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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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NASA NTRS2002

Chromosome aberrations in human lymphocytes induced by 250 MeV protons: effects of dose, dose rate and shielding

Although the space radiation environment consists predominantly of energetic protons, astronauts inside a spacecraft are chronically exposed to both primary particles as well as secondary particles that are generated when the primary particles penetrate the spacecraft shielding. Secondary neutrons and secondary charged particles can have an LET value that is greater than the primary protons and, therefore, produce a higher relative biological effectiveness (RBE). Using the accelerator facility at Loma Linda University, we exposed human lymphocytes in vitro to 250 MeV protons with doses ranging from 0 to 60 cGy at three different dose rates: a low dose rate of 7.5 cGy/h, an intermediate dose rate of 30 cGy/h and a high dose rate of 70 cGy/min. The effect of 15 g/cm2 aluminum shielding on the induction of chromosome aberrations was investigated for each dose rate. After exposure, lymphocytes were incubated in growth medium containing phytohemagglutinin (PHA) and chromosome spreads were collected using a chemical-induced premature chromosome condensation (PCC) technique. Aberrations were analyzed using the fluorescence in situ hybridization (FISH) technique with three different colored chromosome-painting probes. The frequency of reciprocal and complex-type chromosome exchanges were compared in shielded and unshielded samples. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

Non-NASA Center↗
NASA NTRS2017

Single-Event Effect Testing of the Vishay Si7414DN n-Type TrenchFET(Registered Trademark) Power MOSFET

This study was being undertaken to determine the single event effect susceptibility of the commercial Vishay 60-V TrenchFET power MOSFET. Heavy-ion testing was conducted at the Texas AM University Cyclotron Single Event Effects Test Facility (TAMU) and the Lawrence Berkeley National Laboratory BASE Cyclotron Facility (LBNL). In addition, initial 200-MeV proton testing was conducted at Massachusetts General Hospital (MGH) Francis H. Burr Proton Beam Therapy Center. Testing was performed to evaluate this device for single-event effects from lower-LET, lighter ions relevant to higher risk tolerant space missions.

proton testing↗
NASA NTRS2001

BNL accelerator-based radiobiology facilities

For the past several years, the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (USA) has provided ions of iron, silicon and gold, at energies from 600 MeV/nucleon to 10 GeV/nucleon, for the US National Aeronautics and Space Administration (NASA) radiobiology research program. NASA has recently funded the construction of a new dedicated ion facility, the Booster Applications Facility (BAF). The Booster synchrotron will supply ion beams ranging from protons to gold, in an energy range from 40-3000 MeV/nucleon with maximum beam intensities of 10(10) to 10(11) ions per pulse. The BAF Project will be described and the future AGS and BAF operation plans will be presented.

NASA Discipline Radiation Health↗
NASA NTRS1998

Summary of Proton Test on the Actel A1280A at Indiana University

A summary of tests performed at the Indiana University Cycl,oltron Facility, on the Actel A1280A circuit device is described. The intent of the study was to investigate the proton response of the hard-wired S-Module flip-flops with a large sample size. This device is sensitive to protons for S-Modules. The device's performance in the test is shown in graphs, and was typical for devices of this class.

Katz, Richard↗
NASA NTRS1997

AXAF Detector Backgrounds Produced By Cosmic Ray Protons

One of the science instruments on the Advanced X-ray Astrophysics Facility (AXAF), planned for launch in 1998 into a highly elliptical (10,000 km x 140,000 km) orbit, is a microchannel plate High Resolution Camera (HRC). This detector is designed to provide imaging and spectroscopic observations of x-rays emitted by stellar sources in the 0.1 to 10 keV energy range. Described here are analyses made to determine the expected time-dependent detector background from prompt and delayed (activation) radiation initiated by galactic cosmic-ray (GCR) proton interactions in the spacecraft and payload. Numerical simulations were made using the coupled set of Monte Carlo radiation transport codes, analysis software, and data bases shown. The major codes are HETC for nucleon-meson transport, EGS for simulating electromagnetic cascades, and MORSE for low-energy (less than 15 MeV) neutron transport. The simulation follows the transport history of photons in the energy range from - 100 GeV down to approx. 0.1 keV due to gamma-ray sources from neutral pion decay, high-energy (spallation) collisions, and low-energy neutron inelastic scattering and capture reactions. Also included is radioisotope production and the tracking of gamma-rays, electrons, and positrons from induced radioactivity.

