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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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Compact TDLAS based sensor design using interband cascade lasers for mid-IR trace gas sensing
Not Available
Adaptive control of laser-wakefield accelerators driven by mid-IR laser pulses
There has been growing interest both in studying high intensity ultrafast laser plasma interactions with adaptive control systems as well as using long wavelength driver beams. We demonstrate the coherent control of the dynamics of laser-wakefield acceleration driven by ultrashort (~ 100 fs) mid-infrared (~ 3.9 μ m) laser pulses. The critical density at this wavelength is 7.3 × 10 19 cm -3 , which is achievable with an ordinary gas target system. Interactions between mid-infrared laser pulses and such near-critical-density plasma may be beneficial due to much higher absorption of laser energy. In addition, the normalized vector potential of the laser field a 0 increases with longer laser wavelength, lowering the required peak laser intensity to drive non-linear laser-wakefield acceleration. Here, MeV level, collimated electron beams with non-thermal, peaked energy spectra are generated. Optimization of electron beam qualities are realized through adaptive control of the laser wavefront. A genetic algorithm controlling a deformable mirror improves the electron total charge, energy spectra, beam pointing and stability at various plasma density profiles. Particle-in-cell simulations reveal that the optimal wavefront causes an earlier injection on the density up-ramp and thus higher energy gain as well as less filamentation during the interaction, which leads to the improvement in electron beam collimation and energy spectra.
Continuous wave Fe[superscript 2+]:ZnSe mid-IR optical fiber lasers
Abstract not provided
Effect of heating/cooling dynamics in the hysteresis loop and tunable IR emissivity of VO 2 thin films
We experimentally investigate the semiconductor-to-metal transition (SMT) in vanadium dioxide thin films using an infrared thermographic technique. During the semiconductor to metal phase change process, VO 2 optical properties dynamically change and infrared emission undergoes a hysteresis loop due to differences between heating and cooling stages. The shape of the hysteresis loop was accurately monitored under different dynamic heating/cooling rates. In order to quantify and understand the effects of different rates, we used a numerical modelling approach in which a VO 2 thin layer was modeled as metamaterial. The main experimental findings are interpreted assuming that both the rate of formation and shape of metallic inclusions are tuned with the heating/cooling rate. The structural transition from monoclinic to tetragonal phases is the main mechanism for controlling the global properties of the phase transition. However, our experimental results reveal that the dynamics of the heating/cooling process can become a useful parameter for further tuning options and lays out a macroscopic optical sensing scheme for the microscopic phase change dynamics of VO 2 . Our study sheds light on phase-transition dynamics and their effect on the infrared emission spectra of VO 2 thin films, therefore enabling the heating/cooling rate to be an additional parameter to control infrared emission characteristics of thermal emitters. The hysteresis loop represents the phase coexistence region, thus being of fundamental importance for several applications, such as the operation of radiative thermal logic elements based on phase transition materials. For such applications, the phase transition region is shifted for heating and cooling processes. We also show that, depending on the way the phase change elements are heated, the temperature operation range will be slightly modified.
Probing ultrafast excited-state dynamics using EUV-IR six-wave-mixing emission spectroscopy
Non-linear processes such as four-wave-mixing have become instrumental in attosecond EUV spectroscopy. Using EUV high harmonics in conjunction with collinear near-infrared and mid-infrared fields, we extended this approach to high-order-mixing between three colors. Specifically, we find that atomic resonances in neon exhibit a significant cross section for six-wave mixing. The MIR probe frequency tunability in our multicolor scheme is employed to access several optically dark resonances and probe the quantum beat of a coherent electronic wavepacket using background-free EUV emission as a diagnostic. This technique can be easily extended to other atomic and molecular systems, and opens the door to multi-dimensional non-linear spectroscopy.
Compact, ultrastable, high repetition-rate 2 μm and 3 μm fiber laser for seeding mid-IR OPCPA
We report a compact and reliable ultrafast fiber laser system optimized for seeding a high energy, 2 μ m pumped, 3 μ m wavelength optical parametric chirped pulse amplification to drive soft X-ray high harmonics. The system delivers 100 MHz narrowband 2 μ m pulses with >1 nJ energy, synchronized with ultra-broadband optical pulses with a ∼1 μ m FWHM spectrum centered at 3 μ m with 39 pJ pulse energy. The 2 μ m and 3 μ m pulses are derived from a single 1.5 μ m fiber oscillator, fully fiber integrated with free-space downconversion for the 3 μ m. The system operates hands-off with power instabilities <0.2% over extended periods of time.
