Auxiliary titanium sublimation pump produces ultrahigh /10 to the minus 11 torr/ vacuum

Sublimated titanium as a gettering agent in conjunction with a turbine-type pump provides a two-step procedure for obtaining an ultrahigh vacuum of 10 to the minus 11 torr. The pump alone evacuates the chamber to a pressure of 10 to the minus 9 torr. The residual gas is removed by the gettering agent at a pumping speed of 15 liters per second per square inch

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Agricultural and Food Policy,

Introduction to total- and partial-pressure measurements in vacuum systems

An introduction to the fundamentals of total and partial pressure measurement in the vacuum regime (760 x 10 to the -16th power Torr) is presented. The instrument most often used in scientific fields requiring vacuum measurement are discussed with special emphasis on ionization type gauges and quadrupole mass spectrometers. Some attention is also given to potential errors in measurement as well as calibration techniques

Implications of Budget Reconciliation for Commodity Programs

Agricultural and Food Policy,

Effect of vacuum processing on outgassing within an orbiting molecular shield

The limiting hydrogen number density in an orbiting molecular shield is highly dependent on the outgassing rates from the materials of construction for the shield, experimental apparatus, and other hardware contained within the shield. Ordinary degassing temperatures used for ultrahigh vacuum studies (less than 450 C) are not sufficient to process metals so that the contribution to the number density within the shield due to outgassing is less than the theoretically attainable level (approximately 200 per cu. cm). Pure aluminum and type 347 stainless steel were studied as candidate shield materials. Measurements of their hydrogen concentration and diffusion coefficients were made, and the effects of high temperature vacuum processing (greater than 600 C) on their resulting outgassing rates was determined. The densities in a molecular shield due to the outgassing from either metal were substantially less ( 0.003) than the density due to the ambient atomic hydrogen flux at an orbital altitude of 500 km

Artifacts and Commingled Skeletal Remains from a Well on the Medical College of Virginia Campus: Artifact Collection from Archaeological Site 44HE814

This is a report prepared by Douglas W. Owsley and Karin Bruwelheide, Department of Anthropology, National Museum of Natural History, Smithsonian Institution in fulfillment of the Contract Agreement between the Smithsonian Institution. The objectives of this report included identification and documentation of the bones and artifacts recovered from the well, establishing the temporal context, and interpreting the relationship of the materials to the site’s use and history as an early medical school in the city of Richmond. This report has three main sections: a review of the archival history of the school as it related to the use of the well, a description of the artifact assemblage, and documentation of the human remains, including craniometric and postcraniometric analyses. Researchers with differing areas of expertise contributed to this report

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Agricultural and Food Policy,

Physical adsorption of nitrogen gas on the polished surface of 347 stainless steel at very low pressures

Physical adsorption of nitrogen gas on polished surface of 347 stainless steel at low pressure

Description of a landing site indicator (LASI) for light aircraft operation

An experimental cockpit mounted head-up type display system was developed and evaluated by LaRC pilots during the landing phase of light aircraft operations. The Landing Site Indicator (LASI) system display consists of angle of attack, angle of sideslip, and indicated airspeed images superimposed on the pilot's view through the windshield. The information is made visible to the pilot by means of a partially reflective viewing screen which is suspended directly in frot of the pilot's eyes. Synchro transmitters are operated by vanes, located at the left wing tip, which sense angle of attack and sideslip angle. Information is presented near the center of the display in the form of a moving index on a fixed grid. The airspeed is sensed by a pitot-static pressure transducer and is presented in numerical form at the top center of the display

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