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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Deep Space Test Bed

The DSTB Facility provides a new capability for the National Aeronautics and Space Administration s (NASA s) Space Radiation Shielding Project (SRSP). The objective of the DSTB is to provide a platform to conduct radiation shielding investigations in an environment more similar to deep space than most Low Earth orbits or is achievable at a particle accelerator. The DSTB provides a means to experimentally test radiation shielding effectiveness of various materials and to test the accuracy of radiation transport code predictions in the deep space cosmic ray environment more frequently and at a lower cost compared to space flight missions. New spectrometers, dosimeters and other techniques may be exercised and verified using the DSTB before space flight. The DSTB will be implemented through NASA s National Scientific Balloon Facility (NSBF) which provides polar balloon flights that lift science payloads to high altitude (120,000 A. (36.58km)) to escape much of the shielding effects of the Earth s atmosphere and magnetosphere. Polar flights are conducted through NSBF in coordination with the United States Polar Program. The DSTB will be launched on a Long Duration Balloon (LDB) from McMurdo, Antarctica (77.86 degrees south latitude) for circumpolar flights, nominally 20 days, traveling to the west and typically bounded between 73 to 82 degrees south latitude. Float altitudes for these balloons with payload are 115,000 to 130,000 feet (35.05 to 39.62km). The DSTB will be able to accommodate up to 20 investigations per flight. Annual flight opportunities are planned starting in December 2005. Balloon campaigns in Antarctica occur in December and January during the Austral summer. Since a key goal of the DSTB facility is to efficiently serve the varied needs of the radiation shielding community; it must be designed with a flexible architecture. By implementing the DSTB facility with NASA s balloon program, which operates under reduced formalities compared to space flight, the DSTB facility can adjust for different investigation priorities on successive flights. This flexibility in the DSTB will be applied at several levels; in the distribution of the shared resources for each flight; addressing the payload configuration on a system level for each flight; and utilizing a selection process for investigations that considers yearly flight opportunities as well as the possibility for repeated flights. This approach for operating the DSTB facility will allow it to handle a wide range of investigations.

Milton, Martha E.↗
NASA NTRSDate not supplied

Analysis of nonequilibrium molecular nitrogen ultraviolet radiation in pure N2 shockwaves

An analysis of data previously reported from a test series in the Electric Arc Shock Tube Facility for incident shocks composed of pure Nitrogen was performed. The present work focuses on the lowest velocity measured in the test (approximately 7 km/s) where molecular radiation is significant. Analysis of the spectral data with the NEQAIR radiative transport code obtains post-shock trends in temperature and number densities of the states of N2. The results suggest that chemical, and possibly thermal, equilibrium has not been obtained within the distance/time measured (about 5 cm/120 ms). In the nonequilibrium region of the shock, differences between rotational temperatures of different species are observed, as well as differences between rotational and vibrational temperatures. Population of rotational states above the dissociation limit is observed to occur over a distance of several cm. Finally, these data suggest that predissociation strongly affects the C^3 Π_u state of N2, leading to a lower measured radiation than predicted. An effective average pre-dissociation rate is shown to produce reasonable agreement under quasi-steady state approximation.

Augustin Tibere-Inglesse↗
NASA NTRS1991

Overview of fiber optics in the natural space environment

The potential applications of fiber-optic (FO) systems in spacecraft which will be exposed to the space radiation environment are discussed in view of tests conducted aboard the Long-Duration Exposure Facility and the Comet Rendezvous and Asteroid Flyby spacecraft. Attention is given to anticipated trends in the use of FO in spacecraft communications systems. The natural space radiation environment is noted to be far more benign than the military space environment, which encompasses displacement-damage effects due to significant neutron influences.

