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Mookherji, T.

Publications and source records attributed to Mookherji, T..

12 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Space Station microgravity and materials processing facility A national laboratory dedicated to U.S. interests

The Microgravity and Materials Processing Facility (MMPF) of the Space Station is examined. The MMPF is designed to accommodate individual experiments and associated hardware and is to be housed in the Manufacturing and Technology Laboratory Module. The objectives of the microgravity and materials processing study and the user, experiment/equipment, MMPF system requirements, and programmatics and planning development tasks of the study are described. Consideration is given to the acceleration environment, on-orbit sample preparation and analysis, mission-time-line analyses, and payload complement trades. Diagrams of the MMPF are presented.

Atkins, H. L.↗
NASA NTRS1976

Results of an analytical study of spacecraft deposition contamination by internal reflection spectroscopy

Outgassing, deposition, and desorption kinetics of silicone compounds, are examined as examples of optical surface contaminants of spacecraft windows. Their behavior in a space environment after exposure to ultraviolet radiation is also examined. The use of internal reflection spectroscopy is shown to provide a viable means of real-time, in-situ identification of contaminants of orbiting spacecraft. The instrumental techniques are proposed as the basis of further investigations and the development of flight hardware.

Mookherji, T.↗
NASA NTRS1974

Effect of gravity on liquid phase sintering

The unique conditions offered by the earth orbital environment in material processing involving both solid and liquid phases, such as liquid phase sintering, were studied. An experimental development program involving both test and theoretical work was initiated. Experimental work using material combinations selected such that maximum information about the effect of gravity can be derived has been conducted. Wetting of the solid phase by the liquid during sintering is an important phenomenon in liquid phase sintering, and gravity has influence on both capillary phenomenon and density segregation; hence, material combinations were selected such that these two effects can be suitably studies. The experimental work is meant to form the basis for similar comparative work done under low-g conditions. The part of the model dealing with the capillary phenomenon, as related to liquid phase sintering and the effect of gravity on it, suggest that gravity will have negligible effect on the Bond number and that the cohesive force is dependent on both the amount of liquid phase and the angle of contact.

Mookherji, T.↗
NASA NTRS1972

Analytical study of spacecraft deposition contamination by internal reflection spectroscopy

Infrared absorption spectra of ten individual contaminant materials and four binary mixtures of these have been studied using the internal reflection spectroscopy technique. The effect of ultraviolet radiation on these contaminants has also been studied. It has been observed that all siloxanes, silanes, and esters are drastically affected by ultraviolet irradiation. In most cases polymerization and tar formation results.

Mookherji, T.↗
NASA NTRS1972

Electron spin resonance of ultraviolet radiation induced defects in ZnO thermal control coating pigment.

Electron spin resonance measurements on variously treated zinc oxide powders reveal that the resonance signal at g = 1.956 is due to one electron trapped oxygen ion vacancy level, at a depth of (0.31 plus or minus 0.02) eV below the conduction band. The electrons at this level are delocalized. Schottky barrier influences nearly the entire bulk of the powder sample, and the bending of the bands caused by chemisorbed oxygen puts the vacancy level above the Fermi level almost through the entire bulk.

Mookherji, T.↗
NASA NTRS1971

Investigation of space stable thermal control coating properties

A capability to study the nuclear magnetic resonance of spacecraft thermal control coating has been built utilizing an electromagnet and V-series and Wl-series electronics. The electronics associated with the electromagnet had to be modified to make it compatible with the resonance measuring system. Resonance measurements have been performed on ZnO, Zn2TiO4 and FEP Teflon. The failure to observe resonance in ZnO and Zn2TiO4 has been theoretically explained. The linewidth and second moment measurements on ultraviolet irradiated FEP Teflon showed that there was no measurable degradation of the material due to short term irradiation.

Mookherji, T.↗