Abstract: A liquid filled variable capacitor or PFL which provides variable frequen impedance, and pulse length without changing the capacitor or PFL hardware. The capacitor is constructed from two or more conducting surfaces. A dielectric fluid mixture separates the conductors. A fluid supply system furnishes the dielectric fluid mixture to the conductors and provides for varying of the dielectric constant of the fluid and thus the capacitor operating characteristics, by varying the mixture composition. The fluid supply system has a mixing tank connected to both a supply of high dielectric constant fluid and a supply of low dielectric constant fluid. The high dielectric constant fluid and low dielectric constant fluid are mixed proportionally to obtain a dielectric fluid having the desired dielectric constant. A pump conveys the dielectric fluid between the mixing tank and the conductors while a heat exchanger controls the temperature of the dielectric fluid.

Abstract: The intrinsic time constant .tau. of liquids is measured directly by using he apparatus of the present invention termed a "taumeter". The taumeter impresses a predetermined voltage, level between a pair of electrode immersed in the liquid to be measured. The taumeter then measures the time it takes for the foregoing voltage to decay from a predetermined value V.sub.A to a predetermined value V.sub.B. Comparator logic produces a gate pulse having a leading edge at a time T.sub.A corresponding to the occurrance of the predetermined voltage V.sub.A and a trailing edge at a time T.sub.B corresponding to the occurrance of the predetermined voltage V.sub.B. The gate pulse is used to gate a system counter which counts the zero crossings of a very accurate system clock to determine the intrinsic time constant of the liquid. The foregoing pulsing is repeated as determined by a duty cycle generator.

Abstract: A method and apparatus for providing a self-compressing supersonic flow is provided by use of a contoured supersonic nozzle design. The shape of the supersonic nozzle array can be composed of curved blades which provide a focusing effect for a supersonic flow which will provide a gradient change in mach number along the supersonic flow path and efficient pressure recovery. Ideal design permits the self-compressing flow to have a secondary throat with down stream mach number of approximately one. As a result, a gas dynamic laser will have a well defined lasing region shortly after the increase in velocity of the working fluid to supersonic speeds. Controlled shaping of the supersonic flow is provided by means which will either use high speed jets or the Coanda effect. Further refining of the shape of the flow can permit the lasing region to take on the shape of a torus.

Abstract: A method and apparatus for cutting wharf or bridge pilings underwater which tilizes a neutrally buoyant air tube to conduct a laser beam from a laser source on a barge or other surface vessel to an air filled collar which is clamped to the piling to be cut. The laser beam is guided via the air tube to the piling where laser energy and combustion are utilized to cut the pile, and compressed air or other gases purge the collar of smoke and water during the cutting.

Abstract: A hypersonic gas laser to produce coherent infra-red electromagnetic radiation for use in communication, illumination, energy transmission or weather control. The lasing device uses an interaction area consisting of a grid of fine wires or the like to convert the kinetic energy of hypersonic velocity gases to vibrationally excited nitrogen from which the laser energy is extracted.