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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

FOUR IRAC SOURCES WITH AN EXTREMELY RED H - [3.6] COLOR: PASSIVE OR DUSTY GALAXIES AT z > 4.5?

We report the detection of four IRAC sources in the GOODS-South field with an extremely red color of H - [3.6] > 4.5. The four sources are not detected in the deep Hubble Space Telescope WFC3 H-band image with H{sub limit} = 28.3 mag. We find that only three types of SED templates can produce such a red H - [3.6] color: a very dusty SED with the Calzetti extinction of A{sub V} = 16 mag at z = 0.8; a very dusty SED with the SMC extinction of A{sub V} = 8 mag at z = 2.0- 2.2; and an 1 Gyr SSP with A{sub V} {approx} 0.8 at z = 5.7. We argue that these sources are unlikely dusty galaxies at z {<=} 2.2 based on absent strong MIPS 24 {mu}m emission. The old stellar population model at z > 4.5 remains a possible solution for the 4 sources. At z > 4.5, these sources have stellar masses of log(M{sub *}/M{sub Sun }) = 10.6-11.2. One source, ERS-1, is also a type-II X-ray QSO with L{sub 2-8keV} = 1.6 Multiplication-Sign 10{sup 44} erg s{sup -1}. One of the four sources is an X-ray QSO and another one is a HyperLIRG, suggesting a galaxy-merging scenario for the formation of these massive galaxies at high redshifts.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1976

Radio continuum measurements of compact H II regions and other sources

Results are reported for measurements of the flux densities of 33 sources at wavelengths of 13, 4, and 2 cm, which were conducted using the NASA/JPL Deep Space Network 64-m antenna at Goldstone, Calif. Besides compact H II regions, the sources included five Uhuru X-ray sources, several IR sources, an extragalactic radio source, and a H2O maser. The Lyman continuum flux is derived from the measured radio flux and the assumed distance and temperature for 10 possible H II regions; the spectra of previously known sources are extended to higher frequencies, and upper limits are placed on the flux densities for the five X-ray sources. New compact H II regions are found in the bright nebula M78, the nebula K5, and the Ophiuchus dark cloud/IR region.

Matsakis, D. N.↗
DOE OSTI2025

The MIST-1 and MIST-2 multicusp ion sources for high-current $H$$^{+}_{2}$ beams

We present two iterations of the Multicusp Ion Source Technology at MIT (MIST) sources, designed to fulfill the requirements of the HCHC-XX cyclotron design. The HCHC-XX is a novel compact cyclotron accelerating $H$$^{+}_{2}$. Beam is injected through a radio-frequency quadrupole buncher-accelerator (embedded in the cyclotron yoke) and utilizes so-called vortex motion during acceleration. If successful, it will deliver 10 mA of protons at 60 MeV in CW mode. This scheme requires a low-emittance, high-current initial beam with high $H$$^{+}_{2}$ purity. We briefly summarize the design and previous results of the MIST-1 ion source and, for the first time, the detailed design of the new and improved MIST-2, including the mechanical, electrical, and control system design. We further show experimental results of using the MIST-2 backplate on the MIST-1 body, present a study using different types of permanent magnets for confinement (including no magnets), and finally, we present first results of the MIST-2 in full operation. In this first commissioning run, we were able to increase the total extracted current from the MIST-2 to 7 mA—a factor of 2 over the MIST-1.

Winklehner, D. [Massachusetts Institute of Technol↗
DOE OSTI2016

A new H{sub 2}{sup +} source: Conceptual study and experimental test of an upgraded version of the VIS—Versatile ion source

The versatile ion source is an off-resonance microwave discharge ion source which produces a slightly overdense plasma at 2.45 GHz of pumping wave frequency extracting more than 60 mA proton beams and 50 mA He{sup +} beams. DAEδALUS and IsoDAR experiments require high intensities for H{sub 2}{sup +} beams to be accelerated by high power cyclotrons for neutrinos generation. In order to fulfill the new requirements, a new plasma chamber and injection system has been designed and manufactured for increasing the H{sub 2}{sup +} beam intensity. In this paper the studies for the increasing of the H{sub 2}{sup +}/p ratio and for the design of the new plasma chamber and injection system will be shown and discussed together with the experimental tests carried out at Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali del Sud (INFN-LNS) and at Best Cyclotron Systems test-bench in Vancouver, Canada.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

VLA observations of NGC 247: identification of compact radio sources including three candidate UD H II regions

