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NASA NTRS1987

Effects on H(-) production in a multicusp ion source by mixture of H2 with H2O, NH3, CH4, N2H4, and SF6

Effects of H(-) production in a multicusp ion source are measured by separately mixing with hydrogen small amounts (0.33-10 percent) of water, ammonia, methane, and hydrazine these are molecules which produce large amounts of H(-) via dissociative attachment (DA) resonances at higher electron energies. The mixing was done in a separate reservoir, with careful measurement of individual pressures. Experimental enhancements of 1.4 and less were observed, whereas calculated enhancements, using accurate DA cross sections for ground-state H2, should have produced factors of 1.5, 3.0, 1.3, and 2.4 enhancements for water, ammonia methane, and hydrazine, respectively, at a mean electron energy of 1.0 eV in the extraction region. The difference is accounted for by including, in the enhancement calculation, vibrationally and rotationally excited H2 molecules, with v-double prime = 5-11, and J-double prime = 0-5, and the large DA cross sections for the excited H2 (v-double prime, J-double prime). The relative populations of H2 (v-double prime, J-double prime) thus obtained are found to be substantially smaller than those predicted by theoretical calculations. The effect on H(-) current was also studied by mixing small amounts of SF6 with H2. A 1.5 percent mixture was found to reduce the H(-) output by one half.

Orient, O. J.↗

NASA NTRS1991

The relation between FIR and H I emission in galaxies

This project explored the relationship between the global far-infrared and neutral hydrogen (H I) emission from galaxies, based on data from the Infrared Astronomy Satellite (IRAS) and published radio data. 100 and 60 micron IRAS fluxes were used to establish a temperature corrected measure of the cold dust emission, and H I fluxes were drawn from the literature with the greatest possible consistency. The degree of correlation between the FIR and H I fluxes was found to be better than in previous studies, comparable to the correlation previously found between FIR and CO fluxes. The improvement was obtained largely by (1) separating 'stripped' from 'unstripped' galaxies, and (2) using compatible sources of H I data. Stripping occurs in clusters of galaxies and is probably caused by ram-pressure effects as a galaxy travels through the intergalactic medium. Our results suggest that stripped galaxies have had their outer-disk gas removed (approximately 80% of their total H I) while retaining most of their 100-micron-emitting dust. This strongly shifts the ratio of their 100-micron-to-H I fluxes. The second problem, arising from diverse sources of data, arises because differing telescopes and observational techniques give rise to substantial disagreement in the measured H I flux, and this degrades the correlation of the FIR and H I fluxes.

Schneider, Stephen E.↗

DOE OSTI2015

First beam measurements on the vessel for extraction and source plasma analyses (VESPA) at the Rutherford Appleton Laboratory (RAL)

In order to facilitate the testing of advanced H{sup −} ion sources for the ISIS and Front End Test Stand (FETS) facilities at the Rutherford Appleton Laboratory (RAL), a Vessel for Extraction and Source Plasma Analyses (VESPA) has been constructed. This will perform the first detailed plasma measurements on the ISIS Penning-type H{sup −} ion source using emission spectroscopic techniques. In addition, the 30-year-old extraction optics are re-designed from the ground up in order to fully transport the beam. Using multiple beam and plasma diagnostics devices, the ultimate aim is improve H{sup −} production efficiency and subsequent transport for either long-term ISIS user operations or high power FETS requirements. The VESPA will also accommodate and test a new scaled-up Penning H{sup −} source design. This paper details the VESPA design, construction and commissioning, as well as initial beam and spectroscopy results.

43 PARTICLE ACCELERATORS↗

DOE OSTI2011

Towards Understanding the Cesium Cycle of the Persistent H- Beams at SNS

This paper describes the accomplishments of the SNS H- ion source, which delivers routinely ~50 mA at a 5.4% duty factor with ~99% availability, enabling 1 MW beams for neutron production with ~90 % availability. It discusses the need for increasing reliability and beam current. But mostly it focuses on its unexpected feature: H- beams that are apparently persistent for up to 5 weeks without adding Cs after an initial dose of less than ~5 mg. Thermal emission and sputtering are qualitatively evaluated, and appear consistent with a negligible Cs sputter rate after the initial dose disappears from the Cs plasma. It concludes with a list of future experiments that can shed more light on this apparently unique Cs cycle.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2016

Charge neutralized low energy beam transport at Brookhaven 200 MeV linac

The H{sup −} magnetron source provides about 100 mA H{sup −} beam to be match into the radio-frequency quadrupole accelerator. As H{sup −} beam traverses through low energy transport, it ionizes the residual gas and electrons are repelled and positive ions are trapped in the beam, due to negative potential of the beam, providing charge neutralization for the H{sup −} beam. The neutralization time for the critical density depends upon the background gas and its pressure. Critical density for xenon gas at 35 keV is about 43 times smaller than that of hydrogen and stripping cross section is only 5 times than that of hydrogen gas. We are using xenon gas to reduce neutralization time and to improve transmission through the 200 MeV linac. We are also using pulse nitrogen gas to improve transmission and stability of polarized H{sup −} beam from optically pumped polarized ion source.

