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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Scandium oxide antireflection coatings for superluminescent LEDs

For an employment of laser diodes as superluminescent LEDs (SLDs) or amplifiers, the facets of the diodes must be coated with antireflection films. In the work reported, scandium oxide was evaporated from an e-beam source onto Supersil II fused silica substrates. The obtained samples were used for measurements of absorption and reflectivity. Results of index measurements on e-beam evaporated films are presented. It is shown that excellent coatings with reflectivities of 0.00025 can be obtained using these films. Attention is given to the refractive indices for scandium oxide films as a function of wavelength, the power output vs current for laser before coating and after coating with Sc2O3.

Ladany, I.↗
NASA NTRS1990

Dissociation phenomena in electron-beam sustained carbon dioxide lasers

A number of applications are emerging requiring efficient, long pulse, long-life sealed CO2 lasers. Examples include the proposed NASA and ESA wind lidars. Electron-beam sustained discharge devices are strong contenders. Unlike self-sustained discharges, e-beam sustenance readily provides efficient performance from large volume discharges and offers pulse lengths well in excess of the microsecond or so generally associated with self-sustained devices. In the case of the e-beam sustained laser, since the plasma is externally maintained and operated at electric field strengths less than that associated with the glow to arc transition, the discharges can be run even in the presence of strongly attacking species such as O2. Build up of large levels of attacking contaminants is nevertheless undesirable as their presence reduces the current drawn by the plasma and thus the pumping rate to the upper laser level. The impedance rise leads to a mismatch of the pulse forming network with a consequent loss of control over energy deposition, operating E/N, and gain. Clearly CO2 dissociation rates, the influence of dissociation products on the discharge and gain, and tolerance of the discharge to these products need to be determined. This information can then be used to assess co-oxidation catalyst requirements for sealed operation.

Harris, Michael R.↗
DOE OSTI2025

Investigation of CrMnV and CrMnTiV multi principal element alloys thin films for use as exit windows of electron beam accelerators

Here, this study explores CrMnV and CrMnTiV multi principal element alloy (MPEA) films as candidates for electron beam exit windows in industrial, high-power accelerators. Films were deposited via magnetron sputtering on various substrates and exposed to 66 kGy of 10 MeV e-beam irradiation. Structural and mechanical properties were analyzed using FESEM, XRD, and nanoindentation. CrMnTiV films exhibited superior grain uniformity and hardness, regardless of the substrate type. Compared to bulk materials, both MPEA films demonstrated higher hardness and excellent radiation resistance. These results highlight the potential of MPEA films as durable, radiation-tolerant materials for high-performance accelerator exit window applications.

Electron Beam Irradiation↗
DOE OSTI2025

Spatial profile of argon (1s 5 ) metastables in an electron beam generated plasma

Electron beams with an applied magnetic field generate a secondary cold plasma with a selective chemical composition, featuring low-energy ions and metastable species in the discharge periphery, ideal for low-damage plasma treatment of material substrates. In this work, we studied the plasma generated by an e-beam using a 4 kV voltage in a pure argon gas environment under a magnetic field of 150 G and in the pressure range of 25–90 mTorr. We measured the absolute spatial density profile of argon (1 s 5 ) metastables in an electron beam generated plasma by laser-induced fluorescence and found it to be of the order of 10 16 m −3 . The electron temperature and the electron density measured by a Langmuir probe were of the order of 10 16 m −3 and less than an eV respectively. Electron-impact quenching was identified as a significant loss mechanism for the Ar(1s 5 ) state, leading to the saturation of the metastable density at higher pressures. Outside the primary ionization region, the spatial distribution of argon metastables followed a linear diffusion profile, indicating negligible additional production in those regions.