Synthesis, IR spectroscopy and crystal structure of [(UO 2 ) 2 {Be(H 2 O) 2 (PO 4 ) 2 }]·(H 2 O), the first compound with a trimer beryllophosphate anion
The first uranyl beryllophosphate, [(UO 2 ) 2 {Be(H 2 O) 2 (PO 4 ) 2 }]·(H 2 O), has been synthesized under hydrothermal conditions at 200°C. The monoclinic unit-cell parameters are: a =9.3361(1), b =8.8545(4), c =9.6592(10) Å, β=93.211(1)°, V =797.21(6) Å 3 , space group P 2 /n , Z =2. The crystal structure has been solved by direct methods and refined to final R 1 = 4.92% using 1294 I > 3σ( I ) reflections in the anisotropic approximation. The structure consists of sheets of Ur O 5 pentagonal bipyramids and PO 4 tetrahedra. Ur O 5 bipyramids are linked by edge-sharing to form infinite chains. Adjacent chains of Ur O 5 bipyramids are connected by sharing alternating edges of uranyl bipyramids with PO 4 tetrahedra. The resulting sheets are based on the well-known uranophane anion-topology. Be atoms are tetrahedrally coordinated by two oxygen atoms of PO 4 tetrahedra and two water molecules in the interlayer space. One isolated water molecule also occurs in the interlayer space, where it is held in position by H bonds. The connection between the phosphorus and beryllium tetrahedra leads to formation of an unbranched trimer [BeP 2 O 8 (H 2 O) 2 ] 4- observed for the first time in inorganic oxysalts.
Summary of the Optics, IR, Injection, Operations, Reliability and Instrumentation Working Group
The facilities reported on are all in a fairly mature state of operation, as evidenced by the very detailed studies and correction schemes that all groups are working on. First- and higher-order aberrations are diagnosed and planned to be corrected. Very detailed beam measurements are done to get a global picture of the beam dynamics. More than other facilities the high-luminosity colliders are struggling with experimental background issues, mitigation of which is a permanent challenge. The working group dealt with a very wide rage of practical issues which limit performance of the machines and compared their techniques of operations and their performance. We anticipate this to be a first attempt. In a future workshop in this series, we propose to attempt more fundamental comparisons of each machine, including design parameters. For example, DAΦNE and KEKB employ a finite crossing angle. The minimum value of β* y attainable at KEKB seems to relate to this scheme. Effectiveness of compensation solenoids and turn-by-turn BPMs etc. should be examined in more detail. In the near future, CESR-C and VEPP-2000 will start their operation. We expect to hear important new experiences from these machines; in particular VEPP-2000 will be the first machine to have adopted round beams. At SLAC and KEK, next generation B Factories are being considered. It will be worthwhile to discuss the design issues of these machines based on the experiences of the existing factory machines.
Solar Energy Windows and Smart IR Switchable Building Technologies
The three building envelope functions with the largest impact on the energy usage are illumination, energy flux and energy production. In general, these three functions are addressed separately in the building design. A step change toward a zero-energy building can be achieved with a glazing system that combines these three functions and their control into a single unit. In particular, significant value could be realized if illumination into the building is dynamically controlled such that it occurs during periods of low load on the grid (e.g., morning) to augment illumination supplied by interior lights and then to have that same light diverted to PV energy production and the thermal energy rejected during periods of high load on the grid. The objective of this project is to investigate the feasibility of a glazing unit design that integrates these three key functions (illumination and energy flux control, and power production) into a single module.
Time-Resolved Quantitative Measurement of OH HO2 and CH2O in Fuel Oxidation Reactions by High Resolution IR Absorption Spectroscopy.