43 PARTICLE ACCELERATORS↗

NASA NTRS1976

Abundances of simple oxygen-bearing molecules and ions in interstellar clouds

The abundances of simple oxygen-bearing interstellar molecules in warm (T at least 40 K), diffuse, and moderately thick clouds are calculated on the basis of binary gas-phase reactions. The most important reactions are ion-molecule, charge-exchange, and dissociative-recombination reactions, as suggested mainly by earlier workers. The progenitor of these molecules in diffuse clouds is the cosmic-ray-produced H(+) ion, working through the charge-exchange reaction with O. The ionization of H(+) and He(+) is also discussed. Dissociative charge exchange of He(+) with H2 is an important source of H(+) in regions of large fractional abundance of H2, as well as an important destruction mechanism for He(+) even for small f (at least 0.1). The calculated molecular abundances are consistent with some of the available observational information.

Glassgold, A. E.↗

DOE OSTI2019

Accelerated Testing of Selected Filler Compositions

The fillers R&D program, mostly experimental, is part of a broader R&D program that includes new process modeling and performance assessment of criticality effects and the overall importance of criticality to repository performance (consequence screening). A literature research and consultation effort with experts by Hardin and Brady (2018) identified several potentially effective and workable filler materials including cements (primarily phosphate based), molten-metal alloys, and low-temperature glasses. Filler attributes were defined and the preliminary lists were compared qualitatively. Further comparative analysis will be done (e.g., cost estimates) after experimental screening has narrowed the list of alternatives. The following cement filler compositions were selected for experimental development work and accelerated testing in FY19: Aluminum phosphate cements (APCs); more specifically aluminum oxide / aluminum phosphate (Al 2 O 3 / AlPO 4 ) cements in which Al 2 O 3 serves as the filler material bound by an AlPO 4 binder formed by the reaction of Al 2 O 3 with H 3 PO 4 ; Calcium phosphate cements (CPCs); more specifically composed of pure or nearly pure hydroxyapatite (Ca 5 (PO 4 ) 3 (OH)); Magnesium potassium phosphate cements (MKPs) composed of magnesium oxide / magnesium potassium phosphate (MgO / MgKPO 4 ) cements in which MgO serves as the filler and MgKPO 4 serves as the binder formed by the reaction of MgO with monopotassium phosphate (KH 2 PO 4 ) and tricalcium phosphate ((Ca 3 (PO 4 ) 2 ); Two additional potential cement materials were explored preliminarily as the result of: (1) continued literature investigations into other filler candidates (wollastonite-based phosphate ceramic) and (2) the experimental discovery of a well-consolidated fly ash phosphate cement during the evaluation of fly ash as a potential filler material with Al 2 O 3 in APCs. Fly ash phosphate cements, more specifically in which a fly ash material composed primarily of mullite and quartz serves as the filler and is reacted with H 3 PO 4 to form amorphous phosphate phase(s) as the binder; Wollastonite aluminum phosphate cements (WAPC), specifically wollastonite / aluminum phosphate (CaSiO 3 / AlPO 4 ) in which CaSiO 3 serves as the filler material and AlPO 4 serves as the binder formed by Al(OH) 3 or metakaolin as Al sources and H 3 PO 4 or ammonium dihydrogen phosphate (ADP) (NH 4 H 2 PO 4 ) as phosphate sources. The FY19 effort focused on the optimization of compositions and subsequent processing of these five materials to achieve dense and well-consolidated monolithic samples with relatively low porosity. Once these goals were met basic material properties screening evaluations were performed including an assessment of dissolution resistance in water at elevated temperature (200 °C) and mechanical testing including unconfined compressive strength (UCS) testing. To date, the aluminum phosphate cements (APCs) appear to show the most promise for continued development. They are easily prepared and form smooth pourable slurries that remain stable for days with relatively low viscosities of several thousand centipoise (cP). They are then set at elevated temperatures (e.g., 170 °C) under ambient (0.1 MPa) or elevated pressure (~1MPa). Overall, they demonstrate the best dissolution resistance in water at elevated temperature (200 °C) and good compressive strengths. However, additional effort is required to optimize the APC slurry formulations and the process used for thermal curing these materials. The calcium phosphate cements (CPCs) can be formed at room temperature to produce a well-consolidated body. However, their slurry viscosities are very high (and difficult to measure) and they exhibit relatively short cure times of 2 to 3 hours. Also, dissolution resistance is very poor, the poorest of all the cements examined The same is the case for the small number of MKP cements fabricated; they cure very quickly (10 minutes or less) and disintegrate within a few hours upon immersion in distilled water. Surprisingly, fly ash reacts with phosphoric acid to form dense and well-consolidated cements but the mixture rapidly sets at room temperature (less than 30 minutes) and the subsequent conversion of the binder to an amorphous phosphate phase(s) as a function of temperature is complicated. Finally, the wollastonite aluminum phosphate cements (WAPC) are easily prepared and form smooth pourable slurries that remain stable for several hours. They are then set at 130 °C. A WAPC sample exhibited the highest compressive strengths of all the materials we evaluated but in general their dissolution resistance to water is poor.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Techno-economic and life cycle analysis of synthetic natural gas production from low-carbon H 2 and point-source or atmospheric CO 2 in the United States

