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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Helicon waves in uniform plasmas. IV. Bessel beams, Gendrin beams, and helicons

Electromagnetic waves in the low frequency whistler mode regime are investigated experimentally and by digital data superposition. The radiation from a novel circular antenna array is shown to produce highly collimated helicon beams in a uniform unbounded plasma. The differences to Bessel beams in free space are remarked upon. Low divergence beams arise from the parallel group velocity of whistlers with phase velocity either along the guide field or at the Gendrin angle. Waves with angular momentum are produced by phasing the array in the circular direction. The differences in the field topologies for positive and negative modes numbers are shown. It is also shown that in uniform plasmas, the radial amplitude profile of the waves depends on the antenna field topology. Thus, there are no helicon “eigenmodes” with radial Bessel function profiles in uniform plasmas. It is pointed out that phase measurements in helicon devices indicate radial wave propagation which is inconsistent with helicon eigenmode theory based on paraxial wave propagation. Trivelpiece-Gould modes also exist in uniform unbounded plasmas.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Weight-lattice discretization of Weyl-orbit functions

Weyl-orbit functions have been defined for each simple Lie algebra, and permit Fourier-like analysis on the fundamental region of the corresponding affine Weyl group. They have also been discretized, using a refinement of the coweight lattice, so that digitized data on the fundamental region can be Fourier-analyzed. The discretized orbit function has arguments that are redundant if related by the affine Weyl group, while its labels, the Weyl-orbit representatives, invoke the dual affine Weyl group. Here we discretize the orbit functions in a novel way, by using the weight lattice. A cleaner theory results with symmetry between the arguments and labels of the discretized orbit functions. Orthogonality of the new discretized orbit functions is proved, and leads to the construction of unitary, symmetric matrices with Weyl-orbit-valued elements. For one type of orbit function, the matrix coincides with the Kac-Peterson modular S matrix, important for Wess-Zumino-Novikov-Witten conformal field theory.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

An all-digital associated particle imaging system for the 3D determination of isotopic distributions

Associated particle imaging (API) is a non-destructive nuclear technique for the 3D determination of isotopic distributions. By detecting the alpha particle associated with the emitted neutron in the deuterium–tritium fusion reaction with a position- and time-resolving detector, the direction of the 14.1 MeV neutron and its time of emission can be determined. Employing this method, isotope characteristic gamma rays emitted in inelastic neutron scattering events can be correlated with the neutron interaction location. Here, an API system consisting of a sealed-type neutron generator, gamma detectors, and a position-sensitive alpha detector was designed, constructed, and characterized. The system was tested with common soil elements and shown to be sensitive to 12 C, 16 O, 28 Si, 27 Al, and 56 Fe. New aspects of our approach are the use of a yttrium–aluminum–perovskite scintillator, using a sapphire window instead of a fiber-optic faceplate for light transport to the photomultiplier, and the all-digital data acquisition system. We present a description of the system with simulations and experimental results that show a position resolution on the alpha detector of 1 mm, a depth resolution using a LaBr 3 detector of 6.2 cm, and an angular resolution of 4.5°. Additionally, we present single-element gamma response measurements for the elements mentioned above together with a comparison to Monte Carlo simulations (MCNP6).

