33 research outputs found
A preliminary systems-engineering study of an advanced nuclear-electrolytic hydrogen-production facility
An advanced nuclear-electrolytic hydrogen-production facility concept was synthesized at a conceptual level with the objective of minimizing estimated hydrogen-production costs. The concept is a closely-integrated, fully-dedicated (only hydrogen energy is produced) system whose components and subsystems are predicted on ''1985 technology.'' The principal components are: (1) a high-temperature gas-cooled reactor (HTGR) operating a helium-Brayton/ammonia-Rankine binary cycle with a helium reactor-core exit temperature of 980 C, (2) acyclic d-c generators, (3) high-pressure, high-current-density electrolyzers based on solid-polymer electrolyte technology. Based on an assumed 3,000 MWt HTGR the facility is capable of producing 8.7 million std cu m/day of hydrogen at pipeline conditions, 6,900 kPa. Coproduct oxygen is also available at pipeline conditions at one-half this volume. It has further been shown that the incorporation of advanced technology provides an overall efficiency of about 43 percent, as compared with 25 percent for a contemporary nuclear-electric plant powering close-coupled contemporary industrial electrolyzers
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The FIELDS Instrument Suite for Solar Probe Plus: Measuring the Coronal Plasma and Magnetic Field, Plasma Waves and Turbulence, and Radio Signatures of Solar Transients.
NASA's Solar Probe Plus (SPP) mission will make the first in situ measurements of the solar corona and the birthplace of the solar wind. The FIELDS instrument suite on SPP will make direct measurements of electric and magnetic fields, the properties of in situ plasma waves, electron density and temperature profiles, and interplanetary radio emissions, amongst other things. Here, we describe the scientific objectives targeted by the SPP/FIELDS instrument, the instrument design itself, and the instrument concept of operations and planned data products
Nonlinear Active Materials: An Illustration of Controllable Phase Matchability
For a crystal to exhibit nonlinear
optical (NLO) activity such as second-harmonic generation (SHG), it
must belong to a noncentrosymmetric (NCS) space group. Moreover, for
these nonlinear optical (NLO) materials to be suitable for practical
uses, the synthesized crystals should be phase-matchable (PM). Previous
synthetic research into SHG-active crystals has centered on (i) how
to create NCS compounds and/or (ii) how to obtain NCS compounds with
high SHG efficiencies. With these tactics, one can synthesize a material
with a high SHG efficiency, but the material could be unusable if
the material was nonphase-matchable (non-PM). To probe the origin
of phase matchability of NCS structures, we present two new chemically
similar hybrid compounds within one composition space: <b>(I) </b>[Hdpa]<sub>2</sub>NbOF<sub>5</sub>·2H<sub>2</sub>O and <b>(II)</b> HdpaNbOF<sub>4</sub> (dpa = 2,2′-dipyridylamine).
Both compounds are NCS and chemically similar, but <b>(I)</b> is non-PM while <b>(II)</b> is PM. Our results indicateî—¸consistent
with organic crystallographyî—¸the arrangement of the organic
molecule within hybrid materials dictates whether the material is
PM or non-PM
Nonlinear Active Materials: An Illustration of Controllable Phase Matchability
For a crystal to exhibit nonlinear
optical (NLO) activity such as second-harmonic generation (SHG), it
must belong to a noncentrosymmetric (NCS) space group. Moreover, for
these nonlinear optical (NLO) materials to be suitable for practical
uses, the synthesized crystals should be phase-matchable (PM). Previous
synthetic research into SHG-active crystals has centered on (i) how
to create NCS compounds and/or (ii) how to obtain NCS compounds with
high SHG efficiencies. With these tactics, one can synthesize a material
with a high SHG efficiency, but the material could be unusable if
the material was nonphase-matchable (non-PM). To probe the origin
of phase matchability of NCS structures, we present two new chemically
similar hybrid compounds within one composition space: <b>(I) </b>[Hdpa]<sub>2</sub>NbOF<sub>5</sub>·2H<sub>2</sub>O and <b>(II)</b> HdpaNbOF<sub>4</sub> (dpa = 2,2′-dipyridylamine).
Both compounds are NCS and chemically similar, but <b>(I)</b> is non-PM while <b>(II)</b> is PM. Our results indicateî—¸consistent
with organic crystallographyî—¸the arrangement of the organic
molecule within hybrid materials dictates whether the material is
PM or non-PM