Synthetic natural gas (SNG) is of great interest in reducing fossil energy consumption while maintaining compatibility with existing NG infrastructure and end-use applications equipment. SNG can be produced using clean H 2 generated from renewable or nuclear energy and CO 2 captured from stationary sources or the atmosphere. In this study, we develop an engineering process model of SNG production using Aspen Plus® and production scales reported by the industry. We examine the levelized cost and life cycle greenhouse gas (GHG) emissions of SNG production under various CO 2 supply scenarios. Considering the higher cost of H 2 transportation compared with CO 2 transportation, we assume that CO 2 feedstock is transported via pipeline to the H 2 production location, which is collocated with the SNG plant. We also evaluate the cost of CO 2 captured from the atmosphere, assuming the direct air capture process can occur near the SNG facility. Depending on the CO 2 supply chain, the levelized cost of SNG is estimated to be in the range of $\$45–76$ per million British thermal units (MMBtu) on a higher heating value (HHV) basis. The SNG production cost may be reduced to $\$27–57$/MMBtu-HHV by applying a tax credit available in the United States for low-carbon H 2 production (45V). With a lower electricity price of 3¢/kWh for water electrolysis and accounting for a 45V tax credit, the SNG cost reaches parity with the cost of fossil NG. Depending on the CO 2 supply chain, SNG can reduce life cycle GHG emissions by 52–88% compared with fossil NG.

03 NATURAL GAS↗

NASA NTRS1986

Uranian H Ly-alpha emission - The interstellar wind source

IUE observation of Uranian emissions in hydrogen Lyman alpha (H Ly-alpha) over the past four years have recently been summarized by Clarke et al. (1985). Over this time period they find an average H Ly-alpha brightness of 1260 R which they estimate is composed of 200 R of solar scattered radiation and 1060 R from a collisional source. A third component, not considered by previous authors, is the reflection of H Ly-alpha emissions from the interstellar wind. Hydrogen in the interstellar wind forms an extended source of H Ly-alpha whose importance relative to the solar flux increases with distance from the sun. The present paper demonstrates that scattering of interstellar H Ly-alpha is more important than scattering of solar H Ly-alpha for reasonable values of H column abundance and, in fact, may make up 10-40 percent of the observed signal. Large H column abundances are still required to explain the H Ly-alpha brightness solely on the basis of resonant scattering; therefore it is likely that the emissions are due in part to collisional sources and in part to the scattering of interstellar H Ly-alpha with solar scattering playing a minor role.

Yelle, R. V.↗

DOE OSTI2025

Imprint of Anthropogenic Sources and Soil Removal on the Surface Concentration of H2 in the Contiguous US

Hydrogen (H2) is experiencing renewed interest throughout the world as a low carbon fuel alternative or complement to fossil fuels. Significant uncertainties remain regarding the environmental impact of increasing H2 usage, in part due to gaps in our understanding of the H2 atmospheric budget, including the H2 release from industrial activities and the H2 soil removal, the most important sink of H2. This study focuses on H2 dry air mole fractions measured by the NOAA Global Monitoring Laboratory in discrete ambient air samples collected every few days at sites located in the contiguous United States between 2010 and 2022. We take advantage of the long-term observations from this network to study the regional distribution of H2 sources using the potential source contribution function (PSCF). We find that H2 PSCF is consistent with a large anthropogenic source of atmospheric H2 from the incomplete combustion of fossil fuel. However, episodic air masses with high H2 dry air mole fractions (>700 ppb) recorded at some sampling locations in the Western and Southeastern US are not associated with elevated CO, suggesting significant noncombustion anthropogenic or geological sources of H2. Air masses depleted in H2 are recorded in rural or remote continental sites. Our analysis of observations from a tall tower in NE Colorado suggests that the degree of H2 depletion not only reflects differences in soil exposure but also the regional inhibition of the soil sink under arid conditions.

