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All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Collisionless Larmor coupling and blob formation in a laser-plasma expanding into a magnetized ambient plasma

Collisionless Larmor coupling is a fundamental process in space and astrophysical plasmas that enables momentum transfer between an expanding plasma and a magnetized ambient medium. Here, in this paper, we report on the laboratory experimental study of Larmor coupling leading to the formation of a plasma blob associated with a laser-driven, super-Alfvénic plasma flow on the Large Plasma Device at the University of California, Los Angeles. The high-repetition rate enables systematic spatial and temporal scans of the plasma evolution using Doppler spectroscopy, as well as measurements of the magnetic field, electrostatic field, and self-emission of both debris and ambient ions using filtered imaging. We observe the self-focusing of the laser-produced plasma and the formation of a secondary diamagnetic cavity associated with a blob composed of background ions. Doppler spectroscopy reveals the transverse velocity distribution of the background ions, providing direct evidence of ion energization via Larmor coupling. The systematic spatial and temporal scans enabled by the high-repetition-rate experiment allow for a detailed characterization of the ion dynamics. These experimental observations are supported by numerical simulations that provide more insight into the kinetic-scale physics associated with blob formation as well as the role of the ambient plasma density.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Engineering a modular 44 Ti/ 44 Sc generator: eluate evaluation in preclinical models and estimation of human radiation dosimetry

Background: 44 Sc/ 47 Sc is an attractive theranostic pair for targeted in vivo positron emission tomographic (PET) imaging and beta-particle treatment of cancer. The 44 Ti/ 44 Sc generator allows daily onsite production of this diagnostic isotope, which may provide an attractive alternative for PET facilities that lack in-house irradiation capabilities. Early animal and patient studies have demonstrated the utility of 44 Sc. In our current study, we built and evaluated a novel clinical-scale 44 Ti/ 44 Sc generator, explored the pharmacokinetic profiles of 44 ScCl 3 , [ 44 Sc]-citrate and [ 44 Sc]-NODAGA (1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid) in naïve mice, and estimated the radiation burden of 44 ScCl 3 in humans. Methods: 44 Ti/ 44 Sc (101.2 MBq) in 6 M HCl solution was utilized to assemble a modular ZR resin containing generator. After assembly, 44 Sc was eluted with 0.05 M HCl for further PET imaging and biodistribution studies in female Swiss Webster mice. Based on the biodistribution data, absorbed doses of 44 / 47 ScCl 3 in human adults were calculated for 18 organs and tissues using the IDAC-Dose software. Results: 44 Ti in 6 M HCl was loaded onto the organic resin generator with a yield of 99.97%. After loading and initial stabilization, 44 ScCl 3 was eluted with 0.05 M HCl in typical yields of 82.9 ± 5.3% (N = 16), which was normalized to the estimated generator capacity. Estimated generator capacity was computed based on elution time interval and the total amount of 44 Ti loaded on the generator. Run in forward and reverse directions, the 44 Sc/ 44 Ti ratio from a primary column was significantly improved from 1038 ± 440 to 3557 ± 680 (Bq/Bq) when a secondary, replaceable, ZR resin cartridge was employed at the flow outlet. In vivo imaging and ex vivo distribution studies of the reversible modular generator for 44 ScCl 3 , [ 44 Sc]-citrate and [ 44 Sc]-NODAGA show that free 44 Sc remained in the circulation significantly longer than the chelated 44 Sc. The dose estimation of 44 ScCl 3 reveals that the radiation burden is 0.146 mSv/MBq for a 70 kg adult male and 0.179 mSv/MBq for a 57 kg adult female. Liver, spleen and heart wall will receive the highest absorbed dose: 0.524, 0.502, and 0.303 mGy/MBq, respectively, for the adult male. Conclusions: A clinical-scale 44 Ti/ 44 Sc generator system with a modular design was developed to supply 44 ScCl 3 in 0.05 M HCl, which is suitable for further radiolabeling and in vivo use. Our data demonstrated that free 44 ScCl 3 remained in the circulation for extended periods, which resulted in approximately 10 times greater radiation burden than stably chelated 44 Sc. Stable 44 Sc/ 47 Sc-complexation will be more favorable for in vivo use and for clinical utility.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2023

