Abstract: A method and apparatus for laser drilling an article having a nonmetallic layer. One embodiment of the method includes the steps of generating a pulsed laser beam, a pulse of the pulse laser beam having an energy of less than or equal to 0.1 joule and a pulse width of less than or equal to 500 nanoseconds, directing the pulsed laser beam at the article to vaporize the nonmetallic layer, and directing the pulsed laser beam at the article to vaporize the substrate. The method may be carried out with an apparatus which includes a Nd:YAG laser which produces the pulsed laser beam, the pulsed laser beam having a first frequency component, and a harmonic generator which generates a second frequency component, the second frequency being greater than the first frequency, where the laser beam, after passing through the harmonic generator, is incident on the article to vaporize the nonmetallic layer.

Abstract: An exemplary current limiting device comprises first and second electrodes; a composite material between the first and second electrodes, the composite material comprising: (a) a binder, and (b) an electrically conductive filler; a thin layer which provides an inhomogeneous distribution of resistance to the device; a web which reinforces the composite material; and a pressurizer for pressing the electrodes against the composite material; wherein the web is disposed in a volume of the composite material which does not include the thin layer. The current limiting device is simple and reusable, and can be tailored to a plurality of applications, including high voltage/current distribution systems, to protect sensitive components from high fault currents. The device has a robust structure which allows it to repeatedly withstand the high mechanical and thermal stresses which typically accompany switching events in high voltage/current circuits.

Abstract: A method for depositing adherent metal oxide-based protective coatings on glass, metal, and plastic substrates by arc plasma deposition.

Abstract: Decay time in scintillator compositions comprising yttrium or lutetium and gadolinium oxides and europium oxide is decreased by incorporating therein at least one of the oxides of ytterbium, samarium, praseodymium, neodymium, dysprosium, holmium, thulium, cerium and erbium as an acceptor. Other properties including afterglow and radiation damage are maintained at acceptable levels.

Abstract: A method for reducing the corrosion potential of steel vessels and piping used in nuclear reactors, in particular steel vessels and piping carrying high temperature water and/or steam which has a concentration of oxygen therein. A metal hydride is added to the water, the hydrogen of such metal hydride combining with oxidizing agents, typically oxygen, present in the water to reduce the concentration of such oxidizing agents. In the preferred embodiment the metal of the metal hydride is a metal that is capable of reacting with oxygen to form a substantially non-water soluble and substantially electrically insulating compound on the surface of the steel, and in particular is one that may react with and become deposited or incorporated into a pre-existing thin oxide film layer on the surface of the steel to thereby render such thin oxide layer substantially non-electrically conducting.

Abstract: A method of controlling the size of a laser beam comprises the steps of generating the laser beam with a laser, focusing the laser beam, directing the laser beam to a target, directing a portion of the laser beam to an optical detector which generates a signal representative of a fluence distribution of the laser beam, and adjusting a focal point of the laser beam based on the measured fluence distribution to control the size of the laser beam on the target.

Abstract: A method for determining the susceptibility of a sample of Zircaloy alloy to nodular corrosion. A specimen of such Zircaloy sample is annealed at a temperature within a temperature range bounded at its upper limit by the temperature T.sub.c being the temperature at equilibrium wherein sufficient solute would exist in the (.alpha.-matrix of the particular zircaloy to resist nodular corrosion, and bounded by a lower temperature, such temperature being the temperature of the (.alpha.+precipitate)/(.alpha.+.beta.+precipitate) transus for the particular Zircaloy sample. For Zircaloy-2, such temperature range is from approximately 825.degree. C. to 841.degree. C. The specimen is maintained at such selected temperature within such temperature range for a measured period, and subsequently exposed to steam at a fixed temperature and pressure for a fixed time.

Abstract: The invention relates to a method and apparatus for accurately measuring the energy of a laser pulse. The method according to one embodiment comprises directing a first laser pulse to an energy sensor which produces a first signal responsive to the first laser pulse, determining a time constant of the energy sensor based on the first signal, directing a second laser pulse to the energy sensor which produces a second signal responsive to the second laser pulse, and determining the pulse energy of the second laser pulse based on the second signal and the time constant.

Abstract: A method and apparatus are provided for simultaneously measuring the anisotropic orientation and the thickness of an article. The apparatus comprises a transducer assembly which propagates longitudinal and transverse waves through the article and which receives reflections of the waves. A processor is provided to measure respective transit times of the longitudinal and shear waves propagated through the article and to calculate respective predicted transit times of the longitudinal and shear waves based on an estimated thickness, an estimated anisotropic orientation, and an elasticity of the article. The processor adjusts the estimated thickness and the estimated anisotropic orientation to reduce the difference between the measured transit times and the respective predicted transit times of the longitudinal and shear waves.