47 OTHER INSTRUMENTATION↗
DOE OSTI2016

SU-G-TeP2-12: IROCHouston and MDAPL SRS Anthropomorphic Phantom Results

Purpose: To report the results of SRS phantom irradiations Methods: Anthropomorphic SRS head phantoms were sent to institutions participating in NCI sponsored SRS clinical trials and institutions interested in verifying SRS treatment delivery. The phantom shell was purchased from Phantom Laboratory and altered to house dosimetry and imaging inserts. The imaging insert has 1.9 cm diameter spherical target. The dosimetry insert holds two TLD capsules and radiochromic film in the coronal and sagittal planes through the center of the target. Institutions were asked to image, plan and treat the phantom as they would an SRS patient. GammaKnife, CyberKnife and c-arm accelerator institutions were asked to cover the target with 15 Gy, 20 Gy and 25 Gy, respectively. Following these guidelines and typical planning protocols for these three types of machines gives roughly 30 Gy to the center of the target for all units. Submission of the DICOM digital data set was required for analysis. Criteria of 5% for TLD results and 85% of pixels passing 5%/3mm gamma analysis were applied beginning in 2013. Results: The phantom was analyzed 269 times between the beginning of 2013 to present. The pass rate is 81%. Nineteen of the irradiation results failed only the TLD criteria, 19 failed only the film criteria and 12 failed both. Irradiations included 32 CyberKnife 23 GammaKnife, 3 TomoTherapy and 211 c-arm units. Planning systems included Eclipse, Ergo, GammaPlan, Hi-Art, iPlan, Monaco, MultiPlan, Pinnacle, RayStation, XiO and XKnife. Irradiations that were not accompanied with DICOM data were not included in this analysis. Conclusion: The phantom is a valuable end-to-end test used to independently verify the accuracy of SRS treatment delivery. This investigation was supported by IROC grant CA180803 awarded by the NCI.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Fine structure in the α decay of $^{179}$Hg and $^{177}$Au

Abstract The$$\upalpha $$ α -decay fine structure of$$^{179}$$ 179 Hg and$$^{177}$$ 177 Au was studied by means of decay spectroscopy. Two experiments were performed at the Accelerator Laboratory of the University of Jyväskylä (JYFL), Finland, utilizing the recoil separator RITU and a digital data acquisition system. The heavy-ion induced fusion-evaporation reactions$$^{82}_{36}$$ 36 82 Kr + $$^{100}_{44}$$ 44 100 Ru and$$^{88}_{38}$$ 38 88 Kr + $$^{92}_{42}$$ 42 92 Mo were used to produce the$$^{179}$$ 179 Hg and$$^{177}$$ 177 Au nuclei, respectively. Studying the evaporation residues (ER, recoils)-$$\alpha _1$$ α 1 -$$\alpha _2$$ α 2 correlations and$$\upalpha $$ α -$$\gamma $$ γ coincidences, a new$$\upalpha $$ α decay with E$$_\alpha $$ α = 6156(10) keV was observed from$$^{179}$$ 179 Hg. This decay populates the (9/2$$^-$$ - ) excited state at an excitation energy of 131.3(5) keV in$$^{175}$$ 175 Pt. The internal conversion coefficient for the 131.3(5) keV transition de-exciting this state was measured for the first time. Regarding the$$^{177}$$ 177 Au nucleus, a new$$\upalpha $$ α decay with E$$_\alpha $$ α = 5998(9) keV was observed to populate the 156.1(6) keV excited state in$$^{173}$$ 173 Ir. Two de-excitation paths were observed from this excited state. Moreover, a new 215.7(13) keV transition was observed to depopulate the 424.4(13) keV excited state in$$^{173}$$ 173 Ir. Properties of the$$^{179}$$ 179 Hg and$$^{177}$$ 177 Au$$\upalpha $$ α decays were examined in a framework of reduced widths and hindrance factors. For clarity and simplicity, the spin and parity assignments (e.g.$$J^{\pi }$$ J π ) are presented without brackets throughout the text.

Physics↗
DOE OSTI2018

project_0vbb v1.0-beta

This software is designed for the sole purpose of analyzing numerical lattice QCD results computed for one of the developers' research projects related to neutrinoless double beta decay, and will be distributed with their research publication. This software is provided to maximize the dissemination of the research results, to enable other scientists and the general public to easily check the results of their analysis, and also to be in compliance with the public availability of "digital data" as required by the DOE.

Walker-Loud, Andree↗
DOE OSTI2018

lalibe v1.0

This is top-level lattice QCD code developed by employees at LBNL and LLNL. It currently compiles on top of the USQCD Chroma software stack. This code contains high-performance routines that are used in our research, and we intend to release this code publicly to ensure reproducibility and to meet our obligations for complying with the DOE Digital Data rules.