Armstrong, T. W.↗
NASA NTRS2012

Radiation Shielding Materials Containing Hydrogen, Boron, and Nitrogen: Systematic Computational and Experimental Study

The key objectives of this study are to investigate, both computationally and experimentally, which forms, compositions, and layerings of hydrogen, boron, and nitrogen containing materials will offer the greatest shielding in the most structurally robust combination against galactic cosmic radiation (GCR), secondary neutrons, and solar energetic particles (SEP). The objectives and expected significance of this research are to develop a space radiation shielding materials system that has high efficacy for shielding radiation and that also has high strength for load bearing primary structures. Such a materials system does not yet exist. The boron nitride nanotube (BNNT) can theoretically be processed into structural BNNT and used for load bearing structures. Furthermore, the BNNT can be incorporated into high hydrogen polymers and the combination used as matrix reinforcement for structural composites. BNNT's molecular structure is attractive for hydrogen storage and hydrogenation. There are two methods or techniques for introducing hydrogen into BNNT: (1) hydrogen storage in BNNT, and (2) hydrogenation of BNNT (hydrogenated BNNT). In the hydrogen storage method, nanotubes are favored to store hydrogen over particles and sheets because they have much larger surface areas and higher hydrogen binding energy. The carbon nanotube (CNT) and BNNT have been studied as potentially outstanding hydrogen storage materials since 1997. Our study of hydrogen storage in BNNT - as a function of temperature, pressure, and hydrogen gas concentration - will be performed with a hydrogen storage chamber equipped with a hydrogen generator. The second method of introducing hydrogen into BNNT is hydrogenation of BNNT, where hydrogen is covalently bonded onto boron, nitrogen, or both. Hydrogenation of BN and BNNT has been studied theoretically. Hyper-hydrogenated BNNT has been theoretically predicted with hydrogen coverage up to 100% of the individual atoms. This is a higher hydrogen content than possible with hydrogen storage; however, a systematic experimental hydrogenation study has not been reported. A combination of the two approaches may be explored to provide yet higher hydrogen content. The hydrogen containing BNNT produced in our study will be characterized for hydrogen content and thermal stability in simulated space service environments. These new materials systems will be tested for their radiation shielding effectiveness against high energy protons and high energy heavy ions at the HIMAC facility in Japan, or a comparable facility. These high energy particles simulate exposure to SEP and GCR environments. They will also be tested in the LaRC Neutron Exposure Laboratory for their neutron shielding effectiveness, an attribute that determines their capability to shield against the secondary neutrons found inside structures and on lunar and planetary surfaces. The potential significance is to produce a radiation protection enabling technology for future exploration missions. Crew on deep space human exploration missions greater than approximately 90 days cannot remain below current crew Permissible Exposure Limits without shielding and/or biological countermeasures. The intent of this research is to bring the Agency closer to extending space missions beyond the 90-day limit, with 1 year as a long-term goal. We are advocating a systems solution with a structural materials component. Our intent is to develop the best materials system for that materials component. In this Phase I study, we have shown, computationally, that hydrogen containing BNNT is effective for shielding against GCR, SEP, and neutrons over a wide range of energies. This is why we are focusing on hydrogen containing BNNT as an innovative advanced concept. In our future work, we plan to demonstrate, experimentally, that hydrogen, boron, and nitrogen based materials can provide mechanically strong, thermally stable, structural materials with effective radiation shielding against GCR, SEP, and neutrons.

Radiation↗
NASA NTRS1998

Analysis of the Cyclotron Facility Calibration and Aircraft Results Obtained by LIULIN-3M Instrument

The LIULIN-3M instrument is a further development of the LIULIN dosimeter-radiometer, which has been used on the NffR space station in the 1988-1994 time period, The LIULIN-3M is designed for continuous monitoring of the radiation environment during the BION-12 satellite flight in 1999. A semiconductor detector with 1 mm thickness and 1 cm(exp 2) area is used in the instrument. Pulse high analysis technique is used for measurement of the energy losses in the detector. The final data sets from the instrument are the flux and the dose rate for the exposition time and 256 channels of LET spectra if a non-nal coincidence of the particles to the detector is considered. The LIULIN-3M instrument was calibrated by proton fluxes with different energies at the Indiana University Cyclotron Facility in June 1997 and was used for space radiation measurements during commercial aircraft flights. Obtained calibration and flight results are analyzed in the paper.

Dachev, T. P.↗
NASA NTRS1997

Balloon Fuel Cell Power System

NASA Lewis Research Center's Electrochemical Technology Branch has teamed with the NASA Wallops Flight Facility to demonstrate the operation of a hydrogen-oxygen proton exchange membrane (PEM) fuel cell for application in the upper atmosphere. NASA Wallops' Balloon Programs Branch has a requirement for a high-power, long-duration power system for use on a scientific balloon platform. The current power system will not meet these needs. The objective of this program is to deliver a 200-W (minimum) fuel cell system that can deliver approximately 10 kWh of electrical energy.