Barnes, C.↗
NASA NTRS1988

Magnetic emissions testing of the space station engineering model resistojet

The engineering model resistojet intended for altitude maintenance onboard the space station was tested for magnetic radiation emissions in the Radio Frequency Interference (RFI) facility at the Goddard Space Flight Center. The resistojet heater was supplied with power at 20 kHz and low voltage through a power controller. The resistojet was isolated from its power supply in the RFI enclosure, and the magnetic emission measured at three locations around the resistojet at various heater currents. At a heater current of 18.5 A the maximum magnetic emission was 61 dBpt at a distance of 1 m from the resistojet and at a location at the rear of the thruster. Calculations indicate that the case and heat shields provided a minimum of 4 dB of attenuation at a current of 18.5 A. Maximum radiation was measured at the rear of the resistojet along its major axis and was thought to be due to the magnetic radiation from the power leads. At a distance of 37 cm from the resistojet the maximum magnetic radiation measured was 73 dBpt at a current of 11.2 A. The power input leads were also a source of magnetic radiation. The engineering model rssistojet requires about 20 dB of additional shielding.

Briehl, Daniel↗
NASA NTRS1991

The MPD thruster program at JPL

The main topics covered include: (1) the Space Exploration Initiative (SEI) context; (2) critical issues of MPD Thruster design; and (3) the Magnetoplasmadynamic (MPD) Thruster Program at JPL. Under the section on the SEI context the nuclear electric propulsion system and some electric thruster options are addressed. The critical issues of MPD Thruster development deal with the requirements, status, and approach taken. The following areas are covered with respect to the MPD Thruster Program at JPL: (1) the radiation-cooled MPD thruster; (2) the High-Current Cathode Test Facility; (3) thruster component thermal modeling; and (4) alkali metal propellant studies.

Barnett, John↗
NASA NTRS1993

Development of a high specific 1.5 to 5 kW thermal arcjet

A research and development project on the experimental study of a 1.5-5 kW thermal arcjet thruster was started in 1992 at the IRS. Two radiation cooled thrusters were designed, constructed, and adapted to the test facilities, one at each end of the intended power range. These thrusters are currently subjected to an intensive test program with main emphasis on the exploration of thruster performance and thruster behavior at high specific enthalpy and thus high specific impulse. Propelled by simulated hydrazine and ammonia, the thruster's electrode configuration such as constrictor diameter and cathode gap was varied in order to investigate their influence and to optimize these parameters. In addition, test runs with pure hydrogen were performed for both thrusters.

Riehle, M.↗
DOE OSTI2020

Photon Irradiation Effects on the Enduray Vision System for Nuclear Inspections

Video cameras with greater radiation hardening are needed for the operation and remote handling of equipment in nuclear reactor inspection and refueling applications. Vega Wave Systems has developed a radiation-hardened vision system for nuclear energy applications. The program described in this report provided radiation-hardness testing of this vision system using the Argonne Low-Energy Accelerator Facility (LEAF). This report presents the results of irradiation tests performed on several of Vega Wave System’s cameras at dose rates ranging from 1 kGy/hr up to 10 kGy/hr and up to total doses of >500 kGy. The results were excellent, providing proof of the camera system’s immunity to radiation effects at all levels tested.

36 MATERIALS SCIENCE↗
NASA NTRSDate not supplied

Analysis of Nonequilibrium Molecular Nitrogen Ultraviolet Radiation in Pure N2 Shockwaves

This paper presents an analysis of data previously reported from a test series in the Electric Arc Shock Tube Facility for incident shocks composed of pure Nitrogen. The present work focuses on the lowest velocity measured in the test (approximately 7 km/s) where molecular radiation is significant. Analysis of the spectral data with the NEQAIR radiative transport code obtains post-shock trends in temperature and number densities of the states of N2. The results suggest that chemical, and possibly thermal, equilibrium has not been obtained within the distance/time measured (about 5 cm/120 s). In the nonequilibrium region of the shock, differences between rotational temperatures of different species are observed, as well as differences between rotational and vibrational temperatures. Population of rotational states above the dissociation limit is observed to occur over a distance of several cm. Finally, these data suggest that predissociation strongly affects the C^3 Π_u state of N2, leading to a lower measured radiation than predicted. An effective average pre-dissociation rate is shown to produce reasonable agreement under quasi-steady state approximation.

