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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 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Dark Matter Velocity Distributions for Direct Detection: Astrophysical Uncertainties Are Smaller Than They Appear

The sensitivity of direct detection experiments depends on the phase-space distribution of dark matter near the Sun, which can be modeled theoretically using cosmological hydrodynamical simulations of Milky Way–like galaxies. However, capturing the halo-to-halo variation in the local dark matter speeds—a necessary step for quantifying the astrophysical uncertainties that feed into experimental results—requires a sufficiently large sample of simulated galaxies, which has been a challenge. In this Letter, we quantify this variation with nearly 100 Milky Way–like galaxies from the tng50 simulation, the largest sample to date at this resolution. Moreover, we introduce a novel phase-space scaling procedure that endows every system with a reference frame that accurately reproduces the local standard-of-rest speed of our Galaxy, providing a principled way of extrapolating the simulation results to real-world data. The ensemble of predicted speed distributions is well characterized by the standard halo model, a Maxwell-Boltzmann distribution truncated at the escape speed, though the individual distributions can deviate from it, especially at high speeds. The dark matter–nucleon cross section limits placed by these speed distributions vary by ∼ 60% about the median. This places the 1⁢𝜎 astrophysical uncertainty at or below the level of the systematic uncertainty of current ton-scale detectors, even down to the energy threshold. The predicted uncertainty remains unchanged when subselecting on those TNG 50 galaxies with merger histories similar to the Milky Way. Tabulated speed distributions, as well as Maxwell-Boltzmann fits, are provided for use in computing direct detection bounds or projecting sensitivities.

Milky Way↗
DOE OSTI2024

Fail-Safe Logic Design Strategies Within Modern FPGA Architectures

Fail-safe computing refers to computing systems that revert to a non-operational safe state when a fault occurs. In this paper, we investigate a circuit level technique as mitigation for single event upsets (SEUs) and fault injection attacks on field programmable gate arrays (FPGAs), and analyze the effectiveness of the technique as a fail-safe monitor for an encryption algorithm. The propagation of fault effects through FPGA primitives including lookup tables (LUTs) and programmable interconnect points (PIPs) is assessed within an FPGA architecture created using an open source tool, and validated using fault injection experiments on an FPGA. The analysis reveals additional vulnerabilities exist within reconfigurable architectures over those in equivalent fail-safe application specific integrated circuit (ASIC), thus requiring a more elaborate network of redundant circuits and checking logic. The configuration memory bits (CMBs), which configure routing and designate logic functions within the LUTs of the FPGA, add complexity to fail-safe design strategies by introducing additional fault conditions and fault propagation paths. A resource-efficient fail-safe circuit design technique called DEsign for Fail-safe in reCONfigurable systems (DEFCON) is proposed. The benefits and limitations associated with DEFCON are described in the context of fault injection experiments carried out as simulations and in FPGA hardware.

Bhakta, Priya A. [Univ. of New Mexico, Albuquerque↗
DOE OSTI2016

SU-F-T-525: Monitordeep-Inspiratory Breathhold with a Laser Sensor for Radiation Therapy of Left Breast Cancer

Purpose: Radiation therapy (RT) of left sided breast cancers with deep-inspiratory breathhold (DIBH) can reduce the dose to heart. The purpose of this study is to develop and test a new laser-based tool to improve ease of RT delivery using DIBH. Methods: A laser sensor together with breathing monitor device (Anzai Inc., Japan) was used to record the surface breathing motion of phantom/volunteers. The device projects a laser beam to the chestwall and the reflected light creates a focal spot on a light detecting element. The position change of the focal spot correlates with the patient’s breathing motion and is measured through the change of current in the light detecting element. The signal is amplified and displayed on a computer screen, which is used to trigger radiation gating. The laser sensor can be easily mounted to the simulation/treatment couch with a fixing plate and a magnet base, and has a sensitivity range of 10 to 40 cm from the patient. The correlation of breathing signals detected by laser sensor and visionRT is also investigated. Results: It is found that the measured breathing signal from the laser sensor is stable and reproducible and has no noticeable delay. It correlates well with the VisionRT surface imaging system. The DIBH reference level does not change with movement of the couch because the laser sensor and couch move together. Conclusion: The Anzai laser sensor provides a cost-effective way to improve beam gating with DIBH for treating left breast cancer. It can be used alone or together with VisionRT to determine the correct DIBH level during the radiation treatment of left breast cancer with DIBH.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

