Abstract: An acoustic cooling engine with improved thermal performance and reduced internal losses comprises a compressible fluid contained in a resonant pressure vessel. The fluid has a substantial thermal expansion coefficient and is capable of supporting an acoustic standing wave. A thermodynamic element has first and second ends and is located in the resonant pressure vessel in thermal communication with the fluid. The thermal response of the thermodynamic element to the acoustic standing wave pumps heat from the second end to the first end. The thermodynamic element permits substantial flow of the fluid through the thermodynamic element. An acoustic driver cyclically drives the fluid with an acoustic standing wave. The driver is at a location of maximum acoustic impedance in the resonant pressure vessel and proximate the first end of the thermodynamic element. A hot heat exchanger is adjacent to and in thermal communication with the first end of the thermodynamic element.

Abstract: A hydrofluoric acid-resistant composite window and method for its fabrication are disclosed. The composite window comprises a window having first and second sides. The first side is oriented towards an environment containing hydrofluoric acid. An adhesive is applied to the first side. A layer of transparent hydrofluoric acid-resistant material, such as Mylar, is applied to the adhesive and completely covers the first side. The adhesive is then cured.

Abstract: An apparatus and method for measuring solar radiation received in a vegetative canopy. A multiplicity of sensors selectively generates electrical signals in response to impinging photosynthetically active radiation in sunlight. Each sensor is attached to a plant within the canopy and is electrically connected to a separate port in a junction box having a multiplicity of ports. Each port is connected to an operational amplifier. Each amplifier amplifies the signals generated by the sensors. Each amplifier is connected to an analog-to-digital convertor which digitizes each signal. A computer is connected to the convertors and accumulates and stores solar radiation data. A data output device such as a printer is connected to the computer and displays the data.

Abstract: An apparatus for orienting members and for maintaining their rotary alignment during orienting members. The apparatus comprises first and second cylindrical elements, a rotation prevention element, a collar and a retainer. Each element has an outside wall, and first and second ends, each end having an outside edge. The first element has portions defining a first plurality of notches located at the outside edge of its first end. An external threaded portion is on the outside wall of the first element and next to the first plurality of notches. The second element has portions defining a second plurality of notches located at the outside edge of its first end. The first plurality has a different number than the second plurality. The first ends of the first and second tubes have substantially the same outside diameter and are abutted during connection so that a cavity is formed whenever first and second tube notches substantially overlap.

Abstract: An apparatus for measuring the thickness of a tube's wall for the tube's entire length and circumference by determining the deviation of the tube wall thickness from the known thickness of a selected standard item. The apparatus comprises a base and a first support member having first and second ends. The first end is connected to the base and the second end is connected to a spherical element. A second support member is connected to the base and spaced apart from the first support member. A positioning element is connected to and movable relative to the second support member. An indicator is connected to the positioning element and is movable to a location proximate the spherical element. The indicator includes a contact ball for first contacting the selected standard item and holding it against the spherical element. The contact ball then contacts the tube when the tube is disposed about the spherical element.

Abstract: An apparatus for measuring the overall decontamination factor of first and second filters located in a plenum. The first filter separates the plenum's upstream and intermediate chambers. The second filter separates the plenum's intermediate and downstream chambers. The apparatus comprises an aerosol generator that generates a challenge aerosol. An upstream collector collects unfiltered aerosol which is piped to first and second dilution stages and then to a laser aerosol spectrometer. An intermediate collector collects challenge aerosol that penetrates the first filter. The filtered aerosol is piped to the first dilution stage, diluted, and then piped to the laser aerosol spectrometer which detects single particles. A downstream collector collects challenge aerosol that penetrates both filters. The twice-filtered aerosol is piped to the aerosol spectrometer. A pump and several valves control the movement of aerosol within the apparatus.

Abstract: The disclosure is directed to an apparatus for detecting radiation having wavelengths from about 0.4 .mu.m to about 5.6 .mu.m. An optical coating is applied to a thermal sensor that is normally transparent to radiation with such wavelengths. The optical coating is thin and light and includes a modifier and an absorber. The thermal sensor can be a pyroelectric detector such as strontium barium niobate.

Abstract: The disclosure is directed to an apparatus for eliminating background interference during fluorescence measurements in a multiple laser flow cytometer. A biological particle stained with fluorescent dyes is excited by a laser. A fluorescence detector detects the fluorescence. The particle scatters light and a gate signal is generated and delayed until the biological particle reaches the next laser. The delayed signal turns on this next laser, which excites a different stained component of the same biological particle.

Abstract: An apparatus for preventing oxidation by uniformly distributing inert shielding gas over the weld area of workpieces such as pipes being welded together. The apparatus comprises a chamber and a gas introduction element. The chamber has an annular top wall, an annular bottom wall, an inner side wall and an outer side wall connecting the top and bottom walls. One side wall is a screen and the other has a portion defining an orifice. The gas introduction element has a portion which encloses the orifice and can be one or more pipes. The gas introduction element is in fluid communication with the chamber and introduces inert shielding gas into the chamber. The inert gas leaves the chamber through the screen side wall and is dispersed evenly over the weld area.

