Photolysis of spacecraft contaminants

A molecular beam facility, which was designed to measure photochemical cross-sections, has been constructed at the Athens College science facility. The integration of this vacuum system into an operational photochemical instrument was performed with signal processing consisting of both dc and ac techniques. Of the experiments performed to date on the vacuum ultraviolet photolysis of water vapor, it is apparent that a larger pumping capacity (preferably with differential pumping) is required to improve upon the background signal. Both phase-sensitive detection and ion-counting techniques are recommended for future studies

Space processing of electronic materials

The relative values of thermal conductivity of solid and liquid HgCdTe are critically important in the design configuration of the furnaces used for Bridgman crystal growth. The thermal diffusivity of the material is closely linked to the conductivity by the defining relation D = k/rho c, where D is the diffusivity, K is the thermal conductivity, rho is the density, and c is the specific heat. The use of transient and periodic heating approaches to measure the diffusivity are explored. A system for securing and extracting heat from silica or glass tubes under high C vacuum conditions is described

Eddy current inspection of graphite fiber components

The recognition of defects in materials properties still presents a number of problems for nondestructive testing in aerospace systems. This project attempts to utilize current capabilities in eddy current instrumentation, artificial intelligence, and robotics in order to provide insight into defining geometrical aspects of flaws in composite materials which are capable of being evaluated using eddy current inspection techniques. The unique capabilities of E-probes and horseshoe probes for inspecting probes for inspecting graphite fiber materials were evaluated and appear to hold great promise once the technology development matures. The initial results are described of modeling eddy current interactions with certain flaws in graphite fiber samples

Feasibility demonstration for hydrogen chloride detection using a chemisorption technique and a quartz crystal microbalance

A method of measuring concentrations of hydrogen chloride between 1 part per billion and 10 parts per million at standard temperature and pressure is presented. The feasibility of a low-cost device incorporating a chemisorption technique coupled with a quartz crystal microbalance was demonstrated in the field at the Viking B launch using a Titan-Centaur vehicle from Kennedy Space Center on August 20, 1975. Hydrogen chloride is a product of solid rocket combustion. The concentration level of hydrogen chloride for this particular launch was measured as approximately 0.2 parts per million at 4 km from the launch site

AN EXAMINATION OF A DEVELOPMENT RIGHTS PURCHASE PROGRAM FOR ALASKA AGRICULTURAL LANDS

A report submitted to the Department of Natural Resources, State of Alaska, in accordance with terms of research contract OCTO 1142.Many Alaskans are concerned about the conversion of highly productive agricultural lands to nonagricultural uses now occurring in the state. Land on the urban fringes of Anchorage and Fairbanks that once produced vegetables and grains or supported dairy farms appears most vulnerable to this conversion. As major population centers grow, residential, shopping center and industrial land uses displace agriculture because they render greater returns. This displacement is viewed by some as not being in society's best interest. Those concerned about the loss of agricultural lands argue that these lands are some of the best agricultural lands in the state and are vital to maintaining the agricultural economy of the state. In addition, it is suggested that their preservation will help to maintain a much desired way of life and to provide needed open space. The state and municipal governments in Alaska have made attempts to intervene in the land market to slow down or stop agricultural land conversion. Methods employed to date include tax incentives and the sale of only the agricultural rights on state or municipal lands. This report discusses the feasibility of an alternative means of preserving agricultural lands, namely, the public purchase of development rights from private landowners. Under this voluntary arrangement, private agricultural landowners would be compensated for giving up their option to develop their land for nonagricultural purposes.Introduction: Overview, Plan of Report -- Market Failure and the Allocation of Agricultural Land Resources -- Agricultural Land Conversion in Alaska -- Present and Potential Agricultural Development in Alaska: Introduction, Present Agricultural Situation, Agricultural Lands for Future Development, Future Agricultural Development in Alaska -- Purchase of Development Rights: Suffolk County: History, Maryland, New Jersey, Massachusetts and Connecticut, Definition of Development Rights, Strengths and Weaknesses of Development Rights Purchases -- Applicability of a Development Rights Program in Alaska: Introduction, Development Rights Survey in Alaska: Response, Farm Size of Respondents, Interest in Selling Development Rights, Market Values of Cleared and Uncleared Agricultural Lands, Value of Development Rights, Distance from a Population Center, Interest in Selling Development Rights, and Perceived Value of Development Rights -- Economic Size Agricultural Operations -- Potential Costs of a Purchase of Development Rights Program: Other Costs -- Benefits of Development Rights Acquisition: Maintenance of the Local Agricultural Economy, Locally Produced Food, Open Space and Other Public Good Amenities, Removal of Uncertainty -- Other Agricultural Land Control Tools: Comparison of Agricultural Land Preservation Tools -- Summary and Conclusions -- References -- Appendix A: Operation of of Purchase of Development Rights Programs -- Appendix B: Alaska Agricultural Lands Survey -- Appendix C: Additional Comments from Respondents -- Appendix D: Alternative Agricultural Land Control Technique

Vapor transport mechanisms

The Raman scattering furnace for investigating vapor transport mechanisms was completed and checked out. Preliminary experiments demonstate that a temperature resolution of plus and minus 5 C is possible with this system operating in a backscatter mode. In the experiments presented with the GeI 4 plus excess Ge system at temperatures up to 600 C, only the GeI4 band at 150 cm superscript minus 1 was observed. Further experiments are in progress to determine if GeI2 does become the major vapor species above 440 C

Raman backscatter measurement research on water vapor systems

Raman backscatter techniques proved to be a useful remote sensing tool, whose full potential has not been realized. The types of information available from laser probes in atmospheric studies are reviewed. Detection levels for known Raman cross sections are calculated using the laser radar equation. Laboratory experiments performed for H2O, N2, SO2, O2 and HCL indicate that accurate wavelength cross sections need to be obtained, as well as more emphasis on obtaining accurate Raman cross sections of molecular species at wavelengths in the ultraviolet spectra

Study of solar cell welds

The thermal imaging technique was evaluated for its capabilities in the nondestructive evaluation of solar cell welds. The temperature and spatial resolution of state of the art instrumentation was sufficient for both qualitative and quantitative determination of the quality of solar cell welds. The addition of color digitized thermography enhanced the aspects of the thermographic display and allowed easily computerized testing procedures. For automated testing systems an accurate correlation of weld quality with temperature profiles of the welds needs to be performed. In comparison, the holographic technique was complementary with the thermal imaging technique, except that the holographic analysis appeared to be more quantitative at the present time. However, the thermal imaging approach is much more versatile in overall capabilities

Study of surfaces using near infrared optical fiber spectrometry

The measurement and control of cleanliness for critical surfaces during manufacturing and in service provides a unique challenge for fulfillment of environmentally benign operations. Of particular interest has been work performed in maintaining quality in the production of bondline surfaces in propulsion systems and the identification of possible contaminants. This work requires an in-depth study of the possible sources of contamination, methodologies to identify contaminants, discrimination between contaminants and chemical species caused by environment, and the effect of particular contaminants on the bondline integrity of the critical surfaces. This presentation will provide an introduction to the use of optical fiber spectrometry in a nondestructive measurement system for process monitoring and how it can be used to help clarify issues concerning surface chemistry. Correlation of the Near Infrared (NIR) spectroscopic results with Optical Stimulated Electron Emission (OSEE) and ellipsometry will also be presented