Development of Optical Window Material Database for Spaceflight Environments
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Terrelle Cadd↗
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Window Materials Design and Properties for Use in High Power Klystrons
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Bierce, R.↗
Effects of Electron Irradiation on Candidate Materials for Target Window in Accelerator-Driven Molybdenum-99 Production
NorthStar Medical technologies is planning to produce Mo-99 through the photo-nuclear reaction Mo-100 (γ,n) Mo-99 utilizing multiple high-power electron accelerators. In this approach, the production target consists of multiple thin disks of metal Mo-100 cooled by helium gas at high (300–400 psi) pressure [4]. The cost of enriched Mo-100 is on the order of $500 - 1,000 per gram, which makes a smaller target desirable and requires achieving the highest possible electron flux on the target. The heat deposition in the entrance window limits the maximum flux because the window separates the vacuum in the accelerator beam line from the high-pressure helium in the target and is only cooled on one side by the helium flow. Because the window is continuously under stress from the helium pressure and the heat from the electron beam, it is desirable to estimate a lifetime for the window and develop a replacement schedule for the target holder. Such an estimate requires the ability to predict changes in the window material properties under electron irradiation. Candidate materials for the Mo-99 production target window are Inconel 718, 250 maraging steel, and beryllium. These materials encompass a wide range of thermal conductivity, thermal expansion coefficients, Young’s modulus, tensile strength and tensile ductility. The Mo-99 target window is subjected to internal pressure from the helium coolant and thermal stresses. The operating conditions and relative advantages of each material have been described previously [1]. The current work investigates the effects of electron irradiation on the tensile properties of these materials. Axial tensile tests were conducted with electron-irradiated samples and results were compared to baseline results generated for as-fabricated materials.
36 MATERIALS SCIENCE↗
Innovative Glazing Materials
Windows have the unique capability of being able to achieve a net zero energy impact by admitting solar gains in the winter to offset thermal losses and admitting daylight to offset electric lighting. If rejection or admission of solar heat gains and daylight are appropriately timed, then heating, cooling and lighting energy use at the perimeter zone can be reduced to net zero energy levels. Nano-scale switchable coatings on glass have been developed to actively modulate solar intensity and spectral transmission. We provide a brief overview of these switchable glazing materials, discuss the desired performance objectives for such materials, and present results from recently completed monitored studies of state-of-the-art switchable windows, particularly with respect to occupant response and market factors. Careful application of state-of-the-art switchable windows and new material science developments on the horizon can deliver the desired net zero energy performance while meeting critical human factors and market related requirements.
Building energy efficiency↗
Effect of Window-Layer Materials on p-n Junction Location in Cu(In,Ga)Se 2 Solar Cells
We report on measurements of junction location in Cu(In,Ga)Se $_{2}$ (CIGS) solar cells with different window-layer materials by nm-resolution electrical potential/field profiling across the junction using Kelvin probe force microscopy imaging on cross-section of the devices. The results illustrate that the device with a CdS window layer (CdS/CIGS) has a buried homojunction located inside the CIGS absorber with ~40-nm junction depth, whereas the ZnOS/CIGS devices with and without partial electrolyte treatment prior to the window-layer deposition are similar, exhibiting a heterointerface junction. This junction location may contribute in part to the highest efficiency of the CdS/CIGS device among the three devices.
14 SOLAR ENERGY↗
Life test results for an ensemble of CO2 lasers
The effects of cathode material, cathode operating temperature, anode configuration, window materials, and hydrogen additives on laser lifetime are determined. Internally oxidized copper and silber-copper alloy cathodes were tested. The cathode operating temperature was raised in some tubes through the use of thermal insulation. Lasers incorporating thermally insulated silver copper oxide cathodes clearly yielded the longest lifetimes-typically in excess of 22,000 hours. The use of platinum sheet versus platinum pin anodes had no observable effect on laser lifetime. Similarly, the choice of germanium, cadmium telluride, or zinc selenide as the optical window material appears to have no impact on lifetime.