EEDF↗
DOE OSTI2026

Light-tight Skipper-CCDs for X-Ray Detection in Space

Skipper Charge-Coupled Devices (skipper-CCDs) are pixelated silicon detectors with deep sub-electron resolution. Their radiation hardness and capability to reconstruct energy deposits with unprecedented precision make them a promising technology for space-based X-ray astronomy. In this scenario, optical and near-infrared photons may saturate the sensor, distorting the reconstructed signal. We present a light-tight shield for skipper-CCDs to suppress optical backgrounds while preserving X-ray detection efficiency. We deposited thin aluminum layers on the CCD surface using an e-beam evaporator and evaluated their blinding performance across wavelengths from 650 to 1000 nm using a monochromator, as well as the X-ray transmission using an 55 Fe source. We find that 50 and 100 nm layers provide >99.6% light suppression, with no efficiency loss for 5.9 and 6.4 keV X-rays. In addition, we used Geant4 simulations to extend these results to a broader energy range and quantify the efficiency loss for different aluminum thicknesses. Results show that thin aluminum coatings are an effective, low-cost solution for optical suppression in skipper-CCDs intended for X-ray detection and space instrumentation.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2026

Electron-irradiation induced creep in amorphous alloys

Electron-irradiation induced creep rates in amorphous alloys, a-SiO2, Fe79B16Si5, Cu60Ta40, and Cu50Ti50, were measured at room temperature using a miniaturized beam-bending apparatus within a transmission electron microscope operated at 200 keV. The creep rates of these amorphous samples increased nearly linearly with both e-beam current density and applied stress, while a reference crystalline (c-)SiO2 sample failed to creep under the same conditions. The irradiation induced creep compliance of a-SiO2 was ~ 15 times larger than that of Fe79B16Si5 and over 1,000 times larger than that of the two Cu alloys. Molecular dynamics computer simulations were employed to simulate electron irradiation induced creep using interatomic potentials representing amorphous Cu75Zr25, Ni80P20, and SiO2 as model systems. The irradiation induced creep compliances calculated for Cu75Zr25 during 200 keV electron irradiation provided good quantitative agreement with the two Cu-based alloys, but that for a-SiO2 was ~ 180 times too small. These results indicate that unlike neutron or ion-beam induced creep in a-SiO2, creep under electron irradiation is dominated by the effects of ionization owing largely to the far higher ratio of electronic stopping to nuclear stopping for electrons than for ions.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Electron Beam Irradiation for Water Treatment of Per- and Polyfluoroalkyl Substances (PFAS)

Per- and polyfluoroalkyl substances (PFAS) are widely used but are now considered a water contamination risk. Fermi National Accelerator Laboratory’s IARC group has demonstrated that passing water through electron beam radiation can destroy PFAS. This project aims to develop a process to scale the system for bulk water treatment. The key is efficient radiation usage, ensuring that all water receives only the minimum dose. Software was developed for this purpose, consisting of a computational fluid dynamics model (CFD) in COMSOL, which calculates particle trajectories through the radiation area. A MATLAB script integrates the radiation dose of these particles, and statistical analysis is performed to evaluate the radiation utilization efficiency. These models are validated with a flow test where colored dye is injected and optically tracked. Radiation dose is measured by testing under an e-beam to measure the degradation of a PFAS analog.

Mueller, Scott [Northern Illinois U.]↗
NASA NTRS1976

Study of SEM induced current and voltage contrast modes to assess semiconductor reliability

The purpose of the scanning electron microscopy study was to review the failure history of existing integrated circuit technologies to identify predominant failure mechanisms, and to evaluate the feasibility of their detection using SEM application techniques. The study investigated the effects of E-beam irradiation damage and contamination deposition rates; developed the necessary methods for applying the techniques to the detection of latent defects and weaknesses in integrated circuits; and made recommendations for applying the techniques.

Beall, J. R.↗
NASA NTRS1976

Nuclear fission fragment excitation of electronic transition laser media

Specific characteristics of the media including density, excitation rates, wavelength, kinetics, fissile material, scale size, and medium uniformity are assessed. The use of epithermal neutrons, homogeneously mixed fissile material, and special high cross section nuclear isotopes to optimize coupling of the energy to the medium are shown to be important considerations maximizing the scale size, energy deposition, and medium uniformity. It is demonstrated that e-beam excitation can be used to simulate nuclear pumping conditions to facilitate the search for candidate media.