TH-AB-202-07: Radar Tracking of Respiratory Motion in Real Time

Purpose: To propose a method of real time tracking of respiratory motion in patients undergoing radiation therapy. Radar technology can be employed to detection the movement of diaphragm and thoracic anatomy. Methods: A radar transceiver was specially designed. During experiment, the radar device was securely attached to a fixed frame. Respiratory motion was simulated with: 1) Varian RPM phantom, 2) Standard Imaging Respiratory Gating Platform. Signals recorded with radar equipment were compared with those measured with Varian RPM system as a reference. Results: Motion generated by Varian RPM phantom was recorded by the radar device, and compared to the signals recorded by RPM camera. The results showed exact agreement between the two monitoring equipments. Motion was also generated by Standard Imaging Respiratory Motion Platform. The results showed the radar device was capable of measuring motion of various amplitudes and periods. Conclusion: The proposed radar device is able to measure movements such as respiratory motion. Compared to state-of-the-art respiratory detection instrument, the radar device is shown to be equally precise and effective for monitoring respiration in radiation oncology patients.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Distributed fiber sensing systems for 3D combustion temperature field monitoring in coal-fired boilers using optically generated acoustic waves (Final Report)

In this project, we have developed and tested three kinds of fiber optic sensing systems for real time monitoring of temperature variations within an industrial scale boiler furnace. The fiber optic sensing systems target spatial and temporal distributions of high temperature profiles in a boiler furnace in fossil power plants. The reconstructed temperature profile will provide critical input for the control mechanisms to optimize the combustion process. This temperature profile will address the essential problem for fossil power plants in achieving higher efficiency and fewer pollutant emissions. Acoustic pyrometer systems have been used to reconstruct temperature field of power plant boilers based on measuring TOF (times-of-flight) of sound waves along some straight paths in a 2D cross-section of the boiler. In this project, optically generated acoustic signals from a fiber optic sensing system have replaced the acoustic signals generated from an electrical transducer. A 3D reconstruction algorithm replaced the previous 2D model. In this project, three kinds of fiber optic sensing systems have been developed and tested. They are fiber optic sensing system I, fiber optic sensing system II (Distributed Sensing System I) and fiber optic sensing system III (Distributed Sensing System II). For fiber optic sensing system I, the fiber optic ultrasound generator acts as a signal generator. A microphone, hydrophone or other electronic devices serve as a signal receiver. In this system, there are one generator and one receiver. Distance test, water temperature test, air temperature test, air temperature reconstruction, and GE ISBF pilot test were performed by Fiber optic sensing system I. The fiber optic sensing system I successfully detected temperature in all these tests. We got 2D temperature reconstruction results by using the fiber optic sensing system I and it matched the reference data. The fiber optic sensing system I successfully survived in GE ISBF boiler environment (480 °F). For fiber optic sensing system II (Distributed Sensing System I), it is an all optical ultrasound system. The fiber optic ultrasound generator acts as a signal generator. Fiber Bragg Grating (FBG) and Fabry-Perot (FP) sensor act as a signal receiver. In this system, there is one generator and one receiver. Aluminum plate temperature test, furnace high temperature test, and GE ISBF pilot test were performed by the fiber optic sensing system II. Fiber optic sensing system II successfully detected the temperature in all these tests. The fiber optic sensing system II successfully survived at up to 700 °C furnace environment and 320 °C GE ISBF boiler environment. For fiber optic sensing system III (Distributed Sensing System II), it is also an all optical ultrasound system. The fiber optic ultrasound generator acts as a signal generator. Multiple FP fiber sensors act as signal receivers. In this system, there is one generator and three receivers. Three GE ISBF pilot tests were performed by fiber optic sensing system III. The fiber optic sensing system III survived in the cold flow tests in GE’s ISBF pilot test facility. However, we didn’t get high temperature data by using this system since the nanosecond laser issues. During the period of the project, test trials, data simulation and algorithm optimization was performed successfully. For real time temperature field construction, the sampling rate must be fast enough to capture the field variations. The technology of Code-division multiple access (CDMA) is well studied which could allow parallel multiplexing, even if signals overlap in time or frequencies. Moreover, it has been known that extending the length of signal significantly improves SNR. For acoustic signals, these multiplexing techniques have also been widely used, mainly for sonar and acoustic communications. The CDMA modulation technique has been proposed and studied to guarantee high network throughput, low channel access delay and low energy consumption. We have studied the temperature field reconstruction using Gaussian Radial Basis Functions (GRBF)-based approximation approach. Reconstruction of 3D temperature field using Neural Networks with measured TOF and known propagation paths is feasible. 2D and 3D temperature field reconstruction simulation results are achieved. The milestone status is shown in Table 1. We finished milestone 1-8 and milestone 10. For milestone 9, we did three pilot tests by using the fiber optic sensing system III (Distributed Sensing System II) at GE Power. However, due to the failure of the ns laser, we did not get the temperature results. We conducted some additional tasks that were not originally proposed: 1) We fabricated a fiber optic sensing system I and did a pilot test based on this system. 2) In the proposal, we proposed two pilot tests at GE Power. In reality, we finished at least seven pilot tests at GE Power. GE Power has made a lot of efforts for supporting the pilot tests. 3) We got a simulation results based on CDMA. In summary, most of the tasks have been accomplished. The outcome of this project removed a few barriers that hinder the achievement of the final product of the distributed sensing systems. With the successful accomplishment of this project, a prototype of the fiber optic sensing system can be fabricated to attract more interests from companies and other funding agencies.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