Combined with a Herriott-type multi-pass slow flow reactor, high-resolution differential direct absorption spectroscopy has been used to probe, in situ and quantitatively, hydroxyl (OH), hydroperoxy (HO 2 ) and formaldehyde (CH 2 O) molecules in fuel oxidation reactions in the reactor, with a time resolution of about 1 micro-second. While OH and CH 2 O are probed in the mid-infrared (MIR) region near 2870nm and 3574nm respectively, HO 2 can be probed in both regions: near-infrared (NIR) at 1509nm and MIR at 2870nm. Typical sensitivities are on the order of 10 10 - 10 11 molecule cm -3 for OH at 2870nm, 10 11 molecule cm -3 for HO 2 at 1509nm, and 10 11 molecule cm -3 for CH 2 O at 3574nm. Measurements of multiple important intermediates (OH and HO 2 ) and product (CH 2 O) facilitate to understand and further validate chemical mechanisms of fuel oxidation chemistry.
Synergistic Chem-Bio Detection/Classification Combining UV LIF and IR LIDAR (SV)
The objective of this project was to determine if adding data products from Sandia’s Ares laser-induced fluorescence (LIF) system to those from Lockheed Martin Coherent Technologies’ Prototype WANDER Laser Radar (PROWLR) system produces an overall system with an improved ability to discriminate between aerosol-dispersed surrogates of chemical and biological agents and aerosol-dispersed background materials such as dust and smoke from burning wood, diesel fuel, and other common materials. The results of this work demonstrate that the addition of LIF information to PROWLR information significantly improves discrimination performance with respect to either LIF-only or PROWLR-only performance. The primary improvement is a dramatic improvement in false positive, where the best-performing combination of LIF/PROWLR data products improved false positive performance to 6.4% from 20.6% (PROWLR-only) and 11% (LIF-only). It is important to note that the improvement in false positive performance does not come at the expense of true positive performance which remains high at 93%. Sandia, DOE, and the government have benefitted from this project by building capabilities generating supervised machine learning and also in working closely and building professional relationships with private industry partners. Sandia’s CRADA partner benefitted by utilizing Sandia’s expertise to help accomplish work that will be beneficial to their business prospects in the future by allowing the knowledge gained by the CRADA interaction to provide them with a differentiating capability from potential competitors. The public and taxpayers will ultimately benefit from the knowledge has been gained that can be applied for public safety purposes in terms of producing systems with improved capabilities to detect threats to the public from the deployment of chemical and/or biological weapons.
IR Imaging of PDMS Degradation Thin Films on Metal Surfaces
The degradation of poly[dimethyl siloxane] (PDMS) fluids at metal surfaces can produce insulative PDMS films (also known as SiCO films) that lead to high contact resistance events impacting the performance of electrical contacts in PDMS fluid-filled environmental sensing devices(ESDs). To determine the extent of SiCO film formation on metal contact surfaces due to different exposure and aging conditions it is necessary to develop new characterization methods that allow rapid and non-destructive measurement of the location, thickness and quality of the SiCO degradation films.
Thrust #3: Simulation and Measurement of Bio-enabled Lensless Infrared Focusing and Spatially-Controlled Multiwavelength IR reflection
The path to quantitatively characterizing the possible impact of refractive index on the focusing behavior of C. Wailesii diatoms frustules and their replicas first required the careful design of a control experiment that allowed for judicious control of both material and hole pattern variables, which are thought to govern focusing behavior. This was accomplished by FIB-milling synthetic hole patterns with well-controlled dimensions into thin SiO 2 and MgO/Si films. In doing so, an ideal sample is obtained whose pore patterns can be simulated via beam propagation methods and whose relatively simple interference patterns can be measured by far-field diffraction imaging. Together with refractive index measurements via ellipsometry on SiO 2 and MgO/Si thin films, these results showed that the focusing distances at six different wavelengths over 550-1050 nm are strongly correlated with the dispersion of the refractive index in this range. Although assertions have been made to this point in the literature, the results given here presented an improved characterization of the role that refractive index played in focusing behavior in a “diatom-like” hole pattern that otherwise is missing in earlier works due to inadequate characterization of refractive index dispersion and poor control over hole pattern dimensions. These results provided a reference point with which measurements and simulations of diatoms and their replicas can be compared.
Simulations of the IR and Raman spectra of water confined in amorphous silica slit pores.
Abstract not provided.
ELIC Detector and IR design including current R&D
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MAP 3 TeV Lattice and IR Design Studies
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