Paulot, Fabien↗

DOE OSTI2025

LAMP Technical Readiness Evaluation Report

An internal preliminary evaluation of Critical Technology Elements (CTEs) for the LANSCE Modernization Project (LAMP) was completed in 2023. This included determining corresponding Technical Readiness Levels (TRLs) for all subsystems using the criteria of DOE G 413.3-4A, Technical Readiness Assessment Guide. This revised report includes a summary of the recent design modifications required to meet the project Key Performance Requirements (KPPs), some of which may reduce technical risk to the project. These recent design modifications include: • Further optimization of the low-energy and medium-energy beam transport regions (LEBT and MEBT, respectively), including relocation of various functional elements (ie choppers, kickers, and bunchers). • An additional H - ion source to separate ion-source function based on beam delivery requirements. • A high-repetition-rate pulsed kicker magnet to select/merge the two H ion beams into a common low-energy beam transport. • Modification and further optimization to a more conventional RFQ design. Performance of the RFQ has been optimized to deliver the required three types of beams while meeting the project KPPs. • The addition of a second chopper in the medium-energy beam transport (MEBT) line to reduce the required pulser voltages. The scope of the evaluation was limited to the project Work Breakdown Structure (WBS) elements as defined for the RFQ Injector and Drift Tube Linac (DTL) systems only. Integration of Instrumentation and Controls (I&C) and Safety Systems was not considered, although specific technologies as related to the RFQ and DTL systems were included. Other elements of the project such as Shielding, System Design, Technical Management, and additional facility integration needed to enable off-line testing and pre-installation commissioning were also not evaluated. Each technical subsystem element was evaluated for technical readiness, however, not all were found to meet the criteria for a CTE. Three subsystem elements were determined to meet the CTE criteria. Their associated TRLs are summarized in the table below. These subsystem elements of the project have the lowest technical readiness due to either being new, novel or modified, requiring additional R&D before being capable of meeting the project Key Performance Parameters (KPPs) and subsystem requirements, or present technology exists but has not yet been demonstrated in a relevant environment. All other subsystems were determined to have a TRL of 8, indicating that actual operating systems exist having similar performance requirements as needed for LAMP. Details of the technical readiness evaluation for each subsystem is given in the following sections of this report.

43 PARTICLE ACCELERATORS↗

DOE OSTI2026

LAMP Technical Readiness Evaluation Report: LAMP-ENG-RPT-003 (Revision 2)

43 PARTICLE ACCELERATORS↗

DOE OSTI2013

Comparison between ZnO films grown by plasma-assisted atomic layer deposition using H{sub 2}O plasma and O{sub 2} plasma as oxidant

Zinc oxide (ZnO) thin films have attracted significant attention for application in thin film transistors (TFTs) due to their specific characteristics, such as high mobility and transparency. In this paper, the authors fabricated TFTs with ZnO thin films as channel layers deposited by plasma-assisted atomic layer deposition (PAALD) at 100 Degree-Sign C using two different plasma sources, water (H{sub 2}O-plasma) and oxygen gas (O{sub 2}-plasma), as oxidants, and investigated the effects of the plasma sources on TFT performances. The TFT with ZnO channel layer deposited with H{sub 2}O-plasma indicated higher performances such as a field effect mobility ({mu}) of 1.1 cm{sup 2}/Vs. Analysis of the ZnO films revealed that the residual carbon in the film deposited with H{sub 2}O-plasma was lower than that of O{sub 2}-plasma. In addition, the c-axis preferred orientation was obtained in the case of the ZnO film deposited with H{sub 2}O-plasma. These results suggest that it is possible to fabricate high-performance ZnO TFTs at low temperatures by PAALD with H{sub 2}O-plasma.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2014

Testing Single Phase IGBT H-Bridge Switch Plates for the High Voltage Converter Modulator at the Spallation Neutron Source

Three IGBT H-bridge switching networks are used in each High Voltage Converter Modulator (HVCM) system at the Spallation Neutron Source (SNS) to generate drive currents to three boost transformer primaries switching between positive and negative bus voltages at 20 kHz. Every switch plate assembly is tested before installing it into an operational HVCM. A Single Phase Test Stand has been built for this purpose, and it is used for adjustment, measurement and testing of different configurations of switch plates. This paper will present a description of the Test Stand configuration and discuss the results of testing switch plates with two different types of IGBT gate drivers currently in use on the HVCM systems. Comparison of timing characteristics of the original and new drivers and the resulting performance reinforces the necessity to replace the original H-bridge network drivers with the upgraded units.