Life Cycle Inventory of Current Photovoltaic Module Recycling Processes in Europe

Solar photovoltaic (PV) installations must be properly dismantled and any waste treated and disposed at the end of project life. However, because most of the world's nearly 400 GW of PV systems have been built in the past decade - each expected to operate for between 20 and 30 years - current PV module waste volumes do not yet justify widespread operation of PV recycling facilities. The necessary policies and technologies for recycling PV systems are currently under rapid development. With modifications to the European waste electrical and electronic equipment directive (WEEE 2012/19/EU) in 2012, take back and recycling of PV modules is, in fact, already mandatory in Europe. There, take back and recycling is currently performed in small but annually-increasing quantities. Even though waste treatment is considered part of a module's life cycle, only a few life cycle inventories (LCI) of energy and materials flows are available for the industrial recycling processes that are used today to recycle crystalline silicon-based (c-Si) PV modules. LCI are the data inputs that inform lifecycle assessments which quantify the environmental impacts across the full life cycle of PV modules - from manufacturing and use to end of life. To help progress the industry forward, a survey of European recyclers was performed to characterize existing commercial recycling processes and share associated life cycle inventory data. System Boundaries: The reference unit, or "functional unit" in the vocabulary of life cycle assessment, is defined as the processing of one metric ton of crystalline silicon PV modules in recycling lines for laminated glass, metals, and electronic wastes. Today, all modules are processed in discrete batches, yet not metered at that scale. Thus the process energy for a batch is estimated based on scaled annual production data as well as on input and output streams.

14 SOLAR ENERGY↗
DOE OSTI2018

Initial Core Physics and Safety Analyses Supporting the Versatile Test Reactor

The Versatile Test Reactor (VTR) is a proposed integrated facility for investigations into the behavior of fuels and materials subjected to high, fast neutron fluxes prototypical of fast reactor environments. Detailed design of the reactor is currently being performed by a group of U.S. National Laboratories, including Argonne National Laboratory. The current design of the reactor is a 300 MW sodium-cooled pool-type fast reactor fueled with ternary U-20Pu-10Zr metallic fuel. This report documents reactor core physics and preliminary safety analyses that have been performed. The reference VTR core has 313 assembly positions, 66 of which contain fuel assemblies. The remaining assembly positions are loaded with reflector, shield, control rod duct, and test assemblies. Ten positions are available in the reference design for experimental or test assemblies, however the VTR will support test assemblies in any position in the core for alternate core loadings. The performance of the reference VTR core has been assessed for an assumed equilibrium cycle. The core power distribution and reactivity feedback coefficients have been calculated. Preliminary assessments of the reactivity coefficients have shown that each of them results in a negative reactivity change for increasing temperatures. Safety analysis of a VTR layout has been performed using the SAS4A/SASSYS-1 fast reactor safety analysis code. A model has been developed to represent the current core design and a reference heat transport system design. The model has been used to simulate and perform analysis of protected and unprotected loss of heat sink, station blackout, and transient overpower accident scenarios. These scenarios represent the three main ways to perturb the reactor core, through changes to the core inlet temperature, mass flow rate, or reactivity insertions and are credible bounding scenarios for the evaluated transient categories. The results of these simulations have been assessed against simplified criteria for Anticipated Operational Occurrences for the protected transients and for Beyond Design Basis Events for the unprotected transients. Because the primary heat transport system is able to transition quickly and effectively to natural circulation and because the shutdown heat removal system provides sufficient heat rejection capability, large margins for all criteria were predicted for all protected transients. Large margins were also predicted for the unprotected loss of heat sink and station blackout transients due to the strong negative reactivity feedbacks generated by the core. Because of the high power density in the reactor, smaller fuel melting margins are predicted for the unprotected transient overpower accident.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2024