TEAMER: Water Tunnel Data from Testing the Pterofin Skimmer Concept

Pterofin's Skimmer concept relies on a flapping and pitching hydrofoil to extract hydrokinetic energy from water flows. The concept aims to utilize unsteady fluid dynamics phenomena (added mass, shed vorticity, and unsteady boundary layer development) to achieve higher lift coefficients, enabling increased power density of the hydrokinetic device and a fundamental shift in the rpm/torque scaling of the power take off compared with turbines. The Applied Research Laboratory at Penn State, in collaboration with Pterofin, designed and built a proof-of-concept flapping/pitching mechanism which was subsequently tested in ARL's 12-inch water tunnel facility. The mechanical power supplied to or extracted from the mechanism was measured for a range of hydrofoils provided by Pterofin over operating conditions including reduced frequency, Reynolds number, and the ratio between pitching and flapping amplitudes. The power lost to friction in the mechanism was removed from the net power measurement by means of a bare hub tare, with the resultant hydrodynamic power being used to calculate a mechanism-independent and non-dimensional power coefficient. The product of this effort is a dataset describing the power coefficient of a hydrofoil having simultaneous pitching and flapping motions, both of which are approximately sinusoidal. Power coefficients were collected for a range of primary design variables including: - Reduced frequency: 0.01 to 0.95 - Pitching/flapping peak angle ratio: 1.5 to 3.0 - Chord-based Reynolds number: 60,000 to 560,000 Secondary design variables relating to the hydrofoil geometry were explored including: - Aspect ratio - Planform shape - Section thickness distribution - Hydrofoil position relative to the pitching axis - Hydrofoil sweep angle relative to the pitching axis Measured data are provided in mean and time series formats. MATLAB scripts are provided which can be used to generate figures of time-averaged and phase-averaged hydrodynamic power coefficients calculated from the measured data. A complete description of the experiment and data reduction can be found in the Post Access Report for the Pterofin Skimmer test effort which will be available on the TEAMER website. This work was supported by the Pacific Energy Ocean Trust via a TEAMER award.

16 TIDAL AND WAVE POWER↗
DOE OSTI2023

Multi-objective optimization of CEBAF heat load management and trip rates using AI/ML

The goal of this project is to investigate the use of RL to simultaneously optimize the cryogenic heat load and trip rate of the CEBAF linacs and make it generic to solve multi-objective problems that will enable its application at other Department of Energy (DOE) facilities with similar challenges. The existing approach optimizes the gradient distribution to minimize the trip rate and does not take into account the total heat load. A secondary objective of the project is the develop a framework to correct cavity quality curves (Q-curves) or RF-heat to Gradient relation curves for individual cavities. These curves are currently obtained using historical measurements and may have changed their behavior due to various events. Correction in these curves will allow us to accurately approximate the total RF heat generated by the linacs which is critical for the optimization.

43 PARTICLE ACCELERATORS↗
NASA NTRS1982

Ultraviolet light curves of the dwarf novae U Geminorum and VW Hydri

The optical light curves of many dwarf novae show a prominent hump. This hump is attributed to a hot spot located where the gas stream from the cool secondary star strikes the accretion disk around the white dwarf primary. In the present investigation, the energy distribution of the hot spot is obtained from the amplitude of the hump in different wavelength regions. The color temperature of the hot spot is derived, and the temperature and optical thickness for thermal free-free emission models for the spot is discussed. The nature of the disk is studied by comparing its UV-optical energy distribution with computed accretion disk models. The ultraviolet light curves of two quiescent dwarf novae, U Gem and VW Hyi is derived by combining Astronomical Netherlands Satellite (ANS) photometry from several different epochs.

