Abstract: A pair of movable pistons are separated within an enclosed, submerged cylinder by an expansible combustion chamber. Piston rods extend from these pistons through the opposite ends of the cylinder. A pair of dish-shaped, circular plates are carried on the respective extremities of these two rods so that their convex surfaces face inwardly toward the ends of the cylinder in spaced relation. Expansion of an explosive gas mixture within the combustion chamber drives the pistons apart so as to accelerate the plates through the water, producing cavitation bubbles at their convex surfaces. Collapse of these bubbles combines efficiently to produce a single energetic acoustic pulse adapted for seismic prospecting.

Abstract: A gas exploder consisting of a rigid cylindrical lower member and a rigid upper member telescoping therein to form a chamber in which a gas explosion can take place is supported beneath the surface of the water from a float by means of low resilience ropes connected to the bottom of the lower member so as to substantially limit its allowable downward movement. The upper member includes a piston downwardly biased within the lower member by an air spring and a hollow pedestal connected to the piston and extending freely through the float above the surface of the water to accommodate fuel, compressed air and exhaust conduits communicating with the interior of the housing. The energy of an explosion in the combustion chamber is expended primarily through rapid upward movement of the piston, which compresses the air spring and then lifts the lower member. Implosion of the resultant cavitation bubble adjacent the bottom surface of the lower member generates a pressure pulse of large peak amplitude.