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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Advanced Materials & Manufacturing Technology (AMMT): Process understanding for qualifying LPBF 316H SS

Investigations were conducted in fiscal years (FY) 2023 and 2024 to gather relevant data sets addressing challenges related to qualifying 316H stainless steel (SS) for use in future nuclear reactors. This work was a collaborative effort involving researchers from Idaho National Laboratory (INL), Argonne National Laboratory (ANL), and Oak Ridge National Laboratory (ORNL). Key outcomes included: • Development of process-structure-property data sets to better understand the relationships between manufacturing processes, material structure, and performance characteristics. • Establishment of an in-situ monitoring system to link these various data sets together. • Detailed characterization of the raw material feedstock to further strengthen the understanding of process-structure and process-property relationships. Building on this foundation, in FY25 there was interest in exploring the behavior of additively manufactured 316H SS under different test conditions to support the overall material qualification process. Los Alamos National Laboratory (LANL) was tasked with providing specimen samples to the collaborating labs, who then conducted a round-robin study examining factors like selective heat treatment, low-cycle fatigue (LCF), and tensile-creep (T-C) properties. Additionally, high-temperature differential scanning calorimetry (DSC) was performed by LANL to better understand how the material's thermal characteristics change as it is heated up to the melting point. This provided a more comprehensive understanding of the material's behavior. The combined results from these investigations could potentially be used to support the inclusion of 316H stainless steel in Section III, Division 5 of the relevant codes and standards, allowing its use in future nuclear reactor applications.

36 MATERIALS SCIENCE↗
NASA NTRS1979

The bizarre spectrum of SS 433

Results are reported for extensive spectrophotometric observations, over the wavelength range from 3800 to 7800 A, of the peculiar 14th-mag emission-line object Stephenson-Sanduleak (SS) 433, which has been identified with a variable nonthermal radio source and is positionally coincident with the X-ray source A1909+04. It is found that the spectrum is dominated by intense variable Balmer and He I emission, that three of the He I lines have very prominent P Cygni profiles, and that virtually all the emission features undergo changes in equivalent width on a time scale of days. Anomalous emission features are described which consist of three previously unreported, very strong, broad emission lines at unfamiliar wavelengths in the green, red, and IR, and which vary nightly in intensity, profile, and wavelength. SS 433 is inferred to be a luminous object with an absolute visual magnitude of -3.1 or brighter.

Margon, B.↗
NASA NTRS1980

Phase variability in the rapid optical oscillations of SS Cygni

High-speed photometry of SS Cygni on four nights during the 1978 September eruption revealed a small-amplitude optical oscillation with period 8.23 s and mean semiamplitude 0.0005 mag on September 21 and period 8.50 s and mean semiamplitude 0.0006 mag on September 23. If the observed periods present orbital periods near the surface of the white dwarf, then the white dwarf mass must exceed 0.92 solar mass. Phase variability of the oscillation is analyzed quantitatively and found to be less than that observed in 1978 June for soft X-ray pulsations from SS Cygni.

Horne, K.↗
NASA NTRS1981

VLBI observations of SS 433 at 3.6 and 13 centimeters

SS 433 was detected and partially resolved at 2290 MHz on baselines with fringe spacings of 1.4, 0.1, and 0.003 arcsec. It was also detected at 8420 MHz on a baseline with a fringe spacing of 0.009 arcsec. Simple models of the source, consistent with the limited data, have elongated structures greater than 0.1 arcsec in size with position angles in 1979 May that were within about 10 deg of the position angle of the apparent bulges of the supernova remnant W50. The data also imply that the source contains a core less than 0.002 arcsec in size with a brightness temperature greater than 10 to the 9th K. The bright core and aligned structures that seem to be present in SS 433 and W50 resemble the structures seen in powerful extragalactic radio sources which are many orders of magnitude larger.

Walker, R. C.↗
NASA NTRS1981

Periodic changes in the compact radio structure of SS 433

VLBI observations of SS 433 at 2.3 GHz made on 12 days between 1979 May and 1980 August yield the following results: (a) the position angle of the radio 'jet' of angular size of about 0.1 arcsec varies approximately sinusoidally about a mean value of 100.2 + or - 1.7 deg with an amplitude of 19.3 + or - 3.4 deg for a period fixed at 163.6 days. This resolves the ambiguity in the two angles of the optical model of Abell and Margon and assigns the inclination of the axis of the precession cone to the 79 deg value; (b) the position angle of the radio structure on this scale lags that of the optical model by 17.4 + or - 1.6 days; and (c) at least some of the radio emitting material appears to propagate away from the core in blobs. Using the rate of change of angular separation of the blobs from the core obtained from measurements on four different days, and assuming that the radio emission is traveling at the speed derived for the optical jets from the kinematic model, a distance to SS 433 of 5.1 + or - 0.5 kpc is obtained.