Wu, C.-C.↗
NASA NTRS1985

On the cosmic ray diffusion in a violent interstellar medium

A variety of the available observational data on the cosmic ray (CR) spectrum, anisotropy and composition are in good agreement with a suggestion on the diffusion propagation of CR with energy below 10(15) eV in the interstellar medium. The magnitude of the CR diffusion coefficient and its energy dependence are determined by interstellar medium (ISM) magnetic field spectra. Direct observational data on magnetic field spectra are still absent. A theoretical model to the turbulence generation in the multiphase ISM is resented. The model is based on the multiple generation of secondary shocks and concomitant large-scale rarefactions due to supernova shock interactions with interstellar clouds. The distribution function for ISM shocks are derived to include supernova statistics, diffuse cloud distribution, and various shock wave propagation regimes. This permits calculation of the ISM magnetic field fluctuation spectrum and CR diffusion coefficient for the hot phase of ISM.

Bykov, A. M.↗
NASA NTRS1991

Tomographic separation of composite spectra. The components of Plaskett's Star

The UV photospheric lines of Plaskett's Star (HD 47129), a 14.4 day period, double lined O-type spectroscopic binary were analyzed. Archival data from IUE (17 spectra well distributed in orbital phase) were analyzed with several techniques. A cross correlation analysis, which showed that the secondary produces significant lines in the UV, indicates that the mass ratio is q = 1.18 + or - 0.12 (secondary slightly more massive). A tomography algorithm was used to produce the separate spectra of the two stars in six spectral regions. The interpolated spectral classifications of the primary and secondary, 07.3 I and 06.2 I, respectively, were estimated through a comparison of UV line ratios with those in spectral standard stars. The intensity ratio of the stars in the UV is 0.53 + or - 0.05 (primary brighter). The secondary lines appear rotationally broadened, and the projected rotational velocity V sin i for this star is estimated to be 310 + or - 20 km/s. The possible evolutionary history of this system is discussed through a comparison of the positions of the components and evolutionary tracks in the H-R diagram.

Bagnuolo, William G., Jr.↗
NASA NTRS1992

Tomographic separation of composite spectra. I - The components of Plaskett's Star

The UV photospheric lines of Plaskett's Star (HD 47129), a 14.4 day period, double lined O-type spectroscopic binary were analyzed. Archival data from IUE (17 spectra well distributed in orbital phase) were analyzed with several techniques. A cross correlation analysis, which showed that the secondary produces significant lines in the UV, indicates that the mass ratio is q = 1.18 +/- 0.12 (secondary slightly more massive). A tomography algorithm was used to produce the separate spectra of the two stars in six spectral regions. The interpolated spectral classifications of the primary and secondary, 07.3 I and 06.2 I, respectively, were estimated through a comparison of UV line ratios with those in spectral standard stars. The intensity ratio of the stars in the UV is 0.53 +/- 0.05 (primary brighter). The secondary lines appear rotationally broadened, and the projected rotational velocity V sin i for this star is estimated to be 310 +/- 20 km/s. The possible evolutionary history of this system is discussed through a comparison of the positions of the components and evolutionary tracks in the H-R diagram.

Bagnuolo, William G., Jr.↗
NASA NTRS2003

Non-Thermal Hard X-Ray Emission in Galaxy Clusters Observed with the BeppoSAX PDS

We study the X-ray emission in a Sample of galaxy clusters using the BeppoSAX PDS instrument in the 20 - 80 keV energy band. We estimate the non-thermal hard X-ray cluster emission (HXR) by modeling the thermal contribution from the cluster gas and the non-thermal contamination from the unobscured AGN in the clusters. We also evaluate the systematic uncertainties due to the background fluctuations. Assuming negligible contamination from the obscured AGN, the resulting non-thermal component is detected at a 2 sigma level in approx. 50% of the non-significantly AGN-contaminated clusters: A2142, A2199, A2256, A3376, Coma, Ophiuchus and Virgo. The data are consistent with a scenario whereby relaxed clusters have no hard X-ray component of non-thermal origin, whereas merger clusters do. The co-added spectrum of the above clusters indicates a power-law spectrum for the HXR with a photon index of 2.8+0.3-0.4 in the 12 - 115 keV band, and we find indication that it has extended distribution. These indications argue against significant contamination from obscured AGN, which have harder spectra and centrally concentrated distribution. These results are supportive of the assumption of the merger shock acceleration of electrons in clusters, which has been proposed as a possible origin of the non-thermal hard X-ray emission models. Assuming that the Cosmic Microwave Background photons experience Inverse Compton scattering from the merger-accelerated relativistic electrons, and thus produce the observed HXR, the measured hard X-ray slope corresponds to a differential momentum spectra of the relativistic electrons with a slope of mu = 3.8 - 5.0. In presence of cluster magnetic fields this relativistic electron population produces synchrotron emission with a spectral index of 1.4 - 2.1, consistent with radio halo observations of merger clusters. Thus both hard X-ray and radio observations of merger clusters are consistent with the Inverse Compton model. The observed slope of HXR is also consistent with that predicted by the non-thermal bremsstrahlung, which chus cannot be ruled by the fit to the current data, even though this model requires an extreme, untenable cluster energetics. Assuming centrally concentrated distribution of HXR, the data requires a harder slope for the HXR spectrum, which is consistent with secondary electron models, but this model yields a worse fit to the PDS data and thus seems to be disfavored over the primary electron Inverse Compton model.