Source record↗
NASA NTRS1995

Correlation of electron and proton irradiation-induced damage in InP solar cells

When determining the best solar cell technology for a particular space flight mission, accurate prediction of solar cell performance in a space radiation environment is essential. The current methodology used to make such predictions requires extensive experimental data measured under both electron and proton irradiation. Due to the rising cost of accelerators and irradiation facilities, such extensive data sets are expensive to obtain. Moreover, with the rapid development of novel cell designs, the necessary data are often not available. Therefore, a method for predicting cell degradation based on limited data is needed. Such a method has been developed at the Naval Research Laboratory based on damage correlation using 'displacement damage dose' which is the product of the non-ionizing energy loss (NIEL) and the particle fluence. Displacement damage dose is a direct analog of the ionization dose used to correlate the effects of ionizing radiations. In this method, the performance of a solar cell in a complex radiation environment can be predicted from data on a single proton energy and two electron energies, or one proton energy, one electron energy, and Co(exp 60) gammas. This method has been used to accurately predict the extensive data set measured by Anspaugh on GaAs/Ge solar cells under a wide range of electron and proton energies. In this paper, the method is applied to InP solar cells using data measured under 1 MeV electron and 3 MeV proton irradiations, and the calculations are shown to agree well with the measured data. In addition to providing accurate damage predictions, this method also provides a basis for quantitative comparisons of the performance of different cell technologies. The performance of the present InP cells is compared to that published for GaAs/Ge cells. The results show InP to be inherently more resistant to displacement energy deposition than GaAs/Ge.

Walters, Robert J.↗
NASA NTRS1991

Activation calculations for trapped protons below 200 MeV: Appendix

Tables are given displaying of the results of the activation calculations of metal samples and other material aboard the Long Duration Exposure Facility-1 (LDEF-1) and Spacelab-2 with the computer program, PTRAP4. The computer printouts give the reaction, the reactant product, the proton reaction cross sections as a function of the energy of the incident protons, and the activation as a function of distance into the sample from the exposed surface.

Laird, C. E.↗
NASA NTRS1978

Measurements of 15.11-MeV gamma-ray flux produced in the reactions C-12(p, p')-C-12*(15.11 MeV) and O-16(p, p' alpha)-C-12*(15.11 MeV)

The flux of 15.11 MeV gamma rays relative to the flux of 4.44 MeV gamma rays which are emitted from the corresponding states of C-12 are a sensitive measure of the spectrum of exciting particles in solar flares and other cosmic sources. Emission of 15.11 MeV gamma rays may result not only from the direct excitation of C-12 but also from the interaction O-16 (p,p' alpha) C-12* sup 15.11 MeV. Although the cross sections for the direct reaction was studied extensively, the cross section for the spallation interaction with O-16 is not reported in the literature. Preliminary measurements demonstrated the feasibility of measuring the production of 15.11 MeV gamma rays by proton interactions with O-16 using the University of Maryland cyclotron facility. For both carbon and oxygen targets the flux of 15.11 MeV gamma rays is being measured relative to the flux of 4.44 MeV gamma rays. The gamma ray emission from de-excitation of the giant dipole resonances is being measured.

Lapides, J. R.↗
NASA NTRS1993

Single event test methodology for integrated optoelectronics

A single event upset (SEU), defined as a transient or glitch on the output of a device, and its applicability to integrated optoelectronics are discussed in the context of spacecraft design and the need for more than a bit error rate viewpoint for testing and analysis. A methodology for testing integrated optoelectronic receivers and transmitters for SEUs is presented, focusing on the actual test requirements and system schemes needed for integrated optoelectronic devices. Two main causes of single event effects in the space environment, including protons and galactic cosmic rays, are considered along with ground test facilities for simulating the space environment.

Label, Kenneth A.↗
NASA NTRS2000

Optical Analysis of Transparent Polymeric Material Exposed to Simulated Space Environment