A high resolution, Very Large Array continuum survey of NGC 247 was undertaken in order to identify compact thermal and nonthermal radio sources, such as supernova remnants (SNRs) and H II regions. NGC 247 was observed at two frequencies, 20 cm and 6 cm, in order to calculate the spectral index, and the survey resulted in the identification of 19 compact radio sources. Using the spectral index to discriminate between source types, we identify two candidate SNRs and one H II region. Three of the radio sources have inverted spectra, indicative of ultradense H II (UD H II) regions, the short-lived, dense cores where massive stars form. Four of the sources are thermal in origin, but were not detected at 20 cm, so they could be H II regions or UD H II regions. The rest of the sources are nonthermal or undetermined. We compare the radio images with Hα, V band, and infrared archive images to look for correspondences that confirm that the sources reside in NGC 247 and are not background sources. We find that over two-thirds of the radio sources have counterparts in the Hα or V band images and are associated with NGC 247. The most luminous radio source in NGC 247 is a candidate SNR, and if confirmed as an SNR, it would be a very luminous extragalactic SNR. The H II regions and UD H II regions are calculated to have ionizing luminosities of between 4-10 × 10{sup 50} s{sup –1}; each individual source would require between 41-100 O7.5V stars to produce the corresponding ionizing luminosity. The ionizing luminosity of the UD H II regions indicates that these UD H II regions represent the lower luminosity population of the known UD H II regions and thus, they may represent a more typical population of UD H II regions that can be found and studied in the nearby galaxies as opposed to more extreme examples that have been found previously.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

INVISIBLE ACTIVE GALACTIC NUCLEI. II. RADIO MORPHOLOGIES AND FIVE NEW H i 21 cm ABSORPTION LINE DETECTORS

This is the second paper directed toward finding new highly redshifted atomic and molecular absorption lines at radio frequencies. To this end, we selected a sample of 80 candidates for obscured radio-loud active galactic nuclei (AGNs) and presented their basic optical/near-infrared (NIR) properties in Paper I. In this paper, we present both high-resolution radio continuum images for all of these sources and H i 21 cm absorption spectroscopy for a few selected sources in this sample. A-configuration 4.9 and 8.5 GHz Very Large Array continuum observations find that 52 sources are compact or have substantial compact components with size <0.″5 and flux densities >0.1 Jy at 4.9 GHz. The 36 most compact sources were then observed with the Very Long Baseline Array at 1.4 GHz. One definite and 10 candidate Compact Symmetric Objects (CSOs) are newly identified, which is a detection rate of CSOs ∼three times higher than the detection rate previously found in purely flux-limited samples. Based on possessing compact components with high flux densities, 60 of these sources are good candidates for absorption-line searches. Twenty-seven sources were observed for H i 21 cm absorption at their photometric or spectroscopic redshifts with only six detections (five definite and one tentative). However, five of these were from a small subset of six CSOs with pure galaxy optical/NIR spectra (i.e., any AGN emission is obscured) and for which accurate spectroscopic redshifts place the redshifted 21 cm line in a radio frequency intereference (RFI)-free spectral “window” (i.e., the percentage of H i 21 cm absorption-line detections could be as high as ∼90% in this sample). It is likely that the presence of ubiquitous RFI and the absence of accurate spectroscopic redshifts preclude H i detections in similar sources (only 1 detection out of the remaining 22 sources observed, 13 of which have only photometric redshifts); that is, H i absorption may well be present but is masked by the RFI. Future searches for highly redshifted H i and molecular absorption can easily find more distant CSOs among bright, “blank field” radio sources, but will be severely hampered by an inability to determine accurate spectroscopic redshifts due to their lack of rest-frame UV continuum.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

HIghMass-high H I mass, H I-rich galaxies at z ∼ 0 sample definition, optical and Hα imaging, and star formation properties

We present first results of the study of a set of exceptional H I sources identified in the 40% ALFALFA extragalactic H I survey catalog α.40 as both being H I massive (M{sub HI}>10{sup 10} M{sub ⊙}) and having high gas fractions for their stellar masses: the HIghMass galaxy sample. We analyze UV- and optical-broadband and Hα images to understand the nature of their relatively underluminous disks in optical and to test whether their high gas fractions can be tracked to higher dark matter halo spin parameters or late gas accretion. Estimates of their star formation rates (SFRs) based on spectral energy distribution fitting agree within uncertainties with the Hα luminosity inferred current massive SFRs. The H II region luminosity functions, parameterized as dN/dlog L∝L {sup α}, have standard slopes at the luminous end (α ∼ –1). The global SFRs demonstrate that the HIghMass galaxies exhibit active ongoing star formation (SF) with moderate SF efficiency but, relative to normal spirals, a lower integrated SFR in the past. Because the SF activity in these systems is spread throughout their extended disks, they have overall lower SFR surface densities and lower surface brightness in the optical bands. Relative to normal disk galaxies, the majority of HIghMass galaxies have higher Hα equivalent widths and are bluer in their outer disks, implying an inside-out disk growth scenario. Downbending double exponential disks are more frequent than upbending disks among the gas-rich galaxies, suggesting that SF thresholds exist in the downbending disks, probably as a result of concentrated gas distribution.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1986

