SIM Test-bed 3 real-time control software
This paper describes the design of interacting software control loops and how they work together to accomplish SIM System Testbed 3 objectives.
SIM SIM System Testbed 3 STB3 real-time avalanche ↗
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Results for “Sim”
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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SIM Configuration Evolution
The Space Interferometry Mission (SIM) is a space-based 10 m baseline Michelson interferometer.
Space↗
ToF-SIMS Analysis of Chemical Composition of Atmospheric Aerosols in Beijing
Atmospheric aerosols collected from each season in urban Beijing have been studied using time-of-flight secondary ion mass spectrometry (ToF-SIMS). The chemical composition of atmospheric aerosol particles during various atmospheric pollution levels were analyzed and distinguished by principal component analysis (PCA). The differences and sources of the components of the aerosol particles were explored. The results showed that the fine particulate matter from heavily polluted days mainly consists of inorganic salts and organic compounds, such as hydrocarbons, nitrogen- or sulfur-containing hydrocarbons, and their oxides. Samples collected from clean days in the four seasons were also analyzed. Only the samples collected in spring showed a significant difference from the other three seasons. We concluded that the main source of pollution in the Beijing urban area was fossil fuel combustion from motor vehicles.
ToF-SIMS, principal component analysis↗
SIMS and HR-XPS characterization of lithiated graphite from the magnetic fusion device RFX-mod
Lithium wall conditioning has improved the performance of many magnetic fusion devices. Li conditioning in the RFX-mod device was performed by: (1) a single Li pellet injector and (2) a multi-Li pellet injector during He plasma discharges; (3) a Li evaporator after He glow discharge cleaning and He plasma discharge exposure. This report compares the spatial and depth distributions of Li deposited on polycrystalline graphite witness samples at different locations in RFX-mod and the elemental and chemical compositions of the resulting surfaces. The sample surfaces were analyzed ex situ using secondary ion mass spectrometry (SIMS) and high-resolution X-ray photoelectron spectroscopy (HR-XPS). The results showed that Li pellet injection provided a relatively uniform toroidal coverage while Li evaporation produced highly localized Li deposition. A Li 1s HR-XPS peak at 56.5 eV binding energy (BE) characteristic of lithium-intercalated graphite was only observed with the sample exposed to Li evaporation. All of the samples exhibited a HR-XPS C 1s peak at 285.1–285.2 eV BE that is largely attributed to hydrogenated graphite. This finding suggests that hydrogenation of fresh graphite occurs during He plasma discharge exposures. Finally, our results have implications for density control and the selection of Li conditioning techniques in magnetic fusion devices.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Sources of Li isotope bias during SIMS analysis of standard glasses
The 7 Li/ 6 Li ratios in fourteen USGS, MPI-DING, and NIST glass reference materials (RMs) were analyzed by LG-SIMS to assess compositional matrix effects, evaluate RM δ 7 Li homogeneity, and calculate the useful yield of lithium in silicate glasses. The analyzed RMs cover a range of SiO 2 contents from 45.5 to 75.6% (komatiite to rhyolite), the largest compositional range yet evaluated for δ 7 Li matrix effects. We observe a matrix-induced bias (matrix effect) of up to 18‰ over the studied range that linearly correlates with SiO 2 content, demonstrating that SiO 2 content is a critical factor that must be considered when using silicate glasses to standardize for silicate samples of unknown δ 7 Li composition. All RMs were found to be sufficiently reproducible to aid in standardization of variable SiO 2 contents and appear isotopically homogeneous at the precision of our measurements. Lithium ionizes very efficiently in these RMs, with measurable yields >5% in all fused-rock RMs and >15% in low SiO 2 fused-rock RMs measured at high beam intensities. Finally, fused-rock RMs ionize lithium 2-3x more efficiently than synthetic glass RMs, which may be related to differences in major oxide chemistry and the reduced nature of the synthetic glasses relative to their fused counterparts.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Direct observation of key aluminum hydroxide prenucleation oligomers for gibbsite nucleation and crystallization in sodium aluminate solution by liquid ToF-SIMS
The mechanism of gibbsite (aluminum hydroxide) crystallization from highly alkaline solutions such as Bayer liquors remains poorly understood, where aluminum (Al) transforms from largely tetrahedrally coordinated aluminate monomers in sodium aluminate solutions into a network of octahedra in gibbsite crystals. A variety of traditional analytical approaches applied to this system do not readily reveal the presence of higher-order oligomeric intermediates. To overcome this limitation, we employed in-situ liquid Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) to examine the Al species present in concentrated sodium aluminate solutions favoring crystallization of gibbsite or sodium aluminate. A complex mixture of Al oligomers was found. By comparing the change in the relative concentration of Al oligomers with +1 and -1 charge, we were able to identify three major Al oligomer candidates, iso-tetramers, iso-pentamers, and cyclic-hexamers, for the nucleation and crystallization of gibbsite. The concentrations of iso-tetramers and iso-pentamers significantly surpass those of cyclic-hexamers. Time-dependent in-situ Raman spectroscopy analysis indicated that the appearance of gibbsite coincided with the peak concentration of these oligomers. The Density-functional theory (DFT) calculation suggests that the formation of iso-oligomers is more favorable than that of cyclic-hexamers. The combined results suggest that iso-tetramers and iso-pentamers play the most substantial role in the nucleation and growth of gibbsite in the sodium aluminate solutions. Our findings also suggest that the oligomers that promote gibbsite crystallization are more stable in dilute sodium aluminate solutions, making these solutions particularly suitable for efficient gibbsite crystallization. In conclusion, our study fills a major knowledge gap in understanding Al speciation that leads to the nucleation and crystallization of gibbsite in concentrated sodium aluminate solutions.
