Michael Grapperhaus

Non lethal unfriendly swimmer and pipe defense combining sound and flash pulses using a new sparker

This paper presents a concept for protecting ships, harbors, pipes or other assets from unfriendly swimmers, using directed energy from an underwater sparker that simultaneously emits intense pulses of light and sound. This concept is based on patented sparkers and reflectors being developed for Navy and commercial applications. Sparkers employ high voltage pulses to produce a plasma discharge between electrodes in water. The discharge generates a high-pressure shock wave and the plasma emits a light pulse. Depending on sparker design, the peak pressure and light power are typically thousands of pounds per square inch and tens of megawatts, respectively, in the vicinity of the sparker. Sparkers can have reflectors to direct and focus the light and sound to specified areas. The sparker system could be deployed in conjunction with a sensor system and activated remotely when the sensor indicates a possible unfriendly swimmer. The intensity of pressure and light pulses decreases with distance from the sparker. Thus, a diver approaching an operating sparker system would be first hailed and/or warned. As the diver continued toward the sparker, the pressure and light intensity would increase to the minor discomfort level and, closer in, to severe disorientation. The sparker systems can have variable intensity so that, for instance, in a closed-loop feedback system with a diver detection system, the output could start at a low level for hailing/warning and be increased if divers continue toward the sparker.