The cryogenic liquid with vapor bubbles is regarded as phase-changing and unsteady field with heat and mass transfer phenomena. The cryogenic liquid has a characteristic feature of the small latent heat, surface tension, and viscosity, as compared with those of normal temperature water. As the cryogenic laser processing technology is still under development and research, there have been few reports on laser-matter interactions, for example, on micro/nano particle production. This paper firstly deals with behavior of a cavitation bubble induced by a pulsed YAG laser in liquid nitrogen. The interaction of the bubble with the solid wall has been studied by flow visualization, and, furthermore, the laser-particle processing in liquid nitrogen has been studied. As our research on cryogenic laser-submicron particle processing is in the first stage of experiment, the paper concentrates mainly on the microscopic observation of the laser-processed holes on Al surface and small particles.
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