A jet of liquid nitrogen should be able to cut underwater structural materials, by introducing thermal stresses and by rendering the material brittle and thus vulnerable to thermal attack. To successfully maintain a jet of liquid nitrogen in water, however, one must avoid certain adverse phenomena:uncontrolled boiling of liquid nitrogen within a closed volume, premature boiling of the liquid jet within the nozzle, hear or momentum transfer between the jet and the water, freezing of water about the nozzle when the jet is inactive, and freezing of any moving parts within the device. We propose to design two devices, a portable system and a long-duration system, that avoid these phenomena; and to build and test a laboratory prototype.
