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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Development of the FASPAX IC for a high burst rate X-ray imager with very high dynamic range ( 1 0 5 ) capability in small pixels

Development of the FASPAX IC for a high burst rate X-ray imager with very high dynamic range (10 5 ) capability in small pixels. The technique of current splitting is presented as part of an integrated circuit development for an X-ray imager. This method enables integration of charge signals of unprecedented magnitude in small pixels, achieving a dynamic range of 10 5 . Results from two front end prototypes are given and a final optimized design is proposed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

PTF11mnb: First analog of supernova 2005bf: Long-rising, double-peaked supernova Ic from a massive progenitor*

The aim is to study PTF11mnb, a He-poor supernova (SN) whose light curves resemble those of SN 2005bf, a peculiar double-peaked stripped-envelope (SE) SN, until the declining phase after the main peak. We investigate the mechanism powering its light curve and the nature of its progenitor star. Methods. Optical photometry and spectroscopy of PTF11mnb are presented. We compared light curves, colors and spectral properties to those of SN 2005bf and normal SE SNe. We built a bolometric light curve and modeled this light curve with the SuperNova Explosion Code (SNEC) hydrodynamical code explosion of a MESA progenitor star and semi-analytic models. Results. The light curve of PTF11mnb turns out to be similar to that of SN 2005bf until ~50 d when the main (secondary) peaks occur at -18.5 mag. The early peak occurs at ~20 d and is about 1.0 mag fainter. After the main peak, the decline rate of PTF11mnb is remarkably slower than what was observed in SN 2005bf, and it traces well the 56 Co decay rate. The spectra of PTF11mnb reveal a SN Ic and have no traces of He unlike in the case of SN Ib 2005bf, although they have velocities comparable to those of SN 2005bf. The whole evolution of the bolometric light curve is well reproduced by the explosion of a massive (M ej = 7.8 M ⊙ ), He-poor star characterized by a double-peaked 56 Ni distribution, a total 56 Ni mass of 0.59 M ⊙ , and an explosion energy of 2.2 × 10 51 erg. Alternatively, a normal SN Ib/c explosion (M( 56 Ni) = 0.11 M ⊙ , E K = 0.2 × 10 51 erg, M ej = 1 M ⊙ ) can power the first peak while a magnetar, with a magnetic field characterized by B = 5.0 × 10 14 G, and a rotation period of P = 18.1 ms, provides energy for the main peak. The early g-band light curve can be fit with a shock-breakout cooling tail or an extended envelope model from which a radius of at least 30 R ⊙ is obtained. Conclusions. We presented a scenario where PTF11mnb was the explosion of a massive, He-poor star, characterized by a double-peaked 56 Ni distribution. In this case, the ejecta mass and the absence of He imply a large ZAMS mass (~85 M ⊙ ) for the progenitor, which most likely was a Wolf-Rayet star, surrounded by an extended envelope formed either by a pre-SN eruption or due to a binary configuration. Alternatively, PTF11mnb could be powered by a SE SN with a less massive progenitor during the first peak and by a magnetar afterward.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

A controllable IC-compatible thin-film fuse realized using electro-explosion

A controllable IC-compatible thin-film fuse was developed that had Al/SiO{sub 2} thin-film stacks on a silicon substrate. The micro fuse has both a traditional mode and a controllable mode when applied as a fuse. It blows at 800 mA and 913.8 mV in the traditional mode. In the controllable mode, it blows within 400 ns at 10 V. It can be used for small electronic elements as well as electropyrotechnic initiators to improve the no-firing current.

36 MATERIALS SCIENCE↗
DOE OSTI2013

EVIDENCE FOR H{sub 2} FORMATION DRIVEN DUST GRAIN ALIGNMENT IN IC 63

In the interstellar medium (ISM), molecular hydrogen is expected to form almost exclusively on the surfaces of dust grains. Due to that molecule's large formation energy (–4.5 eV), several dynamical effects are likely associated with the process, including the alignment of asymmetric dust grains with the ambient magnetic field. Such aligned dust grains are, in turn, believed to cause the broadband optical/infrared polarization observed in the ISM. Here, we present the first observational evidence for grain alignment driven by H{sub 2} formation, by showing that the polarization of the light from stars behind the reflection nebula IC 63 appears to correlate with the intensity of H{sub 2} fluorescence. While our results strongly suggest a role for 'Purcell rockets' in grain alignment, additional observations are needed to conclusively confirm their role. By showing a direct connection between H{sub 2} formation and a probe of the dust characteristics, these results also provide one of the first direct confirmations of the grain-surface formation of H{sub 2}. We compare our observations to ab initio modeling based on Radiative Torque Alignment (RAT) theory.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Discovery of enhanced radiative recombination continua of He-like iron and calcium from IC 443 and its implications

We present deep observations of the Galactic supernova remnant IC 443 with the Suzaku X-ray satellite. We find prominent K-shell lines from iron and nickel, together with a triangle residual at 8-10 keV, which corresponds to the energy of the radiative recombination continuum (RRC) of He-like iron. In addition, the wavy residuals have been seen at ∼5.1 and ∼5.5 keV. We confirm that the residuals show the first enhanced RRCs of He- and H-like calcium found in supernova remnants. These facts provide robust evidence for the recombining plasma. We reproduce the plasma in the 3.7-10 keV band using a recombining plasma model at the electron temperature 0.65 keV. The recombination parameter n {sub e} t (n {sub e} is electron density and t is elapsed time after formation of a recombining plasma) and abundances of iron and nickel are strongly correlated, and hence the errors are large. On the other hand, the ratio of nickel to iron relative to the solar abundances is well constrained to 11{sub −3}{sup +4} (1σ). A possibility is that the large abundance ratio is a result of an asymmetric explosion of the progenitor star.

79 ASTRONOMY AND ASTROPHYSICS↗