FY24 Report on Water NSTF Testing: Lower Tank Inlet Piping Configuration

The following report serves as a summary of the accomplishments and testing results by the Natural convection Shutdown heat removal Test Facility (NSTF) experimental program over the past 12-month period. A major activity included reconfiguration of the chimney piping geometry which altered the discharge position into the tank from the original 50% tank height to a new lower position at a 10.9% tank height. This modification increases the volume of available coolant thus extending long-term operating capacity, however also results in a decreased liquid driving head which has the potential to reduce the natural circulation efficiency and decrease overall performance. Examination of the tradeoffs for these two configurations is an area of interest for RCCS designers and drove planned test activities this year. Ten matrix tests were performed in FY24, totaling 195 hours of heated operations and 12.9 MWh of electrical heating throughout the year, with eight classified as Accepted per NQA-1 and two classified as Trending. Testing prior to the facility reconfiguration examined the facility response to throttling at the tank inlet, demonstrating increased sensitivity of flow instabilities to throttling within the two-phase region when compared to throttling at the lower sensitivity single-phase inlet region. Testing after the chimney reconfiguration began with a baseline test at conditions of 80% inventory fill and prototypic thermal power input of 2.1 MW t . In addition to establishing a reference for nominal system behavior and performance, repeat testing with multiple subsequent runs demonstrated strong repeatability between tests performed at the same conditions in this new configuration. These tests also examined if influences would occur to system behavior with installation of new higher-resolution instrumentation within the upper chimney. In this critical region where boiling and flashing phenomena dominate, the test results provided confidence that the new instrumentation does not uncharacteristically influence the observed behaviors. An inventory parametric series was then initiated to examine system behavior with the new chimney configuration at six varying initial inventory levels, ranging from high 80% to low 20% fill. Two-phase oscillations with similar peak and mean flow rates were observed when comparing to the previous mid tank configuration. Generally, similar system response trends with inventory were also observed, such as two phase oscillations suppressing as inventories were lowered. However, in one absolute inventory comparison at the highest fill of 80%, flow oscillations saw a gradual growth over the 4 hours of two-phase operation in the new lower tank inlet configuration, opposite of the gradual dampening observed in the mid tank inlet configuration. This can be attributed to, in part, a greater hydrostatic head pressure above the two-phase discharge region where the boiling front is developed. Furthermore, the change resulted in greater sensitivity to liquid degassing phenomena during single-phase heating, causing loop instabilities to form which trigged moderate flow degradation during the period approaching saturation and boiling conditions. This behavior had been observed previously under some conditions but was a common occurrence in recent testing with the newer lower tank inlet configuration. Initial observations from these first data sets suggest an overall larger window of stability for the mid tank inlet configuration compared to the lower tank inlet. Lastly, the lowest inventory fill test was repeated over an extended testing window to examine depletion behavior. Natural circulation flow and effective heat removal performance were observed during most of the testing period; only after the tank became fully drained (0% fill) did flow stagnate and violent geysering events occur. This early observation confirms one relative advantage over the mid tank inlet configuration, which stagnated under comparable conditions at ~20% inventory remaining in the tank.

42 ENGINEERING↗
DOE OSTI2025

Manipulation of Geographic Information in Global Seismology

Geographic data, such as seismic event locations, station locations, etc., are generally given in geographic latitude Φ ’, longitude θ , and depth below sea level, ζ , using the WGS84 ellipsoid as a reference. In software systems that use this type of geographic data, it is necessary to manipulate the data mathematically in order to perform such tasks as finding the angular distance or azimuth from one point to another, to find an array of points along a great circle, to rotate a point about a pole of rotation, to move a point some angular distance in a specified direction, to find the intersections of two great circles or to find the intersections of a great circle and a small circle. In this paper, equations are presented that convert geographic locations first to geocentric coordinates and then to Earth-centered Cartesian coordinates where many mathematical manipulations can be performed conveniently and efficiently.