Walker-Loud, Andre↗
DOE OSTI2020

Real-time dynamic wavelength tuning and intensity modulation of metal-clad nanolasers

To realize ubiquitously used photonic integrated circuits, on-chip nanoscale sources are essential components. Subwavelength nanolasers, especially those based on a metal-clad design, already possess many desirable attributes for an on-chip source such as low thresholds, room-temperature operation and ultra-small footprints accompanied by electromagnetic isolation at pitch sizes down to ∼50 nm. Another valuable characteristic for a source would be control over its emission wavelength and intensity in real-time. Most efforts on tuning/modulation thus far report static changes based on irreversible techniques not suited for high-speed operation. In this study, we demonstrate in-situ dynamical tuning of the emission wavelength of a metallo-dielectric nanolaser at room temperature by applying an external DC electric field. Using an AC electric field, we show that it is also possible to modulate the output intensity of the nanolaser at high speeds. The nanolaser’s emission wavelength in the telecom band can be altered by as much as 8.35 nm with a tuning sensitivity of ∼1.01 nm/V. Additionally, the output intensity can be attenuated by up to 89%, a contrast sufficient for digital data communication purposes. Finally, we achieve an intensity modulation speed up to 400 MHz, limited only by the photodetector bandwidth used in this study, which underlines the capability of high-speed operation via this method. This is the first demonstration of a telecom band nanolaser source with dynamic spectral tuning and intensity modulation based on an external E-field to the best of our knowledge.

Deka, Suruj S. (ORCID:0000000297812317)↗
DOE OSTI2016

Final Report for NMBSA Project, Monika Kaden, 2016

The following pages define the objectives and results for Project 022, requested by Monika Kaden, a sculptor who maintains studios in Santa Fe. This effort was first approved in February 2016, and was completed during several different time segments spread over the year, depending on Monika’s availability. The project deliverables that are of primary use to the customer are digital data files that are to be delivered electronically. This report is a summary overview of how the project was conducted.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Storage Ring Current Monitor

The storage ring current monitor is expected to be utilized for the following functions: measurement of the current circulating in the storage ring; measurement of the beam lifetime; measurement of the injection efficiency; provide the level of the circulating current for the equipment protection system; provide amount of charge required for the next injection cycle in the top-up mode operation. The current will be monitored with a parametric current transformer (DCCT) integrated into the vacuum system of the storage ring. The electronic module will convert the current reading into the corresponding voltage which will be measured with a digital voltmeter (DVM). The digitized data will be processed by the control system.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Development of the Ultimate One-Dimensional Time to Explosion (UODTX) Apparatus

With recent advancements in experimental capabilities and worldwide improvement of digital data acquisition and control, there is sufficient justification to develop a new version of the One Dimensional Time to eXplosion (ODTX) system to allow for additional diagnostics and improved control to increase sample throughput and increase the adaptability of future experiments. The legacy ODTX system was designed to measure time to explosion (TTX) for a given temperature, which it does well, but it was not equipped to handle the recent experimental advances of Pressure-ODTX (PODTX) and Composition-ODTX (CODTX). PODTX involves fielding a pressure transducer as an additional diagnostic and applying arbitrary heating-profiles to the system anvils. CODTX furthers this concept by including in-situ gas-composition analysis via infrared (IR) absorption techniques with plans to extend CODTX to solid composition detection and in-situ mass spectrometry (MS). The legacy ODTX system was not built with these experiments in mind and performing them involves substantial modifications and downtime to the existing machine. Developing a standalone system that can perform all C/P/ODTX experiments and is adaptable to unconceived experiments would allow for the continued use of ODTX as a work-horse for Small Scale Safety Testing (SSST), but also provide a testbed for new explosive safety research. This system would ultimately be housed in the neighboring ODTX cell and would live at the High Explosive Application Facility (HEAF) until the end of its service life. HEAF, Chemistry, and Engineering would be the primary stakeholders for the system’s design as they all have experiments that they want to perform. Engineering would be responsible for the system development and would work closely with HEAF to ensure that the system is built with high explosive (HE) safety in mind. By the end of development and after product realization, HEAF/Chemistry would be the system owner, operator, and primary user. The proposed system design is highly influenced by the existing ODTX design. The system will have load frame to support the experiment, anvils to confine the explosive, and some means of applying confining pressure. The samples will be able to be heated and cooled through the confining the anvils. The biggest change from the legacy design is the ability to add diagnostics to the experiment as needed: thermocouples (TCs), resistance temperature detectors (RTDs), pressure transducers (PTs), infrared transmittance/absorbance (IR), mass spectrometry (MS), strain gages (SGs), photonic doppler velocimeter (PDV), as well as arbitrary 4-20 mV signals and +/- 10 VDC signals. The current design does not allow for flexibility in that respect and is hardwired with a few diagnostic channels. The onus will fall on designing a load frame that can support system modifications as well as a data acquisition system that can handle the multitude of signal types.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Vibration-Based Sensor Design: A Grey-Box Approach