Abstract: The disclosure is directed to a rotary multiposition valve for selectively directing the flow of a fluid through a plurality of paths. The valve comprises an inner member and a hollow housing with a row of ducts on its outer surface. The ducts are in fluid communication with the housing. An engaging section of the inner member is received in the housing. A seal divides the engaging section into a hollow inlet segment and a hollow outlet segment. A plurality of inlet apertures are disposed in the inlet segment and a plurality of outlet apertures are disposed in the outlet segment. The inlet apertures are disposed in a longitudinally and radially spaced-apart pattern that can be a helix. The outlet apertures are disposed in a corresponding pattern. As the inner member is rotated, whenever an inlet aperture overlaps one of the ducts, the corresponding outlet aperture overlaps a different duct, thus forming a fluid pathway.

Abstract: The disclosure is directed to a laser target structure and its method of fabrication. The target structure comprises a target plate containing an orifice across which a pair of crosshairs are affixed. A microsphere is affixed to the crosshairs and enclosed by at least one hollow shell comprising two hemispheres attached together and to the crosshairs so that the microsphere is juxtapositioned at the center of the shell.

Abstract: An apparatus for protecting diagnostic equipment from blast damage by rapidly interposing a shutter between the equipment and the blast area. The apparatus comprises a sensor for sensing a trigger signal associated with the blast and for converting it into a voltage pulse. The voltage pulse is received by the first end of a firing pin. A pressure chamber holds a gas under pressure. The second end of the firing pin is located inside the pressure chamber and is located above a foil member covering an orifice. When the voltage pulse reaches the second end, a point-to-plane discharge ruptures the foil, allowing the gas to enter a drive housing and quickly move a drive piston away from the foil. A drive rod connects the drive piston to a shutter and as the drive piston is moved down, the shutter moves into a closed position, protecting the equipment from debris.

Abstract: An apparatus which thermally protects sensitive components in tools used in a geothermal borehole. The apparatus comprises a Dewar within a housing. The Dewar contains heat pipes such as brass heat pipes for thermally conducting heat from heat sensitive components to a heat sink such as ice.

Abstract: The disclosure is directed to an apparatus for safely supplying breathable gas or air through individual respirators to personnel working in a contaminated area.

Abstract: The disclosure is directed to a low temperature 4 to 20 K. refrigeration apparatus and method utilizing a ring of magnetic material moving through a magnetic field. Heat exchange is accomplished in and out of the magnetic field to appropriately utilize the device to execute Carnot and Stirling cycles.

Abstract: Applicants have discovered a new composition of matter which is an explosive addition compound of ammonium nitrate (AN) and diethylenetriamine trinitrate (DETN) in a 50:50 molar ratio. The compound is stable over extended periods of time only at temperatures higher than 46.degree. C., decomposing to a fine-grained eutectic mixture (which is also believed to be new) of AN and DETN at temperatures lower than 46.degree. C. The compound of the invention has an x-ray density of 1.61 g/cm.sup.3, explodes to form essentially only gaseous products, has higher detonation properties (i.e., detonation velocity and pressure) than those of any mechanical mixture having the same density and composition as the compound of the invention, is a quite insensitive explosive material, can be cast at temperatures attainable by high pressure steam, and is prepared from inexpensive ingredients. Methods of preparing the compound of the invention and the fine-grained eutectic composition of the invention are given.

Abstract: An improved method and apparatus are given for producing cryogenic inertially driven fusion targets in the fast isothermal freezing (FIF) method. Improved coupling efficiency and greater availability of volume near the target for diagnostic purposes and for fusion driver beam propagation result. Other embodiments include a new electrical switch and a new explosive detonator, all embodiments making use of a purposeful heating by means of optical fibers.

Abstract: A method and apparatus for electronically focusing and electronically scanning microscopic specimens are given. In the invention, visual images of even moving, living, opaque specimens can be acoustically obtained and viewed with virtually no time needed for processing (i.e., real time processing is used). And planar samples are not required. The specimens (if planar) need not be moved during scanning, although it will be desirable and possible to move or rotate nonplanar specimens (e.g., laser fusion targets) against the lens of the apparatus. No coupling fluid is needed, so specimens need not be wetted. A phase acoustic microscope is also made from the basic microscope components together with electronic mixers.

Abstract: A heat collector and method suitable for efficiently and cheaply collecting solar and other thermal energy are provided. The collector employs a heat pipe in a gravity-assist mode and is not evacuated. The collector has many advantages, some of which include ease of assembly, reduced structural stresses on the heat pipe enclosure, and a low total materials cost requirement. Natural convective forces drive the collector, which after startup operates entirely passively due in part to differences in molecular weights of gaseous components within the collector.