Peruso, C. J.↗
Insights into radiation resistance of titanium alloys from displacement cascade simulations
Radiation damage in beam window materials limits the use of high power proton beams in high energy physics research. The alloy Ti-6Al-4V is presently used as a beam window material but a prospective alternative, Ti-15V-3Cr-3Sn-3Al has been proposed. Since both these alloys contain dual phases at room temperature, we compare the radiation damage in the α and ß-phases of these two materials via primary knock-on atom (PKA) cascade simulations in the 10-40keV energy range. At PKA energies 30 and 40keV, the number of Frenkel pairs in the ballistic stage is higher in the ß-phase of Ti-6Al-4V than that in the ß-phase of Ti-15V-3Cr-3Sn-3Al almost by a factor of 2. The α-phase, of both these alloys, by far outperforms the ß-phases of the two alloys, both in terms of damage during the ballistic stage and in terms of the surviving defects. The average displacement threshold energy (E d ) in the α-phase of both alloys was found to be 66eV while that in the ß-phase of Ti-15-3 was 55 eV and in the ß-phase of Ti-6-4 was 46. Further, while the number of surviving defects is almost equal in both alloys, the vacancy and interstitial clustering mechanisms differ notably, which can impact the degree of radiation hardening and loss of ductility. Our simulations show larger vacancy and interstitial clusters form in Ti-6Al-4V as compared to that in Ti-15-3-3-3 alloy. These results indicate that Ti-15-3-3-3 alloys may be a promising candidate for next generation beam window material with a higher radiation tolerance than the existing Ti-6-4 alloy.
36 MATERIALS SCIENCE↗
High-temperature strain cell for tomographic imaging
This disclosure provides systems, methods, and apparatus related to the high temperature mechanical testing of materials. In one aspect, a method includes providing an apparatus. The apparatus may include a chamber. The chamber may comprise a top portion and a bottom portion, with the top portion and the bottom portion each joined to a window material. A first cooled fixture and a second cooled fixture may be mounted to the chamber and configured to hold the sample in the chamber. A plurality of heating lamps may be mounted to the chamber and positioned to heat the sample. The sample may be placed in the first and the second cooled fixtures. The sample may be heated to a specific temperature using the heating lamps. Radiation may be directed though the window material, the radiation thereafter interacting with the sample and exiting the chamber through the window material.
42 ENGINEERING↗
Effects of Kapton Sample Cell Windows on the Detection Limit of Smectite: Implications for CheMin on the Mars Science Laboratory Mission
The CheMin instrument on the Mars Science Laboratory (MSL) rover Curiosity is an X-ray diffraction (XRD) and X-ray fluorescence (XRF) instrument capable of providing the mineralogical and chemical compositions of rocks and soils on the surface of Mars. CheMin uses a microfocus X-ray tube with a Co target, transmission geometry, and an energy-discriminating X-ray sensitive CCD to produce simultaneous 2-D XRD patterns and energy-dispersive X-ray histograms from powdered samples. CheMin has two different window materials used for sample cells -- Mylar and Kapton. Instrument details are provided elsewhere. Fe/Mg-smectite (e.g., nontronite) has been identified in Gale Crater, the MSL future landing site, by CRISM spectra. While large quantities of phyllosilicate minerals will be easily detected by CheMin, it is important to establish detection limits of such phases to understand capabilities and limitations of the instrument. A previous study indicated that the (001) peak of smectite at 15 Ang was detectable in a mixture of 1 wt.% smectite with olivine when Mylar is the window material for the sample cell. Complications arise when Kapton is the window material because Kapton itself also has a diffraction peak near 15 Ang (6.8 deg 2 Theta). This study presents results of mineral mixtures of smectite and olivine to determine smectite detection limits for Kapton sample cells. Because the intensity and position of the smectite (001) peak depends on the hydration state, we also analyzed mixtures with "hydrated" and "dehydrated"h smectite to examine the effects of hydration state on detection limits.