Nevalainen, J.↗
NASA NTRS2004

Above-Cloud Precipitable Water Retrievals using the MODIS 0.94 micron Band with Applications for Multi-Layer Cloud Detection

In order to perform satellite retrievals of cloud properties, it is important to account for the effect of the above-cloud atmosphere on the observations. The solar bands used in the operational MODIS Terra and Aqua cloud optical and microphysical algorithms (visible, NIR, and SWIR spectral windows) are primarily affected by water vapor, and to a lesser extent by well-mixed gases. For water vapor, the above-cloud column amount, or precipitable water, provides adequate information for an atmospheric correction; details of the vertical vapor distribution are not typically necessary for the level of correction required. Cloud-top pressure has a secondary effect due to pressure broadening influences. For well- mixed gases, cloud-top pressure is also required for estimates of above-cloud abundances. We present a method for obtaining above-cloud precipitable water over dark Ocean surfaces using the MODIS 0.94 pm vapor absorption band. The retrieval includes an iterative procedure for establishing cloud-top temperature and pressure, and is useful for both single layer water and ice clouds. Knowledge of cloud thermodynamic phase is fundamental in retrieving cloud optical and microphysical properties. However, in cases of optically thin cirrus overlapping lower water clouds, the concept of a single unique phase is ill- defined and depends, at least, on the spectral region of interest. We will present a method for multi-layer and multi-phase cloud detection which uses above-cloud precipitable water retrievals along with several existing MODIS operational cloud products (cloud-top pressure derived from a C02 slicing algorithm, IR and SWIR phase retrievals). Results are catagorized by whether the radiative signature in the MODIS solar bands is primarily that of a water cloud with ice cloud contamination, or visa-versa. Examples in polar and mid-latitude regions will be shown.

Platnick, S.↗
NASA NTRS2014

Interphase Chromosome Conformation and Chromatin-chromatin Interactions in Human Epithelial Cells Cultured Under Different Gravity Conditions

On a multi‐mega base pair scale of the DNA, the arrangement of chromatin is non‐random. In M10 epithelial cells, both telomere regions tend to be located towards the exterior of the chromosome domain, whereas the rest p‐arm of the chromatin region towards the interior. In contrast, most of the q‐arm of the chromatin is found in the peripheral of the domain. In lymphocytes, the p‐arm chromatin regions towards the interior in close proximity with each other, whereas two q‐arm regions are nearness in space. It indicates that G0 lymphocytes may lack secondary 3D chromatin folding. There chromatin folding patterns are consistent with our previous finding of non‐random distribution of intra‐chromosomal exchanges. In simulated microgravity conditions, the chromosome conformation may be altered and new regions in close proximity, especially to region 2 are suggested.

