a primary failure mechanism and is especially impactful if it occurs while power is still being delivered downstream. This report describes a set of experimental and modeling investigations into the cause of these breakdowns, especially focusing on the much less well-understood anode-initiated breakdowns that occur during early parts of power delivery. Additionally, new diagnostics for assessing relevant material properties and behavior of insulators are described. These results describe breakdown behavior and evolution at new temporal and spatial fidelities and provide hypotheses and some answers as to how these breakdowns can occur. This new understanding of the roles of different physics phenomena guide modifications and trade-offs in generating newer insulator stack designs that are smaller and/or have higher electrical stress thresholds.

42 ENGINEERING↗

Laser-actuated mechanical device

Actuator is portable and can be used in high-temperature (over 500 C) environments by incorporating tungsten metal film and quartz window. Actuator can be triggered when it is not directly in laser beam path by utilizing fiber optics. It is advantageous for remotely switching ultra-high voltage systems.

Murphy, A. J.↗

Solar array experiments on the Sphinx satellite

The Space Plasma, High Voltage Interaction Experiment (SPHINX) is the name given to an auxiliary payload satellite scheduled to be launched in January 1974. The principal experiments carried on this satellite are specifically designed to obtain the engineering data on the interaction of high voltage systems with the space plasma. The classes of experiments are solar array segments, insulators, insulators with pin holes and conductors. The satellite is also carrying experiments to obtain flight data on three new solar array configurations; the edge illuminated-multijunction cells, the Teflon encased cells and the violet cells.

Stevens, N. J.↗

Solar array experiments on the SPHINX satellite

The Space Plasma, High Voltage Interaction Experiment (SPHINX) is the name given to an auxiliary payload satellite scheduled to be launched in January 1974. The principal experiments carried on this satellite are specifically designed to obtain the engineering data on the interaction of high voltage systems with the space plasma. The classes of experiments are solar array segments, insulators, insulators with pin holes and conductors. The satellite is also carrying experiments to obtain flight data on three new solar array configurations: the edge illuminated-multijunction cells, the teflon encased cells, and the violet cells.

Stevens, N. J.↗

Proceedings of the Flat-Plate Solar Array Project Research Forum on the Design of Flat-Plate Photovoltaic Arrays for Central Stations

The Flat Plate Solar Array Project, focuses on advancing technologies relevant to the design and construction of megawatt level central station systems. Photovoltaic modules and arrays for flat plate central station or other large scale electric power production facilities require the establishment of a technical base that resolves design issues and results in practical and cost effective configurations. Design, qualification and maintenance issues related to central station arrays derived from the engineering and operating experiences of early applications and parallel laboratory reserch activities are investigated. Technical issues are examined from the viewpoint of the utility engineer, architect/engineer and laboratory researcher. Topics on optimum source circuit designs, module insulation design for high system voltages, array safety, structural interface design, measurements, and array operation and maintenance are discussed.

Source record↗

Spacecraft Environmental Interactions Technology, 1983

State of the art of environment interactions dealing with low-Earth-orbit plasmas; high-voltage systems; spacecraft charging; materials effects; and direction of future programs are contained in over 50 papers.

Source record↗

Test results of a 60 volt bipolar nickel-hydrogen battery

In July, l986, a high-voltage nickel-hydrogen battery was assembled at the NASA Lewis Research Center. This battery incorporated bipolar construction techniques to build a 50-cell stack with approximately 1.0 A-hr capacity (C) and an open-circuit voltage of 65 V. The battery was characterized at both low and high current rates prior to pulsed and nonpulsed discharges. Pulse discharges at 5 and 10 C were performed before placing the battery on over 1400, 40% depth-of-discharge, low-earth-orbit cycles. The successful demonstration of a high-voltage bipolar battery in one containment vessel has advanced the technology to where nickel-hydrogen high-voltage systems can be constructed of several modules instead of hundreds of individual cells.

Cataldo, Russell L.↗

Test results of a 60 volt bipolar nickel-hydrogen battery

In July 1986, a high-voltage nickel-hydrogen battery was assembled at the NASA Lewis Research Center. This battery incorporated bipolar construction techniques to build a 50-cell stack with approximately 1.0 A-hr capacity (C) and an open-circuit voltage of 65 V. The battery was characterized at both low and high current rates prior to pulsed and nonpulsed discharges. Pulse discharges at 5 and 10 C were performed before placing the battery on over 1400, 40-percent depth-of-discharge, low-earth-orbit cycles. The successful demonstration of a high-voltage bipolar battery in one containment vessel has advanced the technology to where nickel-hydrogen high-voltage systems can be constructed of several modules instead of hundreds of individual cells.

Cataldo, Robert L.↗

LDEF SP-HVDE (Space Plasma-High Voltage Drainage Experiment) post-flight results: Leakage current and discharge

TRW designed and fabricated two identical SP-HVDE trays which were flown in the NASA LDEF (Long Duration Exposure Facility) for 5.75 years in the LEO (low earth orbit) environment. One tray was placed near the leading edge and one near the trailing edge, and investigations were performed to compare the environmental interactions on the dielectric samples of the two trays. Each tray consisted of six assemblies with Kapton dielectric samples of varying thicknesses (i.e., 2 mils, 3 mil, and 5 mils) biased under +/- 300 V, +/- 500 V, and +/- 1000 V. The original objective was successfully achieved by measuring the first in-flight average leakage current through the samples. Less than 5 percent of the post-flight coulometers behaved anomalously. The data should be valuable to the design and evaluation of spacecraft with high voltage systems. M/D (micrometeoroid and debris) impacts over the dielectric samples were examined using a SEM (Scanning Electron Microscope) and an EDS (Energy Dispersive x-ray Spectrometer). These impact sites were sprayed by silver which were most likely caused either by the impact or a 'local ESD' (electrostatic discharge).

Yaung, J. Y.↗