The isotopes of hydrogen and helium in the Galactic cosmic radiation - Their source abundances and interstellar propagation

A self-consistent model describing the interstellar propagation of Galactic cosmic radiation is developed using low-energy measurements and calculations of the effects of interstellar propagation and solar modulation. The source ratio H-1/He-4 at constant energy per nucleon is determined to be 12.2 + or - 1.5, and the mean path length for an exponential path length weighting function required to account for the data is 7.2 + or - 1.0 g/sq cm. The measured H-2/He-4 and He-3/He-4 ratios do not vary by more than about 30 percent over the solar cycle. The behavior of the ratios during the solar cycle reflects the energy dependence of the local interstellar ratios, and leads to an energy dependence of the mean path length below 1 GeV per nucleon weaker than that inferred from boron/carbon. The source ratio H-1/He-4 inferred from the low-energy data is consistent both with the value inferred from high-energy cosmic ray data using a model of rigidity-dependent confinement and with the solar system abundance ratio.

Beatty, James J.↗
DOE OSTI2014

Studies of basic limitations on production, transport and acceleration of the high intensity polarized H{sup −} beam in the RHIC polarized ion source

Basic limitations on the high-intensity polarized H{sup −} ion beam production and transport were experimentally studied in charge-exchange collisions of the neutral atomic hydrogen beam in the Na-vaporjet ionizer cell. The energy dependence of space-charge effects on the beam instabilities and losses were studied and described in the model of synthetic H{sup +} — H{sup −} beam transport. A xenon gas admixture to the H{sup −} ion production cell and beam transport line greatly improves the space-charge compensation, which is also successfully described in the simulations. These studies are the part of the polarized source upgrade project for RHIC.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

THE GREEN BANK TELESCOPE H II REGION DISCOVERY SURVEY. II. THE SOURCE CATALOG

The Green Bank Telescope (GBT) H II Region Discovery Survey has doubled the number of known H II regions in the Galactic zone 343{sup 0} {<=} l {<=} 67{sup 0} with | b | {<=} 1{sup 0}. We detected 603 discrete hydrogen radio recombination line (RRL) components at 9 GHz (3 cm) from 448 targets. Our targets were selected based on spatially coincident mid-infrared and 20 cm radio continuum emission. Such sources are almost invariably H II regions; we detected hydrogen RRL emission from 95% of our target sample. The sensitivity of the GBT and the power of its spectrometer together made this survey possible. Here, we provide a catalog of the measured properties of the RRL and continuum emission from the survey nebulae. The derived survey completeness limit, 180 mJy at 9 GHz, is sufficient to detect all H II regions ionized by single O-stars to a distance of 12 kpc. These recently discovered nebulae share the same distribution on the sky as does the previously known census of Galactic H II regions. On average, however, the new nebulae have fainter continuum fluxes, smaller continuum angular sizes, fainter RRL intensities, and smaller RRL line widths. Though small in angular size, many of our new nebulae show little spatial correlation with tracers associated with extremely young H II regions, implying that our sample spans a range of evolutionary states. We discovered 34 first quadrant negative-velocity H II regions, which lie at extreme distances from the Sun and appear to be part of the Outer Arm. We found RRL emission from 208 Spitzer GLIMPSE 8.0 {mu}m 'bubble' sources, 65 of which have been cataloged previously. It thus appears that nearly all GLIMPSE bubbles are H II regions and that {approx}50% of all Galactic H II regions have a bubble morphology at 8.0 {mu}m.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Catalytic Silylation of N 2 and Synthesis of NH 3 and N 2 H 4 by Net Hydrogen Atom Transfer Reactions Using a Chromium P 4 Macrocycle

We report the first discrete molecular Cr-based catalysts for the reduction of N2. This study is focused on the reactivity of the Cr-N2 complex, trans-[Cr(N2)2(PPh4NBn4)] P4Cr(N2)2, bearing a 16-membered tetraphosphine macrocycle. The architecture of the [16]-PPh4NBn4 ligand is critical to preserve the structural integrity of the catalyst. P4Cr(N2)2 was found to mediate the reduction of N2 by three complementary reaction pathways: (1) Cr-catalyzed reduction of N2 to N(SiMe3)3 by Na and Me3SiCl affording up to 34 equiv N(SiMe3)3; (2) stoichiometric reduction of N2 by protons and electrons. For example, the reaction of cobaltocene (CoCp2) and collidinium triflate (ColH[OTf]) at room temperature to afforded 1.9 equiv of NH3, or at -78 °C to afforded a mixture of NH3 and N2H4; (3) the first example of NH3 formation from the reaction of a terminally bound N2 ligand with a traditional H atom source, TEMPOH, (2,2,6,6-tetramethylpiperidine-1-ol). We found that trans-[Cr(15N2)2(PPh4NBn4)] reacts with excess TEMPOH to afford a 1.4 equiv of 15NH3.

