The use of ultrasonic methods in nondestructive testing depends on the interpretation of the scattering of sound waves by flaws. The theory of elastic waves and their scattering in non-uniform media is developed in detail from first principles, and in generality. Both integral equation and differential methods are discussed, with emphasis on the former. General methods for defining scattering cross sections are presented, and conservation theorems are noted. The Born Approximation to the integral equation is presented, and computed results for several experimental situations are discussed. Several corrections to papers in the literature are made, and in particular the exact scattering of a transverse wave by a spherical flaw is compared with the Rayleigh (long wave) limit.

This report summarizes the results of a study of azide decomposition for possible application in a visible chemical laser. Task 1 of the subject contract involved thorough review of the chemical literature pertaining to azide decomposition. Covalently bonded azides decompose directly into an electronically excited nitrene (RN) and ground-state molecular nitrogen. Ionic azides decompose to metal atoms and azide radicals. The azide radicals subsequently recombine to form electronically excited nitrogen molecules. Task 2, the experimental phase of this program, involved the study of azide-radical reactions. A flow reactor was built in which large concentrations (up to 10/sup 13/ molec cm/sup -3/) of N/sub 3/ could be produced from the thermal decomposition of NaN/sub 3/. The kinetics of and chemiluminescent products from several reactions of N/sub 3/ have been studied, and a method for obtaining absolute concentrations of N/sub 3/ is described. The potential utility of azide decomposition for the production of excited electronic states suitable for a laser device and further areas of research germane to this goal are discussed briefly.

Honeywell conducted a parametric analysis of the 10-MW(e) solar pilot plant requirements and expected performance and established an optimum system design. The main analytical simulation tools were the optical (ray trace) and the dynamic simulation models. These are described in detail in Books 2 and 3 of this volume under separate cover. In making design decisions, available performance and cost data were used to provide a design reflecting the overall requirements and economics of a commercial-scale plant. This volume contains a description of this analysis/design process and resultant system/subsystem design and performance.

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Advantages of down-well pumping (vs. free-flowing) of geothermal hot-water wells are presented, and criteria for such a system are discussed. The main body of the report is presented under the following section headings: the Sperry down-well pumping system; field test program; field operations; test results; and, conclusions and recommendations. The appendix includes a summary of boiler heat transfer and pressure drop calculations. (JGB)

Specific compositions of high purity silicon aluminum oxynitride (Sialon) and silicon beryllium oxynitride (Sibeon) solid solutions are shown to be promising refractory materials for handling and manipulating solar grade silicon into silicon ribbon. Well controlled processing schedules were developed for fabricating high purity Sialon and Sibeon materials. Essentially the impurity content of the hot pressed ceramics was due only to impurities from the original starting powders. A ceramic shaping die was successfully formed by diamond machining of a hot pressed blank. Projected manufacturing cost estimate for 10/sup 5/ dies per year is $5.4 per die. Evaluation of the interaction of these materials in contact with molten silicon indicates that solid solutions based upon ..beta..-Si/sub 3/N/sub 4/ are more stable than those based on Si/sub 2/N/sub 2/O. Sibeon is more resistant to molten silicon attack than Sialon, and both materials should preferably be used in an inert atmosphere rather than under vacuum conditions. This is because removal of oxygen from the silicon melt as SiO enhances the dissolution of aluminum and beryllium. The wetting angles of these materials are low enough (37/sup 0/ for x = 0.75 ..beta..' Sialon and 49/sup 0/ for x = 0.35 Sibeon) for these materials to …

HELIAKI is a FORTRAN computer program which simulates the optical/thermal performance of a central receiver solar thermal power plant for the dynamic conversion of solar-generated heat to electricity. The solar power plant which this program simulates consists of a field of individual sun tracking mirror units, or heliostats, redirecting sunlight into a cavity, called the receiver, mounted atop a tower. The program calculates the power retained by that cavity receiver at any point in time or the energy into the receiver over a year's time using a Monte Carlo ray trace technique to solve the multiple integral equations. An artist's concept of this plant is shown.

A simplified approach is presented to the calculation of ground level concentrations of effluents from small industrial and fuel burning installations. It is intended to serve as a first approximation to a very complex process. Because each stack, building, and terrain configuration is different, actual ground concentrations may frequently differ from the values calculated here by a factor of two. Nonetheless, this procedure should be useful for determining whether ambient air quality standards are likely to be met, exceeded, or only marginally obtained. It also predicts the locations where the highest and most frequent ground concentrations are likely. Sampling at several such locations is very advisable, unless the predicted concentrations are quite low. In addition, consultation with a specialist in air pollution meteorology may be desirable, especially in marginal or unique situations. The procedures given here were designed especially for source heights of less than 100 m; some of the simplifications made are not valid for large emissions. In the few cases where more than arithmetic formulas are necessary, simple nomograms are provided.

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A workshop was convened to assist DOE's Technology Assessment Division in evaluating the need to prepare additional environmental- and social-impact assessments of different energy-conservation measures. Attendees participated in a decision-making exercise designed to rank 19 different energy-conservation measures according to their overall potential for achieving important national goals and their ease of implementation. The participants felt that the most-important ranking criteria dealt with questions concerning feasibility (economic, political/institutional, social, and technical) and economic efficiency. Other criteria, such as environmental quality and occupational health and safety received lower weights; possibly because of the widespread belief that most of the conservation measures presented would be environmentally beneficial. In the participants' view, the most-promising and feasible conservation measures include new-building-performance standards, retrofit of existing housing stock, new-appliance-performance standards and increased use of smaller cars. In contrast, conservation options which ranked rather low, such as diesel engines, coal-fired aluminum remelt furnaces, and cupola furnace modifications were expected to have some harmful environmental and health impacts. Most of these impacts are expected to be highly localized and of lesser national concern. Disagreement exists as to the efficacy of funding those projects deemed highly desirable and feasible versus those which are expected to have the greater …

Three methods are described to fabricate by chemical vapor deposition (CVD) molybdenum films which rival conventional mirror materials in their infrared reflectance. With an absolute reflectance of 97.4% at 10 ..mu..m, these Super Molybdenum films reflect better than any other molybdenum film previously reported. When deposited in the presence of oxygen, films of a reduced reflectance over the solar emission range result. If passivated and antireflected by a Si/sub 3/N/sub 4/ layer, such Black Molybdenum films are characterized by a solar absorptance value in excess of 90% and a thermal emittance value of 11% at 500/sup 0/C. No deterioration of these values has yet been observed in ongoing tests after 1000 hours exposure to 500/sup 0/C in a 1 Torr vacuum. Stacks containing Super Molybdenum as the reflector and amorphous silicon as the absorber have thus far survived 1000 hours in open air at 500/sup 0/C.

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This experimental research has probed the nature of resonant absorption (RA) of laser light by laser-produced plasmas. The plasmas were created by optical breakdown of a shockfront produced in an electrothermal shock tube. This procedure allows the density structure of the plasma, and in particular, the orientation of the plasma critical-density surface, to be reproducibly formed from one shot to the next. Thus, for the first time, RA has been controllably and reproducibly studied in isolation from other plasma physics. The angular distribution of fast electrons emitted by RA and wavebreaking has been studied, and it is observed that the emission is directed in a narrow cone centered on the shockfront density-gradient vector, in agreement with the theory of wavebreaking.

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