Niell, A. E.↗
NASA NTRS1981

Wideband, high speed switch matrix development for SS-TDMA applications

The paper describes the design of an SS-TDMA microwave switch matrix being developed as part of the NASA 30/20 GHz Communications Satellite Program. A critical element in the systems development is the high-speed wideband switching capability necessary for 30/20 GHz SS-TDMA trunking service interconnections. A proof-of-concept model of a 20-by-20 microwave switch matrix with a 2.5 GHz bandwidth and 10-nanosecond switching speeds is being developed to realize this capability.

Prather, W. H.↗
NASA NTRS1982

Jitter in SS 433-A clue to the collimation mechanism

The blue and red shift jitter observed in SS 433 is examined with a view to determining its sources. The jitter is characterized by a Delta-z rms amplitude of 0.01, corresponding to a 3000 km/sec Doppler velocity, which is larger than either the width or the error of measurement of the shifted lines. In addition, the amplitude of the jumps is not strongly dependent on the phase in the 164-day cycle, and the amplitudes of the jitter in the redshifted and blueshifted branches are comparable. It is shown that these features set strong constraints on models proposed for SS 433 by Sarazin et al. (1980), Katz (1980), and Van den Heuvel et al. (1980).

Katz, J. I.↗
NASA NTRS1983

A large molecular cloud toward the SNR W50 and SS 433

The CO 1 yields 0 transition at 115 GHz has been mapped over an area of more than 6 deg sq toward W50, the extended SNR surrounding the peculiar object SS 433. W50 is found to lie at the end of a filamentary molecular cloud 4 deg long and 1 deg wide that closely matches a conspicuous dust lane on the Palomar Sky Survey; the cloud's kinematic distance is within 0.7 of 2.2 kpc, in agreement with the distance 2-3.3 kpc estimated for the SNR, and its mass is about 120,000 solar masses. Though there is little evidence of star formation in the molecular filament, or evidence of an interaction between the filament and W50 (or SS 433), the positional coincidence of the two, their similar distance, and their displacement nearly two molecular scale heights from the plane all suggest a physical relationship or common origin. One possibility is that both the molecular filament and the stellar progenitor of W50 were ejected from a large active molecular complex lying in the plane at l = 40 deg.

Huang, Y.-L.↗
NASA NTRS1984

Observations of quasi-coherent soft X-ray oscillations in U Geminorum and SS Cygni

During the HEAO 1 satellite's detection of soft X-ray pulsations from U Geminorum and SS Cygni, both of these dwarf novae were on the declining phase of an optical outburst. The pulsations are quasi-coherent in character, with average pulse amplitudes of 15 percent for U Gem and 18 percent for SS Cyg. From pulse phase X-ray spectroscopic data, an upper limit of 50 percent may be set on any variation in temperature across U Gem's pulse. Attention is given to all data on the X-ray and optical pulsations thus far detected in these two novae, and the observational constraints on the various current models for the pulsations are discussed.

Cordova, F. A.↗
NASA NTRS1984

Rapid intensity variability in the jets of SS 433

The 'moving' emission lines in the spectrum of SS 433 can disappear entirely on a time scale of less than 1 day, remain absent for at least a few days, and reappear equally rapidly. Examples of both disappearance and reappearance episodes are presented. While the majority of SS 433 spectra clearly do show the moving features, isolated spectra lacking the Doppler-shifted lines must now not be regarded as highly unusual. The extreme intensity variability is found to be synchronized in both the red- and blueshifted emission systems, providing an upper limit of 100 AU to the separation of the two relativistic emitting regions. On some occasions the intensity and profile of emission lines from these two separate regions can be identical to very high accuracy, again suggesting that the majority of the relativistic gas originates in a common, compact region.

Margon, B.↗
NASA NTRS1984

Nuclear processes in the jets of SS 433

The very narrow gamma-ray lines observed at 1.495 and 6.695 MeV from SS 433 which are blueshifted 1.369 and 6.129 emissions from deexcitations of (24)Mg-asterisk and (16)O-asterisk in grains moving with the jets and inelastically excited by interactions with the ambient medium are discussed. Energetic particle interactions in grains produce very narrow gamma ray lines from deexcitation of nuclear levels whose lifetimes are long enough that the excited nuclei stop before deexcitation. The presence of grains in the jets resolves hitherto discussed difficulties of inelastic excitation models for gamma ray production in SS 433, the very narrow widths of the observed lines and the absence of other strong lines, expected from abundant elements. A model is proposed which could be distinguished from a previously proposed fusion model by gamma ray line observations.

Ramaty, R.↗
NASA NTRS1984

On the origin of X-ray variability of SS 433

The X-ray flares observed from the central source in SS 433 by the Einstein telescope are attributed to surges in the mass transfer rate due to changes in the critical Roche volume of the companion. Analysis of the Roche potential for a primary with spin misaligned with the orbital axis, as required by the slaved disk model, predicts that the critical Roche volume will contract twice per orbit if the orbit is circular. A critical Roche volume fractional change of 1-2 percent is found by applying this potential to SS 433. The nutation of the companion should not affect the steady precession of its spin. Aspects of this work strengthen the evidence that the compact object might be a black hole.