Augustin Tibere Inglesse↗
DOE OSTI2021

Background measurement methods for opacity experiments conducted at the Z facility

Laboratory experiments typically test opacity models by measuring spectrally resolved transmission of a sample using bright backlight radiation. A potential problem is that any unaccounted background signal contaminating the spectrum will artificially reduce the inferred opacity. Methods developed to measure background signals in opacity experiments at the Sandia Z facility are discussed. Preliminary measurements indicate that backgrounds are 9%–11% of the backlight signal at wavelengths less than 10 Å. Background is thus a relatively modest correction for all Z opacity data published to date. Future work will determine how important background is at longer wavelengths.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Cross-Section Comparison for Pu-238 Production in the Advanced Test Reactor at Idaho National Laboratory

Qualification of Advanced Test Reactor (ATR) positions for Pu-238 production has been ongoing at Idaho National Laboratory (INL). The ATR qualifications have stretched over multiple years during which new techniques have been developed and made available for ATR experiment neutronic analysis. As part of the transition to newer codes, new cross-section libraries have been evaluated for use in the Pu-238 production experiment analysis. A comparative study was done using the MCNP ORGIEN Activation Analysis (MOAA) tool between ENDF/B-VII.0 and ENDF/B-VIII.0 cross sections to capture the impact of the change in cross-sections on the analysis needed to qualify Pu-238 production targets. All comparisons were done assuming the ATR GEN-I targets were located in the south flux trap of the ATR. Finally, an overview of how this qualification and potential irradiation fits into Pu-238 is discussed.

07 ISOTOPE AND RADIATION SOURCES↗
NASA NTRS2000

Steady-State Vacuum Ultraviolet Exposure Facility With Automated Lamp Calibration and Sample Positioning Fabricated

The Next Generation Space Telescope (NGST) will be placed in an orbit that will subject it to constant solar radiation during its planned 10-year mission. A sunshield will be necessary to passively cool the telescope, protecting it from the Sun s energy and assuring proper operating temperatures for the telescope s instruments. This sunshield will be composed of metalized polymer multilayer insulation with an outer polymer membrane (12 to 25 mm in thickness) that will be metalized on the back to assure maximum reflectance of sunlight. The sunshield must maintain mechanical integrity and optical properties for the full 10 years. This durability requirement is most challenging for the outermost, constantly solar-facing polymer membrane of the sunshield. One of the potential threats to the membrane material s durability is from vacuum ultraviolet (VUV) radiation in wavelengths below 200 nm. Such radiation can be absorbed in the bulk of these thin polymer membrane materials and degrade the polymer s optical and mechanical properties. So that a suitable membrane material can be selected that demonstrates durability to solar VUV radiation, ground-based testing of candidate materials must be conducted to simulate the total 10- year VUV exposure expected during the Next Generation Space Telescope mission. The Steady State Vacuum Ultraviolet exposure facility was designed and fabricated at the NASA Glenn Research Center at Lewis Field to provide unattended 24-hr exposure of candidate materials to VUV radiation of 3 to 5 times the Sun s intensity in the wavelength range of 115 to 200 nm. The facility s chamber, which maintains a pressure of approximately 5 10(exp -6) torr, is divided into three individual exposure cells, each with a separate VUV source and sample-positioning mechanism. The three test cells are separated by a water-cooled copper shield plate assembly to minimize thermal effects from adjacent test cells. Part of the interior sample positioning mechanism of one test cell is shown in the illustration. Of primary concern in VUV exposure is the maintenance of constant measured radiation intensity so that the sample s total exposure can be determined in equivalent Sun hours. This is complicated by the fact that a VUV lamp s intensity degrades over time, necessitating a decrease in the distance between the test samples and the lamp. The facility overcomes this challenge by periodically measuring the lamp s intensity with a cesium-iodide phototube and adjusting the sample distance as required to maintain constant exposure intensity. Sample positioning and periodic phototube location under the lamp are both achieved by a single lead-screw assembly. The lamps can be isolated from the main vacuum chamber for cleaning or replacement so that samples are not exposed to the atmosphere during a test.