Bayer liquor↗
Rapid Screening of Single-Atom Catalyst Synthesis Conditions Using ToF-SIMS and Facet-Dependent Single-Crystal Substrates
Single-atom catalysts (SACs) offer superior catalytic performance compared to traditional nanoparticle catalysts but are challenging to develop because of the need for extensive optimization and specialized characterization techniques. Here, this study presents a rapid and versatile method for detecting synthesis conditions and elucidating deposition mechanisms of SACs on various substrates. By depositing active elements (Au, Cu, Ni and Rh) on facet-specific single-crystalline substrates (CeO 2 , TiO 2 , MgO and Al 2 O 3 ) and employing time-of-flight secondary ion mass spectroscopy (ToF-SIMS), we assessed facet-dependent deposition behaviors and identified optimal conditions for solution-based SAC synthesis. On CeO 2 and TiO 2 , we confirmed facet-dependent deposition, primarily influenced by oxygen vacancy density and photocatalytic activity, respectively. MgO exhibited the formation of metal oxide/hydroxide clusters for all active elements, and the degree of clustering for Cu and Ni was correlated with the facet hydrolysis susceptibility. Notably, Au and Rh deposition on MgO was facet-independent, attributed to the formation of hydroxide species in solution. Al 2 O 3 , due to its chemical stability and lack of surface defects, did not show active element deposition. This study not only provides a time and cost-efficient method for prescreening SAC synthesis conditions, but it also provides valuable insights into the various deposition mechanisms governing SAC formation on different substrates, paving the way for the rational design of tailored SACs for various catalytic applications.
ToF-SIMS↗
Solar Energy from a Big Picture Perspective to Nanoscale Insights via TOF-SIMS
The world is undergoing a rapid transformation in the ways that we generate and store energy. This has been driven not only by concerns about the climate but by simple economic factors due to the dramatic cost decreases in wind in solar power. In most places of the world where one would now want to build a new power plant, the cheapest option is to use wind of solar for power generation. Abundant clean energy when the sun shines most is driving new research for daily and seasonal energy storage in many different technologies. Here, we will briefly these discuss energy trends as a whole, before diving into our recent contributions to the field using time-of-flight secondary-ion mass spectrometry (TOF-SIMS) to improve the performance and reliability of solar cells.
14 SOLAR ENERGY↗
SIM astrometric demonstration at the 150 picometer level using the MAM testbed
This paper describes the MAM optical setup, the alignment process, the current data and how the performance relates to SIM.
interferometry SIM picometers metrology astrometry↗
SIM grid verification program RFP
The objective of this program is to verify the astrometric stability of a catalog of stars to be used as the reference grid for SIM's wide-angle astrometric science.
SIM grid RFP↗
Combined feed-forward and feed-back control for dim star fringe tracking on the SIM Test-bed 3
This paper will describe the STB3 setup, the pathlength control architecture and the data collected with the system and how they relate to SIM.
interferometry SIM optics control feed-forward↗
SIM PlanetQuest: Status and Recent Progress
The SIM project is approaching the end of its technology development phase. With the successful completion of a number of testbeds, including micro-arcsecond stellar interferometry, picometer optical truss metrology, and milli-kelvin thermo-optical characterization, the project is now on a sure footing for the development of requirement for the flight instrument. Here we review the latest technological progress and give a status of the project.
astrometry↗
SIM PlanetQuest: The TOM-3 (Thermo-Optical-Mechanical) Siderostat Mirror Test
This slide presentation reviews the Space Interferometry Mission (SIM) PlanetQuest mission. It describes the mission, shows diagrams of the instrument, the collector bays, the Siderostat mirrors, the COL bay thermal environment, the TOM-3 replicating COL Bay Environment, the thermal hardware for the SID heater control, and the results of the test are shown
Space Interferometry Mission (SIM)↗
Description of a proposed on-orbit calibration procedure for SIM based on spacecraft maneuver
The astrometric performance of the Space Interferometry Mission relies on precise measurements of the optical pathlength difference of the starlight through the arms of the interferometers that comprise the SIM instrument, and on precise relative distance between a set of fiducials that define the baselines of the interferometers.
SIM↗
Space Interferometry Mission (SIM) thermal design
This paper will describe how the SIM thermal control designers have addressed some of these very challenging requirements.
SIM↗
SIM science operations
This paper describes the science scheduling and operation of the Space Interferometry Mission (SIM) as a science instrument
SIM↗
Alignment of the MAM testbed to enable micro-arcsecond astrometry performance for SIM
This paper describes the MAM optical setup, the alignment process, the contribution of the fine alignment to the final performance and how they relate to SIM.
interferometry↗
Optical Design of the SIM System Testbed 3
The SIM system testbed III is a full 3-baseline interferometer mounted on a full-scale flexible structure developed at the Jet Propulsion Laboratory under the Interferometry Technology Program.
interferometry↗