Band, D. L.↗
NASA NTRS1985

Infrared variability of SS 433

New JHKLM photometry of SS 433 showing short time scale variabilities is reported for the period of 1983 July 16-22 UT. The entire body of infrared data included in this paper, Giles et al. (1980), and Catchpole et al. (1981), is examined with reference to periods of 164 days and 13.08 days. Comparison of the infrared light curves with the optical light curves of Leibowitz et al. (1984) makes it possible to conclude, within the context of an accretion disk model, that the majority of the infrared flux in the SS 433 system comes from the disk, and that the hot spot responsible for the 'hump' in the visual and infrared light curves has a color similar to the average of the disk. A two-dimensional Fourier analysis of the infrared data suggests that the brightness maximum occurs when, seen from the compact star, the noncompact companion passes through a fixed elongation relative to the disk line of nodes with the orbital plane, if the precession is prograde.

Kodaira, K.↗
NASA NTRS1989

The Baade-Wesselink method applied to field RR Lyrae stars. II - SW Andromedae, SW Draconis, and SS Fornacis

The Baade-Wesselink method has been combined with previous photometry and radial velocities to yield distances of 520 + or - 50 pc, 840 + or - 50 pc, and 780 + or - 150 pc, and mean absolute magnitudes of 0.88 + or - 0.20, 0.86 + or - 0.20, and 0.73 + or - 0.50, for SW And, SW Dra, and SS For, respectively. The present technique is able to account for the problem of phase-lag between spectroscopically and photometrically determined radial displacements in SW Dra, the Blazhko effect in SW And, and both the phase-lag and Blazhko effects in SS For.

Cacciari, C.↗
NASA NTRS1991

Constraints on the physical properties of optical bullets in SS 433

The present study discusses possible mechanisms for continuously heating the H-alpha emitting bullets of SS 433 out to distances of 5 x 10 to the 14th cm and for turning off this emission at 10 to the 15th. Various observational contraints are used to establish bounds on permissible solutions in terms of the two key bullet parameters, mass, and angular radius seen from the central source. The analysis is carried out for the mathematically simplest case of uniform spherical bullets. For radiative heat of such bullets by starlight, solutions are found to exist only for the very massive bullets with about 0.03 radians, which are highly implausible on the grounds of the large implied mean kinetic luminosity of about 10 to the 41st ergs/s. It is concluded that collisional interaction is the most likely mechanism for heating the optical bullets of SS 433. The effects of these constraints being fragmented rather than uniform, and being elongated rather than spherical are discussed.

Brown, John C.↗
NASA NTRS1991

Regular variability of the shape of the primary minimum of the orbital light curve of SS 433 with the phase of the precessional period

The regular variations of the shape of the primary minimum of the orbital 13.082-day light curve of SS 433 with the phase of the 162.5-day processional period were discovered by analysis of the photometrical databank. The regular variability of the shape of the primary minimum of the discovered light curve of SS 433 reflects displacement with the 26-day double orbital period of at least two hot bright spots on the surface of the processional accretional disk and their eclipse by a normal star. Other aspects of the investigation are further discussed.

Cherepashchuk, A. M.↗
NASA NTRS1992

Spectral evolution of accretion disks of dwarf novae. III - Outburst cycle of SS Cygni

A modified disk atmosphere has been used to produce absorption profiles for H-beta, H-gamma, and He I 4471 A lines to fit those at the maximum light during the October 1981 outbursts of SS Cyg and those during the decline. The coexistence of strong emission cores and absorption wings at the maximum light shows that the mass transfer rate at SS Cyg in the outburst was about 5 x 10 exp 17 g/s. The viscosity parameter in the disk during quiescence is between 0.006 and 0.6. The weak emission and shallow absorption during rise indicate that the outburst is initiated from the inner region of the accretion disk during the outburst. This result is compatible with the disk thermal instability hypothesis for CV outbursts, but incompatible with the mass transfer instability scenario for CV outbursts.

Cheng, F. H.↗
NASA NTRS1993

Interaction of a jet with a radiation pressure-dominated atmosphere - The case of SS 433

A phenomenological model for the enigmatic object SS 433 is developed in which SS 433 is a neutron star (NS) surrounded by a dense accreted atmosphere. Jets are created close to the neutron star surface by the rapidly spinning NS, toward which matter flows at a super-Eddington rate. This supercritical accretion leads to a quasi-spherical atmosphere around the NS with very high pressure and density close to the surface. The interaction of the jet with the atmosphere as it propagates through it is discussed in detail. A boundary layer (BL) due to radiation viscosity forms between the jet and the surrounding medium. This BL can be visualized as a cocoon of low-density matter around the jet which prevents mass entrainment into the jet. A study of X-ray spectra shows how the radiation-viscous BL can explain the very small Delta v/v that is observed in the jets.

Arav, Nahum↗