Achilles, C. N.↗
Tensile behavior of dual-phase titanium alloys under high-intensity proton beam exposure: radiation-induced omega phase transformation in Ti-6Al-4V
A high-intensity proton beam exposure with 181 MeV energy has been conducted at Brookhaven Linac Isotope Producer facility on various material specimens for accelerator targetry applications, including titanium alloys as a beam window material. The radiation damage level of the analyzed capsule was 0.25 dpa at the beam center region with an irradiation temperature around 120 oC. Tensile tests showed increased hardness and a large decrease in ductility for the dual a+ß-phase Ti-6Al-4V Grade-5 and Grade-23 extra low interstitial alloys, with the near a-phase Ti-3Al-2.5V Grade-9 alloy still exhibiting uniform elongation of a few % after irradiation. Transmission Electron Microscope analyses on Ti-6Al-4V indicated clear evidence of a high-density of defect clusters with size less than 2 nm in each a-phase grain. The ß-phase grains did not contain any visible defects such as loops or black dots, while the diffraction patterns clearly indicated ?-phase precipitation in an advanced formation stage. The radiation-induced ?-phase transformation in the ß-phase could lead to greater loss of ductility in Ti-6Al-4V alloys in comparison with Ti-3Al-2.5V alloy with less ß-phase.google scho
Tensile Test, titanium, acclerator, proton beam↗
Nanostructured electrochromic smart windows: traditional materials and NIR-selective plasmonic nanocrystals
Electrochromic devices, which dynamically change colour under applied potential, are widely studied for use in energy-efficient smart windows. To improve the viability of smart windows, many researchers are utilizing nanomaterials, which can provide electrochromic devices with improved colouration efficiencies, faster switching times, longer cycle lives, and potentially reduced costs. In an effort to demonstrate a new type of electrochromic device that goes beyond the capabilities of commonly used electrochromic materials, researchers have turned to plasmonic transparent conductive oxide (TCO) nanocrystals. Electrochemical injection of electrons into plasmonic TCO nanocrystal films induces a shift in the plasmon frequency and gives rise to the new functionality of selective optical modulation in the near-infrared region of the solar spectrum. These nanocrystals can be used as building blocks to enable creation of advanced electrochromic devices containing mesoporous electrodes or nanocrystal-in-glass composites. Such devices have been important in advancing the field towards achieving the ideal smart window with independent control over visible and NIR transmittance.
Runnerstrom, EL↗
Development of Gen-II LAPPD TM Systems For Nuclear Physics Experiments
The technical objectives of this Phase I program were to; Demonstrate proof of concept of a pin-free pixelated readout using an inside-out approach. “Inside-out” is a novel approach for having the ground plane on the inside (floor of the anode facing the MCP stack-up) and anode pads on the outside of the LAPPD. The goal is a demonstration of capacitive coupling through the bottom anode plate (9.02 x 8.66”), using ceramic, and, optionally, glass tile components; Develop a ceramic package or Lower Tile Assembly (LTA) consisting of hermetically sealing a ceramic sidewall to a ceramic anode producing a single unit capable of housing the MCP stack up enabling development of a Gen II LAPPDTM having low loss, high bandwidth and mechanical robustness. The ceramic bodies used in this Task will be the same as in Task 1 and Task 3. Our goal was to work with commercial suppliers to economically fabricate the ceramic components; Evaluate alternative LAPPD top window materials to determine compatibility in sealing to the ceramic sidewall described in Task 2. Concurrently we will specify and select an alloy seal material suitable for sealing the top window to the sidewall, and we will perform sealing trials of these components; Demonstrate electrical characteristics of the inside-out anode in the detector context, the seal integrity of the bonded two-piece ceramic lower tile assembly (LTA) as well as the hermetic seal quality of the window to the sidewall; and Secure at least one specific NP, HEP or commercial application for a Gen II LAPPDTM enabled by this technology to be developed in Phase II.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Lasergate: A windowless gas target for enhanced laser preheat in magnetized liner inertial fusion