Zhang, Ye↗
NASA NTRS2016

Trade-Space Analysis Tool for Constellations (TAT-C)

Traditionally, space missions have relied on relatively large and monolithic satellites, but in the past few years, under a changing technological and economic environment, including instrument and spacecraft miniaturization, scalable launchers, secondary launches as well as hosted payloads, there is growing interest in implementing future NASA missions as Distributed Spacecraft Missions (DSM). The objective of our project is to provide a framework that facilitates DSM Pre-Phase A investigations and optimizes DSM designs with respect to a-priori Science goals. In this first version of our Trade-space Analysis Tool for Constellations (TAT-C), we are investigating questions such as: How many spacecraft should be included in the constellation? Which design has the best costrisk value? The main goals of TAT-C are to: Handle multiple spacecraft sharing a mission objective, from SmallSats up through flagships, Explore the variables trade space for pre-defined science, cost and risk goals, and pre-defined metrics Optimize cost and performance across multiple instruments and platforms vs. one at a time.This paper describes the overall architecture of TAT-C including: a User Interface (UI) interacting with multiple users - scientists, missions designers or program managers; an Executive Driver gathering requirements from UI, then formulating Trade-space Search Requests for the Trade-space Search Iterator first with inputs from the Knowledge Base, then, in collaboration with the Orbit Coverage, Reduction Metrics, and Cost Risk modules, generating multiple potential architectures and their associated characteristics. TAT-C leverages the use of the Goddard Mission Analysis Tool (GMAT) to compute coverage and ancillary data, streamlining the computations by modeling orbits in a way that balances accuracy and performance.TAT-C current version includes uniform Walker constellations as well as Ad-Hoc constellations, and its cost model represents an aggregate model consisting of Cost Estimating Relationships (CERs) from widely accepted models. The Knowledge Base supports both analysis and exploration, and the current GUI prototype automatically generates graphics representing metrics such as average revisit time or coverage as a function of cost.

Science Data Processing↗
NASA NTRS2023

A New View of the Lunar South Pole from the Lunar Orbiter Laser Altimeter (LOLA)

Upcoming missions to the lunar south pole require detailed maps over large areas to fully characterize landing sites locally and regionally and to place their data into proper geologic context. To that end, we enhanced the Lunar Orbiter Laser Altimeter (LOLA) altimetry dataset for the south polar region, from which we produced new maps of topography, topographic roughness, and permanently shadowed regions (PSRs). The roughness maps reveal a diversity of terrains characterized by hectometer-scale roughness which is controlled in this region primarily by cratering and downslope mass transport. The south polar region is littered with linear roughness features of order ~1 – 10 km wide and ~10s – 100s of km long hypothesized to be secondary impacts within extended ejecta rays. Non uniformities in these features could reflect variations in secondary impactor properties and/or target terrain properties. Poleward of 80° S, the PSR cumulative size-frequency distribution (CSFD) shows an approximately power-law behavior whose exponent has a spatial variation of ~10%. PSRs with areas < 1 km2 contain 15 ± 5% of the total PSR area. Finally, we studied the effect of false positives and false negatives on the accuracy of the measured PSR cumulative size-frequency distribution (CSFD) and on the area for any individual PSR. The new maps presented here have many applications in the science and exploration of the lunar south polar region, such as geologic mapping and traverse planning.

Michael K. Barker↗
DOE OSTI2021

Peer-to-peer Communication Control Architecture for Engaging Ubiquitous DERs to Support Distribution System Resiliency

In this project, we developed a leader-follower consensus (LFC) control architecture to coordinate between GFM and GFL inverters with the former being leaders and the latter being followers. The objective is to simultaneously achieve a fast frequency and voltage regulation along with accurate real power and var sharing among all inverters under various disturbances. The distinction of our work is that we consider both GFM and GFL inveters for frequency and voltage regulations. In addition, rather than a standard consensus algorithm, our work utilized a leader-follower consensus algorithm which exploits the physical characteristics of GFM-GFL inverters: (i) the GFM inverters directly control frequency and voltage, and hence, serve as leaders, (ii) the GFL inverters measure frequency/voltage to modulate their outputs, and hence, they should serve as followers. The effectiveness of the proposed LFC coordination was tested on a networked microgrid test system under different disturbances and communication degradation events. We demonstrated that the proposed fully coordinated control is robust to disturbances, while outperforming uncoordinated and GFM-only coordinated approaches. Overall, this work emphasized the necessity and benefits of the GFMGFL coordination in the secondary control of microgrids.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1976