Lorents, D. C.↗
NASA NTRS1979

Effects of space environment on composites: An analytical study of critical experimental parameters

A generalized methodology currently employed at JPL, was used to develop an analytical model for effects of high-energy electrons and interactions between electron and ultraviolet effects. Chemical kinetic concepts were applied in defining quantifiable parameters; the need for determining short-lived transient species and their concentration was demonstrated. The results demonstrates a systematic and cost-effective means of addressing the issues and show qualitative and quantitative, applicable relationships between space radiation and simulation parameters. An equally important result is identification of critical initial experiments necessary to further clarify the relationships. Topics discussed include facility and test design; rastered vs. diffuse continuous e-beam; valid acceleration level; simultaneous vs. sequential exposure to different types of radiation; and interruption of test continuity.

Gupta, A.↗
NASA NTRS1983

Microcrystalline silicon growth for heterojunction solar cells

A total of sixteen runs of e-beam vacuum deposition of p type microcrystalline Si (m-Si) films were attempted on n type or p-n junction single crystalline Si (C-Si) substrates. The m-Si film thickness varied from .15 to .7 um and metal contacts were deposited after plasma hydrogenation. The p-m-Si on n-c-Si structure had a Voc of up to 490 m V while no Voc improvements were observed in the p-m-Si on p-n C-Si structure against p-n controls. Both CFF and Jsc were lower than control. Possible problem areas were interfaced between m-Si and C-si and the back contacts due to lack of sintering for fear of dehydrogenation.

Iles, P. A.↗
NASA NTRS1984

Microcrystalline silicon growth for heterojunction solar cells

Microcrystalline Si (m-Si) films with a 1.7eV energy bandgap and crystal size of several hundred A were e-beam evaporated on single crystalline Si (c-Si) to form a heterojunction with the substrate, or a window layer to a single crystalline p-n junction (heteroface structure). The goal was to enhance Voc by such uses of the larger bandgap m-Si, with the intriguing prospect of forming heterostructures with exact lattice match on each layer. The heterojunction structure was affected by interface and shunting problems and the best Voc achieved was only 482mV, well below that of single crystal Si homojunctions. The heteroface structure showed promise for some of the samples with p m-Si/p-n structure (the complementary structure did not show any improvement). Although several runs with different deposition conditions were run, the results were inconsistent. Any Voc enhancement obtained was too small to compensate for the current loss due to the extra absorption and poor carrier transport properties of the m-Si film.

Leung, D. C.↗
NASA NTRS1988

RF surface resistance of YBa2Cu3O(7-x) thin films

The excitement engendered by the discovery of the new T sub c oxide superconductors has led to much speculation about practical applications of thin films of these materials in digital and analog electronic devices. Most of these envisioned applications involve high frequency signals for which a detailed knowledge of the surface impedance of the novel superconductors is very important. We have measured the surface resistance of thin films of YBaCuO in the frequency range 0.5 less than f less than 17 GHz using a stripline-resonator method. The stripline procedure also was used to measure the surface resistance of high quality gold and aluminum films; the resistance values obtained agree with values predicted from the measured dc resistance using the Pippard formalism for the anomalous skin effect. The YBaCuO were produced by a multilayer deposition process. The films are formed by e-beam evaporation of 24 layers of Y, Ba, and Cu. Films with the highest transition temperature were obtained using yttria-stabilized zirconia (YSZ) substrates. After deposition, the films are transferred to a furnace where they are annealed in flowing O2 at 850 C for 2h. The furnace then is turned off and allowed to cool to 100 C in about 16 h. Auger profiling of the films made by this process shows that the concentrations of Y, Ba, Cu, and O are uniform to within 1 percent throughout the thickness of the film.