Sechkar, Edward A.↗
DOE OSTI2021

UPF and Y-12 Criticality Accident Alarm System (CAAS) Radiation Testing Report

This report documents the experimental conditions and results for the testing of the Mirion Technologies CAAS-3S Criticality Accident Alarm System (CAAS) for the Y-12 National Security Complex (Y-12) and Uranium Processing Facility (UPF). The testing was conducted at the Godiva IV Burst Reactor at the National Criticality Experiments Research Center (NCERC) at the Nevada National Security Site (NNSS) during the week of January 11, 2021. The testing was conducted in accordance with 25774-QL-POA-JR00-00002-VDE-27.0, CAAS-3S Radiation Testing of Cabinet Components Test Plan. The tests subjected the CAAS-3S system to intense and short duration mixed neutron and gamma radiation fields and to high integrated radiation doses. The purpose of the test was to environmentally qualify various CAAS-3S components in a radiation environment. Successful completion of the tests was predicated on the collaborative efforts of several organizations. Sandia National Laboratory (SNL) and Lawrence Livermore National Laboratory (LLNL) provided dosimetry to estimate photon and neutron dose. Los Alamos National Laboratory (LANL) manages the NCERC facility, operated the Godiva IV reactor, and provided field support for CAAS-3S placement and communications interface for data acquisition systems supplied by Mirion Technologies. Throughout the test campaign, Y-12 and UPF personnel provided technical support in determining changes to the test schedule, as needed, interpretation of the results, and comparison between the measured dosimetry data and predicted results. Throughout the test campaign, Mirion personnel provided technical support in the operation of the CAAS-3S system itself.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
NASA NTRS2011

Emission Spectroscopic Measurements with an Optical Probe in the NASA Ames IHF Arc Jet Facility

An optical probe was designed to measure radiation (from inside the arc heater) incident on a test sample immersed in the arc-heated stream. Currently, only crude estimates are available for this incident radiation. Unlike efforts of the past, where the probe line of sight was inclined to the nozzle centerline, the present development focuses on having the probe line of sight coincide with the nozzle centerline. A fiber-coupled spectrometer was used to measure the spectral distribution of incident radiation in the wavelength range of 225 to 900 nm. The radiation heat flux in this wavelength range was determined by integration of measured emission spectral intensity calibrated to incident irradiance from an integrating sphere. Two arc-heater conditions, corresponding to stream bulk enthalpy levels of 12 and 22 MJ/kg, were investigated in the 13-inch diameter nozzle of the Interaction Heating Facility at NASA Ames Research Center. With the probe placed at a distance of 10 inches from the nozzle exit plane, total radiative heat fluxes were measured to be 3.3 and 8.4 W/sq cm for the 12 and 22 MJ/kg conditions, respectively. About 17% of these radiative fluxes were due to bound-bound radiation from atoms and molecules, while the remaining 83% could be attributed to continua (bound-free and/or free-free). A comparison with spectral simulation based on CFD solutions for the arc-heater flow field and with spectroscopic measurements in the plenum region indicates that more than 95% of the measured radiation is generated in the arc region. The total radiative heat flux from the line radiation could increase by a factor of two through contributions from wavelengths outside the measured range, i.e., from the vacuum ultraviolet (wavelengths less than 225 nm) and the infrared (wavelengths greater than 900 nm). An extrapolation of the continuum radiation to these two wavelength regions was not attempted. In the tested configuration, the measured radiative heat flux accounts for only about 1.4% of the nominal heat flux on a flat face model and therefore is considered negligible. In the 6-inch diameter nozzle, on account of shorter path lengths, the radiation heat flux could be significant. Therefore, future tests in the 6-inch nozzle will have radiometers in addition to the optical probe.