58 GEOSCIENCES↗
DOE OSTI2022

Effects of Mechanical Recycling on Carbon Fiber-Based Hybrid Composites

Carbon fiber (CF) reinforced composites are high-performing, highly utilized material systems historically used in aerospace. As the cost of CF decreases, other industries, such as automotive and energy generation, seek to adopt CF composites into their applications. A sudden increase in CF demand may create supply chain issues if the adoption happens without scaling up of the CF production. A solution for reducing the reliance on CF is to substitute some portion of the CF content with another fiber type without significantly reducing the material properties. When multiple reinforcing fillers are introduced into a composite system, the materials system is often referred to as a hybrid composite and in this case a CF-based hybrid composite. To further relieve reliance on CF and with sustainable manufacturing becoming more prominent in industry, mechanical recycling can be employed to replace all or a percentage of the virgin material content. Utilizing recycled content in place of virgin content will further aid in reducing the reliance on virgin CF and decrease overall material costs. Here, the effects of utilizing mechanically recycled feedstocks on the mechanical properties of injection molded samples are explored to understand the feasibility of re-manufacturing recycled CF-based hybrid composites. By determining the mechanical properties and mechanisms in which the properties change through varying recycled content, the assessment of how the material will perform in other manufacturing processes can be inferred. As a result, industry will gain better insight into utilizing mechanically recycled feedstocks to reduce their reliance on the CF supply chain.

36 MATERIALS SCIENCE↗
DOE OSTI2017

CHARACTERIZATION OF THE INNER DISK AROUND HD 141569 A FROM KECK/NIRC2 L-BAND VORTEX CORONAGRAPHY

HD 141569 A is a pre-main sequence B9.5 Ve star surrounded by a prominent and complex circumstellar disk, likely still in a transition stage from protoplanetary to debris disk phase. Here, we present a new image of the third inner disk component of HD 141569 A made in the L ′ band (3.8 μ m) during the commissioning of the vector vortex coronagraph that has recently been installed in the near-infrared imager and spectrograph NIRC2 behind the W.M. Keck Observatory Keck II adaptive optics system. We used reference point-spread function subtraction, which reveals the innermost disk component from the inner working distance of ≃23 au and up to ≃70 au. The spatial scale of our detection roughly corresponds to the optical and near-infrared scattered light, thermal Q , N , and 8.6 μ m PAH emission reported earlier. We also see an outward progression in dust location from the L ′ band to the H band (Very Large Telescope/SPHERE image) to the visible ( Hubble Space Telescope ( HST )/STIS image), which is likely indicative of dust blowout. The warm disk component is nested deep inside the two outer belts imaged by HST-NICMOS in 1999 (at 406 and 245 au, respectively). We fit our new L ′-band image and spectral energy distribution of HD 141569 A with the radiative transfer code MCFOST. Our best-fit models favor pure olivine grains and are consistent with the composition of the outer belts. While our image shows a putative very faint point-like clump or source embedded in the inner disk, we did not detect any true companion within the gap between the inner disk and the first outer ring, at a sensitivity of a few Jupiter masses.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

CLM5 CAMELS Basins Ensemble

Land surface models such as Community Land Model Version 5 (CLM5) are essential tools for simulating the behaviors of the terrestrial system. Despite the extensive application of CLM5, limited attention has been paid to the underlying uncertainties associated with its hydrologic parameters and the implications that these uncertainties have on water resources applications. To address this long-standing issue, we conduct a comprehensive hydrologic parameter uncertainty characterization (UC) of CLM5 over the hydroclimatic gradients of the Conterminous United States using five meteorological datasets. Key datasets produced from the UC experiment include a benchmark dataset of CLM5 default hydrological performance, parameter sensitivity identified for 28 hydrological metrics, and large ensemble outputs for hydrological predictions. The presented datasets can assist CLM5 calibration and to support broad applications such as evaluating vulnerabilities to droughts and floods. The dataset can be used to identify under what hydroclimate conditions parametric uncertainties demonstrate substantial effects on hydrological predictions and clarify where further investigations are needed to understand how land runoff uncertainties interact with other Earth system processes. Please refer to the included README.pdf for a description of the included files. Note that raw CLM5 model outputs for each forcing dataset are hosted on a Globus endpoint: https://app.globus.org/file-manager?destination_id=d22ef858-27b0-11ed-a910-fd3165076336.