Source record↗
NASA NTRS1990

Mechanistic studies of the CO-oxidation reaction on catalysts for use in long-life CO2 lasers

The catalytic recombination of carbon monoxide and oxygen was studied under conditions expected to be present in a sealed E-beam CO2 laser system. These conditions are typically a gas inlet temperature of 60 C, a substoichiometric CO/O2 ratio of ca. 2.5/1 with an oxygen feed rate of ca. 5 micromoles/s, a carrier gas comprising He, N2 and CO2 in the ratio of 3:2:1, near atmospheric pressure and a gas velocity of 4 m/s. Heterogeneous catalysts, based on precious metal supported on tin oxide, have been coated onto ceramic monoliths and tested for catalytic activity and stability after a reduction/passivation step. Two catalyst systems have been chosen. These are Pt/Pd/SnO2 and Pt/Ru/SnO2. Under the conditions described above, a characteristic decline in catalytic activity is apparent for both systems, and exit gas temperature has been recognized as a sensitive parameter by which to monitor the activity changes. A semilogarithmic plot of exit temperature as a function of time has revealed two distinct processes connected with the decline in activity: one process is associated with reduction of the oxidized precious metal (at Site A), whilst the other is related to the formation and approach to steady-state of an active site at the metal/support interface (Site B).

Dawood, Talat↗
NASA NTRS1991

Effects on LDEF exposed copper film and bulk

Two forms of copper were exposed to the Long Duration Exposure Facility (LDEF) Mission 1 environment: a copper film, initially 74.2 plus or minus 1.1 nm thick sputter coated on a fused silica flat and a bulk piece of oxygen-free, high conductivity (OFHC) copper. The optical density of the copper film changed from 1.33 to 0.70 where exposed, and the film thickness increased to 106.7 plus or minus 0.5 nm where exposed. The exposed area appears purple by reflection and green by transmission for the thin film and maroon color for the bulk copper piece. The exposed areas increased in thickness, but only increase in the thickness of the thin film sample could be readily measured. The increase in film thickness is consistent with the density changes occurring during conversion of copper to an oxide. However, we have not been able to confirm appreciable conversion to an oxide by x-ray diffraction studies. We have not yet subjected the sample to e-beams or more abusive investigations out of concern that the film might be modified.

Peters, Palmer N.↗
NASA NTRS1992

Effects on LDEF exposed copper film and bulk

Two forms of copper were exposed to the Long Duration Exposure Facility (LDEF) Mission 1 environment: a copper film initially 74.2 plus or minus 1.1 nm thick sputter coated on a fused silical flat and a bulk piece of oxygen free, high conductivity (OFHC) copper. The optical density of the copper film changed from 1.33 to 0.70 where exposed and the film thickness increased to 106.7 plus or minus 0.5 nm where exposed. The exposed area appears purple by reflection and green by transmission for the thin film and maroon color for the bulk copper piece. The exposed areas increased in thickness, but only increase in the thickness of thin film samples could be readily measured. The increase in film thickness is consistent with the density changes occurring during conversion of copper to an oxide. However, we have not been able to confirm appreciable conversion to an oxide by x ray diffraction studies. We have not yet subjected the sample to e-beams or more abusive conditions out of concern that the film might be modified.

Peters, Palmer N.↗
NASA NTRS1992

Phase holograms in polymethyl methacrylate

A procedure is described for the fabrication of complex computer-generated phase holograms in polymethyl methacrylate (PMMA) by means of partial-exposure e-beam lithography and subsequent carefully controlled partial development. Following the development, the pattern appears (rendered in relief) in the PMMA, which then acts as the phase-delay medium. The devices fabricated were designed with 16 equal phase steps per retardation cycle, were up to 3 mm square, and consisted of up to 10 millions of 0.3-2.0-micron square pixels. Data files were up to 60 Mb-long, and the exposure times ranged to several hours. A Fresnel phase lens was fabricated with a diffraction-limited optical performance of 83-percent efficiency.

Maker, P. D.↗
NASA NTRS1992

Feasibility study of the use of synchrotron radiation in the calibration of AXAF - Initial reflectivity results

The 1-percent calibration accuracy goal of the Advanced X-ray Astrophysics Facility is being approached by way of an experiment at the National Synchrotron Light Source that will demonstrate the accuracy achievable in reflectance measurements conducted on coated flat mirrors in the 50 eV-12 keV energy range. The coatings will be of commercially produced Au, Ni, and Ir, deposited either by sputtering or by e-beam deposition. Optical constants will be estimated via the reflectance vs. angle-of-incidence method.

Graessle, D. E.↗