Gate Driver↗

DOE OSTI2016

Measurement of ion species in high current ECR H{sup +}/D{sup +} ion source for IFMIF (International Fusion Materials Irradiation Facility)

Ion species ratio of high current positive hydrogen/deuterium ion beams extracted from an electron-cyclotron-resonance ion source for International Fusion Materials Irradiation Facility accelerator was measured by the Doppler shift Balmer-α line spectroscopy. The proton (H{sup +}) ratio at the middle of the low energy beam transport reached 80% at the hydrogen ion beam extraction of 100 keV/160 mA and the deuteron (D{sup +}) ratio reached 75% at the deuterium ion beam extraction of 100 keV/113 mA. It is found that the H{sup +} ratio measured by the spectroscopy gives lower than that derived from the phase-space diagram measured by an Allison scanner type emittance monitor. The H{sup +}/D{sup +} ratio estimated by the emittance monitor was more than 90% at those extraction currents.

43 PARTICLE ACCELERATORS↗

NASA NTRS2021

SIMS Study of H in Martian Meteorite LAR 06319 for Characterization of the Enriched Shergottite Mantle Source on Mars Reveals Shock-Induced H Diffusion

SIMS study of H in Martian meteorite LAR 06319 for characterization of the enriched shergottite mantlesource on Mars reveals shock-induced H diffusion

J. M. Dudley↗

DOE OSTI2012

THE H I ENVIRONMENT OF THE M101 GROUP

We present a wide (8. Degree-Sign 5 Multiplication-Sign 6. Degree-Sign 7, 1050 Multiplication-Sign 825 kpc), deep ({sigma}{sub N{sub H{sub {sub {sub i}}}}}10{sup 16.8}-10{sup 17.5} cm{sup -2}) neutral hydrogen (H I) map of the M101 galaxy group. We identify two new H I sources in the group environment, one an extremely low surface brightness (and hitherto unknown) dwarf galaxy, and the other a starless H I cloud, possibly primordial in origin. Our data show that M101's extended H I envelope takes the form of a {approx}100 kpc long tidal loop or plume of H I extending to the southwest of the galaxy. The plume has an H I mass of {approx}10{sup 8} M{sub Sun} and a peak column density of N{sub H{sub i}}= 5 Multiplication-Sign 10{sup 17} cm{sup -2}, and while it rotates with the main body of M101, it shows kinematic peculiarities suggestive of a warp or flaring out of the rotation plane of the galaxy. We also find two new H I clouds near the plume with masses {approx}10{sup 7} M{sub Sun }, similar to H I clouds seen in the M81/M82 group, and likely also tidal in nature. Comparing to deep optical imaging of the M101 group, neither the plume nor the clouds have any extended optical counterparts down to a limiting surface brightness of {mu}{sub B} = 29.5. We also trace H I at intermediate velocities between M101 and NGC 5474, strengthening the case for a recent interaction between the two galaxies. The kinematically complex H I structure in the M101 group, coupled with the optical morphology of M101 and its companions, suggests that the group is in a dynamically active state that is likely common for galaxies in group environments.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2013

THE ORIGIN OF THE 6.4 keV LINE EMISSION AND H{sub 2} IONIZATION IN THE DIFFUSE MOLECULAR GAS OF THE GALACTIC CENTER REGION

We investigate the origin of the diffuse 6.4 keV line emission recently detected by Suzaku and the source of H{sub 2} ionization in the diffuse molecular gas of the Galactic center (GC) region. We show that Fe atoms and H{sub 2} molecules in the diffuse interstellar medium of the GC are not ionized by the same particles. The Fe atoms are most likely ionized by X-ray photons emitted by Sgr A* during a previous period of flaring activity of the supermassive black hole. The measured longitudinal intensity distribution of the diffuse 6.4 keV line emission is best explained if the past activity of Sgr A* lasted at least several hundred years and released a mean 2-100 keV luminosity {approx}> 10{sup 38} erg s{sup -1}. The H{sub 2} molecules of the diffuse gas cannot be ionized by photons from Sgr A*, because soft photons are strongly absorbed in the interstellar gas around the central black hole. The molecular hydrogen in the GC region is most likely ionized by low-energy cosmic rays, probably protons rather than electrons, whose contribution into the diffuse 6.4 keV line emission is negligible.

79 ASTRONOMY AND ASTROPHYSICS↗