Yan, Hongxiang↗
DOE OSTI2023

CLM5 CAMELS Basins Ensemble

Land surface models such as Community Land Model Version 5 (CLM5) are essential tools for simulating the behaviors of the terrestrial system. Despite the extensive application of CLM5, limited attention has been paid to the underlying uncertainties associated with its hydrologic parameters and the implications that these uncertainties have on water resources applications. To address this long-standing issue, we conduct a comprehensive hydrologic parameter uncertainty characterization (UC) of CLM5 over the hydroclimatic gradients of the Conterminous United States using five meteorological datasets. Key datasets produced from the UC experiment include a benchmark dataset of CLM5 default hydrological performance, parameter sensitivity identified for 28 hydrological metrics, and large ensemble outputs for hydrological predictions. The presented datasets can assist CLM5 calibration and to support broad applications such as evaluating vulnerabilities to droughts and floods. The dataset can be used to identify under what hydroclimate conditions parametric uncertainties demonstrate substantial effects on hydrological predictions and clarify where further investigations are needed to understand how land runoff uncertainties interact with other Earth system processes. Please refer to the README.pdf for a description of the included files. Note that raw CLM5 model outputs for each forcing dataset are hosted on a Globus endpoint: https://app.globus.org/file-manager?destination_id=d22ef858-27b0-11ed-a910-fd3165076336.

Yan, Hongxiang↗
DOE OSTI2016

The Next Frontier in Computing

Exascale computing refers to computing systems capable of at least one exaflop or a billion calculations per second (1018). That is 50 times faster than the most powerful supercomputers being used today and represents a thousand-fold increase over the first petascale computer that came into operation in 2008. How we use these large-scale simulation resources is the key to solving some of today’s most pressing problems, including clean energy production, nuclear reactor lifetime extension and nuclear stockpile aging.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

A Feasibility Study of a Novel Variable-Aperture Full-Ring SPECT using Large-Area Pixelated CZT Modules: Simulation Results

Emerging single photon emission computed tomography (SPECT) scanner using cadmium zinc telluride (CZT) offers improved quantitative imaging capability over conventional NaI(Tl)-based SPECT scanner. In this study, on top of the previously-developed energy-optimized parallel collimator design [1], we further evaluated a full-ring SPECT system design with eight large-area CZT detectors. In order to evaluate the imaging performance of our proposed CZT-SPECT system, we employed analytical phantom and brain phantom, using a conventional NaI(Tl)-SPECT system as a reference.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Beam controlled nano-robotic device

A system and method (referred to as a method) to fabricate nanorobots. The method generates a pixel map of an atomic object and identifies portions of the atomic object that form a nanorobot. The method stores those identifications in a memory. The method adjusts an electron beam to a noninvasive operating level and images the portions of the atomic object that form the nanorobot. The method executes a plurality of scanning profiles by the electron beam to form the nanorobot and detects nanorobot characteristics and their surroundings via the electron beam in response to executing the plurality of scanning profiles.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2021

Equitable Access to Community Solar: Program Design and Subscription Considerations

Over 2.7 GWac community solar has been installed in the U.S. as of 2020, and 44% (1.2 GWac ) were installed after 2018, which indicates a fast-growing segment of the solar market .Community solar refers to a system that allows customers to subscribe part of a solar PV system and receive credit on their electricity bills based on power production. Although the growth of community solar market makes accessing solar energy easier, low and moderate income (LMI) potential subscribers may still face challenges, such as no or low credit scores.To investigate the program designs and subscription considerations for LMI customers, we provide a summary of existing state-level low-income community solar policies, as well as estimated LMI capacity and subscribers in the U.S.

41 EE - Solar Energy Technologies Office (EE-4S)↗
DOE OSTI2022

An improved synthetic signal injection routine for HAYSTAC

Microwave cavity haloscopes are among the most sensitive direct detection experiments searching for dark matter axions via their coupling to photons. When the power of the expected microwave signal due to axion-photon conversion is on the order of 10-24 W, having the ability to validate the detector response and analysis procedure by injecting realistic synthetic axion signals becomes helpful. Here we present a method based on frequency hopping spread spectrum for synthesizing axion signals in a microwave cavity haloscope experiment. It allows us to generate a narrow and asymmetric shape in frequency space that mimics an axion's spectral distribution, which is derived from a Maxwell-Boltzmann distribution. In addition, we show that the synthetic axion's power can be calibrated with reference to the system noise. Compared to the synthetic axion injection in HAYSTAC phase I, we demonstrated synthetic signal injection with a more realistic lineshape and calibrated power.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