Ultraviolet photometry from the Orbiting Astronomical Observatory. XXII Ultraviolet light variation of Beta Lyrae

Six-color ultraviolet light curves of the complex eclipsing binary system Beta Lyr were obtained with the OAO-2 Wisconsin Experiment Package. The filters had a typical width at half maximum of 150 to 200 A and were centered at 1430, 1550, 1910, 2460, 2980, and 3320 A. The most striking characteristics of the ultraviolet light curves are that the secondary minimum deepens at shorter wavelengths. This indicates that we are not observing the eclipse effect of two stars having roughly a Planckian distribution of energy. In combination with the high-resolution far-ultraviolet spectra of Beta Lyr recently obtained with Copernicus (OAO-3) Princeton Telescope Spectrometer, it is concluded that the far-ultraviolet light curves are dominated by emission from the high-temperature gas surrounding the binary system. The ultraviolet observations of OAO-2 and Copernicus are consistent with a model in which the enigmatic secondary component involves a gravitationally collapsed object; i.e., a black hole. However, alternative models are also admissible.

Kondo, Y.↗
DOE OSTI2020

Smart Contract-Defined Secondary Control and Co-Simulation for Smart Solar Inverters using Blockchain Technology

This paper proposes a cooperative control approach using blockchain technology for solar inverters in a photovoltaic system. Moreover, a co-simulation method for smart inverters and a blockchain network is studied. The blockchain assisted-smart inverter (BASI) consists of a solar inverter and an internet of things device as a client node of a blockchain network, which can fully utilize emerging blockchain technologies such as distributed ledger, security functions, and smart contract. The control includes a primary-level droop control in a BASI and smart contract-defined secondary-level supervisory control in a secured blockchain network. The concept of the proposed smart contract-defined control approach is validated by simulation studies using the cyber-physical co-simulation testbed built-in MATLAB/Simulink in a PC interfacing with a Hyperledger-Fabric blockchain software implemented in a PC.

14 SOLAR ENERGY↗
NASA NTRSDate not supplied

Evidence of High-Angle Ejecta from Impacts Iinto Various Granular Materials

The dominant mechanism for resurfacing airless bodies is the excavation and ejection of material during the formation of impact craters. Ejecta that is deposited proximal to the rim of craters formed in the gravity-regime (where gravitational forces are greater than material strength) form a relatively smooth and continuous deposit. Aside from far-field secondary craters, craters observed on continuous ejecta deposits are mostly assumed to be representative of the primary impactor flux after the time of deposition. Sustained primary bombardment should produce a homogeneous crater population across this surface, thus providing an opportunity to determine crater size-frequency distributions and surface chronologies. Deviations from this ideal have been observed as different crater-size distributions appearing between the continuous deposits and their superimposed melt ponds. Numerous explanations for this discrepancy have been proposed, one of which is the occurrence of self-secondary craters, which would be created by ejecta launched at sufficiently high-angles to re-impact the fresh continuous ejecta deposits. Here, we present results from cratering experiments to explore the influence of density, porosity, and friction on ejecta kinematics and report on the observation of such high-angle ejecta in cohesionless granular targets.

Impact crater↗
NASA NTRS1978

UH cosmic rays - Possible origin in massive stars

The origin of the Z greater than 28, ultraheavy (UH) cosmic rays in supernova explosions of massive stars, at least about 10 solar masses, is considered. For Z greater than 70, the UH data are dominated by an r-process source distribution, but for the elements just beyond iron, Z from 29 to 36, the data cannot be explained by any single process of nucleosynthesis. This problem is solved naturally in a massive-star model by secondary neutron-capture reactions occurring during core helium burning (a limited s-process) and during explosive carbon burning. Interstellar-propagation calculations have been performed with these episodes of synthesis as source distributions, and the results offer an explanation for the current UH cosmic-ray data. Further, the heavy-element synthesis during explosive carbon burning is re-examined by using more realistic initial conditions given by the post-helium-burning configuration of the star. These results are compared with earlier work and the UH cosmic-ray data. Some effects of preferential acceleration, based upon ionization potential, are considered, and experimental tests for this model are discussed.

Wefel, J. P.↗