Winter, Michael↗
NASA NTRS1997

An Exposure Prevention Plan for an Anhydrous Ammonia Handling System

In July of 1996, the Industrial Hygiene Team of the Environmental Management Office at NASA Lewis Research Center was contacted by the Space Station Program Office to conduct ammonia awareness training for a team of engineers and technicians. The team was tasked with assembling and operating an ammonia handling system for testing of a photovoltaic radiator at the NASA Plum Brook Station Space Power Facility. The ammonia handling system supports a radiator designed to radiate excess heat from a photovoltaic array module used to provide power to the International Space Station. The system would consist of a hazardous materials trailer equipped with an anhydrous ammonia tank, heater, accumulator, chiller, and flow bench. Meetings were held with representatives from the Space Station Program Office, the engineers and Plum Brook safety personnel. Guidance was also provided by representatives from Kennedy Space Center. Determinations were made concerning the locations and types of potential exposures and a plan was developed which included training, personal protective equipment, engineering controls and emergency response. Various organizations including the Plum Brook Safety Committee, the Lewis Environmental Management Office, the Test Readiness Review Board and the Program Office all had requirements that had to be met in order to satisfy themselves that all personnel involved in the operation of the system would be safe. What resulted was a comprehensive plan that provided more than adequate safety measures and succeeded in protecting all personnel from the hazards of the ammonia system. Testing of the photovoltaic radiator was successful and although ammonia leaks were detected and maintenance of the system was ongoing, no one was injured. It was felt that the training and controls in place allowed for a comfort level that did not interfere with the operations.

Cathy L Padolewski↗
NASA NTRS1996

Analytical Investigation of a Reflux Boiler

A thermal model of a single Ultralight Fabric Reflux Tube (UFRT) was constructed and tested against data for an array of such tubes tested in the NASA-JSC facility. Modifications to the single fin model were necessary to accommodate the change in radiation shape factors due to adjacent tubes. There was good agreement between the test data and data generated for the same cases by the thermal model. The thermal model was also used to generate single and linear array data for the lunar environment (the primary difference between the test and lunar data was due to lunar gravity). The model was also used to optimize the linear spacing of the reflux tubes in an array. The optimal spacing of the tubes was recommended to be about 5 tube diameters based on maximizing the heat transfer per unit mass. The model also showed that the thermal conductivity of the Nextel fabric was the major limitation to the heat transfer. This led to a suggestion that the feasibility of jacketing the Nextel fiber bundles with copper strands be investigated. This jacketing arrangement was estimated to be able to double the thermal conductivity of the fabric at a volume concentration of about 12-14%. Doubling the thermal conductivity of the fabric would double the amount of heat transferred at the same steam saturation temperature.

Simon, William E.↗
NASA NTRS2016

Validation of High Speed Earth Atmospheric Entry Radiative Heating from 9.5 to 15.5 km/s

This paper presents an overview of the analysis and measurements of equilibrium radiation obtained in the NASA Ames Research Center's Electric Arc Shock Tube (EAST) facility as a part of recent testing aimed at reaching shock velocities up to 15.5 km/s. The goal of these experiments was to measure the level of radiation encountered during high speed Earth entry conditions, such as would be relevant for an asteroid, inter-planetary or lunar return mission. These experiments provide the first spectrally and spatially resolved data for high speed Earth entry and cover conditions ranging from 9.5 to 15.5 km/s at 13.3 and 26.6 Pa (0.1 and 0.2 Torr). The present analysis endeavors to provide a validation of shock tube radiation measurements and simulations at high speed conditions. A comprehensive comparison between the spectrally resolved absolute equilibrium radiance measured in EAST and the predictive tools, NEQAIR and HARA, is presented. In order to provide a more accurate representation of the agreement between the experimental and simulation results, the integrated value of radiance has been compared across four spectral regions (VUV, UV/Vis, Vis/NIR and IR) as a function of velocity. Results have generally shown excellent agreement between the two codes and EAST data for the Vis through IR spectral regions, however, discrepancies have been identified in the VUV and parts of the UV spectral regions. As a result of the analysis presented in this paper, an updated parametric uncertainty for high speed radiation in air has been evaluated to be [9.0%, -6.3%]. Furthermore, due to the nature of the radiating environment at these high shock speeds, initial calculations aimed at modeling phenomena that become more significant with increasing shock speed have been performed. These phenomena include analyzing the radiating species emitting ahead of the shock and the increased significance of radiative cooling mechanisms.

Equilibrium↗
NASA NTRS1969

The Ames combined heating facility.

Heating facility for testing ablative heat shield material models in combined convective and radiative heating environment with constant or transient heating conditions

Gowen, F. E.↗