At the Z Facility at Sandia National Laboratories, the magnetized liner inertial fusion (MagLIF) program aims to study the inertial confinement fusion in deuterium-filled gas cells by implementing a three-step process on the fuel: premagnetization, laser preheat, and Z-pinch compression. In the laser preheat stage, the Z-Beamlet laser focuses through a thin polyimide window to enter the gas cell and heat the fusion fuel. However, it is known that the presence of the few μm thick window reduces the amount of laser energy that enters the gas and causes window material to mix into the fuel. These effects are detrimental to achieving fusion; therefore, a windowless target is desired. The Lasergate concept is designed to accomplish this by “cutting” the window and allowing the interior gas pressure to push the window material out of the beam path just before the heating laser arrives. In this work, we present the proof-of-principle experiments to evaluate a laser-cutting approach to Lasergate and explore the subsequent window and gas dynamics. Further, an experimental comparison of gas preheat with and without Lasergate gives clear indications of an energy deposition advantage using the Lasergate concept, as well as other observed and hypothesized benefits. While Lasergate was conceived with MagLIF in mind, the method is applicable to any laser or diagnostic application requiring direct line of sight to the interior of gas cell targets.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Arcjet exploratory tests of ARC optical window design for the AFE vehicle
Tests were made in the 20 MW arc jet facility at the NASA ARC to determine the suitability of sapphire and fused silica as window materials for the Aeroassist Flight Experiment (AFE) entry vehicle. Twenty nine tests were made; 25 at a heating rate about 80 percent of that expected during the AFE entry and 4 at approximately the full, 100 percent AFE heating rate profile, that produces a temperature of about 2900 F on the surface of the tiles that protect the vehicle. These tests show that a conductively cooled window design using mechanical thermal contacts and sapphire is probably not practical. Cooling the window using mechanical thermal contacts produces thermal stresses in the sapphire that cause the window to crack. An insulated design using sapphire, that cools the window as little as possible, appears promising although some spectral data in the vacuum-ultra-violet (VUV) will be lost due to the high temperature reached by the sapphire. The surface of the insulated sapphire windows, tested at the 100 percent AFE heating rate, showed some slight ablation, and cracks appeared in two of three test windows. One small group of cracks were obviously caused by mechanical binding of the window in the assembly, which can be eliminated with improved design. Other cracks were long, straight, thin crystallographic cracks that have very little effect on the optical transmission of the window. Also, the windows did not fall apart along these crystallographic cracks when the windows were removed from their assemblies. Theoretical results from the thermal analysis computer program SINDA indicate that increasing the window thickness from 4 to 8 mm may enable surface ablation to be avoided. An insulated design using a fused silica window tested at the nominal AFE heating rate experienced severe ablation, thus fused silica is not considered to be an acceptable window material.
Whiting, Ellis E.↗
Reduced-scale hot box method for thermal characterization of window insulation materials
Not provided.
Energy & Fuels↗
Dynamic Interface Instabilities as a Window into Material Behavior.
Abstract not provided.
Vogler, Tracy↗
Dynamic Interface Instabilities as a Window into Material Behavior.
Abstract not provided.
Vogler, Tracy↗
Detectivity enhancement in THz electrooptical sampling
We demonstrate and discuss a simple scheme that significantly enhances the detectivity of THz electro-optical sampling by introducing a sequence of Brewster windows that increases the ellipticity of the probe beam. By varying the window material or the number of Brewster windows, the enhancement factor can be adjusted; we demonstrate an enhancement factor of ≈20 with four ZnSe Brewster windows. The scheme is particularly useful when very small THz fields are to be measured in connection with low-repetition rate amplified Ti:S laser systems.
43 PARTICLE ACCELERATORS↗