Knowledge of the internal structure of an object or device under investigation proceeds from the basic idea of constructing its dynamic behavioral relations governed by a set of differential/algebraic equations that characterize its response. These equations can be partial differential equations leading to finite element or finite difference relations requiring a complex numerical solution on a super computer or ordinary differential equations requiring sophisticated numerical integration techniques to obtain the desired solution. Discrete dynamic systems evolving from digitized data acquisition are typically captured by sampled-data (continuous-to-discrete) representations characterized by a set of difference equations specifying the underlying system dynamics. In any case, with a mathematical description in hand, Grey-Box modeling techniques have evolved, concerned with the estimation of model parameters embedded in a prescribed set of equations (the system) governing its behavior, while capturing the underlying physical phenomenology of the problem at hand.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

Manufacturing Management System Overview [Slides]

Vision: Institute a trusted manufacturing capability within the ALDWP Production Agency enabling digital product acceptance and access to digital manufacturing post-production activities. Mission: Establish a modern manufacturing infrastructure that ensures operator credentials, minimized human transcription errors, capable of managing all aspects of manufacturing including digital data acquisition, NCR resolution, and product acceptance, while providing an effective and intuitive user experience. Strategy: Constitute the modern manufacturing infrastructure to minimize risk and plant disruption while incrementally involving the capability.

42 ENGINEERING↗
DOE OSTI2024

PDV Inspection and Analysis Demonstration: 2024 PDV Workshop

This document walks a user through a demonstration of working with PDV digitizer data using python. This demonstration and included suggested exercises will be used at the 2024 PDV workshop hands-on session as an example and skill-development training session. The tutorial allows the user to generate synthetic but realistic PDV waveform data and visualize/inspect the results using spectrograms and waveform viewing tools.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Association of Supergranule Mean Scales with Solar Cycle Strengths and Total Solar Irradiance

We analyze the long-term behavior of the supergranule scale parameter, in active regions (ARs) and quiet regions (QRs), using the Kodaikanal digitized data archive. This database provides century-long daily full disk observations of the Sun in Ca ii K wavelengths. In this paper, we study the distributions of the supergranular scales, over the whole data duration, which show identical shape in these two regimes. We found that the AR mean scale values are always higher than that of the QR for every solar cycle. The mean scale values are highly correlated with the sunspot number cycle amplitude and also with total solar irradiance (TSI) variations. Such a correlation establishes the cycle-wise mean scale as a potential calibrator for the historical data reconstructions. We also see an upward trend in the mean scales, as has already been reported in TSI. This may provide new input for climate forcing models. These results also give us insight into the different evolutionary scenarios of the supergranules in the presence of strong (AR) and weak (QR) magnetic fields.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Long-term Study of the Solar Filaments from the Synoptic Maps as Derived from H{sub α} Spectroheliograms of the Kodaikanal Observatory

The century long (1914–2007) H{sub α} (656.28 nm) spectroheliograms from the Kodaikanal Solar Observatory (KSO) have been recently digitized. Using these newly calibrated, processed images we study the evolution of dark elongated on-disk structures called filaments, which are potential representatives of magnetic activities on the Sun. To our knowledge, this is the oldest uniform digitized data set with daily images available today in H{sub α}. We generate Carrington maps for the entire time duration and try to find the correlations with maps of the same Carrington rotation from the Ca ii K KSO data. Filaments are segmented from the Carrington maps using a semi-automated technique and are studied individually to extract their centroids and tilts. We plot the time-latitude distribution of the filament centroids, producing a butterfly diagram which clearly shows the presence of poleward migration. We separate polar filaments for each cycle and try to estimate the delay between the polar filament number cycle and the sunspot number cycle peaks. We correlate this delay with the delay between polar reversal and sunspot number maxima. This provides new insight on the role of polar filaments on polar reversal.

79 ASTRONOMY AND ASTROPHYSICS↗