Abstract: A novel device and method are provided herein for the production of underwater sound. This device, termed a plasma jet underwater acoustic source includes a central electrode and a concentric insulator having a longitudinal bore to accommodate the central electrode, the bore being spaced from the central electrode by a longitudinally-extending annular chamber. A plasma cavity is bounded at its upper end by the central electrode, and is in communication with the annular chamber. The cavity is adapted to be connected to a gas supply, so that it may be filled with gas. An outer housing of electrically-conductive material surrounds the insulator and terminates in a centrally-apertured end plate whose central aperture provides an extension to the plasma cavity, the end plate being adapted to be grounded.

Abstract: An improved ignition system is provided for an internal combustion engine having a combustion chamber and a conventional carburetor system, a conventional fuel injection system or a conventional gas mixing system, for feeding an ambient combustible fuel-air mixture to the combustion chamber. In this system, a high speed injector is fed with a gaseous fuel between a spark gap provided by a spark electrode. The spark electrode projects a predetermined distance into the combustion chamber so that the axis of the injector nozzle passes through the spark gap. A puff in the form of a short, abrupt blast of the gaseous fuel is expelled across the spark to produce a well-defined turbulent plume of the injected gaseous fuel. The time and duration of the electric spark and the fast-acting valve actuator controls the length of time it takes to open the fast-acting valve and the length of time the fast-acting valve remains open.