The Airborne Comm.and and

ABSTRACT: High explosive charges were fired in a flooded quarry havinj; a refractive sound velocity structure, in order to observe shock 4ave pressure histories at caustics, or focal surfaces. For such regions, present theoretical understanding and conventional acoustic ray-tracing techniques are inadequate. Peak pressure amplification factors up to 5.8 were measured; the smaller the charge, the more extreme the focusing. Energy flux density was also enhanced, but impulse per unit area was relatively unaffected., i UNDERWATER EXPLOSIONS DIVISIO