Many innovations in spacecraft power and propulsion have been recently tested at NASA, particularly in non-chemical propulsion. One improvement in solar array technology is solar concentration using thin polymer film Fresnel lenses. Weight and cost savings were proven with the Solar Concentrator Arrays with Refractive Linear Element Technology (SCARLET)-II array on NASA's Deep Space I spacecraft. The Fresnel lens concentrates solar energy onto high-efficiency solar cells, decreasing the area of solar cells needed for power. Continued efficiency of this power system relies on the thin film's durability in the space environment and maintaining transmission in the 300 - 1000 nm bandwidth. Various polymeric materials have been tested for use in solar concentrators, including Lexan(TM), polyethylene terephthalate (PET), several formulations of Tefzel(Tm) and Teflon(TM), and DC 93-500, the material selected for SCARLET-II. Also tested were several innovative materials including Langley Research Center's CPI and CP2 polymers and atomic oxygen- resistant polymers developed by Triton Systems, Inc. The Environmental Effects Group of the Marshall Space Flight Center's Materials, Processes, and Manufacturing Department exposed these materials to simulated space environment and evaluated them for any change in optical transmission. Samples were exposed to a minimum of 1000 equivalent Sun hours of near-UV radiation (250 - 400 nm wavelength). Materials that appeared robust after near-UV exposure were then exposed to charged particle radiation equivalent to a five-year dose in geosynchronous orbit. These exposures were performed in MSFC's Combined Environmental Effects Test Chamber, a unique facility with the capability to expose materials simultaneously or sequentially to protons, low-energy electrons, high-energy electrons, near UV radiation and vacuum UV radiation. Reflectance measurements can be made on the samples in vacuum. Prolonged exposure to the space environment will decrease the polymer film's transmission and thus reduce the conversion efficiency. A method was developed to normalize the transmission loss and thus rank the materials according to their tolerance to space environmental exposure. Spectral results and the material ranking according to transmission loss are presented.

Edwards, David L.↗
NASA NTRS1999

Optical Analysis of Transparent Polymeric Material Exposed to Simulated Space Environment

Transparent polymeric materials are being designed and utilized as solar concentrating lenses for spacecraft power and propulsion systems. These polymeric lenses concentrate solar energy onto energy conversion devices such as solar cells and thermal energy systems. The conversion efficiency is directly related to the transmissivity of the polymeric lens. The Environmental Effects Group of the Marshall Space Flight Center's Materials, Processes, and Manufacturing Department exposed a variety of materials to a simulated space environment and evaluated them for an, change in optical transmission. These materials include Lexan(TM), polyethylene terephthalate (PET). several formulations of Tefzel(TM). and Teflon(TM), and silicone DC 93-500. Samples were exposed to a minimum of 1000 Equivalent Sun Hours (ESH) of near-UV radiation (250 - 400 nm wavelength). Data will be presented on materials exposed to charged particle radiation equivalent to a five-year dose in geosynchronous orbit. These exposures were performed in MSFC's Combined Environmental Effects Test Chamber, a unique facility with the capability to expose materials simultaneously or sequentially to protons, low-energy electrons, high-energy electrons, near UV radiation and vacuum UV radiation.Prolonged exposure to the space environment will decrease the polymer film's transmission and thus reduce the conversion efficiency. A method was developed to normalize the transmission loss and thus rank the materials according to their tolerance to space environmental exposure. Spectral results and the material ranking according to transmission loss are presented.

Edwards, David L.↗
NASA NTRS2002

Radiation Durability of Candidate Polymer Films for the Next Generation Space Telescope Sunshield

The Next Generation Space Telescope (NGST), anticipated to be launched in 2009 for a 10-year mission, will make observations in the infrared portion of the spectrum to examine the origins and evolution of our universe. Because it must operate at cold temperatures in order to make these sensitive measurements, it will use a large, lightweight, deployable sunshield, comprised of several polymer film layers, to block heat and stray light. This paper describes laboratory radiation durability testing of candidate NGST sunshield polymer film materials. Samples of fluorinated polyimides CP1 and CP2, and a polvarylene ether benzimidazole. TOR-LM(TM), were exposed to 40 keV electron and 40 keV proton radiation followed by exposure to vacuum ultraviolet (VUV) radiation in the 115 to 200 nm wavelength range. Samples of these materials were also exposed to VUV without prior electron and proton exposure. Samples of polyimides Kapton HN, Kapton E, and Upilex-S were exposed to electrons and protons only, due to limited available exposure area in the VUV facility. Exposed samples were evaluated for changes in solar absorptance and thermal emittance and mechanical properties of ultimate tensile strength and elongation at failure. Data obtained are compared with previously published data for radiation durability testing of these polymer film materials.

Dever, Joyce↗
NASA NTRS2018

Space Environmental Effects on Additively Manufactured Materials

Space simulations including thermal vacuum, atomic oxygen, and ultraviolet radiation were performed to study the durability of various additively manufactured materials. In addition to ground simulations, additively manufactured materials were selected for a one-year flight on the Materials on International Space Station Experiment (MISSE) Flight Facility. The space environment is composed of atomic oxygen, ultraviolet radiation, protons, electrons, meteoroid/space debris impacts, thermal cycling, and hard vacuum. An improved UV sensor is also discussed.

Finckenor, M. M.↗