Kendall, Alexander J.↗
NASA NTRS1991

Triton's atmosphere - A source of N and H for Neptune's magnetosphere

Mass loading of the Neptunian magnetosphere occurs primarily by thermal escape of H, H2, and N from Triton's upper atmosphere. The global escape rate of hydrogen is about 7 x 10 exp 25/s, determined by the global average methane photolysis rate, whereas the escape rate of nitrogen for the present preferred model is about 3.4 x 10 exp 25/s, and is controlled by the global and orbital average energy deposition rate due to precipitating magnetospheric electrons. The escape rate of H(+) and N(+) is less than 4 percent of the neutral escape rate and implies that mass loading of the Neptunian magnetosphere is not localized to Triton's corona. The ratio of hydrogen to nitrogen escape rates for the present preferred model is about 2:1, comparable to the H(+)/N(+) abundance ratio inferred for Neptune's magnetosphere.

Summers, Michael E.↗
DOE OSTI2023

Overview of H- radio frequency ion sources for particle accelerators

Particle accelerators are among the most important scientific tools of the modern era. Large accelerator complexes have supported scientific user facilities which have had an enormous societal impact spanning many decades and enabling the work of thousands of scientific users worldwide contributing to many Nobel prizes in physics, biology and chemistry [1]. Many of the large hadron facilities employ accelerator complexes which include cyclotrons, synchrotrons, storage rings, linear or tandem accelerators and deliver ion beams of very high-intensity and/or very high-energy to their user facilities. These accelerator complexes require the injection of high-intensity beams of ions which are produced within an ion source and formed within a plasma or by bombardment of a surface [2]. Increasingly, RF systems are being utilized, to generate these ion-rich plasmas due to their high reliability and minimal use of consumable components. This report will first discuss the basic mechanisms of ion formation and plasma generation as well as some specifics of RF/microwave generators, matching circuits and plasma coupling structures typically employed. A detailed discussion will then be given of the RF-driven negative ion source systems employed by US Spallation Neutron Source as well as those used in similar facilities located around the globe. REFERENCES [1]Vladimir Shiltsev, “Particle beams behind physics discoveries”, Physics Today 73, Issue 4, 32 (2020) [2]Robert Welton et al, “Negative hydrogen ion sources for particle accelerators: Sustainability issues and recent improvements in long-term operations”, Journal of Physics Conf Series, 2244 012045

Welton, Robert F.↗
DOE OSTI2014

The RHIC polarized source upgrade

The RHIC polarized H{sup −} ion source is being upgraded to higher intensity and polarization for use in the RHIC polarization physics program at enhanced luminosity RHIC operation. The higher beam intensity will allow reduction of the longitudinal transverse beam emittance at injection to AGS to reduce polarization losses in AGS. There is also a planned RHIC luminosity upgrade by using the electron beam lens to compensate the beam-beam interaction at collision points. This upgrade is also essential for future BNL plans for a high-luminosity electron-proton (ion) Collider eRHIC. The basic limitations on the high-intensity H{sup −} ion beam production in charge-exchange collisions of the neutral atomic hydrogen beam in the Na-vapor jet ionizer cell were experimentally studied.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

J- AND H-BAND IMAGING OF AKARI NORTH ECLIPTIC POLE SURVEY FIELD

We present the J- and H-band source catalog covering the AKARI North Ecliptic Pole field. Filling the gap between the optical data from other follow-up observations and mid-infrared (MIR) data from AKARI, our near-infrared (NIR) data provides contiguous wavelength coverage from optical to MIR. For the J- and H-band imaging, we used the FLoridA Multi-object Imaging Near-ir Grism Observational Spectrometer on the Kitt Peak National Observatory 2.1m telescope covering a 5.1 deg{sup 2} area down to a 5σ depth of ∼21.6 mag and ∼21.3 mag (AB) for the J and H bands with an astrometric accuracy of 0.''14 and 0.''17 for 1σ in R.A. and decl. directions, respectively. We detected 208,020 sources for the J band and 203,832 sources for the H band. This NIR data is being used for studies including the analysis of the physical properties of infrared sources such as stellar mass and photometric redshifts, and will be a valuable data set for various future missions.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1974

Infrared studies of H II regions and OH sources

This paper presents the observational results of a high spatial-resolution mapping and photometric study in the wavelength range from 1.65 to 20 microns of four H II regions and seven OH sources. Infrared emission indicative of the presence of heated dust was found from the compact H II condensations in W51, DR21, and NGC7538. Infrared emission was also found from the positions of maser sources in NGC 7538, W75(N) W75(S) and Sharpless 269, but not from that in W51. An extended infrared source was found coincident with the peculiar OH source OH 0739-14.

Wynn-Williams, C. G.↗