Abstract: A washing machine with an improved mode shifter comprises a basket for holding an article to be washed, a basket collar coupled to the basket, an agitator disposed within the basket, an agitator collar coupled to the agitator, a brake for reducing a rotational velocity of the basket, a brake collar coupled to the brake, a first spring disposed around the basket collar and the agitator collar, and a second spring disposed around the first spring, the basket collar, and the brake collar. The mode shifter provides a mechanically simple, inexpensive, and reliable mechanism for shifting from the agitation mode to the spin mode to the brake mode in a wash cycle.

Abstract: An electrode assembly for electrical discharge machining (EDM) a slot in a wall includes a plurality of laterally abutting individual electrodes having a collective perimeter configuration complementary with the slot. The electrodes define a collective height equal to the sum of their individual heights which may be substantially greater than the individual widths thereof for machining a correspondingly high aspect ratio slot in the wall.

Abstract: A method and apparatus are provided for hardsurface cladding a workpiece such as a tip shroud notch face of a turbine bucket configured for contact engagement with an adjacent tip shroud notch face. A continuous wave laser beam is generated in a Nd:YAG laser and directed on the notch face at a spot to provide heat thereat. A hardsurface cladding wire is dispensed at the spot under a shielding gas for being melted by the laser beam to form a molten cladding layer on the notch face. The laser beam and wire are traversed over the notch face to form a cladding layer over the entire notch face, which is cooled and solidified in a hardsurface cladding layer integrally bonded to the notch face.

Abstract: Decay time in scintillator compositions comprising yttrium or lutetium and gadolinium oxides and europium oxide is decreased by incorporating therein at least one of the oxides of ytterbium, samarium, praseodymium, neodymium, dysprosium, holmium, thulium, cerium and erbium as an acceptor. Other properties including afterglow and radiation damage are maintained at acceptable levels.

Abstract: A drill according to an exemplary embodiment of the invention comprises a shank from which the drill is driven; a body connected to the shank, the body having a surface; a flute in the body; a cutting edge at a drill point; and a peripheral relief surface which extends outwardly from the surface of the body to an outer circumference of the drill, wherein the peripheral relief surface, for a cross section of the drill perpendicular to a drill axis, intersects the outer circumference at a peripheral point at an edge of the flute. The drill has an improved capacity to withstand a loss of coolant during drilling without severe overheating of the drill or workpiece and with little damage to the drill and workpiece.

Abstract: A laser head includes a body having opposite ends, and a bore extending axially therethrough for defining a reflector. The body is a unitary member circumferentially around the reflector. The reflector includes a center cavity for coaxially receiving a laser rod, and a plurality of lateral cavities disposed parallel to and extending radially outwardly from the center cavity for receiving flashlamps for optically pumping the laser rod. Reflector and lamp endcaps are removably mounted to the body for mounting the lamps and rod, and allowing individual replacement thereof.

Abstract: A brazing process is enhanced by the employment of an external electromagnetic field. In complex joints of large components, gravity and surface tension forces acting on the molten braze alloy are insufficient for completely filling the interfacial gap. An external electromagnetic field enhances molten braze flow into voids between the components.

Abstract: A fresnel reflection termination system includes a laser source, a folding mirror to reflect a laser beam, a focusing lens to focus the laser beam on the folding mirror, and a laser beam dump. The laser beam dump has an outer absorption surface for absorbing fresnel reflections, an inner termination area for capturing fresnel reflections, and a cooling mechanism within the inner termination area for dissipating heat generated by the captured fresnel reflections. The system terminates fresnel reflections to prevent costly damage to the environment or hardware surrounding the system.

Abstract: A reducible glass lubricant on a metal workpiece provides a duplex film during hot working of the workpiece. A silicate glass powder which contains from about 3 to 50 mole percent of an oxide of bismuth, tin or copper is used for the reducible glass lubricant. During preheating in a preheat furnace the glass lubricant is reduced to the duplex glass film.

Abstract: A laser shock peening apparatus includes a cavity dumping laser oscillator including in optical serial alignment a first mirror, a Pockels cell, a polarizer, a laser rod, and a second mirror defining a cavity having an optical length between the mirrors. The laser rod is optically pumped to generate a laser beam in the cavity, and the Pockels cell has selective wave retardation to allow the beam to oscillate between the mirrors and increase energy therein, followed in turn by dumping the beam into a laser amplifier. The laser amplifier directs the amplified pulse at a target for laser shock peening thereof. The cavity length is selected to develop a substantially square-wave laser pulse for temporally shaping the resulting pressure pulse at the target.

Abstract: An almen strip has a plurality of corrugations on one surface while the opposite surface is smooth and flat. This strip measures directly peening intensity on chamfers.